摘要:

INTERACTION OF GLYCEROL AND OXALIC ACID. 151XX. -Interaction of Glycerol and Oxalic Acid.By FREDERICK DANIEL CHATTAWAY.ALTHOUGH the interaction of glycerol and oxalic acid is no longeremployed to prepare formic acid on a large scale, it is still thesimplest process for obtaining a small quantity in the laboratory,and is a practical exercise habitually performed by students. Themore complicated decomposition which takes place when the initialproduct is heated to a higher temperature is by far the mostconvenient source of ally1 alcohol, and is invariably used for itspreparation.The explanations, which are given in most textbooks, of thesefamiliar reactions are fundamentally incorrect.Oxalic acid reacts with glycerol as it does with other alcohols,both an acid and a normal oxalate being produced.The former,* like all such compounds, is unstable at a slightly* This explanation of the production of formic acid has been suggested as anobviocs alternative in Wade’s and Richter’s text-boolrs, but no evidence in supportof it is brought forward152 CHATTAWAY : INTERACTION OFelevated temperature, and decomposes when this is reached intocarbon dioxide and monoformin.The oxalic acid subsequentlyadded displaces the formic acid from the monoformin, and the cycleof operations is repeated.That this is the correct explanation of the reactions leading t othe production of formic acid is shown by the observations thatglycerol and oxalic acid interact readily at temperatures below thata t which carbon dioxide begins to be evolved, and that, althoughthe acid oxalate which must be formed has not yet been isolated,the products of its interaction with aniline and with ammonia,oxsnilic acid, and oxamic acid respectively are readily obtainable.That the whole course of the reaction is as above stated isrendered practically certain by the fact that a precisely similarcycle of operations can be carried out with ethyl alcohol and oxalicacid when the products can easily be isolated a t every stage.As is well known, ethyl hydrogen oxalate, which is formed whenethyl alcohol and oxalic acid are heated together, and which can bedistilled under diminished pressure, decomposes into carbon dioxideand ethyl formate when heated under ordinary atmospheric pres-sure, this being the source of the ethyl formate always obtained insuch quantity when the product of heating together oxalic acid andethyl alcohol is distilled.Oxalic acid, when heated with ethyl formate, displaces the formicacid, producing ethyl hydrogen oxalate.It is possible, although it seems unlikely, that the peculiar decom-position of monoformin, invariably stated in textbooks to be thesource of allyl alcohol, can occur to a very limited extent, but thechief, if not the sole, source of the allyl alcohol is the normal oxalicH,--$!H *CH,*OH, This on heating decomposes o-co*co*o ester, dioxt-lin,into carbon dioxide and allyl alcohol.The presence of this compound in the reaction mixture, after thefirst evolution of carbon dioxide has ceased, is shown by the produc-tion of oxamide or oxanilide when ammonia or aniline is added.These can ocly be produced from a normal ester of oxalic acid, andthe more complicated esters in which two glyceryl residues areunited by two oxalyl residues, although they may exist, are unlikelyto be produced in large amount.As the quantity of oxamide obtainable always corresponds, withinthe limits of experimental error, with the amount of allyl alcoholobtainable, the correctness of this theory of the process is estab-lished.The allyl formate, a little of which is always obtained as aby-product, results from a similar decomposition of monoformoGLYCEROL AND OXALIC ACID.15.3(?H2--?H* CH2*o*CHo, which is produced from mono-0 * co*co * 0 dioxalin,formin by the action of oxalic acid o r from dioxalin by theformation and decomposition of an acid osalate.The small amount of acrolein and the large quantity of carbonmonoxide which also are formed as by-products in the reactionresult from the decomposition of glycerol and monoformin respec-tively by heat, the latter yielding carbon monoxide and glycerol,as formic acid yields carbon monoxide and water, when heated.The main reactions, resulting in the production of formic acid,allyl alcohol, allyl formate, and carbon monoxide respectively,should therefore be formulated thus * : y H ,' 0 * (10- I IC;H=OH +(TO,yH2*OH FH,*O*CO*COPH------*+ cIi,.oIl(?H*OH C O 2 5 (?H*OH .CH,*O+ 70CI1,*OEi c H ,*OH '-9 I 7 H-0-CoC 1 I . p H$!H,*OIl7 H,*O-CO*H CH;OHC11;OH >G+ 7 H,-O*CO*CO,H,--+ YEI-OH + CO-+ YH*OHc02rf C: t i 00 H + 1I.C L2HI Ct4 ,*onp 2CH +3CO,--? I s]tI,*O*$!O 1- CH,.C)H-+ y€-c)--COCI I 2 * 0 € I >p $!H,*O.p p 2 c:O,a YH-O-CO -+ C;H + 3C0,CH,*O*CO~CO,ll CH,-O*CO*HAction of Anhydrous Oxulic Acid on Ethyl Formate.One hundred grams of ethyl formate (2 mols.) were heated toboiling for five hours with 60 grams (1 mol.) of anhydrous oxalicacid.Eleven grams of oxalic acid, which crystallised out on cooling,were filtered off, and as much as possible of the unchanged ethylformate distilled off under the ordinary pressure on a water-bath.* In the first action, either the a- or the P-hjdroxyl grouii may irlteiact, the firstonly is represented as acting.Di- and possibly tri-forruin may also Lq Yimilarlyproduced in snrall quantity and react similarly154 CHATTAWAY: INTERACTION OFThe mobile, strongly acid, pungent-smelling residue, which weighed71 grams and still contained some ethyl formate, was fractionatedunder diminished pressure, when 12 grams of formic acid, 20 gramsof ethyl hydrogen oxalate, and 12 grams of ethyl oxalate wereobtained.Actiod of Anhydrous Oxalic Acid on Glycerol.Nine grams of finely-powdered anhydrous oxalic acid (1 mol.)were thoroughly mixed with 184 grams (20 mols.) of glycerol(D 1*2638), and the acid dissolved by warming to about 50° for ashort time. The liquid was then allowed to remain for three monthsa t the laboratory temperature, small weighed quantities beingremoved from time t o time, and the free acid titrated withN/lO-potassium hydroxide.The titre fell rapidly a t first, and moreslowly afterwards, until it became practically constant at about54 per cent. of its original value. No recognisable amount of carbondioxide was at any time given off.An excess of concentrated aqueous ammonia was added to aquantity of the h a 1 product, when a copious precipitate consistingof oxamide and ammonium oxamate was formed. The additionof concentrated aqueous ammonia t o a similar quantity which hadbeen neutralised as rapidly as possible by N / 10-potassium hydroxidegave no oxamide, showing that the normal eater is very rapidlypartly hydrolysed t o a salt of the acid ester.When concentrated aqueous ammonia is added to precipitate theoxamide this partial hydrolysis takes place to a considerable exf,ent,so that a much larger yield of oxamide with a correspondinglysmaller yield of ammonium oxamate is obtained when a saturatedalcoholic solution of ammonia is used.When the product obtained as above by the interaction of oxalicacid and glycerol is warmed for some hours to about 90° with excessof aniline, a mixture of oxanilic acid and oxanilide is produced,which can easily be separated on account of the sparing solubilityof the latter.The fall of the titre and the production of these compounds showthat an a.cid ester and a normal ester are formed without evolutionof carbon dioxide when glycerol and oxalic acid interact.If such a mixture is heated until the first evolution of carbondioxide ceases and is then allowed to react with alcoholic ammoniaor a.niline, although oxamide or oxanilide is obtained as before,neither oxamic acid nor oxanilic acid is produced, showing thatduring the first evolution of carbon dioxide the acid oxalic ester isdecomposed.I n the normal ester the oxalyl residue must be attached in thGLYCEROL AND OXALIC ACID.155C]H,-YH*CH,*OH 9 o*co~co*o or in some manner shown in the formulasimilar way. This normal ester decomposes during the secondevolution of carbon dioxide, for if the product left when thedisengagement of gas has ceased is treated with ammonia nooxamide is obtained.I n order to prove experimentally that the allyl alcohol is formedby the decomposition of this normal ester, it is necessary to showthat the amount of the latter formed corresponds with the amountof allyl alcohol obtainable by further heating the product.Sixty-three grams of anhydrous oxalic acid and 252 grams ofglycerol, the relative proportions found most advantageous byTollens and Henninger, were mixed and heated for a few hoursto 80-90° on a water-bath, and then under diminished pressureuntil the temperature of the liquid reached 1 8 0 O .The productthus obtained weighed 280 grams. A tenth of this (28 grams)was cooled, mixed with a cold saturated solution of ammoniain absolute alcohol, and a rapid stream of dry ammonia passedthrough the liquid for some minutes. The heavy, white precipitateof oxamide which was deposited was collected, well washed withhot water and alcohol, and dried.It was found to weigh 1.8 grams.The remainder (252 grams) was then heated under the ordinaryatmospheric pressure until the temperature of the liquid reached270O. The distillate, which weighed 24.5 grams, was allowed t oremain over dry potassium carbonate, then separated, the potassiumcarbonate washed with a little ether, and the mixed liquids frac-tionated, using a distilling column. Nine grams of allyl alcohol ofcorrect boiling point were obtained.The amount of oxamide precipitated from the one-tenth showsthat in the remainder which was distilled there must have been26.8 grams of the normal ester, which shovld have yielded 10.6grams of allyl alcohol.The result is within the limits of experimental error consideringthe conditions of thO experiment, and proves that the formationof allyl alcohol is due to the decomposition of the normal ester.The quantity of allyl formate produced was too small to be isolatedsatisfactorily ; if its amount could have been determined the approxi-mation would have been somewhat clmr.On treating with alcoholic ammonia, the residue left after heatingto 270°, from which no more allyl alcohol could be obtained, nooxamide was precipitated,The carbon monoxide so freely liberated during the later stagesof the heating is formed by the decomposition of the mono- andpossibly di-formin produced during the first evolution of carbo156 CAIN AND SIMONSEN: NITRO-ACIDS DERIVED FROMdioxide, whilst the acrolein also produced is due to a decompositionof the glycerol itself at the high temperature of the reaction.Thewhole of the monoformin ie not destroyed a t the temperature atwhich the normal ester decomposes, and if the residue, even afterheating t o 250--260°, is distilled in a, current of steam a smallquantity of formic acid can be obtained.I n conclusion, the author desires to express his thanks to Mr.Dalziel, General Manager of Price’s Candle Company, who kindlysupplied him with the specially distilled glycerol (D 1.2638) withwhich the work was carried out.UNIVERBITY CHEMICAL LABORATORY,OXFOKD

ISSN:0368-1645    

DOI:10.1039/CT9140500151

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

156 CAIN AND SIMONSEN: NITRO-ACIDS DERIVED FROMXXI. -Nityo-acids Dertved from 2 3- Dimethoxy-benxoic Acid and 4-Methoxyphthulic Acid.By JOHN CANNELL CAIN and JOHN LIONEL SIMONSEN.DURING the course of an investigation of the products obtainedby the oxidation of nitrosantalin dimethyl ether with potassiumpermanganate (T., 1912, 101, 1073) we isolated certain acids whichappeared to us to be nitro-derivatives of 2 : 3-dimethoxybenzoicacid and 4-methoxyphthalic acid. Since our knowledge of theseisomeric acids is somewhat scanty, we were unable t o identify theacids isolated, and we have therefore attempted the synthesis ofthe three isomeric nitro-2 : 3-dimethoxybenzoic acids and also of themononitro-derivatives of 4-methoxyphthalic acid. Although wehave not succeedFd in preparing all six acids, we have devisedmethods for the preparation of four of them.Of the three isomeric nitro-2 : 3-dimethoxybenzoic acids, only6-nitro-2 : 3-dimethoxybenzoic acid (I) has so far been described,0 Me OMe OMe/'\Oh2e (\OM(? NO,/\OM~\)CO,H NO,,,!CO,H \>cc), H(111.)having been prepaxed by Wegscheider and Klemenc (Monatsh.,1910, 31, 709) by the nitration of hemipink acid, during whichprocess one of the carboxyl groups was eliminated.They alsoNO2(1.1 w.2 : 3-DIMETHOXYBENZOIC ACID, ETC. 157brought forward evidence which left no doubt as to the constitutionof the acid they obtained.When 2 : 3-dimethoxybenzoic acid is nitrated under the con-ditions described in the experimental part of this paper (p.159),the main product of the reaction is an acid which melts at174-175O. This acid must be 5-nitro-2 : S-dimethozyben.zol.‘c acid(11), since it yields 4-nitroveratrole when heated with aniline.We have carried out a large number of experiments with theview of devising a method for the synthesis of the remainingisomeride, namely, 4-nitro-2 : 3-diinethoxybenzoic acid (111), especi-ally owing to the fact that the acid isolated by us from theoxidation of nitrosantalin dimethyl ether is apparently this acid.Unfortunately our efforts have so far not met with success.When 3-hydroxy-o-tolyl methyl ether (IV) is nitrated (seep. 160), it yields a dinitro-derivative, which is probably best repre-sented by the formula (V). This compound, on methylation andOM^ NO2,’\o~~e-, KO~(\OM~ XO,/\OM~ 1 \/ \OH --+- K02(/OH NH,j/OMe--f \/ I IOR/IC-~Me T\l0 Me Me(VI.) (VII.)CO,,H Me(1.) (VIII.)reduction, yields 2-nitro-5 : 6-dimethoxy-m-toluidine (VI), which, onelimination of the amino-group, gives 6-nitro-2 : 3-di~methoxytoluene(VII).The constitution of this substance is definitely proved bythe fact that it gave on oxidation 6-nitro-2 : 3-dimethoxybenzoicacid (I), identical in all respects with the acid described byWegscheider and Klemenc (loc. cit.). From this it follows thatthe dinitro-derivative mentioned above must be represented byeither formula, V or V a . An attempt was made t o decide betweenthese two formuh by the preparation of the diamine, since thisshould, were it an ortho-diamine, yield a phenazine derivative.The results obtained in these experiments were, unfortunately,inconclusive. We are, however, of the opinion that this substanceis 5 : 6-dinitrq-3-hydroxy-o-tolyl methyl ether (V), since, onmethylation and reduction, it yields only one nitroamine, whereasif it were represented by formula V a , one would expect to obtaina mixture of the two isomeric nitroamines.It has been pointe158 CAIN AKD SIMONSEK NITRO-ACIDS DERIVED FROMout recently by Hewitt, Johnson, and Pope (T., 1913, 103, 1628)that phenols possessing a nitro-group in the ortho-position withrespect to the hydroxy-group are esterified only with great diffi-culty. Although the nitro-group in 5 : 6-dinitro-3-hydroxy-o-tolylmethyl ether is in the meta-position with respect t o the hydroxy-group, we have in this case, too, found great difficulty in obtainingthe methyl ether.It is possible that this may be due in part tothe sparing solubility of the potassium salt.We next investigated the nitration of 2 : 3-dimethoxytoEuene,and we have found that in this case a mononitro-derivative (VIII)is formed, the nitro-group entering position 5 in the nucleus, sinceon oxidation 5-nitro-2 : 3-dimethoxybenzoic acid, identical with theacid formed by the nitration of 2 : 3-dimethoxybenzoic acid, wasobtained.So far as we are aware, the three isomeric nitro-4-methoxy-phthalic acids have not so far been prepared. The preparation oftwo of these acids did not offer any great difficulty, and is readilyfollowed from the scheme given below :Me(/\/' + MeO/\CO,H R'IeO&!O,H + MeO/\Me BO,J [MeNO2 NO2\/ 'CO,H KO2] lCO,H\/I I\/\/(XI.) (XIII.)M eO/\Cc ),H(XII.)When 4-methoxyphthalic acid (XII) is nitrated, a mixture ofacids is obtained, which can be readily separated by means of thedifference in the ease with which they undergo esterification (seep.162). The acid, which was completely esterified under theconditions of the experiment, gave a methyl ester melting a t 115O,and was evidently 5-nitro-4-niethozyphtha~~c acid (X), the aciditself melting at 2 0 1 O . That this view is correct was confirmed bythe fact that when 5-nitro-4-7nethozy-o-xylene (XIII) was oxidised,\ i . O 2 l lit yielded the same acid.The other product of the nitration was an acid which melted a t215-217O. This acid must obviously be either 3-7aitro-4-methoxy-phthalic acid ( I X ) or the isomeric 6-nitro-acid.That it is theformer is proved by the fact that it was prepared by the oxidationof 1-nitro-2-naphthyl methyl ether (XI)2 : 3-DIMETHOXYBENZOIC ACID, ETC.EXPERIMENTAL.1595-Nitro-2 : 3-dimethoxybenzoic Acid (11).As has been mentioned in the introduction (pp. 157, 158), wehave devised two methods for the preparation of this acid.(1) Nitratiou of 2 : 3-Bimethoxybenaoic Acid.--2 : 3-Dimethoxy-benzoic acid (1 gram) was mixed with nitric acid (D 1-25; 20 c.c.),and allowed to remain 'in the cold for ten minutes with constantstirring. The solid gradually passes into solution, and in a shorttime the liquid becomes pasty owing t o the separation of the nitro-acid.This was collected and purified by crystallisation from hotwater. Yield, 0.65 gram:0.1084 gave 0.19 CO, and 0.043 H,O.C,HSO,N requires C=47*6; H=3.9 per cent.5-Nitro-2 : 3-dinzethozybei~zoic ucid separates from hot water, inwhich it is only sparingly soluble, in prismatic needles, melting a t(2) Nitration of 2 : 3-Dimethoxytolue1ze.*-2 : 3-Dimethoxytoluene(6 grams) was dissolved in acetic acid (6 grams), and after coolingin a freezing mixture was gradually treated with a mixture ofnitric acid (D 1.4; 9 grams) and acetic acid (9 grams). In ashort time, crystals of 5-nitro-2 : 3-dimethoxytoluene (VIII)separated. These were collected, well washed with water, anddrained on porous porcelain (yield, 3 grams).For analysis, thenitro-compound was recrystallised from dilute alcohol, from whichi t separated in fine, colourless needles, melting at 175-176O:C=54*5; H=5*4.C=47.8; H=4*4.174-1 75'.0,1168 gave 0.2333 CO, and 0.0565 H,O.The mother liquors from the nitration gave a further quantityof the same substance on dilution with water.Oxidation of 5-Nitro-2 : 3-dimethozytolue1~e. - 5-Nitro-2 : 3-di-methoxytoluene (3 grams) was suspended in dilute sodium carbonatesolution, and heated to boiling for several hours with a 5 per cent.solution of potassium permanganate (350 c.c.). A@er removingthe manganese dioxide, the solution was concentrated and acidified,when the nitro-acid separated as a flocculent precipitate.The acidwas collected, and, after crystallisation from hot water, it melted a t174-175O and, was identical in every way with the acid obtained* 2 : 3-Dirnet?ioxyto2uei~e, C,H,,O,, does not seem, so fa1 as we are aware, to havebeen lweviously prepared. It was readily obtained by methylating 3-hydroxy-o- tolylmethyl ether by means of methyl sulphtite and potassium hydroxide, when itSeparated as a pleasant smelling liquid boiling at about 202-203".C,H,,O,N requires C = 54.8 ; H = 5.6 per cent160 CBIN AND SIRIONYEN 1 NITBO-ACIDS DERIVED E'ROXby the nitration of 2 : 3-dimethoxybenzoic acid (Found, C = 47.8 ;H=4.1. C,H906N requires C=47.6, H =3*9 per cent.).Ethyl 5-nitro-2 : 3-dimethoxybenzoate, which was prepared fromthe silver salt by means of ethyl iodide in the usual manner,crystallises from alcohol in fine, felted needles, melting a t 79O:C=51*8; H=5*0.0.1222 gave 0.2323 CO, and 0.0540 H,Q.CllHI3O6N requires C = 51.8 ; 13. = 5.1 per cent.I n order t o prove the constitution of the acid prepared by themethods described above, it was converted into 4-nitroveratrole inthe following manner. The acid (2 grams) was mixed with aniline(5 c.c.) and heated on the sand-bath f o r one hour. The darkbrown product was cooled, poured into dilute sulphuric acid andextracted with ether, when, on evaporation of the solvent, a semi-solid mass was obtained. This was drained on porous porcelain,and the so,lid remaining was found to consist of a phenolic acid,and not further examined.The plate which contained the main product of the reaction wasextracted in the usual manner, and the oil thus isolated wasmethylated with methyl sulphate.I n bhis way a yellow solid wasobtained which crystanised from alcohol in needles, melting at95-96O. When mixed with 4-nitroveratrole obtained from anothersource the melting point was unaltered.Nitration of 3-Hydroxy-o-tolyl itlethyl Ether (IV).5 : 6-Dinitro-3-hydroxy-o-tolyl Meth$ Ether (V).-For the p r eparation of this substance the phenol (5 grams) was dissolved inacetic acid (5 grams), and after cooling in a freezing mixture asolution of nitric acid (D 1.4; 8 grams) in acetic acid (8 grams)was slowly added. The deep brown solution was allowed to remainfor fifteen minutes in the cold, and then poured on ice, when abrown oil separated.This was dissolved in ether, the etherevaporated, and the viscid oil thus isolated was mixed with excessof a concentrated solution of potassium hydroxide, when a sparinglysoluble potassium salt (2.5 grams) was deposited. This wascollected and decomposed with dilute hydrochloric acid, when thephenol was obtained as a pale yellow oil, which rapidly solidified.On crystallisation from dilute alcohol, 5 : 6-diiiitro-3-hydroxy-o-tolyl methyl ether separated in sulphur-yellow needles, meltinga t 6 1 O :0.1307 gave 0-2035 CO, and 0.0445 H,O.C8H,0,N2 requires C = 42.1 ; H = 3.5 per cent.The phenol gives no colour with ferric chloride, and the potassiumsalt crystallises from water, in which it is only sparingly soluble,C=42.5; H=3-82 : &DIMETHOXY*BENZOIC ACID, ETC 161in yellow needles, which, when heated, explode with considerableviolence.5 : 6-Dimityo-2 : 3-dimethoxytoZuene.-Great difficulty was expe-rienced in preparing this substance, but ultimately the followingmethod was found to give satisfactory results.The dry and finelypowdered potassium salt of the phenol (7 grams) was mixed withmethyl sulphate (5 grams) and heated in a sealed tube for threehours a t 140-150°. The product, which was slightly charred, wasextracted with ether, the solution washed with potassium hydroxidesolution to remove any unchanged phenol, and evaporated, when5 : 6-di&r0-2 : 3-dinzethoxytoEuelte was obtained. On crystallisationfrom alcohol, it separated in colourless plates, melting a t 76-77O:0.146 gave 0.2372 CO, and 0.0582 H,O.C,H,,O,N, requires C = 44.5 ; H = 4-1 per cent.WlieJi this dinitro-compound was reduced with tin aiid hydro-chloric acid in the usual manner, the diamine was isolated as acolourless solid, which darkened with extreme rapidity on exposuret o the air.Attempts to prepare a plienazine derivative by meansof phenantliraquinone were unsuccessful, but for the reasons statedin the introduction we are inclined to the view that the amino-groups occupy the 5 : 6-positions.2-Xi tro-5 : 6-dim e t hoxy-m-t oluidiit e (VI) .-This substance wasobtained in an excellent yield when 5 : 6-dinitro-2 : 3-dimethoxy-toluene was reduced by ammonium hydrogen sulphide. The amineseparates from alcohol in orange-coloured, prismatic needles, meltinga t 9 5 O :C = 4 4 .3 ; H = 4 * 4 .0.1328 gave 0.2463 CO, and 0.0703 H,O.CgH1204Nz requires C = 50.9 ; H = 5-7 per cent.6-Nitro-2 : 3-dimethoxytolue?te (VII). -The nitroamine justdescribed (0.7 gram) was dissolved in alcohol (10 c.c.), and, afterthe addition of sulphuric acid (0.7 gram), amyl nitrite (1 grani)was slowly added to the well-cooled mixture. After fifteen minutesthe solution was heated on the water-bath until the evolutionof nitrogen had ceased. On the addition of water an oil separatedand rapidly solidified. It was collected and purified by repeatedcrystallisation from dilute alcohol, when i t separated iu fine needles,melting a t 47-48O :C=50*4; H=5*9.0.1067 gave 0.2055 UO, aiid 0.051 H,O.CgHl,04N,~H,0 requires C = 52.4 ; H = 5.8 per cent,.0 LC idn t io IZ of 6-Yi TO-2 : 3-di m e t ho zy t oZu e ne .-The ni tro-con1 y ouiitl(1 gram) was suspended in dilute sodium carbonate solution aiidtreated with a 5 per cent.solution of potassium permanganate until* Aiialysis of a different specimen gave C = 52 '4, H = 5-2.C!-512.5; H-5*3.%*VOL. cv. 162 CAIN AND SIMONSEN : NITRO-ACIDS DERIVED FROMa permanent pink colour was obtained. After removing themanganese dioxide the solution was concentrated, and on acidifi-cation 6-nitro-2 : 3-dimethosybenzoic acid separated as a flocculent,white precipitate. This was collected and purified by crystallisationfrom hot water, when it was obtained in needles melting a t 185O.Wegscheider and Klemenc (Zoc.cit.) give 189-1 90° (Found,C = 47.3 ; H = 4.3. CgHgO,N requires C =47*6 ; H = 3.9 per cent.).The identity of this acid with that obtained by the above mentionedauthors was confirmed by the preparation of the methyl ester,which melted, as stated by them, a t 76-77O.3- ciibd 5-ATitro-4-methoxyph thalic A cids.4-Methoxyplithalic acid (4 grams) was mixed with nitric acid(D 1-4; 12 c.c.), and heated on the water-bath for fifteen minutes.The acid gradually dissolved, and, on cooling, a small amount ofsolid separated. In order to separate the mixture of acids, thesolution was diluted with water, extracted with ether, the etherealsolution dried and evaporated, when a somewhat viscid, crystallinemass was obtained (4.6 grams).This was mixed with methylalcohol (30 c.c.), the solution saturated with hydrogen chloridea t Oo, and allowed t o remain overnight in the cold. On pouringinto water, an oil separated which was dissolved in ether, theethereal solution washed with sodium carbonate solution (whichwas reserved for further examination, see below), dried andevaporated. The viscid oil thus obtained slowly solidified in fineneedles, which were drained on porous porcelain -x (yield, 0.27 gram),Methyl 5-,?Vitro-4-methoxyphthalate was crystallised from methylalcohol, from which it separates in fine, silky needles, melting a t115O :0.1036 gave 0.1866 CO, and 0.0405 H,O.C,,H,,07N requires C = 49.1 ; H = 4.1 per cent,5-Nitro-4-methoxyphthaZic acid (X), obtained by the hydrolysisof this ester, crystallises from water in prisms which melt anddecompose a t 201O:C =$gel; H =4*3.0.1175 gave 0.1938 CO, and 0.0364 H,O.C9H707N requires C = 44.8 ; H = 2.9 per cent.This acid was also syntliesised as follows.5-Nitro-o-4-xyIenol(Diepolder, Her., 1909, 42, 2916; Crossley, T., 1913, 101, 1299)* This plate was extracted with ethyl acetate, a i d the cil thus obtained wasdistilled under diniinished pressure, wlieii it was found to boil a t 18'i-188"/13 iim.,and was unchanged methyl 4-methoxyphthalate. A small residue reiiiainerl in thedistilling flask, which solidified on cooling and, after crystallisation from methylalcohol, melted a t 115", and consisted of the nitro-ester.C = 45.0; H = 3-42 : 3-DIMETHOXYBENZOIC ACID, ETC.163was methylated by means of methyl sulphate to 5-nitro-4-nzetkoxy-o-xyZeTLe (XIII), which separates from alcohol in very pale yellowcrystals, melting a t 79O:0'1685 gave 11.6 C.C. N, a t 20° and 763.8 mm.C,H,,O,N requires N=7*7 per cent.On oxidation with dilute nitric acid (see Crossley and Renouf,T., 1909, 95, 207), a small amount of a ~~itromet~~~oxy-o-toZ~u~c acid,C,H,O,N,(Me : C0,H : NO, : Me0 = 1 : 2 : 4 : 5 or 1 : 2 : 5 : 4 ) , crys-tallising from water in white needles, melting a t 2 3 5 O , was collected,and the filtrate, on evaporation, yielded 5-nitro-4-methoxyphthalicacid, melting a t 2 0 1 O . The methyl ester of this acid was provedto be identical with that described above.The sodium carbonate washings from the ester mentioned abovewere acidified, when a solid separated; this was dissolved in ether,the ether removed, and the resulting solid boiled with alcoholicpotassium hydroxide, when the potassium salt separated in fineneedles.These were collected and decomposed with hydrochloricacid, and the solution extracted with ethyl acetate. On removingthe solvent, the acid was obtained in slender needles, which, oncrystallisation from moist ether, melted and decomposed a t215-217O :N=8.0.0.1029 gave 0.1688 CO, and 0.032 H,O.C,H,O,N requires C = 44.8 ; H = 2.9 per cent.3-Nitro-4-methoxyphthalic acid (IX) is only very sparinglysoluble in berume, chloroform, or dry ether, more readily so inmoist ether. It is somewhat readily soluble in water, ethyl acetate,or alcohol.The barium salt separates from a neutral solution ofthe ammonium salt on treatment with barium chloride in longneedles radiating from a centre, and is only very sparingly solublein water.The silver salt, preqared in the usual manner, was obtained asa caseous, white precipitate:0.1797 gave 0.0855 Ag. Ag=47*6.C,H,O7NAg, requires Ag = 47.6 per cent.The anhydride, prepared in the usual manner by means of acetylchloride, crystallises from benzene in glistening, prismatic needles,melting a t 137-138O :C=44*7; H=3*4.Found, C = 48.6 ; H = 2.7.The ethyl ester, prepared from the silver salt, crystallises fro~n0.1187 gave 0.2293 CO, and 0-0513 H,O. C-552.2; H=4*8.C,H50,N requires C = 48.4 ; H = 2.2 per ceut.alcohol in hair-like needles, melting a t 93-940 :C18H1S07N requires C = 52.5 .; H = 5.0 per cent.M 164 CIAIN AND SIMONSEN : NITRO-ACIDS, ETC'.OxidataojL of l-iVZ'tr0-2-i~apltt h$ M e t kyl Ether (XI).1-Nitro-2-naphthyl methyl ether (1 2 grains) was suspended indilute sodium carbonate solution and heated on the water-bathwith excess of potassium permanganate solution until the oxidation,which proceeds only very slowly, was complete.After separatingthe inangane2e dioxide, the solution was concentrated, acidified,and extracted several times with ethyl acetate. On removing thesolvent, an oil (3 grams) was obtained, wliicli rapidly solidified.After draining on porous porcelain, it was crystallised from a smallamount of water, when a sparingly soluble acid separated in needles(-1 ).The filtrate was evaporated t o dryness, the residue (2.8 grams)dissolved i n iuetliyl alcohol, and tlie solution saturated wit11hydrogen chloride and allowed to remain overniglit. T t was thenpoured into water, extracted wit11 ether, the ethereal solutionwaslietl with sodium carbonate solution, dried and evaporated.Tlie ester obtaiiiecl in this way was reserved for later investigation(see B below).The sodium carbonate washings from the above-mentioned esterwere acidified, and the solid which separated was dissolved inether. Tlie crystalline acid thus obthined evidently contained tracesof an ester, and was therefox mixed with alcoholic potassiumhydroxide, when the potassium salt separated in fine needles. Thefree acid obtained from the potassium salt was crystallised frommoist ether, when it was found to melt and decompose a t 215--217O,and was identical with the acid obtained by the nitration of4-methoxyphthalic acid.The identity was confirmed by deter-mination of the mixed melting points of the anhydride and of theethyl ester. There is therefore no doubt that the acid obtainedby tlie nitration of 4-metlioxyphtl~alic acid is 3-iiitro-4-methoxy-plithalic acid.It was mentioned above that a sparingly soluble acid (a) wasisolated on crystallising the crude oxidation product from water.For the purpose of purification this acid was converted by meansof its silver salt into the ethyl ester, which separates from alcoholin small prisms, melting a t 113O :0.1135 gave 0.2218 CO, and 0.053 H,O.This is apparently ethyl 2-nitro-3-methoxybenaoate, which doesnot seem to have been previously prepared. With the object ofseeing if this were tlie case, the remainder of the ester was hydro-lysed, and the acid, after isolation in the usual inaniier, crystallisedfrom hot water, when it separated in needles.The determinationC=53-3; H=5-3.C,,H,,O,N requires C = 53.3 ; H = 4.9 per centof the melting point was found to give considerable difficulty, sinceit was not a t all definite, and depended on the rate of heating.If the bath is previously heated to 135*, and the capillary tubethen introduced, the acid becomes slightly yellow a t 145O, andmelts with very vigorous decomposition a t 205-207O.2-Nitro-3-methoxybenzoic acid has been previously prepared byRieche (Ber., 1889, 22, 2352), and is stated to decompose a t 2 5 1 O .It is possible that the difference observed is due to water ofcrystallisation, since our acid, after drying in a vacuum oversulphuric acid, evidently contained water of crystallisation :0.1112 gave 0.1734 CO, and 0.0352 H,O.C!,H,O5N,1 +H,O requires C = 42.9 ; H = 4.4 per cent.Uiifortunately we had not sufficient of this acid for furtherinvestigation, but there seems little doubt from the method of itspreparation that it has the constitution assigned to it.The methyl ester mentioned above (B) consisted of methylphthalate, since on hydrolysis it gave phtha1ic acid, which wasidentified by the usual tests.C =42*5 ; H = 3.6.In conclusion we desire to express our thanks to Dr. C. Weizmannfor kindly supplying us with the 4-methoxyphthalic acid used inthis work, and to the Research Fund Committee of the ChemicalSociety for a grant which partly defrayed the cost of the investi-gation.24, AYLESTONE AVENUE,BRDNDESBURY PARK, N.W

ISSN:0368-1645    

DOI:10.1039/CT9140500156

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

XXIL-Aronmtic Compounds Obtained from the Hycho-aromatic Series. Part III. Bromoxylenols fromDirnethy ldihydy-o resorcin.By ARTHUR WILLIAM CROSSLEY and NORA RENOUF.IN the course of an investigation on the action of phosphorushaloids on diinethyldihydroresorcin (Crossley and Le Sueur, T.,1903, 83, llO), it was shown that the primary products of thereactions, which were of a hydroaromatic nature, readily underwentrearrangement t o I orm aromatic substances. More particularly wasthis the case when phosphorus pentabromide was employed, andfrom the resulting products there were isolated a monobromoxylenol,melting a t 84O, and a dibromoxylenol, melting a t 9To, both of whic166 CROSSLEY AND RENOVF : AROMATIC COMPOUNDSsubstaiices wer.e showii t o be derivatives of 0-3-xylenol, because 011treatment with bromine they gave tribromo-o-3-xylenol, melting at183O.Further, it was stated that a second tribromoxylenol hadbeen encountered, melting a t 177O, but this ha.e zow b&n proved,despite its constant melting point, t o be a mixture of the tribromo-derivatives of o-3-xylenol and o-4-xylenol.The question of the constitution of the mono- and di-bromo-xylenols was not studied in detail at the time, although it waspointed out that the conversion of the hydroaromatic substancesinto aromatic compounds took place so readily, that the reactionsmight afford the easiest means of preparing certain substitutedxylenols, otherwise difficult of production. Such is indeed the case,as is proved by the work now described.On renewing the study of the direct action of phosphorus penta-bromide on dimethyldihydroresorcin, it was soon found that thereactions are of an extremely complicated nature, being susceptibleto the slightest variation in experimental conditions.For example,on repeating the experiment (Zoc. cit., p. 128) in which the mono-bromoxylenol, melting a t 84O, was originally obtained, and employ-ing apparently precisely the same conditions, neither the mono-bromoxylenol (m. p. 84O) nor the dibromoxylenol (m. p. 9 7 O ) wasactually isolated, but in their place a new bromoxylenol, melting a t103O. It is, however, certain that, with the additional knowledgeof the properties of the derivatives of these substaiices, accumulatedduring the progress of tlie present work, all three xylenols coiildnow be isolated froin the mixture.I n the paper already alluded to, it was shown that the primaryproducts of the action of phosplioru s pentabromide on dimethyl-dihydroresorcin or of phosphorus tribromide on bromodimethyl-dihydroresorcin were dibromo- and tribromo-dimethylcyclohexenones(I and II), and the statement was made that “the xylenol obtainedin the latter reaction must be produced by rearrangement of eithermono- or di-brornodimethylcyclohexefiones (dibromoketodimetE,y!-tetrahydrobenzene) .’,H,C{ \CH2ErC\\,CO(1.) (11.1It was therefore decided to study the possible transformationsof these substances and also tribromodimethylcyclohexenone toaromatic compounds, because, as their constitutions are known, iOBTAINED FROM THE HYDROAROMATIC SERIES.PART III. 167would be easier to obtain clues as to the orientation of the bromo-xylenols produced from them.Tho reagents employed for the transformations were potassiumhydroxide in alcoholic solution, which gives rise to derivatives ofo-3-xylenol only ; and heat, which produces derivatives of botho-3-xylenol and o-4-xylenol.Other reagents were also tried, for example, (a) sulphuric acid,which, however, is of little value, because, although xylenols areproduced, the reaction is complicated by the presence of bromine,due t o the action of the sulphuric acid on the liberated hydrogenbromide, which appears to cause bromination to take place in theside-chain as well m in the nucleus; ( b ) nitric acid (D 1-42}, whichdoes not give rise-to aromatic compounds, but partly oxidises thehydroaromatic bromoketones, and also brominates them (compareT., 1904, 85, 273); ( c ) diethylaniline, which does not transformthe hydroaromatic substances when heated to 210-220° for a fewminutes, and on prolonged heating gives rise only to 'resinousproducts.The various bromoxylenols isolated in the course of the workwere identified, although as a rule no details are mentioned in thepractical portion of the paper, by analysis in some cases, andalways by the determination of the mixed melting points of thesubstances themselves and of their benzoyl derivatives with syntheticpreparations of similar compounds.Having first established the fact that bromodimethylcyclo-hexenone does not give aromatic compounds with the above-mentioned reagents, the next action tried was that of potassiumhydroxide on dibromodimethylcyclohexenone (111), which givesrise to ti-bromo-o-3-xylenol (IV) and small quantities of 4 : 5-di-(IV.) (111.) (V.)bromo-o-3-xylenol (V). The yield of bromoxylenols is not large,and the main product of the reaction is a liquid, insoluble inpotassium hydroxide, which appears to consist mainly of ethoxy-compounds, their formation being explained by the fact that thereaction is carried out in alcoholic solution. The formation ofethoxy-compounds under these conditions has frequently beennoticed, as, for example, in the action of alcoholic potassiumhydroxide on 1 : 2-dibromocycZohexane, when the product is mainlethoxycyclohexene (T., 1904, 85, 1415; compare also T., 1905, 87,1499).The above rearrangement is extremely interesting, but of asomewhat startling nature when an attempt is made to account inan adequate manner for its mechanism.No simple explanationis forthcoming, for the reaction necessitates a wholesale migrationof atoms of which the most unexpected is perhaps the initialremoval of hydrogen bromide, the bromine from carbon atom 4with a hydrogen atom in the meta-position to it a t either 2 or 6.Simultaneously with this movement a hydrogen atom in eitherposition 2 or 6 must wander into the meta-position to replace tliebromine atom thus removed.From a casual glance at the formula for dibroniodimethylt.yc.lo-hexenone, i t would seem that tlie bromine atom in position 5 woul(1certainly be tlie one to be removed as hydrogen bromide togetherwith one of tlie hydrogen atonis in position 6.Yet such is iiotthe case, for the constitution of the resulting bromoxylenol hasbeen proved by synthesis (T., 1913, 103, 2179), and therefore therecan be no doubt that it is the bromine atom in position 4 which iseliminated.It is, however, t o be noted that, as in so many instances alreadyquoted (T., 1902, 81, 1533; 1904, 85, 264; 1906, 80, 875; 1908,93, 633), the methyl group has again wandered into an ortho-position.It would seem bhat the production of a small amount of 4: 5-di-bromo-0-3-xylenol in this process can only be due to side reactions,where bromine is liberated, causing further bromination, of5-bromo-o-3-xyleno1, as it is impossible for a dibromoxylenol toresult from dibromodimethylcyclohexenone by the removal of theelemenb of hydrogen bromide.When dibroniodimethylcyclohexenone is heated, hydrogenbromide is evolved, and about half the weight of substance takenis recovered as a mixture of 5-bromo-o-3-x~lenol (VI), melting a t84O, and 6-bromo-o-4-xylenol (VII), meltingCH3 C(CW2/ b H 3 H,Cf\C H2B ~ , ,!OH BrC\)CO(TI.) CBr (VII.)There is again the same difficulty iii offering any adequateexplanation of these transformations, but a new point of interestis raised.Again a methyl group has wandered into an ortho-position, but in the one case from position 1 to position 2, whereasin the second case, the wandering is from position 1 to position 6ORTAINET, FROM TElE H\’DlIOAROMATIC! SERIES.PART 111. 169This is the first occasion on which this particular wandering hasbeen noticed by the present authors.Although, as already pointed out, it would seem probable thatthe hydrogen and bromine atoms in positions 5 and 6 would beeliminated as hydrogen bromide, this is not the case, for hydrogenbromide is again removed from carbon atoms in the meta-positionto one another. The produdion of derivatives of 0-3-xylenol andof o-4-xylenol is due to the swinging of a methyl group in theone case from position 1 t o position 2, and in the other casefrom position 1 to position 6, otherwise the rearrangement is of anentirely similar nature.In the previous paper (loc.cit., p. 115) it was stated tJiat broino-dimethylcyclohexenone readily absorbed bromine, giving offhydrogen bromide and undergoing a transformation which had notbeen worked out,. so that dibromodiruethylcyclohexenone (VIII)could not be obtained by the action of bromine on bromodimethyl-cyclohexenone (IX), which seemed somewhat remarkable in viewof the action of bromine on the similarly constituted dimethyl-dihydroresorciii and of the stability of dibromodimethylcy d o -hexenone.(VIII.) (IX.1I n again carrying out this action of bromine on bromodimethyl-cyclohexenone, although only minute quantities of dibromodimethyl-cyclohexenone have been actually isolated, there can be no doubtthat this substance is, in reality, the main product of the reaction,although it cannot be separated on account of admixture withunchanged bromodimethylcycEohexenone and some tribromodi-methylcyclohexenone, as is also the case in the action of phosphorustribromide on bromodimethyldihydroresorcin (Zoc. cit., p.121).This would seem t o be demonstrated beyond doubt by a study ofthe transformation products of the liquid obtained initially fromthe action of bromine on bromodimethylcyclohexenone, which istotally insoluble in potassium hydroxide, and entirely hydro-aromatic in nature.This crude material gave, on treatment with potassium hydroxidein alcoholic solution, mainly 5-bromo-o-3-xylenol and smallquantities of 4 : 5-dibromo-o-3-xyleno1, in approximately the sameproportions as when these xylenols were obtained by the actionof alcoholic pot,assium hydroxide on pure dibromodimeth ylcpclo-1 texenone170 CROSSLEI' ANT) RENOUF : AROMATIC COMPOUNDSMoreover, the crude product ~ gave, when heatled, 5-bromo-o-3-xylenol and 6-bromo-o-4-xylenol, again the same products andin approximately the same proportions as have been obtained bythe action of heat on pure dibromodimethylcyclohexenone.Incidentally, it may be mentioned that this process provides amuch easier method for the preparation of these two bromoxylenolsin quantity than the methods described for their syntheses (T., 1913,103, 1297, 2179).When tribromodimethylcyclohexenone (X) is transformed eitherunder the influence of heat or of potassium hydroxide in alcoholicsolution, the only bromoxylenol isolated is 4 : 5-dibromo-o-3-xyleno1,melting a t 97O.There is a doubt as to the position of the thirdbromine atom in tribromodimethylcydohexenone (Zoc. cit., p. 114),which may be represented by either of the two formulze X or XI,(X. 1 (XI.)although the former would appear to be the more likely. Which-ever of the two positions is actually occupied by the bromine atomis, however, of no importance on the present occasion, because, asshown by the synthesis of 4 : 5-dibromo-o-3-xylenol (T., 1913, 103,989), this is the bromine atom eliminated from the molecule, andhence again hydrogen and bromine are removed as hydrogenbromide when occupying the meta-position to one another.EXPER TMENTAL.Preparation of 4 : 5-Dibromo-1 : l-dimethy2cyclohexen-3-one(4 : 5-Da'brom0-3-keto-l: l-dimet~~l-L\4-tetrahy~r~~enzene).The conditions originally given (T., 1903, 83, 121) for the p r eparation of dibromodimethylcyclohexenone have been modified, thequantities of materials now used being 25 grams of anhydrousbromodimethyldihydroresorcin (3 mols.), 100 grams of dry chloro-form, and 15.5 grams (14 mols.) of phosphorus tribromide, andheating was only continued for one and a-half hours.The yieldof dibromodimethylcyclohexenone is thereby doubled, being from6 to 7 grams, but although the mother liquor ( A , see below) containsmuch more of this substance, itl cannot be isolated on account ofits solublity in the accompanying bromodimethylcyclohexenone.In the previous paper (loc.cit., p. 114) it was pointed out that(( the production of bromodimethylcyclohexenone (XII) from bromoOBTAINED FROM THE HYDROAROMATIC SERIES. PART IIT. 171diinethyldihydroresorcin (XIII) is a reaction for which no adequateexplanation is at presoiit forthcoming.”C(CH,\,H,C/\CH,ROC1 ICO \/CBr(XII.) (XIII.)It is, however, most probably due t o the fact that bromodimethyl-dihydroresorcin crystallism with 1H,O, which is not easy to removecompletely when .working with the substance in large bulk. Hencethe hydrogen bromide formed by the action of phosphorus tribromidewith this molecule of water, would hydrolyse the bromodimethyl-dihydroresorcin to dimethyldihydroresorcin, which would then beacted on by phosphorus tribromide to form bromodimethylcyclo-hexenone.This supposition seems to be supported by the fact thatin one preparation where cryst,alline bromodimethyldihydroresorcinhad been employed, without being dried in a vacuum, the resultingmaterial consisted principally of bromodimethylcycZohexenone, or,a t all events, no dibromodimethylcyclohexenone crystallised out.Action of Potassium Hydroxide on Dibromodimetkylcyclohexenone.Five grams of dibromodimethylcyclohexenone were dissolved in200 C.C. of absolute alcohol, and N / 4-alcoholic potassium hydroxidegradually added in small portions, and the whole heated, betweeneach addition, until no longer alkaline. The amount of potassiumhydroxide used was 0.994 Ram, corresponding exactly with onemolecule.The major portion of the alcohol was evaporated, thewhole poured into water, acidified, extracted with ether, theethereal solution washed with potassium hydroxide solution, thewashings acidified, and distilled in a current of steam. On extra&ing the distillate with ether, etc., a residue of 1 gram remained,which was recrystallised from light petroleum (b. p. 40-60°), when0.6 gram of radiating clusters of long, transparent needles, meltinga t 84O, separated, which gave a benzoyl derivative, melting a t 98O,neither of which melting pokts was altered on admixture withrespectively 5-bromo-o-3-xylenol and its benzoyl derivative.The light petroleum mother liquor was evaporated to dryness,the residue spread on porous plate, and crystallised from aqueousalcohol, when 0.1 gram of 4: 5-dibromo-o-3-xylenol (T., 1913, 103,989), melting a t 97O, was obtainedA ction of Iieat on D i h o moclirri e t Ji~lcyclolwxetm tLe.Five grams of dibromodimethylcyclohexenone were heated ona sand-bath in a flask attached to an air condenser until a reactionset in, when the source of heat was removed.The reaction wasvigorous, and torrents 0.f hydrogen bromide were evolved. Thewhole was dissolved in ether, washed with potassium hydroxide,the washings acidified and distilled in a current of steam, and thedistillate extracted with ether, when 2.3 grams of solid wereobtained. This was benzoylated and treated exactly as describedon p. 173, when there were obtained 0.7 gram of 5-bromo-o-3-xyleno1, melting at, 84O, and 0.5 grain of 6-?pino-o-4 -xyleiiol,melting at 103O.Many attempts have been made to extract larger quailtities ofthe dibromoketone froin the mother liquors 9 (see above), but,without success.It was originally investigated by submitting i tto fractional distillation, whgn it appeared to consist mainly ofbromodimethylqclohexenone Fnd a higher fraction of aromaticsubstances formed by the action of heat on the liyclroaromaticcompounds present.Under the altered conditions of preparation the mother liquorcontains not more than 25 per cent. of broinodimet hylcyclohexenone,together with nearly 70 per cent. of dibrornodimethylc~yc7ohexenone,as is proved by the following experiments.Twenty grams of the nmther liquor were heated and worked upas described above, under the action of heat on pure dibromo-dimethylcyclohexenone.There were obtained 6.3 grams of bromo-xylenols, from which 2.4 grams of pure 5-bromo-o-3-xylenol (m. p.84O) and 1.4 grams of 6-bromo-o-4-xylenol (m. p. 103O) wereisolated. Calculating from the amounts of these substances pro-duced by the action o f heat on pure dibromodimethylc!/cZo-hexenone, it would appear that nearly 14 of the 20 grams of motherliquor consisted of dibromodimethylcyclohexenone, which could notbe crystallised on account of its admixture with bromodimethyl-cyclohexenone. Moreover, similar results were obtained by theaction of potassium hydroxide on the mother liquor, when 5-bromo-0-3-xylenol and 4 : 5-dibromo-o-3-xyleno1 were obtained, in amountscorresponding with what would have been expected, on the assump-tion that the mother Iiquor contained about 70 per cent.ofdibrom odiinetliylcycEohexenone.When dibromdimethylcyclohexenone was warmed with concen-trated sulphuric acid, i t dissolved, and solid soon separated, which,after crystallisation from alcohol, melted a t 187-18807 but as thesubstance was n o t phenolic in natiire, it, was n o t further investi-gatedOBTAINED FROM THE HYDROAROMATfC SERIES. PART 111. 173A c tio rz of Bro inane o 15 Brom odim e $16 ylcyclohexenone.Bromodimethylcyclohexenone was prepared as previously de-scribed (T., 1903, 8 3 , 1 2 0 ) ; it boils a t 126O/32 mm., that is, some-what lower than stated, and the yield is about 40 per cent.of thetheoretical amount. The substance previously mentioned as meltinga t 296O was again encountered, but as it has now been shown tocontain phosphorus, i t is iiot proposed further to investigate itsiiat ur 6.Twenty grams of bromodimethylcycloliexenone were dissolved in40 grams of dry chloroform, and a solution of 16 grams of bromine(1 molecule), in an equal weight of dry chloroform, was graduallyadded, care being taken iiot to allow the temperature to rise aboveOo. No hydrogen bromide was given off, and the bromine was notcompletely absorbed.On removing from the cooliiig medium, the temperature verygradually rose to 1 5 O , then very rapidly to 28O, when a reactioiiset in, all the bromine was used up and hydrogen bromide evolvedin quantities.After evaporation of the chloroform, the residueweighed 29 grams, and was a pale yellow liquid, completely insolublein potassium hydroxide, and possessing a camphoraceous odour.On standing for months, only a very small amount of solidwas deposited, which proved to be a mixture of dibromo- and tri-bromo-dimethylcyclohexenones. As the liquid could not be distilledwithout losing hydrogen bromide with partial transformation intoaromatic substances it was decided to investigate the latter in orderto get an idea of its composition.In the first place, 12 grams of the crude product were treatedwith alcoholic potassium hydroxide exactly as described in the caseof dibromodimethylcyclohexenone (see p. 1 7 1 ), when, on extractingthe steam distillate with ether, 2 grams of solid were obtained,which yielded 1.0 gram of 5-bromo-o-3-xyleno1, melting a t 84O, and0.3 gram of 4 : 5-dibromo-o-3-xyleno1, melting a t 9 7 O .In the second place, 36 grams of the crude product were heatedin a flask attached to an air condenser and worked up in exactlythe same manner as described under the action of heat on dibromo-dimethylcy clohexenone, when the steam distillate yielded 17 gramsof solid bromoxylenols.Previous attempts to separate pure sub-stances from this mixture, by repeated fractional steam distillationand crystallisation from light petroleum, had only resulted in theisolation of a zery sinall ainount of 6-broino-o-4-xy1eno1, meltinga t 1 0 3 O ; but by adliering strictly t o the following conditions asharp separation can be effected.Seventeen grams of crude productwere benzoylated in the usual manner, and the resulting 25 gram174 CltOSSLEY AND BENOUF : AROMATIC COMPOUNDSof benzoyl derivatives dissolved in 500 C.C. of absolute alcohol,when, after standing, 5.8 grams of a substance melting a t 94-96Owere obtained. By slow evaporation of the alcohol further fractionsof similar melting point have sometimes been isolated, but as arule all fractions but the first melt between 65O and 75O. Oncrystallising this solid (m. p. 94-96O) from alcohol, the meltingpoint rose to 98O, and examination showed it to be the benzoylderivative of 5-bromo-o-3-xylenol (see T., 1913, 103, 2182). Thealcohol was then evaporated t o a low bulk, and the benzoylderivative hydrolysed by boiling with potassium hydroxide. Thealcohol was evaporated and the acidified product extracted withether, the ethereal solution washed with sodium carbonate solution,then with water, dried over calcium chloride, and evaporated, when13.2 grams of solid were obtained, which on crystallisation fromlight petroleum (b.p. SO-looo) gave 2.8 grams, melting a t 103O:0.1100 gave 0.1025 AgBr. Br=39.65.C8H,0Br requires Br = 39.80 per cent.The synthetic formation of this bromoxylenol, which proves it tobe 6-bromo-o-4-xyleno1, has already been described (T., 1913, 103,1297). After separation of this substance the light petroleummother liquor was evaporated, the residue benzoylated, and thewhole process repeated twice, when there were finally obtained,from the original 17 grams of bromoxylenols, 6 grams of 5-bromo-0-3-xyleno1, melting a t 8@, and 4.6 grams of 6-bromo-o4-xylenol,melting a t 103O.The numerous processes through which the inaterial has to betaken necessitate some loss, and finally a small residue of just overone gram was obtained, from which nothing further could beisolated. If any other bromoxylenol is produced during thereaction, other than those above mentioned, it can only be presentin very small amount.Preparation of 2 : 4 ; 5-Yribromo-1 : l-dimethylcyclol~,exe~~-3-otie(Tribromo ketodimethyltetrnh ydro b enzene) .The method of preparation of this substance (T., 1903, 83, 124)has been so much modified as to necessitate redescription.Twenty-eight grams of dimethyldihydroresorcin (one molecule)were suspended in 400 grams of dry chloroform, 32 grams of bromine(one molecule) gradually added, then 172 grains of phosphoruspentabromide (two molecules), and the whole heated 011 the water-bath for one hour.The major portion of the cliloroform was tlieiievaporated, and this is a point which considerably influelices theyield of material, which is diminished if it is attempted to removOBTAINED FROM THE HYDROAROMATIC SERIES. PART 111. 1’75the last traces of chloroform. The whole was then poured intowater, extracted with ether, the ethereal solution washed withpotassium hydroxide so”lution (washings =A), etc., when 54 gramsof a semi-solid mass were obtained, which after triturating withlight petroleum (b.p. 40-60°) gave 34 grams of a clean, whitesolid, and this, after crystallisation from light petroleum (b. p.80-looo), yielded 28 grams of pure tribromodimethylcyclohexenone,melting a t 107O.The potassium hydroxide washngs ( A , see above) were acidifiedand distilled in a current of steam, when there separated from thedistillate a small quantity of a bromoxylenol, crystallising fromdilute alcohol in glistening, transparent needles, melting a t 96-97O.It is not identical with 4: 5-dibromo-o-3-xyleno17 melting a t 97O,because the mixed melting point was 63O. The amount was, how-ever, too small for an investigation of its constitution, which mustbe left over for decision, until further experiments, now beingcarried out, are completed.Action of Potassium Hydroxide o n Tribromodimethylcyclohexenone.Ten grams of the tribromoketone were treated with alcoholicpotassium hydroxide solution exactly as described on p.171. Thesteam distillate yielded 6.9 grams of solid, which, after crys-tallisation from alcohoI, gave 1.3 grams of pure 4 : 5-dibromo-0-3-xylenol (T., 1913, 103, 989). A small quantity of some otherbromoxylenol is also produced in this reaction, but its identity hasnot so far been established.A c t io n of Een t on Tr i b r o modim e thy lcy clok ex e n on t .Tribromodimethylcy clohexenone was heated in quantities of5 grams at one time, as described on p. 172. It is essential for thesuccess of the experiment that the source of heat should be a t onceremoved on the appearance of the first signs of a reaction, asotherwise the whole mass is resinified. Twenty grams of the tri-bronioketone gave 9.5 grams of bromoxylenols, which, after treat-nient with light petroleum (b.p. 40-60°) in the cold, gave 2.4grams of 4 : 5-dibromo-0-3-xy~eno1, melting a t 97O.The portion of bromoxylenols soluble in light petroleum (6.5grams) is a mixture, which has defied, up to the present, all themany attempts that have been made to separate its constituents.The problem will again be attacked when a systematic series ofexperiments on the separation of various bromoxylenols, now incourse of progress, has been coppleted176 CROYSLBY ANb RENOUF ! AROMATIC! C'OllIPOtTNDS, ETC.Action of SuEphuric Acid on Tribromodimethylcyclohexenone.Although the results obtained from the action of sulphuric acidon tribromodimethylcyclohexenone are of an unsatisfactory nature,the following brief account is quoted.It shows that trans-forma.tions do take place, but also illustrates the difficulty, met within some cases, of deducing correct conclusions from the mixedmelting-point method for the identification of compounds.When tribromodimethylcyclohexenone is warmed with twentytimes its weight of concentrated sulphuric acid, i t readily passesinto solution, and almost at once needle-shaped crystals separate,2 grams from 3 grams of the tribromoketone. This solid containedbromine, was phenolic in nature, and after repeated crystallisationfrom alcohol, melted sharply a t 178--179O, nor was this ineltingpoint lowered on mixing with tribromo-rn-4-xylenol.Moreover, thesolid gave an acetyl derivative melting a t 120°, which is the meltingpoint of acetyl tribromo-m-4-xy1eno1, but on mixing with this lattersubstance, an appreciable lowering of melting point was observed(110O). The melting point was not lowered, however, on mixingwith acetyl tribromo-o-3-xylenol, so the substance was hydrolysed,and the bromoxylenol crystallised from alcohol, when it melted a t182--184O, nor was this melting point lowered on mixing with puretribromo-o-3-xylenol. Nevertheless the two substances are notidentical, for on again acetylating and fractionating the resultingacetyl derivative, the melting point of a small portion was finallyraised to 150--153O, which is a t least 25O higher than the meltingpoint of any known acetyl derivative of the various tribromo-xylenols.For the purposes of this research, it has been necessary to prepareseveral tribromoxylenols and their acetyl derivatives, because, 011consulting the literature, it was found that there were considerabledifferences in the recorded melting points f o r one and the samesubstance. Further, one of the acetyl derivatives had not beenpreviously described. There is therefore appended a list of themelting poinss of certain tribromoxylenols and their acetylderivatives, together with their mixed melting points, which mayprove of use to other investigators.The acetyl derivative of tribromo-o-3-xyleno1, prepared by heatingthe xylenol with acetic anhydride, crystallises from either glacial:icetic acid or alcohol in clusters of transparent needles, meltingat 120O:0.1054 gave 0.1484 AgBr.Br = 59.91.CloH,O,Br, requires Br = 59.85 per centTHE PO1,TSULPHIDES OF THE ALKALI METALS. PART 1. 177Melting Points of Tribromoxylenols and their Acetyl Derivatives.Tribromc-o-3-xylenol .. ....... 185" Acetyl derivative ............ 120Tribromo o-4-xylennl.. 172-173" ) ) ............ 112"Tribromo-~n.4-xylenol 178-179" ............ 121"Tribromo-p-2-xylenol 179-180" ............ 125"....... 9 99 9 ,,9 , ? I..... .....Mixed Melting Points of Tribromoxylenols and their correspondingAcetyl Derivatives.F. P.Tribronio-xyleiiols.Tribroino-o-3-xylenol+ tiib~ot1io-o-4-xylenol ...... 176-183"Tribromo-o-3-xylenol+ tribromo-m-4-xylenol .... 158-181"Tribromo-o-3-xylenol+ tribromop-2-xylenol ...... 180-1 82"Trihroi1~0-0-4-xylenol+ tribromo-m-4-xylenol.. .... 173-1 76"Tribromo-o-4-xylenol+ tribronio-p-2-xylenol ...... 177-1 78"Tiibrotno-nt-4-sylenol+ tribromo-p2-xylenol ...... 178-180"RESEARCH LABOBATORIES, PHARMACEUTICAL SOCIRTY,17, BI.OOMSBUBY SQUARE, W.C.31. p.Acetjlderivatives.110-113"109-1 10"121-121 -5"109-111"11 2-1 14"109-1 10

ISSN:0368-1645    

DOI:10.1039/CT9140500165

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

THE PO1,TSULPHIDES OF THE ALKALI METALS. PART 1. 177XXLI.L.-The Polysulphides of the Alkali Metals. Part I.The Pohysulphides of Sodium.By ALEXANDER RULE and JOHN SMEATH THOMAS.THE preparation and constitution of the polysulphides of the alkalimetals have attracted the attention of many workers, but even atthe present day the chemical individuality of many of the productsdescribed as polysulphides remains in doubt.Bloxam (Thesis, London, 1898) has given a detailed r6sumk andcriticism of work done on this subject up t o the year 1898, andsince then important contributions to our knowledge of the poly-sulphides have been made by Bloxam (T,, 1900, 77, 753), Kusterand Heberlein (Zeitsch. anorg. Chem., 1905, 43, 53; 44, 431),and Biltz and Dorfurt (Ber., 1905, 38, 123; Zeitsch.nnorg. Chem.,1906, 48, 29'7; 50, 67).The method almost universally employed for the preparation o lthe polysulphides is the action of varying amounts of sulphur 011aqueous solutions of the monosulpliides or hydrosulphides of themetals, but this method has been shown by Bloxam to be unsatis-factory in the case of sodium and potassium. Sodium nionosulphideundergoes considerable hydrolysis in aqueous solution, and Bloxamfound that the solid products obtained after the action of sulphur011 such solutions always contained thiosulphate. When the hydro-VOL. cv. 178 RULE AND THOMAS : THE POLYSULPRIDESsulphides were used, the products were not, as a general rule, thosecorresponding with the proportions of sulphur used in the reaction.On the other hand, Biltz and Dijrfurt (Zoc.cit.), using the formermethod, were able to obtain definite polysulphides of rubidium andcaxium.The only definite sodium compound obtained by Bloxam wastetrasodium nonasulphide, Na4S,,14H,O.Kuster (Zoc. cit.) determined the solubility of sulphur in aqueoussolutions of sodium monosulphide, but he did not isolate any solidproducts. His conclusions are of interest, for he shows that mix-tures of polysulphides are formed, and that complex equilibria existbetween the different substances in solution. He points out thatthe tetrasulphide is characterised by particular stability, anobservation which is confirmed by the work of the present authors.Bottger (Annulen, 1884, 223, 335) investigated the action ofsulphur on alcoholic solutions of the hydrated monosulphide, andobtained the hydrated di-, tri-, tetra-, and penta-sulphides, butBloxam, on repeating these experiments, was unable to confirmBottger’s results.Any difficulties which are to be attributed t othe disturbing factor of hydrolysis might obvioixsly be overcome bythe use of alcohol a,s a solvent, granted that it were possible inthe first place to obtain the mono- or hydro-sulphide in the pureanhydrous condition ; until recently, however, no satisfactorymethod had been descrjbed for the preparation of the anhydrouscompounds.I n a previous paper (T., 1911, 99, 558) one of us showed that,by the action of hydrogen sulphide on alcoholic solutions of sodiumethoxide and subsequent precipitation with ether, practicallyquantitative yields of pure sodium hydrosulphide were obtained,and in a later paper (T., 1913, 103, 871) the authors mentionedthe fact that sulphur readily reacted with the hydrosulphide inalcoholic solution forming polysulphides, hydrogen sulphide beingevolved a t the same time.A systematic investigation of thisreaction has been carried out in order to determine if definite poly-sulphides could be obtained, and the results are described in thepresent paper.A series of experiments was performed in which varying quantitiesof sulphur were added to alcoholic solutions of sodium hydro-sulphide of the same concentration throughout. An approximatelysaturated solution of the hydrosulphide was prepared by adding2 grams of metallic sodium to 40 C.C.of absolute ethyl alcohol ina flask fitted with a short reflux condenser and a gas delivery tube.The solution of sodium ethoxide thus obtained was saturated withdry hydrogen sulphide, and the excess of the gas was afterwardOF THE ALKALI METALS. PART I. 179removed by heating the solution to boiling on the water-bath andpassing through it a vigorous stream of dry hydrogen. The solutionwas then heated t o boiling on the water-bath until all the sulphurhad dissolved, the current of hydrogen being maintained through-out;.I n some cases the solution was allowed t o cool and the productprecipitated with dry ether. In other cases the water wassrunout of the condenser and the alcohol was evaporated off until aconsiderable amount of solid had separated on the walls of theflask and in the solution.Amounts of sulphur corresponding with the di-, tri-, tetra-, andpenta-sulphides, as well as large excess of sulphur, were used.I nthe case of each product an estimation of the polysulphide sulphurwas made by the method described by Kuster and Heberlein(Zoc. cit.), in addition t o t2le determinations of sodium and totalsulphur.Using the proportions for the disulphide, no solid separated fromthe solution until some of the alcohol had been driven off. A paleyellow product was obtained, which, after drying in a vacuum, wasclearly not homogeneous. On treating a portion of the solutionwith more sulphur, hydrogen sulphide was evolved, indicating thepresence of unchanged hydrosulphide.In another experiment the solution was allowed, to cool, andwas then treated with exce~s of dry ether.A very pale yellowprecipitate was obtained which became almost white on drying ina vacuum, but gave a yellow solution in water. It contained aconsiderable amount of alcohol, which was evolved on heating :0.3484 gave- 0.3477 Na,SO,.0.7829 ,, 002349 S. *(S)=30.00.0.4619 ,, 1.7773 BaSO,. S=52.84.Na2S2=2 : 1 : 2.Na = 32.38.Na : (S) : S =2 : 1-33 : 2.34.Using the proportions for the trisulphide and treating the solutionwith ether, a viscid, yellow precipitate was obtained, which wasdifficult to filter. It was freed as well as possible from the solution,and allowed to remain in a vacuum desiccator over phosphoricoxide.The dry product was orange-yellow, but was not homo-geneous. It was very hygroscopic, and a solution in alcohol, ontreatment with sulphur, evolved hydrogen sulphide.It was obvious from their appearance and behaviour that thesesubstances were mixtures, and since they contained unchangedhydrosulphide, the sulphur had apparently reacted with only aportion of the latter. This fact may be explained by assuming that* (S) indicates " polysulphicie " sulphur.N 180 RULE AND THOMAS : THE POLYSULPHIDESthe reaction results in the formation of a polysulphide higher thanthe di- or tri-sulphide.Sodium Te trusuZphide.-Using the proportions of sodium andsulphur for the tetrasulphide, a very deep red solution was obtainedon boiling, and the sulphur dissolved completely.After boilingfor about an hour in a current of hydrogen, a small quantity ofglistening, yellow crystals had separated out. The solution wasconcentrated to about 5 C.C. by allowing the alcohol vapour toescape through the condenser, and the solid product, which formedcrystalline crusts on the walls of the flask, was filtered off froiiithe hot solution, washed with a little alcohol, and dried in avacuum desiccator over phosphoric oxide.The product was quite homogeneous, and was dark yellow, witha curious olive-green tinge.0.7071 gave 0.5758 Na,SO,.0.6362 ,, 0.3481 S. (S)=54.71.0.2048 ,, 1.0936 BaS04. S=73*34.Na2S, requires Na = 26.44 ; (S) = 55-17 ; S = 73.56 per cent.On heating in a capillary tube the substance became orangereda t 115-120°, began t o sinter a t 258O, and melted to a dark-redliquid a t about 267O.Sodium tetrasulphide is extremely hygroscopic, and readily dis-solves in water to form a clear, deep orange solution, which becomesdark red on heating.The solution soon begins to deposit sulphurwhen allowed to remain in the air. Alcoholic solutions behavesimilarly, but appear to be even more sensitive to the action of air.A microscopic examination of the crystals suspended in a xylenesolution of Canada balsam showed them to be quite homogeneous,and to consist of perfectly defined cubes.In the case of the tetrasulphide, therefore, it is possible to obtaina pure product by simply using the necessary proportions of sulphurand the hydrosulphide.The tetrasulphide may also be obtained by treating the con-centrated alcoholic solution with ether in excess.A red oilseparates, and it may be converted into a viscid, yellow, crystallinesolid by continued stirring. The product is difficult to filter, andit contains alcohol, which can be almost entirely removed by allow-ing the substance to remain in a vacuum over phosphoric oxide;it gradually shrinks and assumes the characteristic brownish-yellowcolour of the anhydrous tetrasulphide. The substance appears tocling very tenaciously to the last traces of alcohol, and attemptsto remove them by heating in a current of hydrogen always led t oslight loss of sulphur. The same difficulty has always been encoun-tered in the attempts to prepare anhydrous polysulphides from theNa = 26.37OF THE ALKALI METATS.PART I. 181hydrated products (compare Biltz and Dorfurt, Zoc. cit.), partlyowing to hydrolysis, and, in the case of the higher polysulphides,partly owing to direct dissociation.The product of the precipitation by ether is probably a definitealcoholate, but it is hoped that further information on this pointwill be provided by an investigation of the system sodium tetra-sulphide-ethyl alcohol, which is now being carried out by the authors.Using the proportions of sodium and sulphur corresponding withthe pentasulphide, an interesting result was obtained. The wholeof the sulphur dissolved in the boiling solution, and, on concen-trating to a small bulk, a crystalline product separated on thewalls of the flask; it wa8 collected, washed with alcohol, and driedover phosphoric oxide.The product was yellow, and not homo-geneous. On treating it' with water, a residue of sulphur remainedundissolved, and the substance was therefore thoroughly extractedand washed with carbon disulphide, then with ether, and dried in avacuum over phosphoric oxide. After collecting the washings andallowing them to evaporate to dryness, a considerable residue ofsulphur remained.The final product possessed all the characteristics of the tetra-sulphide. It was soluble in water, forming a clear solution, andmelted a t about 267O. A portion of the product, which still con-tained a little ether, was analysed:0-4986 gave 0.3978 Na,SO,.0*4050 ,, 0.2161 S.(S)=53.36.0*2947 ,, 1.5471 BaSO,. S=72*09.Na = 25.84.Na: (S): S=2: 2'97: 4.01.Na,S4 requires Na = 26.44 ; (S) = 55*17 ; S = 73-56 per cent.Using the proportions for a possible hexasulphide, some indicationwas obtained of the separation of a polysulphide higher than thetetrasulphide. The solid product was not homogeneous, but con-tained particles of a red substance. On treatment with water, acopious precipitate of sulphur was obtained. A portion of thesolid was extracted and washed with carbon disulphide, but aftercontinued treabment in this way the substance was only partlysoluble in water and still left a residue of sulphur. The finalproduct was not homogeneous, and contained carbon disulphide,which was evolved on heating. Its behaviour resembles that ofrubidium pentasulphide described by Bijtz and Dorfurt (Zoc.cit .),and it is possible that the substance contained a certain amount ofsodium pentasulphide :0*4880 gave 0.3287 Na,SO,.0'2571 ,, 1,2734 BaS04. S = 68-02,Na = 21.82.0,4634 ,, 0.2443 S. (S) =52*71.Na: (a) : S =4 : 6.92 : 8-96182 RULE AKD THOMAS : THE POLYSULPHIDESThe ratio corresponds very closely with that required by thenonasulphide, NaaS9, a hydrate of which is described by Bloxam,but the substance is almost certainly a mixture, and, moreover,contains carbon disulphide.As will be seen from the figures given below, the limit ofsolubility of sulphur is reached when the proportions of sodiumand sulphur approach Na2: S,.The results of these experiments, which were carried out underprecisely similar conditions, may be briefly summarised by statingthat, only when the proportions for the tetrasulphide are used is itpossible to obtain a pure product.Below these proportions theproducts are probably mixtures of the t e t r h l p h i d e and unchangedhydrosulphide. A t the pentasiilphide stage the solid product is amixture of the tetrasulphide and sulphur, whilst with largeramounts of sulphur there is some indication of the presence ofhigher polysulphides in the solid which is always a mixture.Kuster and Heberlein (Zoc. cit.) found that aqueous solutionsof the monosulphide, under certain conditions of concentration andtemperature, were able to dissolve sulphur up to a point repre-sented by the formula Na,S,.2i.No systematic investigation of the solubility of .sulphur inalcoholic solutions of the hydrosulphide has yet been caried out bythe authors, but one determination made just below the boilingpoint of the solution shows that under these conditions a stillgreater proportion of sulphur is dissolved, even when the solubilityof sulphur in alcohol is taken into consideration.It is probable,therefore, that even more complex polysulphides are present inalcoholic solutions than those recorded by Kiister and Heberleinas existing in aqueous solutions.I n the apparatus described above a 2N-solution of sodium hydro-sulphide in absolute alcohol was treated with an excess of sulphur,and, after the hydrogen sulphide had been removed by boiling, thetemperature was maintained a t 8l0 for about four hours, thecontents of the flask being kept thoroughly agitated by means ofa current of dry hydrogen. After allowing to settle in an atmo-sphere of hydrogen, a portion of the solution was removed by meansof a specially constructed vacuum pipette, and introduced intobromine water.When oxidation was complete the solution wasmade up t o one litre, and sodivm and sulphur were determined inaliquot portions :250 C.C. gave 0.2512 Na,SO,.250 C.C. ,, 2.8447 BaSO,. S =0*3907.Other considerations also render it probable that a t and beyondNa=0*0812.Atomic ratio, Na = 1 : S = 3'45, corresponding with Na, : S6.9OF THE ALKALI METALS. PART I. 183the tetrasulphide stage polysulphides higher than the tetrasulphideare present in the solution.A very noticeable feature of thereaction is the increase in the depth of colour of the solution withincrease in the amount of sulphur added. The tetrasulphide is ayellow substance, but the solution from which it separates in thepure state is dark red. With larger amounts of sulphur the solutionbecomes quite opaque.Valuable information as to the nature of the substances presentin the solution after the action of sulphur on the hydrosulphide,as well as to the course of the reaction, may be gained by deter-mining the amount of hydrogen sulphide evolved during thereaction.According to the equation 2NaHS -t- SS =NaZSx+l +H2S, it isobvious that the amount of hydrogen sulphide formed is strictIyproportional t o the amount of hydrosulphide involved in thereaction.There are three powibilities, namely: (1) that a series of poly-sulphides is formed according to the amount of sulphur added, asrepresented by the above equation where x=1, 2, 3, 4, 5.. . . Inthis case, if the reaction proceeded t o completion, the amount ofhydrogen sulphide evolved would always be the same, and wouldcorrespond with the complete decomposition of the hydrosulphide.It has already been shown that the reaction does not proceed inthis manner.(2) Partial decomposition of the hydrosulphide, resulting in theformation of an equilibrium mixture of different polysulphidesand the hydrosulphide.(3) The formation of only one polysulphide, whatever the pro-portion of sulphur present, involving the decomposition of anamount of hydrosulphide suEcient to produce the polysulphide inquestion.In this case the amount of hydrogen sulphide evolvedwill vary directly with the amount of sulphur present up to acertain maximum corresponding with complete decomposition of thehydrosulphide, and will then become constant. The minimumamount of sulphur required t o bring about complete decompositionwill indicate the composition of the polysulphide.A series of determinations of the amount of hydrogen sulphideevolved was carried out in order to ascertain which of the threepossibilities mentioned applies t o the reaction,The apparatus used is shown in Fig. 1. It consists of a round-bottomed Jena-glass flask of about 400 C.C.capacity, fitting bymeans of a ground gas-tight joint to a reflux condenser. A gasdelivery tube and the tube of a dropping funnel are sealed into thelower portion of the condenser, and dip nearly to the bottom o184 RULE AND THOMAS : THE YOLYSULPHIDESthe flask. A long tube sealed to the top of the inner tube of thecondenser is bent twice a t right-angles, and connected with theabsorption apparatus by means of a securely wired rubber joint.I n the apparatus figured it was found that perfect absorption wasattained with the use of a minimum quantity of absorbent.Before each experiment t k whole apparatus was carefully dried,and the absorption tubes were then connected. A weighed quantityof pure : sodium hydrosulphide WL.S introduced into the flask, aFro.I .hour, a conetantweighed quantity ofsulphur which hadbeen recrystallisedfrom carbon disul-phide was added, andthe flask was at oncefitted to the condenser.A current of hydrogendried by sulphuricacid and freed fromtraces of acid by pass-ing over solid potass-ium hydroxide wasthen passed tlwoughthe apparatus untilthe air was displaced.The amount of abso-lute ethyl a l c o h 01necessary to form anapproximately 1-5N-solution of the hydro-sulphide used was runin from the funnel,and the solution wasgradually heated toboiling on the water-bath. The boiling wascontinued for about anstream of hydrogen being maintained.In one series qf experiments ammoniacal hydrogen peroxide wasused as an absorbent, but later it was found more convenient toemploy concentrated bromine water.I n each case the sulphur wasweighed as barium sulphate.The results obtained are expressed graphically in the diagram(Fig. 2).I n the diagram (Fig. 2) the values for hydrogen sulphide andsulphur arp, calculzted for one gram-molecule of hydrosulphideOF THE ALKALI NETALS. PART I. 185The curve indicates that there is, a t first, a gradual increase inthe amount of hydrogen sulphide obtained with increase in theamount of sulphur added. The first part of the curve lies veryclose to the theoretical straight line representing the values forhydrogen sulphide, if the tetrasulphide were the only polysulphideformed, but there is a gradual divergence from this line as theamount of sulphur is increased.All points on the curve lie belowthis line, and therefore it is practically certain that little, if any,di- or tri-sulphide is formed, otherwise larger values for hydrogensulphide would be expected. This conclusion agrees with the resultsof the experiments described above.At the tetrasulphide stage, considerably less hydrogen sulphideFIG. 2.0 20 40 ti0 80 100 120 141R’a2S2 No& Na& Ka& = Ka2S6Grums of mslphur added per 56 gram of NaHS.cq Bmnine trscd as absorbent.0 J1mmoniacnl H,02 used as absorbent.is evolved than would be the case if the tetrasulphide were theonly polysulphide in solution. This is in accordance with the factspreviously mentioned, which point to the probability that a t thetetrasulphide stage higher polysulphides are present in the solution.The latter must therefore contain an equilibrium mixture of tetra-sulphide, higher polysulphides, and unchanged hydrosulphide.Beyond the pentasulphide stage the values for hydrogen sulphideare nearly constant. I f we consider the highest value obtained,which lies slightly off the curve and represents the amount ofhydrogen sulphide evolved when excess of sulphur is used, it willbe seen that this value is not very much lower than the maximumobtainable186 RULE AND THOMAS : THE POLYSULPHIDESConsidering the course of the curve as a whole there is ano very great divergence from the course of the straight lines repre-senting the theoretical values for hydrogen sulphide assuming thatthe tetrasulphide is the only polysulphide formed in the reaction,so that it is fair t o draw the coiiclusion that the tetrasulphide isthe predominating compound present.Small quantities of higherpolysulphides are also present, and the concentration of these higherpolysulphides probably increases with amount of sulphur added.It bas already been shown that a t the tetrasulphide stage theonly solid product which separates is the tetrasulphide itself, evenwhen the solution is evaporated completely to dryness. The higherpolysulphides- must theref ore decompose into tetrasulphide andsulphur as the evaporation proceeds, thus :Na,S, --+ Na,S, + S,or else react with the hydrosulphide still present as the concen-tration of the latter increases.I n either case the result will bethe formation of more tetrasulphide, and these processw will con-tinue until the whole of the alcohol is removed. Since the amountof sulphur present was that required to form the tetrasulphide,none will separate out in the free state with the solid product.At the pentasulphide stage there is again no separation of poly-sulphides higher than the tetrasulphide under the conditions ofexperiment. In this case also it must be assumed that the higherpolysulphides decompose into tetrasulphide and free sulphur, andas the latter is in excess the solid product must necessarily be amixture of the tetrasulphide and sulphur.Kuster and Heberlein mention that in aqueous solutions in whichthe proportions for the pentasulphide are used, that substance isonly obtained after a' large quantity of the tetrasulphide hasseparated out, whilst in the case of other bases the only productis a mixture of the tetrasulphide and free sulphur. Kuster andHeberlein point out that it does not necessarily follow that thetetrasulphide is the polysulphide present in predominating amount,but that its solubility product may be exceeded sooner than inthe case of the higher polysulphides. At the hexasulphide stagein the authors' experiments, there is certainly some indication ofthe separation of a higher polysulphide, and it therefore seemsprobable that a t this stage the concentration of the higher poly-sulphides is considerably increased.On evaporation of the solution,the compound decomposes to some extent into tetrasulphide andsulphur, as before, but as the evaporation is moderately rapid, acertain proportion separates in the free state.The extent t o which ionic dissociation takes place in alcoholicsolutions of such high concentration is no doubt very small, anOF THE ALKALI METALS. PART I. 187in the absence of any data it is unsafe t o introduce any reasoningwith regard to the solubility products.Considering the results generally, there is little doubt that underthe conditions described the tetrasulphide is always the chiefproduct of the action of sulphur on alcoholic solutions of the hydro-sulphide.Action of Metallic Copper on Alcoholic Solutions of thePol ysulphides.When solutions of the polysulphides are treated with excess offinely divided copper and boiled for some time, complete reductiontakes place, and a colourless solution is obtained.On removingthe black copper sulphide by filtration and concentrating thesolution in a current of hydrogen a white solid separates out whichappears to be a mixture of the hydrosulphide and monosulphids ofsodium (compare T., 1913, 103, 871).Action of Metallic Sodium om Alcoholic Solutions of theTe trasuJphi.de.When metallic sodium is added to a solution of the tetrasulphidethere is an immediate separation of a yellow, crystalline solid.This product, on examination, exhibited all the characteristicsof a polysulphide, and analysis showed i t to be the disulphide.Aseries of experiments with varying amounts of sodium alwaysresulted in the same product being obtained. The action is one ofreduction of the higher polysulphides present in the aolution bythe nascent hydrogen produced in the action of sodium on alcohol,but in this case the reduction only proceeds as far as the disulphide.No hydrogen sulphide is evolved during the reaction owing to thepresence of sodium ethoxide with which it reacts forming thehydrosulphide. The presence of the 1at;ter in the solution afterfiltration was proved by adding sulphur, when hydrogen sulphidewas a t once evolved.Addition of a solution of sodium ethoxide t o a solution of thetetrasulphide simply salts out the latter compound, but the productis always contaminated wizh sodium ethoxide, and the washingnecessary to remove it results in a considerable loss of the tetra-sulphide.Analysis of such a product resulted as follows :0.3515 gave 0.2907 Na,SO,.0.3521 ,, 1.8456 BaS04.S=71*98.0'5941 ,, 0.3186 S. (S)=53*62.Na = 26.79.Na,S, requires Na = 26.44 ; S = 73.56 ; (S) = 55-11 per cent188 THE POLYSULPHIDES OF THE ALKALI METATS. PART 1.The figures indicate that a small amount of sodium ethoxide wasstill present.Sodium JJiszilphide.The preparation was carried out by dissolving 2 grams of sodiuiiiin 50 C.C. of absolute ethyl alcohol and saturating the solution withhydrogen sulphide. 4.17 Grams of sulphur were added, and thesolution was boiled on the water-bath for about one hour, a rapidcurrent of hydrogen being passed through it.In one experimentexcess of sodium (4 grams) was added t o the hot solution, andafter boiling for a short time the bright yellow precipitate wascollected, washed with absolute ethyl alcohol, and dried in r2vacuum over phosphoric oxide :0.3166 gave 0.4066 Na,SO,.0.2697 ,, 1,1362 BaSO,. S=57*96.Na = 41.60.0.3902 ,, 0.1102 S. (S) =28.24.NazSz requires Na = 41-82 ; S = 58.18 ; (S) = 29.09 per cent.Usiiig lower proportions of sodium for effecting the reduction,a similar precipitate was obtained, but analysis showed that theratios of sodium to polysulphide sulphur and to total sulphurwere, as a rule, slightly low. It is probable that small quantitiesof the tetrasulphide separate out with the disulphide owing t o thesalting out action of the sodium ethoxide mentioned above. Thedisulphide is only sparingly soluble in alcohol, and it ought there-fore to be possible to wash out the more soluble tetrasulphide, butit was noticed that continued washing, especially with hot alcohol,appeared to bring about slight decomposition of the product, andwhite patches appeared on its surface.Sodium disulphide is a bright yellow, micro-crystalline powder.I t dissolves readily in water, forming a deep yellow solution, which,unlike that of the tetrasulphide, becomes only slightly da,rker onboiling.It is only sparingly soluble in cold alcohol, but on heatingwith alcohol an intensely green solution is produced, which becomesyellow and cloudy on further heating. This occurs to some extentin the case of the tetrasulphide, and appears t o be due t o slightdecomposition and the probable liberation of sulphur. Thedisulphide is apparently more sensitive in this respect, as a minuteamount heated with excess of alcohol gives a bright blue solution,a phenomenon which has been noticed in the case of other sulphurcompounds. The green coloration is evidently the superimposedeffect of the blue colour due to decomposition and the yellow colourof the actual solution of the polysulphide.The disulphide behaves very like the tetrasulphide on heating,as it becomes red, and finally fuses t o a dark red liquidRESEARCHES ON RESI1>UAL AFFINITY AND CO-ORDINATION. 189Since the di- and tetra-sulphides have been obtained in the pureanhydrous state, it is now possible to settle the question of theexistence of polysulphides higher than the pentasulphide, and alsoof the various intermediate polysulphides which have been described.With this object in view, we are a t present making use of thedi- and tetra-sulphides for carrying out an investigation of thefreezing-point curves of the system sodium-sulphur.INORUANIC LABORATORIES,UNIVERSITY OF LIVERPOOL

ISSN:0368-1645    

DOI:10.1039/CT9140500177

出版商:RSC    

年代:1914

数据来源: RSC

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RESEARCHES ON BESI1)UAL AFFINlTY AND CO-ORDINATION. 189XX I V.-Reseawhes on Residual Aflizity and Co-ordi-nation. Pwt I. Metallic Acetylacetones an cltheii- Absorption Spectra.By GILBERT T. MORGAN and HENRY WEBSTER Moss.THE remarkable properties exhibited by many metallic acetyl-acetones, their non-ionisable character, their solubility in anhydrousorganic solvents, their stability on heating, and, in certain instances,their anomalous colours, have led to the view that in these com-pounds the metallic atoms are combined with the unsaturatedorganic complex, not only through their principal valencies, butalso by means of their residual affinity or auxiliary valency. More-over, as the univalent organic complex (formula I) consists of anopen-chain of five atoms, its intimate association with the metal isassumed to arise from the general tendency to form six-memberedrings (formula II), the metallic atom serving as the connecting linkbetween the ends of the organic group :y 3 3 ( p 3c,H<c: F-0- 0.* --+ CH<!:;>M~CH, CH3(1.1 (11.1Jii,fliLctice of Syitimetry O I L the 8tubilit,y of HetulEic Acetylucetones.The acetylacetone radicle (I) being univalent, the number ofthese groups co,rnbining with a metallic atom will depend primarily011 the principal valency of this atom, and as each acetylacetonegroup is equivalent to two associating units it follows that theacetylacetones of univalent, bivalent, tervalent, and quadrivalentmetals will be characterised respectively by a molecular arrange190 MORGAN AND MOSS: RESEARCHES ON RESIDUALment of two, four, six, and eight pointa on the sphere of influenceof the metallic atom.Of these arrangements the last two will probably correspondwith the octahedron and the cube. The second cam may corre-spond with the tetrahedron, or alternately the molecule may havethe less symmetrical plane configuration.The first case, that oftwo points on the sphere, cannot in the circumstances be a sym-metrical arrangement. I n an earlier communication (T., 1913,103, 81) the authors advocated the view that co-ordination is duenotl only to the residual affinity of the central atom, but also tothe mutual attractions of the associating units, and, this hypothesisbeing accepted, thO most stable systems will be those in which theforces interacting between the associating units are symmetricallydistributed, a condition which is satisfied by arranging these unitssymmetrically round the sphere of influence of the central atom.Acetylacetones of Univaleiat Metals (Formula II).-On the fore-going assumption, these compounds should manifest their want ofsymmetry by their instability.Lithium and thallous acetylacetoneare the most stable members of this series, an'd both are decom-posed on heating, the latter at 160° (Kurovski, Ber., 1910, 63,1078). The sodium, potassium, and czesium acetylacetones charon heating, and are unstable in solution or in a moist condition.They are decomposed by hot water into acetone and alkali acetate(Comb-, Compt.rend., 1887, 105, 871). Silver acetylacetonedecomposes spontaneously a t the ordinary temperature, with theliberation of silver.This summary of the properties of the acetylacetones of univalentmetals justifies the contention that dissymmetry leads to instability.Acetylacetones of Bivalent Metals.-The compounds of this series,which may possess either a tetrahedral (formula 111) or a plane(formula IV) configuration, are on either alternat'ive more sym-metrical than the acetylacetones of univalent metals. They alsodisplay a higher degree of stability.The acetylacetones of the metals of the second periodic serieshave all been prepared; those of the alkaline earth metals are(111.) (1V.)dwidedly more stable than the correspondiug compounds of thealkali metals (Tanatar and Kurovski, J .Russ. Phys. C'hem. .Soc.AFFINITY AND CO-ORDINATION. PART 1. 1911906, 40, 580). Glucinum and zinc acetylacetones can be distilledwithout decomposition, the former under atmospheric, and the latterunder reduced pressure (Combes, Compt. rend., 1894, 119, 1222;Tanatar and Kuroveki, Zoc. cit.):The following metals functioning as diads have also yielded stableacetylacetones : copper, lead, iron, cobalt, nickel, and platinum(Combes, Compt. r e d . , 1887, 105, 868; Gach, Monatsh., 1900, 21,98; Werner, Ber., 1901, 34, 2584).The bivalent radicles, vanadyl, VOII, and uranyl, UOZI, havefurnished stable acetylacetones, which may be of this type (T., 1913,103, 86; Biltz, Zeitsch. anorg. Chem., 1904, 40, 221).From the ease with which the acetylacetones of bivalent metalsform stable additive compounds (Biltz, Zoc. cit.; Werner, Zoc. cit.)of the type RI1Ac2,2X having the co-ordination number 6, and con-sequently an octahedral symmetry, it is probable, although it doesnot necessarily follow, that these acetylacetones themselves havethe plane configuration (formula IV).Acetylacetones of TervaZent Elements.-The cam of boron is ofgreat interest; this element resembles carbon in having a verysmall atomic volume, and probably on this account it also resemblescarbon in having a maximum co-ordination number 4, as exhibitedby fluoboric acid, H(BE’,), and its salts. Boron accordingly =so-ciates only with two acetylacetone radicles, and the products havethe general formula [BAc,lX, where X is an ionisable radicle(Dilthey, AnnaleiL, 1905, 344, 326).The acetylacetones of the tervalent metals, which are the moststable examples of tmhis class, undoubtedly possess the octahedralsymmetry, although they have not yet been resolved into theirenantiornorphous components (compare T., 1913, 103, 84). Alumin-ium and indium acetylacetones can be distilled (Combes, Compt.rend., 1S89, 108, 405; Chabri6 and Rengade, ihid., 1900, 181,1300), and vaporisable acetylacetones of tervalent vanadium,chromium, manganese, iron, and cobalt have also been prepared(T., 1913, 133, 85; Urbain and Debierne, Compt.rend., 1899, 129,302). Many members of the rare earth metals (lanthanum, sama-rium, neodymium, praseodymium, and tervalent cerium) haveyielded fairly stable acetylacetones (Hantzsch and Desch, ibid.,1902, 323, 26; Biltz, Annalen, 1904, 331, 334), and the scandiumcompound can be distilled without decomposition.The behaviour on heating of this group of acetylacetones justifiesthe contention that a symmetrical arrangement of associating unitsconduces to stability.-4 cetylucetones of Quadrivalent Metals.-These compounds, whichcorrespond with an arrangement of eight associating units round192 MORGAN AND MOSS: RESEARCHES ON RESlDUALthe central atom, have in all probability a cubic symmetry, andshould be resolvable into two stereoisomeric non-enantiomorphouscomponents (V and VI):\;4c t\iFour cf these compounds are now known, namely, thorium,zirconium, ceric and uranous acetylacetones (Urbain, BdZ.SOC.chim., 1896, [iii], 15, 338, 347; Biltz, Zeitsch. anorg. Chem., 1904,40, 219; Job and Goissedet, Compt. r e d . , 1913, 157, 51).Residual Afinity of Metallic Acetplacetones : Additive Compounds.The additive cornpounds of metallic acetylacetones with water,alcohol, ammonia, or organic bases may be divided into two classes:the more stable additive compounds in which addition is accom-panied by an increase of symmetry, and an unstable class, in whichthe addition decreases the symmetry. The acetylacetones ofbivalent metals furnish the best examples of the first class, for theycombine additively with two molecular proportions of alcohol,ammonia, or organic amine, yielding in general compounds havingthe general formula, M11Ac2,2X, where X may be water, alcohol,ammonia, pyridine, or aniline (Tanatar and Kurovski, Zoc. cit.;Biltz, Zeitsch. anorg. Chem., loc. cit.). Whether the acetylacetones,M1*Ac2, have the tetrahedral or the plane configuration (formulaI11 and IV), there can be little doubt that the additive compoundshave the octahedral symmetry.The unstable additive compounds are formed by the combinationof ammonia or an organic &mine with acetylacetones of the metalsof the rare earths, including thorium; the products have the generalformula 2M*IAc3,NH3, 3MrIfAc,2NH,, and 2ThAc,,NH, (Biltz,A4?maZen, loc. cit.). It is noteworthy that the acetylacetones whichcombine in this way with ammonia also ma<nifest their residualaffinity by forming complex molecules, (MIIIAC~)~, in solution.Scandium acetylacetone, the most stable, compound of the series,lleither combines with ammonia nor exhibits association in organicsolvents, in this respect resembling aluminium acetylacetoneAFFINITY AND CO-ORDINATION.PAHT I. 193Yhe Structure of the Organic Cornpiex in the Metallic,4 ce t ylace tones.Compounds resembling the metallic acetylacetones have beenobtained with benzoylacetone, acetylmethylacetone, ethyl aceto-acetate, acetyl mesityl oxide, and numerous other 8-diketones and8-keto-esters. These substances and their metallic derivatives maybe represented by either of the formulz VII and IX, from whichit will be seen that structural isomerism is possible if the arrange-ment is regarded as static in either case, but inasmuch as a t presentthere is no experimental evidenca that isomerism of this kind existsamong these compounds, it is much more likely that these twoformuh are analogous to the two phases of KekulB’s benzeneformula.The configuration of the metallic acetylacetones andtheir analogues may oscillate between these two extreme positions,or a rearrangement may lead to an intermediate centric distributionof the chemical affinities corresponding with the Armstrong-Baeyercentric formula for benzene and its homologues. This arrangementis indicated by the formula VIII:0 0 0//CH,*C\ /H( Al‘)1 :CH,*C: H(31’)HC 6/I .. .I/\1 1 nc 0CH,*C H(iU’)--L7--1-7- HC’,\O\/C \I/ C\/CR it it(VII.) (17111.) UX.1When R=CH,, a6 in acetylacetone and its metallic derivatives,the organic complex in formula VIII becomes symmetrical on eitherside of the metallic radicle MI, and, if this symmetry exists in themolecule, the acetylacetones of bivalent metals would not be resolv-able into enantiomorphs, even although possessing the tetrahedralconfiguration indicated by formula 111.An examination of the absorption spectra of fourteen acetyl-acetones shows that, with the exception of the chromium compound,which has two bands, they all exhibit one absorption band like theparent diketone itself.The character of the absorption is notmaterially altered by substituting the benzoylacetone for the acetyl-acetone complex (T., 1913, 103, 89).Neither is any change effectedby substituting methyl for the hydrogen attached to the a-carbonatom in formula VII, VIII, or IX, as is done by the use of acetyl-methylacetone instead of acetylacetone. The absorption band, whichchazacterises this whole series of P-diketones and their metallicderivatives, is certainly not due to any oscillatory migration ofVOL. cv. 194 MORGAK AND MOSS: ICESEARCHES OK RESIDUALlabile hydrogen from its carbon attachment to an enolic combinationwith oxygen, for in the case of vanadyl bisacetylmethylacetone theband persists ev'en when both labile hydrogens have been sub-stituted, one by methyl and the other by vanadyl (T., 1913, 103,90).EXPERIMENTAL.Acetylacetones of Uniualent M e t a l s .O*C(CH 3)Lithium Acetylacetone, LiLithium carbonate does not react to any appreciable extent withacetylacetone in dilute alcohol, even after prolonged boiling.Lithium oxide, prepared by igniting lithium nitrate, was boiled ina reflux apparatus for two hours with acetylacetone in 60 per cent.alcohol.The filtered solution on concentration yielded acicularcrystals of lithium acetylacetone, but the yield was not good, asmuch of the oxide remained undissolved. A solution of lithiumhydroxide, prepared by boiling aqueous lithium carbonate withfresh lime (from calcite) in a nickel basin for two hours, was filteredthrough asbestos, and treated whilst warm with excess of acetyl-acetone, when, after concentrating, several crops of crystallinelithium acetylacetone were obtained :0.3508 gave 0.1 724 Li,SO,.Lithium acetylacetone chars on heating, without exhibiting anydefinite melting point.When pure the compound is colourless,but its alcoholic and aqueous solutions soon become yellow, owingto the decomposition of the organic complex by the alkali set freeby hydrolysis. It dissolvw readily in water, sparingly in cold, morefreely in hot alcohol, and is insoluble in benzene or chloroform.Caesium acetylacetone, a colourless, crystalline substance, wasproduced by the interaction of cesium hydroxide and acetylacetonein alcoholic solution, the filtered solution being concentrated underdiminished pressure a t the ordinary temperature until the productseparated. (Found, Cs= 59.81. C,H702Cs requires Cs= 57.33 percent.) The compound is very soluble in water or alcohol, andattempts to purify it by repeated crystallisation led to decomposi-tion.It charred on heating, and had no definite melting point.Silver -4 cetylacetone.-Interaction between silver nitrate andacetylacetone in aqueous or aqueous-alcoholic solution generally ledt o the production of a silver mirror. The compound was obtained asit white, granular mass by shaking freshly prepared moist silveroxide in the cold with excess of acetylacetone. The productrapidly blackened on exposure ; i t was sparingly soluble in water,Li = 6-27.C,H,O,Li requires Li = 6.55 per centAFFINITY AND CO-ORDINATION. PAKl‘ I. 195but the solution was unstable, generally depositing the silver as amirror.Thallous acetylacetone (compare E.Kurovski, Uer., 1910, 43,1078).-Interaction between thallous hydroxide and acetylacetone inaqueous solution gave rise to a basic product crystallising fromalcohol, which even after recrystallisation contained approximatelyone molecular proportion of thallous hydroxide combined with thenormal acetylacetone. The normal compound wm prepared byisolating thallous hydroxide, obtained by the double decompositionof thallous sulphate, and crystallised barium hydroxide ; the yellow,acicular crystals were dissolved in alcohol containing acetylacetone,and the solution concentrated a t the ordinary temperature underdiminished pressure. Thallous acetylacetone separated in well-defined, colourless, flattened needles and flakes, very soluble inwarm alcohol; it melted sharply, and decomposed a t 1 5 3 O ..Acetylacetones of B i v a l e n t H e t a l s (compare Tanatar andKurovski, J .Buss. Phys. Chem ~SOC., 1908, 40, 580).Ca.lcaurn acetylacetone, Ca[\o.C(C,3)~CH] ./O :C( CHJ \ , prepared by theinteraction of aqueous carcium hydroxide and alcoholic acetyl-acetone, crystdlised in needles, and was freed from water of crystal-lisation by drying in a vacuum desiccator over sulphuric acida t 60°:0.4134 gave 0.2442 CaSO,.The calcium compound had no definite melting point, but charredCa = 17.37.CloH1404Ca requires Ca = 16.80 per cent.on heating. -Barium acetylacetone, Ba >CHI , prepared by dis-solving crystallised barium hydroxide in warm water and boilingwith alcoholic acetylacetone fir a few minutes; the filtrate yieldedthe compound in nacreous flakes and plates, the yield being practi-cally quantitative.The dihydrated acetylacetone (Found, Ba =36.47. Calc., Ba=36.92 per cent.) was dehydrated in a vacuumover sulphuric acid a t 60°:0.7350 gave 0.5053 BaSO,.The compound charred on heating.xiiu ucetyltrcetone, Zn < 0 : C ( C H 3 b ~ ti , iorrrierly describedas a yellow compound (Tanatar and Kurovski, loc. cit.), wasobtained in well-defined, colourlw needles by boiling zinc hydroxidewith aqueous acetylacetone, and allowing the filtrate to cool :0 2Ba = 40.46.C,,H,,O,Ba requires Ba = 40.89 per cent;.[ O*C(CH,)’ 1196 MORGAN AND MOSS: RESEARCHES ON RESIDUAL0.1385 gave 0.0435 ZnO.Zinc acetylacetone melted to an opaque, white liquid a t 138O.Cadmium acefylacetone, which is much less soluble than its zincanalogue, was prepared by digesting cadmium hydroxide withexcess of aqueous acetylacetone, and also by double decompositionfrom cadmium acetate and sodium acetylacetone :Zn= 25-20.CloH1,O4Zn requires Zn = 24-81 per cent.0.5084 gave 0.3402 CdSO,.Cl,HI,O,Cd requires Cd = 36.21 per cent.llejrcuric acetylacetone was obtained by mixing equivalmtamounts of mercuric chloride and sodium acetylacetone in aqueoussolution; it separated at once as a sparingly soluble, granular, whiteprecipitate.When mercurous nitrate was employed in this reaction, partialreduction occurred, the precipitate containing mercury and mercuricacetylacetone.Copper acetylacetone was prepared by the inter-action Of cupric chloride, acetylacetone, and aqueous sodiumacetate, the powdery, pale blue precipitate crystallising from chloro-for= in deep violet-blue needles. This compound dissolved inquinoline, and the solution on cooling deposited green crystals ofan additive compound.Cd = 36.08.A c e t y lace tomes o f T erval e n t M e t a h .Scandium A cetylacetome, Sc[ <0:C(CH3)>CH O*C(CH 3)R. J. Meyer and Winter, Zeifsch.. anorg. Chem., 1910, 67, 398).For the scandia employed in the following experiments, theauthors are indebted to Sir William Crookes, and tender their bestthanks. The oxide (1.0164 grams) was covered with pure concen-trated nitric acid, and digested f o r about four hours on the steam-bath.The product was syrupy scandium nitrate with about 6 percent. of undissolved oxide. After dilution with water and filtration,the solution was digested in a reflux apparatus with a moderateexcess of acetylacetone and ammonia in the presence of benzene.The organic solvent removed quantitatively the scandium acetyl-acetone from the aqueous solntion, and after concentration depositedcolourless plates of scandium acetylacetone. The substance waspurified by dissolving in benzene, in which it was readily soluble,and precipitating with light petroleum, when it separated in colour-less needles. From chloroform, scandium acetylacetone crystallisedin colourless, square plates, and it also separated from alcohol insimilar, colourless, acicular prisms.The mother liquors f rom thesAFFINITY AND CO-ORDINATION. PART I. 197crystallisations become yellow, and on warming evolved an odourresembling that of p-benzoquinons :0.1985 gave 0.0402 Sc,O,. Sc = 13.14.0.2520 ,, 0.0525 Sc,O,. Sc=13.15.( a ) 0-1186 gave 0.2264 CO, and 0.0755 H,O. C=52.14 ; H = 7.08.( b ) 0.1228 ,, 0.2340 CO, ,, 0.0728 HZO. C=51.95; H=6*58.C,,H210,Sc requires Sc= 12.90 ; C = 52-78 ; H = 6-15 per cent.The preparations used in the foregoing analyses were purifiedby crystallisation (a) from benzene and light petroleum, ( b ) fromalcohol. When dried a t the ordinary temperature these prepara-tions melted somewhat indefinitely from 177O to 1 8 7 O . The indefi-niteness of the melting points of acetylacetones .of other metals ofthe rare earths was previously commented on by Biltz ( A ~ z n a l : ! ~ ~ ,Zoc.cit., p. 349). Comparative experiments on the distillation ofthe acetylacetones of scandium and thorium showed that scandiumacetylacetone was the more stable a t temperatures near its meltingpoint.Volatility of Scandium A cety1acetone.-Recrystallised specimensof this compound dried a t SOo were heated in small tubes placedin a metal bath, the pressure being reduced to 8-10 mm. A t 157Othe substance began to sublime appreciably, and condensed on thecooler parts of the tubes in small, well-defined, brilliant, colourleescrystals of cubical form. The sublimation proceeded smoothly untilthe melting point ( 1 8 7 O ) mas reached, when the distillation wasrapidly completed.The purified specimens, as prepared foranalysis, sublimed completely below the melting point, and leftno non-volatile rmidue. There was no charring, and the sublimedcontents of the tubes had no d o u r of acetylacetone or other organicmaterial.Sublimed scandium acetylacetone melted sharply a t 187-1873O.Under atmospheric pressure very little scandium acetylacetonedistilled below 190° ; colourless crystals sublimed from 210° to 250O.At 260° the sublimate showed a yellow tinge, but even a t 360°very little decomposition was noticed.Thorium acetylacetone, purified by crystallisation and throughits ammonia additive compound (Biltz, Zoc. cit.), melted at 168-169O(Urbain gives 171-172O, Bztll.SOC. chim., 1896, [iii], 15, 338).When heated under 8-10 mm. pressure it began to sublime a t160° in colourless crysfals, closely resembling those of the scandiumcompound. Very little volatilisakion occurred below the meltingpoint; the compound boiled a t about 260-270°, and the condensedsolid showed a faint yellow tinge.Under the atmospheric pressure very little thorium acetylacetonesublimed below 210O. At 250° the distillate was yellow, and onl198 MORGAN AND MOSS: RESEARCHES ON RESlDITAT,partly solid. At 260° further decomposition occurred, and a brown,charred residue remained.These comparakive experiments showed that scandium acetyl-acetone could be distilled under atmospheric pressure withoutdecomposition, whereas in similar circumstances the thoriumcompound underwent considerable decomposition.Molecular-weight determinations by the ebullioscopic methodshowed that scandium acetylacetone did not undergo associationin boiling chloroform or benzene:0.074 in 20.00 CHC1, gave At=0.039. M.W.=347.0.1016 ,, 12.40 ,, At=0*060.M.W.=312.Sc(C5H,02), requires M.W. = 341.The acetylacetones of tervalent chromium, iron and cobalt wereprepared by the general method (Urbain and Debierne, Compt.mnd., 1899, 129, 302), and for the purpose of comparison the corre-sponding compound of bivalent cobalt was also obtained (Gach,Monatsli., 1900, 21, 98).Ulf,*a-violet A bsorption Spectra of Metallic A cetylacetone.The compounds were dissolved in absolute alcohol to N / S O O O -solutions, and examined in thicknesses of 1.6, 2.5, 4.0, 6.3, 10*0,20.0, 31.6, 50.1, and 100.0 mm.with a one-prism Hilger spectro-meter and an iron arc. In Fig. la the absorption curve of lithiumacetylacetone (unbroken line) is compared with that of acetylacetoneitself (dot and dash line). The two curves are closely coincident,but the band of the lithium compound is less persistent than thatof the parent B-diketone. This comparison is of interest becausenext to hydrogen, lithium is the element of least atomic weightavailable for the purpose of these comparative experiments.On Fig. 2a the absorption curve for thallous acetylacetone isshown by the broken line (dash and two dots). The metal in thiscompound has the high atomic weight of 204, and functions as aunivalent element.The absorption band is as persistent as thatof the lithium compound, but is decidedly narrower.The third curve on Fig. l a (dotted line) representing the absorp-tion band of copper acetylacetone is remarkably like the absorptionof vanadyl bisacetylacetone (T., 1913, 103, SS), the band beingequally persistent, but shifted towards ths more refrangible end ofthe spectrum.The five curves of Fig. 16 are those of certain bivalent metalsof the second vertical series of the periodic classification. Thecalcium acetylacetone curve (unbroken line) has an absorption bandwith its head a t l / h 3500; the barium acetylacetone curve (dasAFFINITY AND CO-ORDINATION. PART I. 199and two dots) has a wider, shallower absorption band, with its headat l / h 3650.The zinc acetylacetone curve (dotted line) and theF I G . la.Oscill&n~ ~?Y?q26ellCiCS.Lithium ncct?jImelone --Copper _ . - - - - - - - -Acely lncetonl: _ _ _ - _ - - $ 92400 6 8 3000 2 4 6 8 4000 2 420181614cadmium acetyIacetone curve (dot and dash) are closely coincident,but the former has the deeper band. The mercuric acetylacetonecurve (dash and three dots) shows a shallower band than those du200 RESEARCHES ON RESIDUAL AFFINITY AND CO-ORDTNATION.to zinc and cadmium, with a decided shift towards the more refrang-ible end, the bands being situated as follows: Zn 1/h 3550,Cd 1/ A 3500, and HgII 1 / h 3700.FIG. 213.Oscillnt ion fmqueitcics.Scandium nectglncetone --Thnllous ,,Ytlriicm ,, _ _ _ - _ _ _ _ _ _- - _ - - - -2400 6 8 3000 2 4 6 8 4000 2 4Fig. 2b show3 the absorption curves of the acetylacetones ofchromium (unbroken line), iron (dotted line), tervalent cobalt (dashand three dots), and bivalent cobalt (dash and two dots). The curvCHEMICAL EXAMINATION O F SARSAPARILLA ROOT. 201for the chromium compound is exceptional in showing two bands,the more refrangible being undoubt,edly the acetylacetone band,whereas that towards the red end is probably due to the metallicradicle.The curve for ferric acetylacetone shows a shallow band withhead a t l / h 3750. The curve for cobaltic acetylacetone, like thepreceding curve, exhibits a somewhat shallow band, the band forcobaltous acetylacetone being much deeper.The change from cobaltous to cobaltic acetylacetone involves ashifting of the band towards the more refrangible end, similar tothe change observed in passing from vanadyl bisacetylacetone tovanadium teracetylacetone (T., 1913, 103, 89), the heads of thebands being situated as follows:VOII 1 / h 3300 ; CoII 1 / h 3500.V1IX l / h 3600; CoIII l/h3600.Fig. 2a shows the absorption curves for scandium acetylacetone(unbroken line) and yttrium acetylacetone (dotted line) ; the twocurves are almost superposable, each exhibiting a strong band at1 / A 3450. The absorption spectrum of thorium acetylacetone, whichwas previously examined by Baly and Desch (T., 1904, 86, 1029;1905, 87, 766), exhibited a strong band a t 1 / ~ 3600.The authors desire to express their thanks to the Research GrantCommittee of the Royal Society for a grant which has partlydefrayed the expenses of this investigation.ROYAL COLLEGE OF ~ C I E N C ' R FOP, IRELAS'I~,DUBLIN

ISSN:0368-1645    

DOI:10.1039/CT9140500189

出版商:RSC    

年代:1914

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CHEMICAL EXAMINATION O F SARSAPARILLA ROOT. 201XXV -Chemical Bxanaiization of Sarsaparilla Root.By FREDERICK BELDING POWER and ARTHUR HENRY SAUWAY.Sarsaparilla root is obtained from different species of Smdaa whichare indigenous to tropical America, from Mexico to Brazil. It hasbeen used medicinally for several centuries, and still maintains aplace in the various national Pharmacopoeias.The above-mentioned root has been the subject of numerouschemical investigations, which appear to have been conducted chieflywith the object of ascertaining the nature of its so-called activeprinciplee, or the constituents to which the assumed therapeuticvirtues of the root are due. The earliest of these investigations wa202 POWER AND SALIVAS:apparently that of Pallotta (J.Pharm. Chim., 1824, 10, 543), whoobtained a substance in the form of a white powder, possessing apeculiar odour and a bitter taste. This evidently impure substancewas considered to bo a new organic base, and was designatedpariglina or parillin. Berzelius, in 1826, suggested for it the namesmilacin. Products were subsequently obtained by Thubeuf ( J .Pharm. Chim., 1832, 18, 734; 1834, 20, 162, 679) and by Batka(Annden, 1834, 11, 313; J . Pharm. Chim., 1834, 20, 43), whichwere designated respectively salseparin and parillinic acid, but itwas shown by Poggiale (J. Phwm. Chim., 1834, 20, 553) that thesesubstances, although obtained by different methods, were practicallyidentical in composition and properties with the pariglina (parillin)of Pallotta.The investigations mentioned were followed by variousothers, which need not be here enumerated, until Fluckiger ( A rch.]'harm., 1877, 210, 535) isolated and described a substance, forwhich he retained the original name of parillin. This was definitelyshown to be a glucoside, and to belong to the class of saponins, theglucosidal nature of " smilacin " having previously been observedby 0. Gmelin (Annulen, 1859, 110, 174). Fluckiger proposed forparillin the alternative fo.I'TILulz, @40H70018 or C48H86018, and con-sidered that the saponins as a class might be represented by thegeneral formula CnH2~-ioO18.The most recent extended investigation of sarsaparilla root wasconducted by W. v. Schulz (Pharm. J., 1892, 52, 6; Arb. despharmkol.Inst. z u D o r p t , 1896, 14, 14), who has stated it tocontain three distinct saponin glucosides, to which the followingnames, formulae, and characters were assigned :I. Parillin, of Pallotta and of Fluckiger (" Sinilaciii " of Ber-zelius), C26H4,0,,,2~H2,0. M. p. 176-14O; [a]= - 42'33O. Crystalline,and almost insoluble in cold water.11. Smilasaponin (" Smilacin " of Merck), (C,,H,,0,0)5,12H20.[aID -26.25O. Amorphous, and soluble in water.111. Sarsasaponin, (C22~,0,,),,,24H,0. M. p. 220.26' ;[a]= - 16'25O. Crystalline, and readily soluble in water.It was noted by v. Schulz that although the analysis of the last-mentioned compound gave somewhat higher figures for the hydrogenthan the formula C,,H,,O,, requires, and the formula (&H&&would therefore, appear at first sight to be more correct, he hasadopted the former expression in order to bring the substance intothe series having the general formula CnH2n-8010.This generalformula has been considered by Kobert to represent the compositionof all the above-mentioned compounds, as well as that of a numberof other substances belonging to the class of saponins (compare vanRyn, Die GEykoside, p. 217). It has, furthermore, been stated bCHEMICAL EXAMINATION OF SARSAPARILLA ROOT. 203v. Schulz that the hydrolysis of the sarsapadla glucosida is noteasily effected by heating under ordinary conditions with diluteacids, and that it is most completely accomplished when the opra-tion is conducted in a sealed tube. The ultimate products of thehydrolysis, besides sugar, have been designated respectively a.aparigenin, smilasapogenin, and sarsasapogenin, and to all of thesethe formula C,,H,O, or C2,H,,04 has been assigned.It has been assumed by v.Schulz (Zoc. cit.) that the above-mentioned behaviour of the sarsaparilla glucosides on heating withdilute acids is due to the presence of several sugar complexes inthe molecule, which become successively eliminated, and that thefirst products of hydrolysis therefore still retain the character ofglucosides. This view has also been entertained by Rosenthalerand Strom (Arch. Phnrm., 1912, 250, 290) with respect to thesaponiu obtained from the white or Levant soaproot (from a speciesof G y p ~ ~ p h i l a ) . The last-mentioned authors propose to designatethe first product of hydrolysis as ‘‘ pro-sapogenin,” restricting theterm sapogenin to the final productl of hydrolysis, which is obtainedby heating the glucoside with acid under pressure.The so-calledpro-sapogenin, although crystalline, did not yield satisf actor1 resultson analysis, which it was thought might be due to the presence ofsome impurity, such as sapogenin.Although some glucosides are known which, by suitable methodsof hydrolysis, are capable of yielding intermediate glucosidalproducts, such, for example, as amygdalin and apiin (Ber., 1895,29, 1508; A?tnden, 1901, 318, 121), i t appears very doubtfulwhether the saponins in a pure state actually possess this character.The present investigation of sarsaparilla root has shown it to containbut one definite saponin glucoside, which agrees fairly well in itspercentago composition arid characters with the sarsasaponin ofv.Schulz (Zoc. cit.), and this name has therefore been retained,although a different formula has now been assigned to it. Thesarsasaponin of the present authors is, however, readily hydrolysedby heating with dilute acids, without the formation of an inter-mediate product, but it has now been ascertained that it is accom-panied in sarsaparilla root by a phyhsterolin (phytosterol gluco-side), which, as has recently been shown (T., 1913, 103, 399, 1022),is not changed by the ordinary methods of hydrolysis. There canbe little doubt that the glucosidic products other than sarsasaponinwhich have hitherto been obtained from sarsaparilla root were notpure substances.The composition and characters assigned to the=called parillin would appear to indicate that it consisted essen-tially of a mixture of the substance now designated ils sarsasaponinwith varying proportions of a phytosterolin, whilst in the course o204 POWER AND SALWAY:the present investigation i t has been definitely ascertained thatsmilasaponin ((' smilacin ") is not a homogeneous compound.With consideration of the confusion which has existed respectingthe glumsides of sarsaparilla root, and the fact that nothing hasbeen known of its other constituents, apart from the recorded pres-ence of starch, traces of an essential oil, a little fatty oil, resin, andinorganic salts, it has seemed desirable to subject this root to a moresystematic and complete chemical examination.The results of thepresent research, together with the deductions from them, aresummarised at the end of this paper.EXPERIMENTAL.The material employed for this investigation consisted of a goodquality of commercial grey Jamaica sarsaparilla, such as is recog-nised by the British Pharmacopaeia, and which is there describedas the dried root of Smilax ornata, Hooker, fil.In order to ascertain whether an enzyme were present, a, quantity(500 grams) of the powdered material was mixed with water andkept for two days a t the ordinary temperature. The mixture waethen filtered under pressure, and alcohol added to the filtrate.Aflocculent precipitate was thus produced, which, when dried in avacuum over sulphuric acid, amounted to 2.6 grams, or 0.52 percent. of the weight of root employed. This substance slowly hydro-lysed amygdalin, thus indicating its enzymic activity.Another portion (10 grams) of the powdered root ww tested f o rthe presence of a.n alkaloid, but with a negative result.Twenty-five gram9 of the powdered root were next extractedsuccessively in a Soxhlet apparatus with various solvenb, when thefollowing amounts of extract, dried a t looo, were obtained :Petroleum (b. p, 35-50') extracted 0.11 gram = 0'44 per cent.Xther ,, 0.11 ,, = 0'44 ,,Chloroform ,, 0.07 ,, = 0.28 ,,Alcohol ,, 1-30 ,, = 5-20 ,, Ethyl acetate ,, 0.20 ,, = 0.80 ,,- -Total ...............1.79 grams== 7-16 per cent.For the purpose of a complete chemical examination 22.1 kilo-grams of the ground material were extracted by continuous perco-lation with hot alcohol. After the removal of the greater portionof the alcohol, a viscid, dark-coloured extract was obtained, amount-ing to 2-95 kilogramsCHEMICAL EXAMINATION OF SARSAPARILLA ROOT. 205Distillation of the Eztract with Steam. Separation of anEssential Oil.The whole of the above extract was mixed with water, and avigorous current of steam passed through the mixture for severalhours. The distillate, on extraction with ether, yielded 2.6 gramsof an essential oil, being thus equivalent to about 0.01 per cent.of the weight of root employed. This essential oil, when distilledunder diminished pressure, passed over between 70 and 200°/ 15 mm.as a pale yellow liquid, which possessed a pleasant, somewhataromatic odour, a density of 0.977 a t 15O/15O, and was not com-pletely soluble in 70 per cent.alcohol. It was found to containfurfuraldehyde, and also gave a bluish-black coloration with ferricchloride, thus indicating the presence. of a phenolic substance.a f t e r the above operation the steam distillation flask containeda considerable quantity of a brown resin, which formed with theaqueous liquid a viscid emulsion. Since the resin did not separateon keeping, the mixture was agitated with hot amyl alcohol. Bythis means a very dark-coloured aqueous liquid ( A ) was obtained,whilst the amyl-alcoholic extract contained the resin (B), partlyin solution and partly in suspension. This extract was filtered, thefiltrate well washed with water, the solvent then removed, and theresidual semi-solid resin, together with that portion of the resinwhich was insoluble in amyl alcohol, put aside for subsequentexamination.Examination of the Aqueous Liquid (A).Isolation of a new Dicarboxylic Acid, Sarsapic Acid, C,H,O,.The aqueous liquid from which the resin had been removed, asabove described, was repeakedly extracted with ether.The combinedethereal extracts were then concentrated to a convenient volumeand shaken with an aqueous solution of ammonium carbonate. Onacidifying the ammonium carbonate extract it yielded about 6 gramsof a semi-solid substance, which was dissolved in ether, the etherealsolution being washed, dried, and the solvent removed.The residue,which gradually solidified, was first freed from a little adhering oilby drying on a porous tile, and then crystallised from hot watercontaining a little alcohol. A substance was thus obtained whichseparated in slender, colourless needles, melting at 3 0 5 O :0.0850 gave 0.1307 CO, and 0.0200 H,O. C=41-9; H=2*6.0.1728 required for neutralisation 20.0 C.C. AT/ 10-KOH.C,H,O, requires 0=41*9; H=2.3 per cent.N.V. =64-9206 POWER AN]) SALWAY:A dicarboxylic acid, C,H,06, requires N.V. = 65.2.The molecular weight of the substance was determined by Barger’s0*0700 in 5.6 C.C. alcohol was between 0.065 and 0.075 mol.It is evident from these results that the above substance is adibasic acid possessing the empirical formula C6H406.The onlycompounds of this formula hitherto recorded are tetrahydroxybenzo-microscopic method, with the following result :Mean M.W. = 179. C,H,O, requires M.W. = 172.quinone, C O < ~ ~ ~ ~ ~ ~ $ ~ ~ { > C O , and 3 : 5-dihydroxy-4-pyrone-2-carboxylic acid, CO<C(oH)L--&a C( OH)‘C( CO H)> 0, neither of which, liowever,is identical with the above-described substance. Since the latteris therefore a new compound, it is proposed to designate i t snrscipicctcid, with reference to the source from which it has been obtained.Sarsapk acid, C4H,0,(C0,H),, is sparingly soluble in cold wateror ether, but very soluble in alcohol. It is moderately soluble inhot water, from which it separates, on cooling, in colourless needles.It gives no coloration with ferric chloride.Its metJtyZ ester,C4H20,(C0,*CH,),, prepared by passing dry hydrogen chloride intoa hot methyl-alcoholic solution of the acid, crystallises from alcoholin colourless leaflets, melting at 1 2 1 O . This substance is volatilein steam, and, when gently heated, possesses an odour suggestive ofsafrole. It was analysed with the following result :0.0995 gave 0.1746 CO, and 0.0363 H,O.C8H80, requires C = 48.0 ; H = 4.0 per cent.From the above-mentioned properties of sarsapic acid it wouldappear to contain two carboxylic groups, which would account forthe state of combination of four of the oxygen atoms. I n order toascertain the manner in which the two remaining oxygen atomsare combined, methyl sarsapate was heated for some time withacetic anhydride, but no change took place.The same ester washeated for several hours with sodium acetate and hydroxylaminehydrochloride in aqueous alcohol, but no reaction occurred. Itwould appear, therefore, that sarsapic acid contains neither ahydroxyl nor a carbonyl group. With consideration of these factsit is highly probable that the acid possesses the constitution :C=47.9; H=4*1.,-yC:H :C(CO,H>>,‘CH:C(CO,H) *The ethereal liquid , which had been shaken with aqueous alumon-iuni carbonate for the removal of the sarsapic acid, as describedabove, was subsequently extracted with aqueous solutions of sodiumcarbonate and sodium hydroxide.Both of these extracts, on acidiCHEMICAL EXAMINATION OF SARSAPARILLA ROOT. 207fication, yielded only a small amount of a brown, amorphous solid,whilst the ethereal liquid remaining after the treatment withalkalis also contained nothing definite in character.The aqueous liquid, after being extracted with ether as abovedescribed, gave on agitation a copious and persistent froth, andevidently contained some saponaceous substance. I n order to isolatethe latter, if possible, the aqueous liquid was extracted repeatedlywith a.myl alcohol. The combined extracts were first washed witha little water, and then concentrated under diminished pressure,when a considerable quantity (20 grams) of a pale brown, amor-phous solid was deposited.This substance was found to be gluco-sidic in character, and also to possess saponin-like properties, butno definite compound could be isolated directly from it. With theobject of ascertaining whether any definite hydrolytic productcould be obtained from the substance, the latter was heated forsome timz with dilute sulphuric acid, when a brown solid soon beganto separate. After the hydrolysis was complete the mixture wasextracted with ether, when some indefinite material remained undis-solved. The ethereal solution was then first washed with aqueoussodium hydroxide, which removed some colouring matter, andsubsequently with water, after which i t was dried and the etherremoved, when about 1 gram of a crystalline solid remained.Thissubstance was purified by recrystallisation from alcohol, whenit formed colourless, prismatic needles, melting a t 183O. It wasfound to be identical with sarsasapogenin, C,,H,,O,, the hydrolyticproduct of the glucoside (sarsasaponin) , which was subsequentlyisolated, as described below.The aqueous liquid obtained in the above-described hydrolysiswas treated with baryta water for the removal of the sulphuricacid, and concentrated to a small volume. It then readily reducedFehling’s solution, but no ositzone could be prepared from it.It is evident from the above results that the brown, amorphoussolid which had been obtained by extraction with amyl alcoholcontained a small amount of sarsasaponin, together with a consider-able proportion of indefinite material.The ampl-alcoholic filtrate remaining after the removal of theabove-described brown, amorphous solid also yielded a small amountof sarsasapogenin on hydrolysis with sulphuric acid.The original aqueous liquid, after having been extracted withainyl alcohol as above described, wits treated with an exceN of basiclead acetate, when an abundant, dark brown precipitate wasproduced.This was collected and washed with water, then sus-pended in water, and decomposed by hydrogen sulphide. Thefiltered liquid, which was very darkly coloured, was concentrate208 POWER AND $AL,WAY:to a small volume, but nothing crystalline separated on keeping.A portion of the liquid was therefore heated for a short time withaqueous potassium hydroxide, after which treatment the mixturewas acidified and extracted with ether.The ethereal liquid wasthen shaken with aqueous ammonium carbonate, which removed asmall quantity of a crystalline acid. This substance, after purifica-tion, melted a t 305O, and was identified as sarsapic acid, C6H406,which had previously been isolated as described above. Since thissmall amount of acid was only obtained after heating with alkali,it must have been present in the aqueous liquid in some form ofcombination. The ethereal liquid, after the removal of the sarsapicacid, contained only indefinite colouring matter.The filtrate from the basic lead acetate precipitate was treatedwith hydrogen sulphide for the removal of the excess of lead, andthe filtrate concentrated to a syrup.On keeping the latter for sometime about 10 grams of a crystalline solid separated in long needles.This substance consisted of potassium nitrate, which had previouslybeen observed to occur in sarsaparilla root. The syrup also con-tained an abundance of sugar, since it readily yielded d-phenyl-glucosazone, melting and decomposing a t 2 1 2 O . I n order furtherto confirm the identity of the sugar a portion of the syrup washeated with acetic anhydride. An acetyl derivative wm thusobtained, which, when crystallised several times from alcohol, melteda t 130-131°, and consisted of 6-penta-acetyldextrose. The above-mentioned eyrup gave no precipitate with potassium-mercuric iodide,iodine, phosphomolybdic acid, o r mercuric nitrate, but, when heatedwith potassium hydroxide, ammoniacal vapours were evolved.Sinceit still possessed saponaceous properties, a portion of the syrup washeated with 5 per cent. aqueous sulphuric acid, and the mixturesubsequently extracted with ether, when a small amount of sarsa-sapogenin, C26H4203, was obtained, thus indicating the presence ofsarsasaponin in the original aqueous liquid.Examhation of the ResitL (B).The crude resin, which had been separated from the aqueousliquid ( A ) by means of amyl alcohol as above described, wasdissolved in alcohol, mixed with purified sawdust, and the driedmixture successively extracted in a large Soxhlet apparatus withlight petroleum, ether, chloroform, ethyl acetate, and alcohol.Petroleunt Bstrcici of *.the IZesi~z.Isolation of Sitosterol, C2,H460.The petroleum extract of the resin was a dark-coloured, viscidSince it consisted chiefly of fatty solid, amounting to 125 gramsCHEMICAL EXBMINATION OF SARSAPARILLA l-iOOT.209matter, it was heated for some time with 50 grame of potassiumhydroxide in the presence of alcohol. The greater portion of thealcohol was then removed, water added, and the mixture subse-quently extracted many times with ether. The combined etherealextracts yielded on evaporation 10 grams of an oily residue, whichrapidly solidified. This material was dissolved in a hot mixture ofalcohol and ethyl acetate, when, on cooling, a substance separatedin colourless needles, melting a t 135-13607 which gave the colourreaction of the phytosterols :0.0958, heated at llOo, lost 0*0040 H,O.H,O=4.2.0.0918 * gave 0.2818 GO, and 0.0995 H,O. C= 83.7 ; H = 12.0.C$,H,,O,&O requires H,O = 4.5 per cent.C2,H4,0 requires C= 83.9 ; H = 11.9 per cent.A determination of the optical rotatory power of the substance0*3048,* made up to 20 C.C. with chloroform, gave a, -Oo50/ in aThe acetyl derivative, when crystallised from a mixture of alcoholand ethyl acetate, separated in stellar clusters of colourless needles,melting a t 126-127O.It is evident from these results that the above-described substanceis sitosterol.gave the following result:2-dcm. tube, whence [aID -27.3O.Isolatiotb of Sitosterol-d-gl,ucoside (PliytosterolirL), C,,H,O,.The alkaline liquid, from which the abovedescribed sitoeterol hadbeen removed by ether, was acidified with dilute hydrochloric acid,and the precipitated material extracted with ether.A portion ofthe precipitate, amounting to about 3 grams, was very sparinglysoluble in ether. This w a ~ therefore separately collected, and thenpurified by crystallisation from amyl alcohol. It was thus obtainedin microscopic needles, melting and decomposing a t 280-285O :0.1062 gave 0.2802 CO, and 0.0984 H20. C = 72.0; H = 10.3.C,H,,06 requires Q= 72.3 ; H = 10.2 per cent.From the analysis and properties of the above-mentioned sub-stance it appeared to consist of a phytosterolin (phytosterol gluco-side). The correctness of this supposition was confirmed by hydro-lysing tho substance in amyl-alcoholic solution with hydrochloricacid (compare T., 1913, 103, 403), when it was resolved intodextrose, which was identified by means of its osazone, and asubstance melting a t 1 3 6 O .The latter gave the characteristiccolour reaction of the phytosterols, possmsed an optical rotation inchloroform of [aID - 35'2O, and yielded an acetyl derivative meltingVOL. cv.* Auhydrous substancc.1210 POWER AND SALWAY:at 124O. This hydrolytic product was thus identified as sitosterol,and the substance from which i t was obtained was consequentlysitasterold-glucoside.Zdenfiification of the Fatty Acids.The above-mentioned ethereal solution, from which the phyto-sterolin had been removed by filtration, yielded, on evaporation,about 70 grams of crude fatty acids.These were converted intotheir methyl esters, and then subjected to fractional distillationunder diminished pressure, when the greater portion passed overat 210--230°/15 mm., but a small fraction was collected above230°/15 mm. The latter fraction solidified in the receiver, and,when crystallised from ethyl acetate, separated in glistening leaflets,melting a t 58-59O:0.1174 gave 0.3354 CO, and 0.1381 H,O.The above substance appeared. to consist of methyl behenate, andthis view of its character was confirmed on hydrolysis, when afatty acid wm obtained melting a t 76-77O, and possessing anectralisation value of 157 (C~H4402 requires N.V. = 165). Thefatty acid was thus identified ils behenic acid.The fraction of methyl esters distilling a t 210-230°/15 rnm.washydrolysed, and the resulting fatty acids separated into liquid andsolid portions by conversion into the lead salts, and treating thelatter with ether.The Solid Acids.-This portion of acid, amounting to about30 grams, was crystallised once from a mixture of alcohol and ethylacetate, when it melted a t 54-56O. The product was analysed withthe following result:C= 77.9 ; H = 13.1.C,,H,1,02 requires C = 78.0 ; H= 13.0 per cent.0.1148 gave 0.3168 CO, and 0.1289 H,O. C=75*3; H=12*5.C,,H,O, requires C?='75-0; H=12*5 per cent.It is thus evident that the solid acids consisted of a mixture of. palmitic and stearic acids.The Liquid A cids.-These acids, when distilled under diminishedpressure, passed over between 230° and 240°/15 mm., and amountedto 20 grams.An analysis and a determination of the iodine valuegave the following results :CIgHsO2 ,, C=76*1; H=12.7 ,, ,,0-1132 gave 0.3178 CO, and 0.1170 H,O. C=76*6; H=11-5.0' 1492 absorbed 0-2333 iodine.C,,H,O, requires C = 76.6 ; H'= 12-1 per cent. Iodine value =i 90.1.C,slI,20, ,, C=77.1; IT=11*4 ,, ,, Iodine ,, =181.4,Iodine value= 156CHEMICAL EXAMINATION OF SAR.SAPARILLA ROOT. 21 1From these results it would appear that the liquid acids consistedof a mixture of deic and linolic acids, the latter predominating.Ethereal Extract of the Resin.This extract was a dark-coloured solid, amounting to 32 grams.It was digested with a considerable volume of ether, when a portiorlwas found to be very sparingly soluble.The mixture was thereforefiltered, and the insoluble material purified by crystallisation froma mixture of amyl and ethyl alcohols, when about 1 gram of amicrocrystalline solid, melting at 295-300°, was obtained. Thissubstance was identified as sitosterol-d-glucoside, since it yielded, onhydrolysis, sitosterol and dextrose.The ethereal liquid from which the above-mentioned glumidehad been removed was next shaken with aqueous ammoniumcarbonate. The alkaline liquid, on acidification, yielded 1.5 gramsof an oily acid, which became partly crystalline on keeping. Thecrystals were freed from oily matter by pressing on a porous plate,and then recrystallised from dilute alcohol, when colourless needles,melting at 300-305°, were obtained.This acid yielded a methylester, melting at 121°, and was thus identified as sarsapic acid,c6H406, which had previously been isolated from the aqueousliquid.The ethereal liquid was subsequently shaken with aqueous sodiumcarbonate, but only a small amount of a brown, amorphous solidwas thus removed. It was then treated with a 10 per cent. solutionof sodium hydroxide, when an extract was obtained which, onacidification, yielded a quantity of a brown, amorphous solid. Thiswas collected and dissolved in hot dcohol, from which it separatedin an indistinctly crystalline form. Attempts were made to obtainthis substance in a purer condition, but after several separationsfrom alcohol it still retained a brown colour, and was not definitelycrystalline.It began to sinter a t 78O, and melted completely a t145O. It was glucosidic in character, for, on heating with hydro-chloric acid in the presence of alcohol, it yielded an aqueous liquidwhich readily reduced Fehling’s solution, and also a hydrolyticproduct melting a t 50-55O. The latter possessed the propertiesof a fatty alcohol, but the amount obtained was not sufficient forits complete characterisation. It would appear probable, however,from the result, of the hydrolysis, and also from the properties ofthe glucoside, that the latter was somewhat impure cetyl-d-glucoside,which is known t o sinter a t 78O, and become completely melted a t150° (Salway, T., 1913, 103, 1028).P 212 1’OWEH. AND GBLWAYldentificatioit of Stigmasterol, C,,H,,O.The ethereal liquid, which had been shaken with alkalis, as abovedescribed, was finally washed with water, dried, and the etherremoved. A crystalline solid, amounting t o 2 grams, was thusobtained, which, when recrystallised from a mixture of ethyl acetateand alcohol, separated in colourless leaflets, melting a t 1 4 0 O .Thesubstance possessed the properties of a phytosterol, and evidentlyconsisted for the most part of sitosterol, which had previously beenisolated from the petroleum extract of the resin. Its high meltingpoint indicated, however, the presence of some stigmasterol, andthe substance was theref ore successively acetylated and brominated,according to the method described by Windaus and Hauth (Ber.,1906, 39, 4378; 1907, 40, 3681).I n this manner a sparinglysoluble bromo-derivative was isolated, which crystallised from amixture of alcohol and chloroform in colourless leaflets, decom-posing a t 208O:0.0656 gave 0.1162 CO, and 0.0408 H20.C,Hb20,Br4 requires C = 48.7 ; H = 6.6 per cent.From the analysis and properties of the above compound i t isevidently identical with tetrabromoacetyl stigmasterol, thus provingthe presence of stigmasterol .in sarsaparilla root.C-48.3; H=6*9.Chloroform and Ethyl Acetate Extracts of the Resin.These extracts were dark-coloured, brittle solids, amounting to55 and 20 grams respectively. Both of these extracts were gluco-sidic in character, but no definite glucoside could be isolated fromthem. The ethyl acetate extract of the resin, however, on heatingwith dilute sulphuric acid, yielded a small amount of sarsapicacid, C,H,O,.Alcohol Extract of the Resin.Itwas dissolved in alcohol, and the solution kept for some time, whena quantity of a crystalline solid separated, which was collected.The alcoholic liquid was then concentrated to a convenient bulk,and heated for some time with aqueous hydrochloric acid.Afterremoving the alcohol in a current of steam, the remaining aqueousliquid was separated by filtration from a dark-coloured resin, andthe filtrate extracted with ether. The resin also was dige8ted withether, which, however, dissolved but a small proportion of it. Thetwo ethereal liquids were united, washed first with aqueous sodiumhydroxide, subsequently with water, then dried, and the solventThis extract was a dark brown solid, amounting to 45 gramsCHEMICAL EXAMINATZON OF SARSAPARILIA ROOT.213removed. A crystalline residue (0.2 gram) was thus obtained, whichmelted a t 183O, and was found to be identical with the saraa-sapogenin described below,Isolation of Sarsasaponirb, C4$3760,,,7H20.The above-mentioned crystalline solid, which separated from thealcoholic solution of the resin, was purified by several crystallisationsfrom alcohol, when colourless, elongated needles were obtained,which began to sinter a t about 200°, and melted completely a t248O. The substance was glucosidic in character, and its aqueoussolution, when agitated, yielded a copious and persistent froth. Itthus possessed the properties of a saponin.The amount of puresubstance isolated from the above extract of the resin was 1.5 grams,It was analysed, with the following results:0.1089, on heating a t 125O, lost 0.0130 H,O.0.0934 * gave 0.1967 CO, and 0.0663 H,O.H,O=11.9.C = 57.4 ; H = 7.9.0.1048 * ,, 0.2213 CO, ,, 0.0758 HZO. C=57*6; H=8.0.C44H760zo,7H,0 requires HL20 = 12'0 per cent.C44H76020 requires C = 57.1 ; H = 8.2 ,,c44H7,02, ,, c=57'4; H=7*8 ,,The above analytical figures will be seen to be in somewhatbetter agreement with the formula C44H7zOzo than with C44H,6020,but the data subsequently obtained by the hydrolysis of theglucoside are more in accordance with the latter formula, and thishas therefore been adopted as having the greater probability ofcorrectness.W. v.Schulz (Zoc. cit.) had previously isolated from sarsaparillaroot a saponin glucoside, which possessed nearly the same per-centage composition as that above described (Found, C = 57.1 ;H = 8.1), and was designated sarsasaponin. This compound, towhich the formula (C22H,0,,),,,24Hz0 was assigned, was stated tomelt a t 220*26O, to have [a], -16*25O, and to yield an indefinitehydrolytic product of variable composition. Its hydrolysis was,however, considered t o result in the formation of sarsasapogenin,C28H4604, dextrose, and an undeterxined acid or mixture of acids,C4H606, in accordance wi€h the following equation :2(C,,H360,0) + 2H,O = C I , J & 3 0 4 + 2C~H,206 + C4H606.The saponin glucoside, which has now been isolated fromsarsaparilla root, yields a well-defined, crystalline, hydrolyticproduct, which will subsequently be described.Although thisglucoside differs in some of its other characters, such as meltingpoint and optical rotation, from the sarsasaponin of v. Schulz, and* Dried a t 125"214 POWER AND 8ALWA4Y:a somewhat different formula has now been assigned to it, there canbe no doubt of the fundamental identity of the compounds. It istherefore deemed desirable that the name sarsasaponin should beretained for the glucoside which is here described.Sarsasaponin is readily soluble in water or hot alcohol, but onlyvery sparingly soluble in ether. It cani?ot be crystallised fromwater, and is best purified by crystallisation from 95 per cent.alcohol.It shows, however, a great tendency to separate fromconcentrated alcoholic solutions in a gelatinous form.Sarsasaponin can be removed for the most part from its aqueoussolution by shaking the latter with finely divided substances whichare insoluble in water, and it had been observed by v. Schulz(Zoc. cit.) that when its lead compound was decomposed by hydrogensulphide, the glucoside was contaiiied to a large extent in theprecipitated lead sulpliide. I n the course of the present investi-gation sarsasaponin couici only he isolated in a pure state fromthe resinqus material, notwithstanding the fact that i t is readilysoluble in water, and was evidently contained, in part, in theaqueous liquid obtained by treating the alcoholic extract of theroot with water.From the facility with which i t is mechanicallyprecipitated, as well as from- the results of cryoscopic observations,it seems highly probable that sdrsasaponin forms with water onlycolloidal solutions. The property of forming such solutions wouldalso account for the persistent froth which is produced by thesubstances designated as saponins when shaken with water.When sarsasaponin 3s dissolved in acetic anhydride, and sub-sequently a few drops of concentrated sulphuric acid added, a yellowcolour is produced, and the liquid rapidly develops a greenfluorescence. On keeping for some time, o r on the addition of alarger amount of sulphuric acid, the liquid acquires a reddish-brown colour.The specific rotatory power of sarvasaponin was determined withthe following result :0-2130,* made cp to 20 C.C.with water, gave a, - l02/ in a 2-dcm.v. Schulz (Zoc. cif..) has recorded that the substance designatedtube, whence [a],, - 48*fi0.by him as sarsasaponin had 3 rotation of [a], -16.25O.H y d ~ o l y s i ~ o{ Sarscisnponin.Formation of Snrsccsnpoyc~tl.n,, CiGH4203, atid Dextrose.One gram of sarsasaponin, in aqueous solution, was heated with5 per cent. sulphuric acid, when, after a short time, a gelatinous,* Anhydrous substanceCHEMlCAL EXAMINATION OF SARSAPARILLA ROOT. 21 5hydrolytic product separated, which gradually became crystalline.The heating was continued for several hours, and the mixture thendistilled in a current of steam, but no volatile product of hydrolysiswas found in the distillate.After this operation there remainedin the distillation flask a crystalline solid, which was collected byfiltration, the filtrate being set aside for the subsequent examinationof the sugar. The solid substance was washed with water, andrecrystallised from alcohol, when i t separated in slender, colourlessneedles, melting at 183O, and containing water of crystallisation :0.1936, heated a t 120°, lost 0.0113 H,O.0.0961 * gave 0'2724 CO, and 0.0906 H20. C=77.3; H=10.5.The molecular weight of the subdance was determined by boththe cryoscopic and the microscopic method, with the followingresults :0,1681,* in 19.8 C.C. benzene, gave A t - O'lOOo, whence M.W. = 424.0.1820,* in 10 C.C.alcohol, was between 0.05 and 0.04 mol.H,O=5'8.Mean M.W. = 404.C26H4203,1iH20 requires H20 = 6.3 per cent.C20H4203 requires C = 77.6 ; H = 10.4 per cent,. M.W. = 402.From the above results it is evident that the hydrolytic productof sarsasaponin, for which the name sarsasapogenin may be retained,possessea the empirical formula C2,H,,O3. This is further con-firmed by the analysis of its acetyl derivative, described below.It has been stated by W. v. Schulz (Zoc. tit.) that the completehydrolysis of sarsasaponin is only effected with great difficulty,and that the resulting hydrolytic product, sarsasapogenin, possessesthe formula C2,H4,04. Inasmuch as the sarsasaponin obtained inthe present investigation was easily and completely hydrolysed bythe above-described treatment, it is probable that the glucoside ofv.Schulz was contaminated with some phytosterolin, such as is nowknown t o be present in sarsaparilla root, and which is only veryslowly liydrolysed by aqueous acids.Sarsasnpogeiziia, C,,H4,02*OH, is readily soluble in chloroform orbenzene, but only moderately so in ether or cold alcohol. Whenthe substance is dissolved in acetic anhydride, and a few drops ofconcentrated sulphuric acid subsequently added, a yellow colorationis produced, and the liquid soon develops a green fluorescence. Onkeeping for some time, or on the addition of a larger amount ofsulphuric acid, the liquid acquires a reddish-brown colour. Sarsa-sapogenin is optically active :0.1133, made up to 20 C.C.with methyl alcohol, gave a, - 0 O 4 1 'in a 2-dcm. tube, whence [aJD -60-3O.* Anhydrous substance21 6 POWER AND SALWAY:Monoacetylsarsasapogenim, Cz6R4,O3*CO*CH,. - This compoundwas prepared by heating sarsasapogenin for an hour with aceticanhydride, the solution being then concentrated to a small bulk,and a little alcohol subsequently added. A-fter a short thee anacetyl derivative separated, which, when collected and recrystallisedfrom alcohol, was obtained in colourless needles, melting a t 137O.It was analysed and its specific rotation determined, with thefollowing results :0.0968 gave 0.2684 CO, and 0.0872 H20.0.1160, made up to 20 C.C. with chloroform, gave aD -0O40‘ inC=75*6; H=10.0.CZ8H4,O4 requires C = 75.7 ; H = 9.9 per cent.a 2-dcm. tube, whence [aID -57’5O.The acid, aqueous liquid resulting from the hydrolysis of sarsa-saponin was treated with just sufficient barium hydroxide to pre-cipitate the sulphuric acid completely, and the mixture thenfiltered.The filtrate, on evaporation, yielded a syrup, from whichd-phenylglucosazone (m. p. 2 1 4 O ) was prepared, thus proving thepresence of dextrose. No evidence could be obtained of theformation of any other sugar as a product of hydrolysis of theglucoside.The above results have shown that sarsasaponin is resolved onhydrolysis into sarsasapogenin, C26€1420s, and dextrose. I n orderto ascertain the relative proportion of sarsasapogenin which isyielded by the glucoside, a definite quantity of the latter, dried at1 20°, was hydrolysed, and the respective hydrolytic productcollected, dried a t l l O o , and weighed.The amount of sarsa-sapogenin thus obtained was 38 per cent. of the weight of sarsa-saponin employed (C44H76020 requires C26H42O3 = 43.5 per cent.).The hydrolysis of the glucoside may thus be represented by thefollowing equation :C,,H7G0,, + H20 = C5-&34203 + 3C,H1,06.The assumption of v. Schulz (loc. cit.) that by the hydrolysis ofsarsasaponin an acid or a mixture of acids is formed, together withthe other products mentioned, cannot be confirmed, and is obviouslyincorrect. The acid observed by him was doubtless only such as isproduced by the action of the hydrolysing agent on the sugar.Examination of “ Smilclcin ’’ ((( Smilasapomh ” of ‘N.Schulz).The substance described by v. Schulz (loc. cit.) as ‘( smilasaponin,”and recorded in the literature undei that name or as “smilacin,”was evidently regarded by him as a dstinct glucoside of sarsaparillaroot. Although an amorphsus product, he assigned to i t thCHEMICAL EXAMINATION OF SARSAPARILLA ROOT. 21’7formula (C20H320,,),,1 2H,O, and observed its optical rotation t o be[uJD - 26.25O. Inasmuch as the “smilasaponin ” examined byv. Schulz was stated to have been the preparation known in corn-inerce as ‘( smilacin,” i t was deemed desirable in connexion with thepresent investigation to determine its character. A small quantityof the preparation was therefore obtained from the same soiirceof supply as had been indicated by v.Schulz.“Smilacin,” as procured from the source indicated, was a palebrownish-yellow, amorphous powder. It dissolved readily in water,yielding a yellow solution, which frothed strongly on agitation, anddid not reduce Fehling’s solution. The substance, when heated ina capillary tube, began to sinter a t 140°, and decomposed withevolution of gas a t 1 6 0 O . When heated a t l l O o , it lost 17-7 percent. of its weight, and on ignit:on it left a small amount ofinorganic residue. I n view of the character of the substance, itwas not deemed suitable for analysis, and on account of the colourof its aqueous solution the optical rotatory power could only bedetermined with approximate accuracy.‘0.2250 of anhydrous substance, made up to 20 C.C.with water,gave a, about - loo’ in a 2-dcm. tube, whence [a],, -44’4O.When a little o+ the substance was dissolved in acetic anhydride,and a few drops of concentrated sulphuric acid subsequently added,a reddish-brown coloration was produced, the liquid also showinga faint green fluorescence.Hydrolysis of ‘( &‘milacin.”-Three grams of the substance weredissolved in 30 C.C, of amyl alcohol, and 10 C.C. of 15 per cent.aqueous hydrogen chloride added, together with sufficient alcohol(about 1 c.c.) to render the mixture homogeneous. This solutionwas heated for three hours, and the amyl alcohol then removedin a current of steam, when a dark-coloured solid remained in thedistillation flask. The solid was extracted with ether, and theethereal solution washed with aqueous sodium carbonate, whichremoved a small amount of brown, amorphous material.Theethereal liquid was then dried, and the solvent removed, when0.3 gram of a substance was obtained, which, when crystallised fromalcohol, separated in colourless, feathery needles, melting a t184-185O. When the substance was mixed with a specimen ofpure sarsasapogenin (m. p. 183O) no depression of the melting pointensued. It also showed tho same behaviour as the last-mentionedcompound when dissolved in acetic anhydride and a drop of con-centrated sulphuric acid subsequently added. The identity ofthe substance with sarsasapogenin was further confirmed byanalysis 218 CHEMICAL EXAMINATION OF SARSAPARILLA ROOT.0.0712 gave 0.2035 CO, and 0.0665 H,O.C2,H4,03 requires C = 77.6 ; H = 10*4 per cent.The aqueous liquid resulting from the above-described hydrolysiswas exactly neutralised with sodium carbonate, and then evaporatedto dryness under diminished pressure.This residue was digestedwith hot alcohol, the mix$ure filtered, and the filtrate evaporated.A syrupy liquid was thus obtained, which readily reduced Fehling’ssolution, and yielded an osazone melting a t 212O.It is evident from the above results that the so-called “smilacin,”which has now been examined, contained a relatively small pro-portion of the glucoside sarsasaponin, but that i t consisted for themost part of indefinite amorphous products.C=77*9; H=10*4.2Yummary and Con c1iisiot)s.The material used for the present iiivestigatiori c.onsistetl of n.good quality of grey Jaiuaica sarsaparilla root.The root was found to contain a small amount, of azi enzyme,which slowly hydrolysed ainygdalin.An alcoholic extract of the root, when distilled in a current ofsteam, yielded an amount of essential oil equivalent to about 0.01per cent.of the weight of root employed. This essential oil wasa pale yellow liquid, which distilled between 70° and 200°/15 mm.,and had a density of 0.977 a t 1 5 O / 1 5 O .The alcoholic extract was found to contain the following definitecompounds : (i) a crystalline glucoside, sarsasaponin, C,,H7,0,,,7H,O(m. p. 248O; [aID -48*5O), which, on hydrolysis, is resolved intosarsasapogenin, C,,H,,O, (m. p. 183O; [ a ] , - 60’3O), and dextrose.Sarsasapogenin yields a mo~~oacetyE derivative, C,,H,,O,-CO*CH,(m. p. 137O ; [alp - 57.5O) ; (ii) sitosterol-d-glucoside (phytosterolin),C33H5606 (m. p. 280-285O); (iii) sitosterol, C,,H,,O (m. p.135-136O; [a],, - 27‘3O) ; (iv) stigmasterol, C,,H,,O, identified byits tetrabromoacetyl derivative, CmH490Br4*CO*CH, (In. p. 208O) ;(v) a nsw, crystalline, dicarboxylic acid, sarsapic acid,C,H,O,(CO,H),, melting a t 305O, and yielding a dimethgl ester,C,H80, (m. p. 121O) ; (vi) dextrose, from which B-penta-acetyldextrose (m. p. 131-132O) and d-phenylglucosazone (m. p. 212O)were prepared; (vii) a mixture of Fatty acids, consisting of palmitic,stearic, behenic, oleic, and linolic acids. The alcoholic extract con-tained, furthermore, a small quantity of a substance which possessedthe characters of cetyl-d-glucoside, and a considerable quantity ofpotassium nitrate was also present. The total amount of resinousmaterial was equivalent to about 1’25 per cent. of the weight ofthe rootIDENTITY OF THE SUPPOSED B-2 : 5-DIMETHYLPIPERAZINE. 219The results of the present investigation have shown that Jamaicasarsaparilla root contains but one definite saponin glucoside, namely,sarsasaponin. This is accompanied, however, in the root by aphytosterolin (sitosterol-d-glucoside), which represents a class ofcompounds that has only quite recently been known t o occur inplants (compare T., 1913, 103, 399, 1022). It is probable that thesame or similar conditions exist with respect to the constituents ofother commercial varieties of sarsaparilla root, and the compositimand properties of the compound designated by v. Schulz and earlierinvestigators as parillin would, in fact, indicate that it consistedof a mixture of sarsasaponin and a phytosterolin. The-so-called‘I smilacin ” ( ’ I smilasaponin ” of v. Schulz), as examined by tEepresent authors, has been ascertained not to be a homogeneoussubstance, but t o contain some sarsasaponin, together with indefiniteamorphous products.It may finally be noted that v. Schulz (Zoc. cit.) had foundsarsasaponin to be, physiologically, the most active of the glucosidicproducts described by him, and this observation ia quite inaccordance with the above conclusions respecting the character of(( parillin ” and (‘ smilasaponin.”THE WRLLCONUE CHEMICAL RESEARCH hBORATORIES,LONDON, E.C

ISSN:0368-1645    

DOI:10.1039/CT9140500201

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

IDENTITY OF THE SUPPOSED @-2 : 5-DIMETHYLPIPERAZINE. 219XXVI.-I'he Identity of the Supposc?d p-2 : 5-Dimethyl-papra xzn.e.By WILLIAM JACKSON POPE and JOHN READ.IN a recent paper (T., 1912, 101, 2325) we have called at+ntionto the interesting character of the stereoisomerism which shouldbe exhibited by substances of the constitution :and have pointed out that the isomeride of the &-configurationshould Kiossess an axis of two-fold symmetry, but should be ofenanti0:rnorphous molecular configuration. Such a substance wouldthereforre be expected to exhibit optical activity in the amorphousstate. ,For the purpose of experimeiitally illustrating the importantsbreoc- ,hemica1 relationships which should hold between isomerideso f f h e constitution depicted, we endeavoured to resolve both of thedescrik led 2 : 5-dimethylpiperazines 220 POPE AND READ: THE IDENTITY OF THEinto enantiomorphously related components ; the substance of thetrans-configuration should, in accordance with the van't Hoff-LeBelconception, not be so resolvable, whilst the cis-compound ought t oexist in enantiomorphous, and therefore optically active, modifica-tions.Although the methods which we employed were of exhaus-tive applicability, neither substance could be resolved ; we weretherefore forced to the conclusion that both the a- and 8-2:5-di-methylpiperazines are potentially inactive, a conclusion which is indisaccord with t'he theoretical interpretation of the configurations.We have now subjected a- and &2:5-dimethylpiperazine to afurther experimental examination, arid have arrived a t the conclu-sion (1) that the substance described as B-2 : 5-dimethylpiperazinehas not the constitution hitherto assigned to it, and must be thecis-2 : 6-dimethylpiperazine,NH<CH(CI-I,)*CH,>NH.CH( C H 3)*C H,the conclusion (2) is also drawn that the non-resolution of thea-2 : 5-dimethylpiperazine indicates that this substance is t~ans-2 : 5-dimeth ylpiperazine.Conclusion (1) is based on the following experimental evidence :The so-called p-2 : 5-dimethylpiperazine cannot be resolved intooptically active components by means of its salts with opticallyactive acids or by means of its condensation products with d-oxy-methylenecamphor ; as it is scarcely credible that these methodsshould fail to reveal potential optical activity, it would seemimprobable that the substance is the cis-isomeride of the 2:5-di-methyl derivative. I n the present paper we increase the evidenceagainst the potential optical activity of this 8-isomeride by failingto resolve its N-dimethyl derivative, which, if it had the cis-con-figuration of the constitutionCH N( CH,)*C H Z>C<F3, b>C<cH, .N (C H ,)should, together with the parent secondary base, be resclvable.It is, however, conceivable that in spite of E.Fischar's demon-stration of a parallel case amongst the alanyl anhydri&es (Ber-,1906, 39, 467; 1906, 40, 3981), some discrepancy exists betweentheory and experiment, and that the cis-2 : 5-dimethylpi$~%Zineand its M-dimethyl derivative are both potentially inactive, ihecausethe configuration of both contains an axis of two-fold syp fimetrYalthough it is enantiomorphous. We have, however, prepar ed themonomethiodide of the tertiary base, and have been une bIe f~resolve this substance into optically active isomerides; thic: C c m -pound should have the constitutioSUPPOSED p-Z : 5-DIMETHY LPIPERAZINE.221and the configuration contains two dissimilar asymmetric carbonatoms, and possesses neither axes nor a centre of symmetry. Themolecular configuration is theref ore enantiomorphous in a differentdegree from those of the parent secondary or tertiary base, andshould consequently again be resolvable, whether it possesses thecis- or the trans-configuration.These facts led us to suspect strongly that the so-called 8-2 : 5-di-methylpiperazine has not the constitution which this nameindicates.I f we mume that the failure to resolve the quaternary ammon-ium salt named proves the absence of asymmetric carbon atoms inthe configuration of the compound, and that the preparation of the@secondary base by reduction- of a pyrazine derivative proves thatthe two methyl groups are attached to two different carbon atomsin the c l o d ring, the 8-base can only be the cis-2:6-dimethyl-piperazine of the constitutionThis constitution, which is suggested by the failure to resolve theseveral compounds named above into optically active components,is capable of verification in a quite different manner.The twosecondary nitrogen atoms in ths above molecular constitution aredifferent in kind, and each moneacidic derivative of the baseshould therefore exist in two isomeric forms; we accordinglyattempted to prepare isomerides of this kind, and were completelysuccessful. The supposed /3-2 : 5-dimethylpiperazine yields twomonobenzoyl derivatives, melting at 1 1 7 O and 109O respectively,and consequently the subsiance in question must have the constitu-tion of the 2 : 6-dimethylpiperazine given above.The preparation of a monobenzoyl derivative of a di-secondarybase, in which the two tervalent nitrogen atoms exhibit the sameorder of basicity, is known to be difficult; with the &base inquestion all modifications of the Schotten-Baumann reactionyielded the dibenzoyl derivative. The monobenzoyl derivative wasultimately obtained by treating the base in acetone solution withone molecular proportion of benzoyl chloride; as the latter reagentis added, the hydrochloride of the monobenzoyl derivative separatesfrom solution, and is thus conserved from the further action ofthe acid chloride.I n the present paper it is assumed, for purposesof description only and without other adequate ground, that thisbenzoyl group which first enters the molecule attaches itself to the4-nitrogen atom.The preparation of the 1-monobenzoyl derivative is less simple.In our previous paper we have shown that dimethylpiperazined222 POPE AND REAU: THE IDENTITY OF THEmethylenecamphar results from treating the base with d-oxy-methylenecamphor i n alcoholic acetic acid solution ; we now findthat on heating d-chloromethylenecamphor and the di-secondarybase, the monomethylenecamphor derivative,separates as its hydrochloride.The resulting methylenecamphorderivative can be benzoylated by the Schotten-Baumann reaction ;the methylenecamphor radicle can then be eliminated by treatmentwith bromine in the manner previously described (T., 1912, 101,2337), and the 1-monobenzoyl derivative of the secondary base isobtained.The two monobenzoyl derivatives thus obtained are, as alreadynoted, different substances, and neither is resolvable into opticallyactive components ; in connexion with their preparation we havebeen able t o prepare the isomeric 1-benzoyl-2 : 6-dimethylpiperazino-4-d-methylenecamphor and 4 - benzoyl - 2 : 6 - dimethylpiperazino-l-d-methylenecamphor, the different identity of which is made parti-cularly evident by the different rotation constants which theyexhibit.These and other corresponding derivatives described inthe present paper, in accordance with the conclusion that they arederived from the cis-2 : 6-dimethylpiperazine, have proved non-resolvable into optically active components.The mono-acidic derivatives of the dimethylpiperazine, in whichone acidic radicle, 9, has been introduced in the 4-position by thenew method, am capable of undergoing the Schotten-Baumannreaction; a second acidic radicle, B, can thus be introduced in the1-position. We have thus been able to prepare pairs of isomericdiacidic derivatives of the parent base, of the constitutions4-A .l-B and 4-B.1-8; this is again in accordance with theconstitution now proposed for the base.Lastly, we have been able to introduce a d-methylenecamphorresidue into the molecule of the base in the 4-position and aI-methylenecamphor radicle into the 1-position ; the product isoptically active, proving conclusively that the 1- and 4-positions arenot identically similar.The experimental evidence, briefly summarised above and statedin detail in the following pages, which indicates that the so-calledp-2 : 5-dimethylpiperazine is really the cis-2 : 6-dirnethylpiperazine,appears to be convincing. It is, however, difficult t o show in whatmanner the latter compound has resulted from the method ofpreparation used.Stoehr has described ( J .pr. C'hem., 1893, [ii], 47, 494; 1897, 55,49) several methods for the preparation of the 2 : 5-dimethylSUPPOSED p-2 : 5-DIMETHYLPIPERAZINE. 223pyrazine, which, by reduction, yielded him a-2 : 5-dimethylpiperazinemixed with a very small proportion of the j3-isomeride; he statesthat the parent tertiary base is conveniently obtained by thereduction of isonitrosoacetone, and that he was only able to isolatethe B-reduction product in quantity from the residues obtained onworking on an industrial scale. It may be suggested that in thetechnical procese the 2 : 5-dirnethylpyrazine used is not highlypurified before reduction to the piperazine derivative, and that i tcontains a small proportion of the isomeric 2 : 6-dimethylpyrazine ;we are not able to settle this point.It should, however, be notedthat Stoehr and Brandes ( J . p. Chem., 1896, [ii], 54,492) separateda crystalline base, which they presumed to be 2 : 6-dimethylpyrazine,from the product of the action of ammonia on dextrose; the reduc-tion of this substance may be expected to yield the B-base nowunder discussion.The a-2 : 5-dimethylpiperazine described by Stoehr, which we havepreviously investigated, is, in the present paper, shown to differin behaviour from the 8-isomeride; on applying the methods whichproved successful in the case of the latter substance it was notfound possible to prepare derivatives containing but one acidic ormethylenecamphor radicle in the molecule.There is therefore noreason to doubt that the constitution of the a-isomeride wascorrectly stated by Stoehr, and, since this substance has not beenfound capable of resolution into optically active antipodes, it appearssafe to conclude that it is actually trans-2 : 5dimethylpiperazine.It is remarkable that the a- and Bdimethylpiperazines, which wenow show to be the trans-2 : 5- and cis-2 : 6-dimethylpiperazinesrespectively, resemble each other extremely closely in physicalproperties ; the melting points, boiling points, and solubility rela-tionships are very similar, and, as has been indicated by Btoehr,the only certain rapid way t o distinguish between them is by meansof their dibenzoyl derivatives.The dibenzoyl derivative of thea-base melts at 225O, and that of the &base contains a molecule ofwater of crystallisation and melts at 147-148O; it is very note-worthy that almost identical crystalline forms are assigned to thetwo by Fock ( J . I;r. Chem., 1893, [ii], 47, 505; 1897, 55, 61); theyare monosymmetric, with the following axial ratios :a-Dibsnzoyl, a : 7) : c = 2.6233 : 1 : 1.6623.B-Dibenzoyl, a : b : c = 2.6833 : 1 : 1.6013.B = 71Q52J.~3 = 7201 7'.It is llot easy to see how two isomeric substances, one anhydrousand the other containing a molecular proportion of water of crystal-lisation, can resemble each other so closely in crystalline form224 POPE AND READ: THE IDENTITY OF THEEXPERIMENTAL.cis-1 : 2,: 4 : 6 - T e t ~ u m e t J t y l ~ ~ ~ ~ r u z i ? c e ,The P-base, separated from technical residues, very kindlysupplied by the Farbenfabriken vorm.I?. Bayer & Co., in themanner previously described, is finally purified by crystallisationfrom petroleum (b. p. 90-looo) and acetone; the colourless, trans-parent plates obtained in this way melt at l l O - l l l o , and are onlymoderately soluble in hot acetone, which is therefore the mostconvenient solvent to use in the final purification. The diberizoylderivative prepared from it by the Schotten-Baumann reactionafter drying a t looo, melts sharply a t 153O; there is therefore nodoubt that the P-base we have used in the present work is identicalwith that of Stoehr.The base is methylated in aqueous solution with methyl sulphate(three molecular proportions) ; the latter is added gradually togetherwith dilute sodium hydroxide in such a manner that the solution isalways kept cool and slightly alkaline.After warming to completethe reaction, solid sodium hydroxide is added when the liquid baseand solid sodium methyl sulphate separate; the former is causedto rise to the surface of the liquid by slight warming, and, afterremoval from the aqueous layer, is dried with potassium hydroxideand distilled. The base is obtained as a colourless liquid boilinga t 163--164O, which possesses a characteristic ammoniacal odour,and is practically non-volatile in steam; i t is miscible with waterand most organic solvents, including light petroleum, in all propor-tions.The pZu t iizic hZo&Ze, C8H,,N2,H2P tC1,,3H20, crys t allises from hotwater in lustrous, orange needles, which blacken a t about 270° anddecompose profoundly a t 275O; it is moderately soluble in hotwater, and practically insoluble in alcohol and other organicsolvents :0.5816 lost 0-0350 a t looo.C8HI8N,,H,PtC1,,2H@ requires H,O = 6.12 per cent.0.3960, dried a t looo, gave 0.1393 Pt.C8H,,N2,H2PtC1, requires Pt = 35.35 per cent.The picrate forms small, yellow crystals, and is practicallyinsoluble in water, alcohol, and acetone, but dissolves in excess ofbase or in dilute ammonia ; it decomposes suddenly a t about 280° :CsHI8N2,2C6Ha0,N3 requires C= 40.00; H= 4.03 per cent,H,0=6'02.Pt=35*17.0'1257 gave 0.1864 C02 and 0.0524 H20.@=40*44; H=4*66SUPPOSED 6-2 : 5-DIMETEYLPIPERAZINE. 225The above base, practically non-volatile in steam, is the soleproduct of methylation with methyl sulphate under the conditionsstated above. On treating the parent secondary base with alcoholicpotassium hydroxide and methyl iodide (two molecular proportions)two tertiary bases appear to be produced; one of these is identicalwith that just above described, whilst the other volatilisea readilyin steam. The latter yields a platinichloride, which, like that of theprevious base, contains two molecular proportions of water ofcrystallisation. The apparent difference between these two productahas not yet been further studied aa it does not affect the mainquestion under investigation.Attempts to Resolve cis-1 : 2 : 4 : 6-Xetramethylpiperaaine.The base combines with two molecular proportions of d-camphor-&sulphonic acid to yield a single crystalline salt, which melts a t223O, and forms minute, glistening needles or prisms when crystal-lised from a mixture of alcohol and acetone:0'1096 gave 0.2221 CO, and 0.0819 q0. C=55*27; H=8.36.CsHlsN2,2Cl,Hl,0*S03H requires C= 55.44 ; q=8-25 per cent.An aqwuus solution of 0.1949 gram, made up to 30 C.C.withwater at 20°, gave ~ + 0 * 5 6 ~ for the mercury-green line,whence [a] + 21'6O and [MI12 + 6503~.As no appreciable change in the rotatory power of the saltoccurred on recrystallisation, and as the value obtained is practi-cally identical with that for the acidic ion in aqueous solution, itis clear that the base cannot be resolved'by means of this salt.cis-1 : 2 : 4 : 6-Tetrameth~ylpiierazine d-a-Bromocampho&sdphonate, CsH18N2,2C,oHl,0Br~S0,H.This salt, prepared by evaporating t o dryness an aqueous solutionof the component base and acid, is very soluble in water or alcohol,and readily so in warm acetone.It separates from the lattersolvent in minute, glistening crystals, melting at 175O; the crystalsretain about 1.5 per cent. of water, which is driven off at looo,and the data given below refer to the salt which has been thusrendered anhydrous :0.0984 gave 0.1570 cy), and 0'0547 H20. C=43*47; H=6*21.CsH,,N,,C20H,0,Br2S2 requires C = 43-97 ; H = 6.33 per cent.The rotation constants are not altered by fractional crystallisa-tion : 0.1980 gram, made up to 30 C.C.with water, gave aHg green +2'57O in a 4-dcm. tube a t ZOO, whence [a] + 97.4O and [MI12 + 372O.These results show that the base has not been resolved into opticallyactive components by the aid of this salt.VOL. cv. 226 POPE AND READ: THE IDENTITY OF TEEcis-1 : 2 : 4 : 6-Tetrarnethglpipera~ke d-a-Bromocamphor-n-sdphonu t e, C8H,,N,,2 Cl,Hl,OBr* SO&This salt crystallises readily from acetone, in which it is sparinglysoluble, containing a little alcohol, in fine, colourless needlm, meltingat 249O:0.0787 gave 0.1267 C02 and 0*0468 H,O. C=43.91; H=6*65.C8H18N2,CmH,08Br,S, requires c= 43.97 ; H = 6-33 per cent.An aqueous solution containing 0.2010 gram of the salt in 30 C.C.gave aHggreen+ 2 3 6 O a t 20°, whence [a] + 88.1O and [MI12 + 336.5O.The final separation obtained on fractional crystallisation gave,with 0.2089 gram in 30 c.c., a +2*46O for the same wavelength,whence [a] +88.3O and [M]/2 +337O.The molecular rotatorypowers of the fractionated and unfractionated salt are nearly thesame, and are practically identical with the value determined forthe acidic ion; it is therefore concluded that no resolution hasbeen effected.The normal d-tartrate of the baae dissolves readily in water, andis moderately soluble in alcohol, from which solvent it crystallisesin white, opaque nodules containing about 10 per cent. of waterof crystallisstion, and melting below looo. The salt, both beforeand after fractional crystallisation, gives the specific rotatorypower of about + 20° in aqueous solution; as it was clearthat no resolution was effected by means of the tartrate the saltwas not further examined.The picrate prepared from the fractionated d-tartrate provedinactive in ammonia solution.cis-l : 2 : 4 : 6-Tetramethylp'perazine Monomethiodide,ct3H1sN2,cH31*On mixing acetone solutions of the tertiary base and excess ofmethyl iodide heat is evolved, and, provided the solution is notallowed to become too hot, long, lustrous, colourless needles of themethiodide slowly separate; the substance is readily soluble inwater or alcohol, and moderately so in acetone.It crystalliw froma mixture of alcohol and ether in small needles melting a t 227O,and deliquesces in the air; the solutions are neutral in reaction,and the salt does not combine with a second eqwivalent of anacid :0.2025 precipitated 7.2 C.C. N / 10-AgNO,.1=45*1.C,H,,N,,CH,I requires I = 44.7 per centSUPPOSEDr@-2 : 5-DIMETHYLPIPERAZINE. 227cis-l : 2 ; 4 : 4 ; 6-Pentarnethylpiperasonium d-a-Bromocamphor-.rr-sulphonut e, CS,H2,N,*~0,*C1,H1,OBr,l*5 H20.This salt is obtained by double decomposition between the abovemethiodide and the silver salt of the optically active acid inaqueous solution; it is extremely soluble in water or alcohol, and,when crystallised from a mixture of alcohol and acetone, is oblainedin glistening plates melting at 214O:0.1017 * gave 0.1823 GO, and 0.0665 H20.C9~1N2*S03*C,,Hl,0Brequires C=48*79 ; H = 7-55 per cent.0.8133 lost 0.0453 a t looo.H20=5'57.. C9H21N,*S03*C10H,40Br,l~5~0 requires H,O = 5-47 per cent.The rotatory power of the salt was not appreciably changed byfractional crystallisation ; 0'2020 gram of the anhydrous substance,made up to 30 C.C. with water, gave a t 20° uHggreen + 2*00° in a4-dcm. tube, whence [a] +74*3O and [MI +347O. No resolution isthyefore effected with the aid of this compound.C = 48-89 ; H = 7-32.cis-l : 2 : 4 : 4 : 6-€'entametiiybpiperazoni&n d-a-Bromocamphor-&sutphona.t e, C9~1N2~S03*CloH,,0Br.This salt, obtained by double decomposition in the same manneras the previous om, is very soluble in water or alcohol, and crystal-lises from a mixture of alcohol and acetone in colourless, lustrousprisms, melting a t 226--227O; it does not retain water of crystal-lisation :0*1388 gave 0'24'70 CO, and 0.0918 H20.C=48.53; H=7*40.C9~,N2*S03*CloH,,0Br requires C=48*79 ; H = 7-55 per cent.The salt as first prepared (a) and the final product of its frac-tional crystallisation ( b ) gave the following values for the rotationconstants with solutions containing 0-2000 gram in 30 C.C. ofaqueous solution a t ZOO for the mercury-green ray, 4-dcm. tubesbeing used:( a ) a + 2 * 1 6 O . [a] +51*Oo. [MI + 3 7 8 O .(b) u +2.18O. [a] +81.S0. [MI + 3 8 2 O .The fact that the molecular rotatory power is not appreciablyaltered by fractionation and is practically identical with that of theacid ion, indicates again that resolution has not been effected.cis-1 : 2 : 4 : 4 : 6-Pe~ztamef.hylpiperazonium d-Camphor-&wlphonate,C,~1N2'S03°C,0H,,0,H20.The salt prepared by the interaction of aqueous solutions of themethiodide and the silver salt of the optically active acid is very* Dried at 100".Q 228 POPE AND READ: THE IDENTITY OF THEsoluble in water or alcohol, and crystallises from hot acetone, inwhich it is moderately soluble, in small, colourless needles, melting,at 254O:0.1214 * gave 0.2609 CO, and 0.1014 H,O.C=58.61; H=9-35.0.5160 lost 0.0205 a t looo. H,O=3*97.The rotatory power of the salt was unchanged by fractionation,0.2014 gram, dried at looo, made up to 30 C.C. with water a t20°, gave a +0*46O for mercury-green light in a 4-dcm. tube,whence [a] -t-17*lo and [MI +66.5O.The corresponding d-tartrates, containing one and two equiva-lents of the acid to one of the base, were also prepared; they arevery soluble in water, but practically insoluble in alcohol or acetone,and are also very hygroscopic and difficult to obtain crystalline.In view of their unpromising character, they were not furtherinvestigated.C?91i&lN2*S03*Cl,H,,0 requires 0=58*71; H = 9-34 per cent.C9~lN2*S0,*Cl,Hl,0,H20 requires H20 = 4.43 per cent.and is practically identical with that of the acid ion:cis-1 : 2 : 4 : 6-Tetramethylpiperazin,e Dimethiodide,The pure cis-1 : 2 :4 : 6-tetramethylpiperazine boiling a t 163-164Ois heated at 150° in a sealed tube with a little methyl alcohol andrather more than two molecular proportions of methyl iodide forthree hours; the dark-coloured residue, after evaporation to dryness,is dissolved in alcohol and caused to crystallise.On repeated crystal-lisation from hot alcohol the dimethiodide is obtained in long,colourless needles, which are moderately soluble in the solvent andmelt at 241-242O. The substance is deliquescent, and practicallyinsoluble in acetone or chloroform :0*2000 precipitated 9.3 C.C. N / 10-AgNO,. I = 59.30.C8H18N2,2CH,I requires I = 59-63 per cent.cis-1 : 1 : 2 : 4 : 4 : 6-Eexamethylpiperazom~wm d-a-Bromocamphor-1-sulphonate, CloH&N2(S03*~oH140Br)2,H20.The dimethiodide reacts readily in aqueous solution with thesilver salt of the optically active acid; the new salt is extremelysoluble in water or alcohol, and insoluble in acetone.It crystallisesfrom a mixture of alcohol and acetone in lustrous, colourlessneedles, melting a t 287O:* Dried a t 100"SUPPOSED b-2 : 5-DIMETHYLPIPERAZINE. 2290.5317 lost 0.0112 a t looo.C,,€i&N,( S0,*Cl,H,,0Br),,H20 requires H20 = 2-22 per cent.0.1344 * gave 0'2252 CO, and 0.0769 H,O. C =45.70 ; H = 6.40.C,,H,N2(S03*C,,H,,0Br), requires C- 45.43 ; H= 6-62 per cent.On fractional crystallisation it was found that all the fractionsexhibit the same rotatory power; the weigh& of the first (a) andlast fractions (b) noted below, dried at looo, w0re made up to30 C.C. with water at 20°, and the rotatory powers determined formercury-green light in 4-dcm. tubes :(a) 0.2001 gram: a ;2.32O. [a] +87.0°. [M]i2 +344O.( b ) 0.1987 ,, a + 2.29O.[a] + 86'4O. [M]/2 + 342O.The constancy of the molecular rotation and the fact that itapproximates closely to that for the acidic ion indicates that thesalt is a uniform substance.H20=2.11.cis-1 : 1 ; 2 : 4 ; 4 6-€lexamethylp~peruzonium d-a-Bromocamphor-fl-sulphonat e, Clo&Nz( S03Cl,H,,0Br)2.This salt, prepared in the same manner it8 the preceding one,separates from a mixture of alcohol and acetone in soft, colourlessneedles, melting at 262O; on heating a t looo it loses less than1 per cent. in weight. The following data refer to material driedat looo, and the rotation constants for the first (a) and last (b)fractions are stated in the same terms as before:0.1107 gave 0.1848 CO, and 0.0676 H,O. C=45.53; H=6.83.C,,H,N,(S03~C?l,H,,0Br), requires C=45*43 ; H = 6-62 per cent.(a) 0.2070 gram: a +2*55O.[a] +92*5O. [M]/2 +366O.( 6 ) 0.2041 ,, a + 2'54O. [a] + 93'3O. [M]/2 + 370O.No indication of resolution is thus obtained, and the observedmolecular rotatory power is practically identical with that of theacidic ion.cis-1 ; 1 ; 2 ; 4 : 4 : 6-Hemmethylp~perazonium d-Camphor-fl-sulphonat e, C10&N2( S0,-Cl,H,,0)2,H20.This salt waa prepared by the interaction of the dimethiodideand the silver salt of the acid, and is very soluble in water oralcohol; it separates in glistening, colourless leaflets or needles onadding acetone to its warm alcoholic solution, and melts a t 306O :0'3566 lost 0.0110 at looo.C,,H,N,( S03*CloH,,0)2,H20 requires H20 = 2.76 per cent.0.1153" gave 0.2287 CO, and 0-0878 H,O.C=56-46; H=8*62#C,oH~N,(S0,*CloH,,0)2 requires C= 56-73 ; H= 8.58 per cent.* Dried at 100".%0=3.09230 POPE AND READ: THE IDENTITY OF THE0.2001 gram of the salt, dried a t looo, made up to 30 C.C. withwater at 20°, gave a +0*56O for mercury-green light in a4-dcm. ’tube, whence [a] +21*O0 and [M]/2 +66*5O.The several fractions had the same rotatory power, so that noevidence of resolution is afforded.The experimental results described in the previous pages indicatethat the Ndimethyl derivative of Stoehr’s fldimethylpiperazine ”and the corresponding mono- and di-methiodides, like the originalsecondary base, ars‘irresolvable into optically active components,Mono-acidic D er iva t i u es of fl-Dim e th ylpiperazine.”cis-4-Benzoyl-2 : 6-dimethylpipera&e,We spent some time in finding a method for the prepakationof these substances, in view of their importance, and are able todescribe the following method, which is of general application.An acetone solution of benzoyl chloride (1 mol.) is slowly runinto an acetone solution of the base (1 mol.) with constant stirring;the solution becomes hot, and a white, crystalline solid separates.After remaining for an hour the deposit is collected and well washedwith acetone; analysis shows it to be the pure hydrochloride of themonobenzoyl derivative :0.2515 precipitated 10.2 C.C.iV/lO-AgNO,. C1= 14.36.C13H,,0N2,HCl requires C1 =.l3*95 per cent.The hydrochloride is obtained in theoretical yield, and is readilysoluble in water or alcohol; it separates in minute, colourless crystalson slowly adding acetone to its alcoholic solution.The salt is dissolved in water, rendered alkaline with sodiumhydroxide, and the solution distilled in steam t o drive off ahyunchanged &base ; the residual liquor is then extracted withbenzene, and the monobenzoyldimethylpiperazine obtained by dis-tilling off the benzene.The free base is soluble in water, but isdeposited from the solution on addition of much sodium hydroxide ;it is very soluble in the ordinary organic solvents, with the excep-tion of light petroleum. It separates slowly from the cooledsolutions in hot light petroleum in arborescent growths of colourless,fine needles, melting at 117O; the crystals retain about one-half amolecular proportion of water of crystallisation, which is driven offa t looo:0.1000 * gave 0.2629 CO, and 0.0778 H20.C=71*70; H=8*71.CI3Hl8ON2 requira C= 71-51 ; H = 8-32 per cent.* Dried at 100”SUPPOSED a-2 : 5-DIMETHYLPIPERAZINE. 231The base is readily hydrolysed by boiling dilute hydrochloric acid,and benzoic acid crystallises out on cooling; it is noteworthy thatthe corresponding dibenzoyl derivative is stable even towardsboiling concentrated hydrochloric acid.The platinichloride separates from hot water in small, glistening,yellow crystals, melting and decomposing a t 256O; it is practicallyinsoluble in alcohol :0.4007 gave 0.0921 Pt. Pt=23*02.(C13H,,0N2),,~PtC16 requires Pt = 23.05 per cent.cis-4-Benzoyl-2 : 6-a?imethylp*perazine d-Camphor-&sulphona te,C6H13~20@OoC6H5,C10H150~ S;03H.On evaporating an aqueous solution of equivalent quantities ofthe acid and base to dryness a gummy residue is obtained, whichslowly becomes crystalline; after well washing with acetone thecrystalline salt is fractionally crystallised from hot acetone, inwhich it is sparingly soluble. The salt is obtained in fine, colourlessneedles, melting a t 197--199O, and is very soluble in water:0.1007 gave 0.2260 CO, and 0.0661 H,O.Cl,H,,0N,,CloH,,04s requires c= 61.29 ; H'= 7.61 per cent.The various fractions of the salts proved to be identical; thefirst (a) and last ( 6 ) fractions gave the following rotatory powersunder the conditions previously stated :( a ) .0.2074 gram : a + 0.41O. [MI + 66'7O.( 6 ) 0.2004 ,, a +0.40°. [a] + 15*0°. [MI + 67.4O.C=61*21; H=7*35.[a] + 14'8O.The molecular rotatory power is practically that of the acidic ion,and consequently no resolution has occurred.cis-4-Ben zo yl-2 : 6-dimet h ylpi prazine Hydrogen d-Tartrat e,C6Hl3N,* CO*C,H,,C,€&O,.ThO base and d-tartaric acid in molecular proportions ar0 evapor-ated to dryness in aqueous solution with repeated addition ofalcohol; the gummy residue is disaolved in a little alcohol andprecipitated as a gum by addition of excess of acetone. On boilingthe solution the gummy mass becomes crystalline, and is collected;after several crystallisations from boiling alcohol the salt is obtainedin minute, colourless, glistening crystals, melting a t 227-228O :0.1462 gave 0.2978 CO, and 0.0846 H,O.C =55.55 ; H= 6.48.C&~0N,,c$&@6 requires C = 55-40 ; H = 6-57 per cent.The salt has a specific rotatory power in aqueous solution formercury-green light of about [a] + 12O, and the rotation ia notchanged by fractional crystallisation. The base separated from thefrequently crystallised salt was optically inactive in alcoholi232 POPE AND READ: THE IDENTITY O F THEsolution, as was also the base recovered from the gummy residuesof the salt.The normal tartrate could not be obtained crystalline, and thetwo d-bromocamphorsulphonates, although crystalline, were sosoluble as to be unsuitable for fractional crystallisation.On treating the monobenzoyl derivative with benzoyl chlorideand sodium hydroxide solution it undergoes the Schotten-Baumannreaction, and the ordinary dibenzoyl derivative of the &base isformed.cis-p-Nitro-4-benzoyl-2 : 6-dimet~ylyipernziiae,The 8-dimethylpiperazine reacts with pnitrobenzoyl chloride inacetone solution in the manner just above described, and the hydrechloride of the mono-acidic derivative separates as a crystallinepowder; the salt is dissolved in warm water, the solution filteredand allowed to crystallise, when the hydrochloride is obtained insmall, opaque, white crystals.It is sparingly soluble in cold waterand less so in alcohol:0.3010 precipitated 10.0 C.C. N / 10-AgNO,. Cl= 11.80.C,,H,,O,N,,HCI requires C1= 11.85 per cent.The free base is obtained by adding sodium hydroxide solutionto the hydrochloride and extracting with benzene; it dissolvesreadily in hot water, benzene, alcohol, or acetone, and crystallisesfrom a mixture of acetone and light petroleum in small, glistening,yellow crystals, which melt a t 135-136O:0.1211 gave 0.2647 CO, and 0.0686 H,O.The salts of this base do not crystallise well, and no crystallinesalts with optically active acids could be obtained.When the crude hydrochloride is dissolved in water during itspurification a slight residue remains undissolved ; this consists ofthe corresponding diacidic derivative.The di-p-nitrob enzoyl deriv-ative is a very sparingly soluble substance, which crystallises fromboiling nitrobenzene in minute, yellow needles, melting a t 3150; itis not produced by aid of the Schotten-Baumann reaction on thecorresponding mono-substituted acidic derivative.C=59.61; H=6.34.Cl3R1,O3N3 requires C= 59-28 ; H = 6.51 per cent.cis-p-Bromo-4-b enzoyl-2 : 6-dimethyZpiperazine,C6Hl,N,- CO*c&f&Br.The base and the acid chloride interact in acetone solution in theusual way, and the hydrochloride is obtained in a 90 per cent,yield as a heavy, white precipitate; on treatment with aodiuSUPPOSED p-2 : 5-DIMETHYLPIPERAZINE. 233hydroxide the mono-substituted base results.This substance ispractically insoluble in water, but dissolves readily in alcohol orwarm acetone, from which it separates in aggregates of large,lustrous, opaque crystals, melting a t 126O :0-0997 * gave 0.1931 CO, and 0.0557 H20.C=52*82; H=6*25.The salts with optically active acids proved so soluble that theycould not be subjected to fractional crystallisation.The di-p-bromobenzoyl derivative is not formed during the abovemethod of preparation, but is obtained by the Schotten-Baumannreaction as a colourless compound, which crystallises from hotalcohol in glistening leaflets melting a t 215-216O.cis-4-Anisoyl-2 : 6-dimet hylpiperazine is obtained aa its hydrechloride in good yield with the aid of anisoyl chloride in acetonesolution; the base forms a viscid gum, which crystallises very slowly.The d-camphor-8-sulphonate crystallises in small, glistening needles,and its molecular rotatory power, [MIHggeen +62*5O in aqueoussolution, is not changed by fractional crystallisation.Thed-a-bromocamphor-wsdphomte could not be caused to crystallise.CI3H,,0N2Br requirw C = 52.51 ; H= 5-77 per cent.cis4-Nuph t ha1 ene-a-sulphon yL2 : 6dim e th y lpip erazine,C~H,3N2*SO2~C~oH,.Since the experimental results described above indicate that thesalts of the carboxylic derivatives of 8-dimethylpiperazine " withoptically active acids do not, as a class, crystallise readily, and i twas deeirable to obtain further evidence as to the non-resolvabilityof the mono-substitution derivatives, an attempt was made toprepare corresponding derivatives of the aromatic sulphonic acids.a-Naphthalenesulphonyl chloride reacts with the 8-base in acetonesolution, and the precipitation of the raulting hydrochloride iscompleted by warming on the water-bath.The salt formed is completely soluble in water, and is cleansed bywashing with acetone; after filtration, it is treated in aqueoussolution with sodium hydroxide, when the base separates as a gum,which rapidly crystallises.On crystallisation from aqueous alcoholit is obtained in glistening, colourless prisms, melting at about loooin its water of crystallisation; after drying a t looo the base meltsa t 122-123O. It is readily soluble in the ordinary organic solvents,but practically insoluble in water :0*1099 gave 0'2486 COz and 0.0646 H,O. C=61*69; H=6*58.0-3474 lost 0,0084 at looo. H,O= 2-42.C,,H,02N2S,+H20 requires C = 61.29 ; H = 6-76 ;H20 = 2-88 per cent.* Dried a t 100"234 POPE AND READ: THE IDENTITY OF THEThe hydrochloride separates in minute, glistening crystals whenan acetone solution of the base is treated with concentrated hydro-chloric acid in the requisite quantity; it dissolves readily in water :c1= 10.50.C,,H200~2S,HC1 requires C1= 10.41 per cent.0.3006 precipitated 8.9 C.C.NIlO-AgNO,.cis4-Naphthalene-a-sulphoql-2 : 6-dimethylpiperazine d-Camphor-/3-sdphonnte, C,6H200,dN2S,CloH160*S0,H.Equivalent quantities of the base and acid are mixed with water,and sufficient alcohol added to effect solution at the boiling tempera-ture; the salt separates on cooling in glistening, colourless needles,melting a t 256-257O :0.1055 gave 0'2240 CO, and 0.0644 H,O. C=57*91; H=6*83.C,,H,,O,N,S,C,,H,,O,S requires c= 58.16 ; H = 6.76 per cent.The salt wits found to be homogeneous on fractional crystallisa-tion from aqueous alcohol, and all the fractions exhibited the samerotatory power; 0.2023 gram, made up to 30 C.C.with water, gaveaHgmeen +0*33O in a 4-dcm. tube a t 20°, whence [a] +12*2O and[MI + 65-6O. The rotatory power is not sensibly different from thatattributable to the acidic ion. The base liberated from the severalfractions of the salt proved to be optically inactive in alcoholicsolut.ion.cis-4-Naphthale/ne-a-szcll)lTonyl-2 : 6-&met hylpiperazine d-a-Bromo-camphor-B-sulphonate, C16Hzo0,~,S,C,,H,,0~r*S0,H.This salt is prepared in the same manner as the preceding one,and is practically insoluble in water, although freely soluble inalcohol or acetone; it crystallises from aqueous alcohol in large,glistening, colourless prisms, melting a t 240-241O :0.1066 gave 0.1976 CO, and 0-0572 H,O.C = 50.55 ; H= 6.00.~ l , ~ 2 , ~ 2 ~ , ~ , ~ , o ~ , 6 ~ , ~ r ~ requires c= 50'70 ; H= 5-73 per cent.The rotatory power of the salt is unaffected by repeated crystal-lisation from aqueous alcohol; 0.1022 gram, made up to 30 C.C.with water, gave aHggreen +0.83O in a 4-dcm. tube a t 20°, whence[a] +60*9O and [MJ +375O. Alcoholic solutions of the base liber-ated from thO various fractions of the salt were found to beopticalIy inactive.cis-4-Naph t hal en e-a-sul ph onyL2 : &dime thy 1p.p e ~ a zin e d-a-Br om 0-camphor-r-sulphorte, C,,H2,0,N2S,Cl,H,,0Br*S0,H,H,0.On evaporating an aqueous alcoholic solution of correspondingweights of the acid and base t o drynew, a gummy residue isobtained, which slowly cryatalfises ; after washing the solid witSUPPOSED p-2 : 5-DIMETHYLPIPERAZINE.235cold water i t is recrystallised from warm aqueous alcohol. The saltis thus obtained in fine, soft, colourless needles, which char a t 150°and begin to melt at about 185O. A slight loss of weight occurs at100°, but the whole of the water of crystallisation can only beaccounted for in the combustion; the salt readily dissolves inalcohol or acetone, but is very sparingly soluble in water:0'1112 gave 0.2012 CO, and 0.0585 H,O. C=49*35; H=5*89.C16H2002N2S,C,0H,604BrS,H20 requires C = 49.26 ;H = 5-89 per cent.Ths rotatory power is not appreciably altered by fractionalcrystallisation; 0.1008 gram, made up to 30 C.C.with water, gaveaBggree,, +0*72O in a 4-dcm. tube a t 20°, whence [a] +53*6O and[MI +339O. The base separated from the several fractions provedt o be optically inactive in alcoholic solution.cis-4-d-Camph~or-~-s~phonyL2 : 6-dimethylpipe~azine,The exhaustive attempts described above indicate that the4-benzoyl and 4-naphthalene-a-sulphonyl derivatives of the parentbass cannot be resolved into optically active isomerides, and anothermethod of effecting the resolution was therefore applied. A 4-acidicderivative of the base wm prepared, in which the acidic group itselfwas optically active ; the possession of an enantiomorphous molecularconfiguration by the original base should then reveal itself by theproduction of two isomerides, conta.ining the d and Lforms of thebase respectively associated with the &form of the acid radicle(compare Kipping and Salway, T., 1904, 85, 438).On mixing acetone solutions of equivalent amounts of the baseand d-camphop-j3-sulphonyl chloride, reaction occurs, and is com-pleted by boiling for a short time; the hydrochloride of the abovesecondary monamine separates as a white, crystalline powder, whichis completely soluble in water, and is purified by washing withacetone.The base is separated from the salt by addition of sodiumhydroxide to the aqueous solution and extraction with benzene; itcrystallises from hot aqueous alcohol in large, lustrous, colourlessneedles, melting a t 166-167O :0-1516 gave 0.3260 CO, and 0.1164 H,O.U=58*65; H=8%9.C,,H,O,N,S requires C = 58.48 ; H= 8-60 per cent.The base is readily soluble in alcohol or benzene, but dissolvessparingly ih water ; the rotation constants were determined in alco-holic solution with the appended results. In this and the followingsets of rotatory-power determinations given in the present paper236 POPE AND READ: THE IDENTITY OF THEthe weight of substance was made up to 30 C.C. with the solvent,and the measuremenb made in 4-dcm. tubes a t 20°:0.1535 gram in alcohol.Hg, 5461. Hg, 5780. Na, 5893.a ............ -t O'i3" + 0.63" + 0-58"[a] ............ + 35 *7 + 30-8 + 28'3[MI ............ +117'0 -t 101.0 f 9 2 . 8Hg, 5461/Na, 5893 = 1.259. Hg, 5780/Na, 5893 = 1.086.The hydrochloride separates in a pure state on adding concen-trated hydrochloric acid to the acetone solution of the base, andforms minute, white crystals, very soluble in water :0.4142 precipitated 11.4 C.C.AT/ 10-AgNO,. C1= 9-76,C16H2,0,N28,HC1 requires c1= 9.74 per cent.0.3106 gram in water.tfg, 5461. Hg, 5780. Na, 5893.a ............ 4- 0.90" + 0.75" +0.70"[a] ............ + 21 *7 + 18'1 + 16'9[MI ........... +79.2 + 66-0 + 61.6Hg, 5461/Na, 5893 = 1'286. Hg, 5780/Na, 5893=1*071.The platinichzoride separates from water, in which it is sparinglysoluble, in small, granular, yellow crystals, melting at 264O; it isinsoluble in alcohol :0*5000 gave 0.0911 Pt. Pt=18*22.(C,6H280,N2S),,H~Ptc16 requires Pt = 18.29 per cent.Although this optically active compound gave every indication ofbeing homogeneous, i t appeared desirable to ascertain whether itis resolvable by crystallisation with the d- and Z-a-bromocamphor-a-sulphonic acids; the following salts were therefore examined :cis-4-d-Camphor-~-sulphonyl-2 : 6-dimetkylpiperazined-a-Bromocam phor-a-sdphonat e.The salt was prepared by crystallisation from equivalent amountsof the base and acid in hot dilute alcoholic solution; it is sparinglysoluble in boiling water, from which it separates in fine, long,glistening needles, melting at 277-279O :0.1302 gave 0.2324 CO, and 0.0748 H20.C=48.68; H=6*43.C,6H2s0,N2S,@,,Hl,0,BrS requiree C = 48-79 ; H = 6.78 per centSUPPOSED b-2 : 5-DIMETHYLPIPERAZINE. 2370.2071 gram in water.Hg, 5461.Hg, 5780. Na, 5893.u ............ + 1 -82" + 1 -55" + 1 -46"[MI.. .......... -+ 421 -0 + 359 *o + 338.0[u] ........... + 65 *9 + 56.1 + 52'9Hg, 5461/Na, 5893 = 1'247. Hg, 5780/Na, 5893 = 1-062.During the fractional crystallisation of this salt a very emallproportion was separated from the final mother liquors, which wasvery soluble in water and acetone, and melts a t 260-264O; analysisshowed this salt to be isomeric with the main product (C=48.98;H=6.78 per cent.), but the substance exhibite a molecular rotatorypower in aqueous solution of only [MI:,, gree,, + 372O. The quantityof this saIt obtained was so small that it affords no evidence thatthe base has been resolved; its production indicates rather thatd-camphor-j3-sulphonyl chloride is not a uniform substance.cis-4-d-Camphor-&sdphonyl-2 : 6-dimethylpiperazinel-a-Brom o camphor-r-sdphonu t e.This substance is prepared in the same way as its isomeride, andis somewhat more readily soluble in boiling water than is thatcompound ; it crystallises in short, glistening prism, melting a t284-285' :0.1395 gave 0.2484 CO, and 0.0842 H,O.c!=48*56; H=6*75,C,,~,803N,S,C,,H,,048rS requires C = 48-79 ; H = 6.78 per cent.0.2011 gram in water.a ............ - I .09" - 0 '92" - 0.88"[a] .......... - 40.7 - 34.3 - 32.8[&I] ........... - 260 .O '- 219'0 - 210-0Hg, 5461. Hg, 5780. Na, 5893.Hg, 5461/Na, 5893 = 1.139. Hg, 5780/Na, 5893 = 1.045.On endeavouring t o trace the quantitative correspondence whichshould exist between the molecular rotatory powers of these twosalts ( D d A and dBZA), the hydrochloride of the base (dB,HCl)and the ammonium salt of the acid (NH,,dA; Pope and Read, T.,1910, 97, 2201), no very close agreement is observed.The calcula-tion is summarised in the appended table :[MI in water. Hg, 5461. Hg, 5780. Na, 5893.dBdA (observed) ............ + 421 -2 -t 358 *7 + 337.8dBZA ,, ............ - 259'7 - 219.2 - 209 '6dl5 ion (calculated) ......... + 80.7 + 69.7 + 64.1dB,HCl (observed) ......... + 79.2 + 66% +61'6dA ion (calculated) ......... -k 340'4 + 288.9 + 273.7dA,NH, (obseived) ......... + 346'6 -k 295-2 + 2i8.238 POPE AND READ: THE IDENTITY OF THEFrom the final mother liquors obtained during the fractionalcrystallisation of the above salt a small fraction was again separ-ated, which differed from the main bulk of the salt; this substancemelted a t 271-274O, had the same composition as the latter(C=49.17; H=6*50 per cent.), and gave the molecular rotatorypower for the mercury-green of [MI -240° in aqueous solution.Isomeric jT)iacidic-cis-2 : 6-dimethylpiperazi~~es.The application of the method given above for introducing oneacidic group into position 4 of the cis-2 : 6-dimethylpiperazinemolecule, together with the Schotten-Baumann reaction, by meansof which two acidic groups may be simultaneously introduced intothe 4- and 1-positions in the.molecule, renders it possible to preparediacidic derivatives in which the two acidic radicles introduced aredifferent in constitution or composition.We can also introduce thetwo acidic radicles in the two alternative orders so as to produceisomeric diacidic derivatives of the constitutions 1A4B and 1B4A ;the characterisation of isomerides thus related naturally supportsour conclusion that the 1- and 4-positions in the molecule of theparent base are constitutionally different in environment. Onapplying benzoyl chloride to the cis-4-benzoyl-2 : 6-dimethylpiper-azine dmcribed above in accordance with the Schotten-Baumannreaction, the " dibenzoyl-/3-2 : 5-dimethylpiperazine " of Stoehr isobtained.cis-4-Bertzoyl-p-nitro-1-6 enzoyl-2 ; 6-dimethylpiperazine,On treating cis-4-benzoyl-2 : 6-dimethylpiperazine with p-nitro-benzoyl chloride according to the Schotten-Baumann method, bothsubstances being dissolved in acetone before addition of the aqueoussodium hydroxide solution, reaction occurs readily in the cold ;after addition of excess of alkali and dilution with much water theprecipitated diacidic derivative is collected.The product crystal-lises from hot alcohol, in which it is freely soluble, in clusters offaintly yellow, lustrous needles, melting a t 198O; the isomericcompound described below is not formed at the same time, and if atrace of the latter is mixed with the substance melting a t 198O themixture melts very indefinitely from 190° upwards:0.1193 gave 0.2860 (10, and 0.0596 H20. C=65*38; H=5*59.C,,H210,N, requires C'= 65-36 ; H = 5.77 per centSUPPOSED 8-2 : 5-DIMETHYLPIPERAZINE.239cis-1-Be~zoyl-p-nitro-4-benzoyl-2 : 6dimet Aylpiperazine,This substance is obtained by treating cis-pnitro-4-benzoyl-2 : 6-dimethylpiperazine with benzoyl chloride and sodium hydroxidesolution; it is somewhat less soluble in hot alcohol than itsisoxeride, and separates as the solution cools in small, yellow,crystalline granules, melting a t 206-207O. On melting the com-pound with a trace of its isomeride the mixture begins to softena t 192O, but does not melt completely until 202O; the non-identityof the two substances is thus proved by the test devised by Kippingand Pope (T., 1893, 63, 557):0.1145 gave 0.2'762 CO, and 0.0602 q0. C=65.79; H=5.88.C?BH,,O,N, requires C = 65-36 ; H = 5.77 per cent.cis-4-BenzoyLp-bromo-1-benzoyl-2 : 6-ctimethlylpipera.zine,C,H,*CO*N<CH2'C CB ,*CH(CR,) H(CHs)>N =CO*C,H,Br.The compound is obtained by the Schotten-Baumann reactionwith p-bromobenzoyl chloride on the 4-monobenzoyl derivative ofthe parent base already described; it separates from its hot alco-holic solution in long, transparent, colourless prisms, melting a t185-186O.Addition of a small quantity of the iaomeride describedbelow depresses the melting point to about 182O:0.1073 gave 0.2375 CO, and 0.0507 H,O. C=60*37; H=5-29.C2,H,,O2N,Br requires @= 59.85 ; E= 5-28 per cent.The isomeride of the preceding substance is produced by theSchotten-Baumann reaction with benzoyl chloride and cis-p-bromo-4-benzoyl-2 : 6-dimethylpiperazine ; it is more sparingly soluble inhot alcohol than the above compound, and crystallises in opaqueaggregates of colourless leaflets melting at 192-1 93O.Additionof a trace of the isomeride depresses the melting point to about182O :0.1027 gave 0.2267 CO, and 0.0479 S O . C= 60.20; H =5-22.C2,H,02N2Br requires C = 59.85 ; H = 5.28 per cent240 POPE AND READ: THE IDENTITY OF THEcis-4-Benzoyl-1-anisoyL2 : 6-dimet hylpiperazine,Anisoyl chloride reacts with the 4-monobenzoyl derivative in thepresence of aqueous sodium hydroxide to yield the above com-pound; the latter is readily soluble in most organic solvents, andcrystallises from aqueous alcohol in fine, glistening needles, meltinga t 140-141O:0.1202 gave 0.3162 CO, and 0.0752 H,O. C=71.83; H=7*01.C,,H2,0,N2 requires C= 71.55 ; H = 6-87 per cent.This compound is prepared by the action of benzoyl chloride oncis-4-anisoyl-2 : 6-dimethylpiperazine and sodium hydroxide ; it ismore easily soluble than its isomeride, and separates as a soft,opaque crust of crystals from its aqueous alcoholic solution.Itmelts not quite sharply at 87-91O:0.1002 gave 0,2636 CO, and 0.0623 -0. C= 71.75 ; H = 6.96.C&,H,O,N, requires C = 71.55 ; IT= 6.87 per cent.The preparation of the above three pairs of isomeric diacidicderivatives of " #I-dimethylpiperazine " proves the dissimilarity ofthe 1- and 4-positions in the molecule.cis-4-BemzoyLl-d-meth ylenecmphor-2 : 6-dime thytpiperazine,Since we have been able to prepare cis-4-benzoyl-2 : 6-dimethyl-piperazine it should be possible to obtain from it a monomethylene-camphor derivative by the same process which we have applied inmaking the dimethylenecamphor derivative of the parent diamine(T., 1912, 101, 2334).cis4-Benzoyl-2 : 6-dimethylpiperazine, dis-solved in 30 per cent. acetic acid, is treated in the manner previ-ously described with one molecular proportion of d-oxymethylene-camphor dissolved in ethyl alcohol; after warming for a short timethe solution is diluted with water and extracted with benzene.After extracting the benzene solution once with dilute hydrochloricacid and several times with dilute sodium hydroxide solution it isevapora-ted, and the solid residue crystallised from a mixture ofacetone and light petroleum. The new compound is then obtainedin small, glistening leaflets, melting a t 165-166O SUPPOSED p-2 : 5-DIMETHY LPIPERAZINE.2410.1164 gave 0.3260 CO, and 0.0950 H20. C= 76.38 ; H = 9.13.C2,H3,O2N2 requires C= 75.73 ; H = 8.48 per cent.0-1020 gram in alcohol.Hg, 5461. Hg, 5780. Na, 5893.u ......... ".. + 5-64" + 4'79" + 4'54"[u] ............ + 415.0 + 352.0 + 334.0[MI.. .......... + 1576.0 + 1338.0 + 1268'0Hg, 5461/Na, 5893 = 1.242. Hg, 57FO/Na, 5893 = 1.055.The constants are unaltered by fractional crystallisation, so thatthe compound is evidently homogeneous. The substance is readilyhydrolysed by hot concentrated hydrochloric acid in the usualmanner, and on treatment with bromine in alcoholic solution yieldsthe hydrobromide of the parent 4-benzoyl derivative; the baserecovered from the hydrobromide melts as before a t 117O, and isoptically inactive in alcoholic solution.cis-4-d-Me thy1 enecamphor-2 : 6-dim e t htylpiperazine,It appeared desirable to attempt the preparation of this corn-pound by a method similar in kind to that used in making thecorresponding 4-acidic derivatives ; the methylenecamphor derivativeshould yield a monobenzoyl derivative isomeric with the compoundjust described, and, since both must be optically active, a furtherconfirmation of the difference between the 1- and thO $-position inthe parent diamine should be furnished by observation of differ-ences between the optical properties of the two isomerides.On warming together equimolecular proportions of d-chloro-methylenecamphor (Bishop, Claisen, and Sinclair, A n d e n , 1894,281, 361), 8-dimethylpiperazine, and a small quantity of acetoneon the water-bath, the mixture soon becomes crystalline; when theproduct is dissolved in boiling alcohol, and acetone added afterconcentrating the solution, the hydrochloride of the new secondarybase quickly separates in small, colourless crystals.After separat-ing the salt it is dissolved in water and sodium hydroxide added;the base is extracted with benzene, and the benzene solution evapor-ated after washing with water to remove any unchanged diamine.The compound is very soluble in most organic solvents, butpractically insoluble in water ; it crystallises from light petroleumin very lustrous, glistening, colourlelss plates, melting at 71°, whichcontain water of crystallisation.After drying a t looo the anhydroussubstance melts a t 65-66O:VOL. cv. 242 POPE AND READ: THE IDENTlTY OF THE0.2551 lost 0.0198 a t looo. H20=7*76.0.1071 gave 0.2726 CO, and 0.1004 H20. C= 69.42 ; H = 10'49.C,7H,,0N,,H20 requires C = 69.33 ; H = 10.28 ; H20 = 6-12 per cent.0.1576 gram in alcohol.Hg, 5461. Hg, 5780. Na, 5893.a ............ + 10'86" + 9'18" + 8 -68"[u] ............ + 517.0 + 437'0 + 413-0[RI] .......... + 1519-0 + 1234.0 + 1215.0Hg, 5461/Na, 5893 = 1 *251. Hg, 5780/Xa, 5893 = 1,058.The hydrochloride, C,7H,,0N2,HCl, separates in fine, colourlessneedles when acetone solutions of hydrogen chloride and the baseare mixed in equivalent quantities; it is very soluble in water,and is hydrolyaed by addition of excess of hydrochloric acid, thecis-2 : 6-dimethylpiperazine hydrochloride produced being opticallyinactive :0.4038 precipitated 13.0 C.C.N / 10-AgNO,. C1= 11-42,C,7H,80N2,HCl requires C1= 11.34 per cent.0.2029 gram in water.a ............ +11*75" + 9.9')" + 9 *30"[u] ............ + 434.0 4- 366'0 + 344'0[MI ............ + 1357.0 + 1144-0 + 1074.0Hg, 6461. Hg, 5780. Na, 5893.HgJ 5561/NaJ 5803= 1'263. Hg, 5780/Na, 5893-1 065.The solution in water exhibits slight mutarotation, and thevalues give above were obtained one hour after the solution hadbeen made up; the value of aM61 + 11'75O fell t o + 1 1 ' 2 5 O in forty-two hours, and after three days rose to a constant value of + 11-33O.The sensitiveness of the base towards acid made i t impossible toprepare the platinichloride ; when an aqueous solution of the purehydrochloride is boiled, d-oxymethylenecamphor separates.Themonomethylenecamphor derivative is theref ore much more readilyhydrolysed than are the corresponding dimethylcnecamphor deriv-atives (T., 1912, 101, 2336).cis-l-Bems yl-4-d-me t h y le 11 e camphor-2 : 6-dime t hylpiperaa ine,The hydrochloride of the previously described secondary basereacts readily with benzoyl chloride in accordance with theSchotten-Baumann reaction; care must be taken to keep the solutionalkaline, as otherwise hydrolysis occurs, and d-methylenecamphorbenzoate and cicdibenzoyl-2 : 6-dimethylpiperazine are producedSUPPOSED p-2 : 5-DIMETHYLPIPERAZINE.243When about 50 per cent. excms of benzoyl chloride is added inportions to the alkaline mixture, excellent yields are obtained. Thenew derivative which separates is readily soluble in alcohol, andcrystallises from dilute alcohol in colourless, glistening platesmelting at %02-203° :0.1183 gave 0-3293 CO, and 0.0881 H,O. C=75.92; H=8*33.C24.H,0zNz requires C = 75.73 ; H = 8.48 per cent.0-1066 gram in alcohol.Hg, 5461. ~ g , 5780. Na, 5893.a ........... + 5 52" + 4.67" + 4'45"LMJ ............ + 1476'0 + 1254'0 + 1190'0[a] ............ + 388.0 + 327 *O + 313-0Hg, 6461/Na, 5893 = 1.240. Hg, 5780/Na, 5893 = 1.049.On boiling with dilute hydrochloric acid the substance readilyhydrolyses, yielding the l-monobenzoyl derivative described belowand d-oxymethylenecamphor.cis-1-23 en zo yl-2 : 6-dim e t h y Jpipe raz iiz e,On titrating the warm alcoholic solution of the previouslydescribed substance with bromine, evaporating, and shaking theresidue with benzene and water, the hydrobromide of the newsecondary base is found in the aqueous solution; after renderingthe latter alkaline and extracting with benzene, the base is obtainedin theoretical yield itg a crystalline mass on evaporating off thesolvent.The base is conveniently crystallised from hot lightpetroleum, in which it is readily soluble, and is obtained in hard,colourless, glistening prisms, melting at 109-1 loo. The substanceretains about 2.3 per cent. of wa-ter of crystallisation, which isdriven off a t looo, after crystallisation from petroleum; the analysiswas made with the anhydrous material:0.1100 gave 0.2877 CO, and 0.0812 H,O.q= 71-33 ; H = 8.26.C,,H,,ON, requires @= 71-51 ; H= 8.32 per cent.It will bO seen that this substance is quite different in propertiesfrom the isomeric 4-benzoyl derivative; it has a lower meltingpoint, and is much more soluble than the latter compound. Furtherconfirmation is thus obtained of the difference between the 1- and$-positions in the molecule of the parent base.It seemed desirable to attempt the resolution into optically activecomponents of the l-benzoyl derivative in the same manner ae wasdone with the isomeride244 POPE AND READ: THE IDENTITY OF THEcis-1-Benzo yl-2 : 6-dime t h ylp'perazine d-Cu m phor-B-su Zphon,at e,On evaporating an aqueous solution of the component base andacid a gummy residue is obtained, which crystallises on keeping ;the salt is extremely soluble in water or alcohol, but dissolves lessreadily in dry acetone.By fractional crystallisation from acetonea number of identical fractions are obtained, consisting of small,glistening crystals, melting a t 165O; the several fractions gave themolecular rotatory power [MI HZ gree,, + 67.4O in aqueous solution :C,$H1sON27C10HIij0 *SO,H.0*1026 gave 0.2293 CO, and 0.0693 H,O. C=60.95; H=7*56.CISHl,ON,,C,,H,,O,S requires C = 61.29; H= 7.61 per cent.cis-1-Benaoyl-2 ; 6-dim etA yllpiperuzin e d-a-Bromocnmphor-B-sulphomte, C,,H180N2,C,,H,,0Br*S0,H.This salt crystallises readily on evaporation of the aqueoussolution of the component acid and base; it separates from amixture of acetone and alcohol in soft, minute needles, melting at209O, and is shown t o be homogeneous by fractional crystallisationfrom the mixed solvent.All the fractions exhibit approximatelythe same molecular rotatory power of [MI Hp gree,l + 382O in diluteaqueous solution :0.1031 gave 0.1979 CO, and 0.0595 H20. C=52.35; H=6-46.C,,H,80N2,C,oH1,04BrS requires C= 52.15 ; H = 6-28 per cent.It is thus not possible to resolve the base by crystallisation withthe two optically active sulphonic acids.cis-4-d-l-l-.Dimethyler~ecamphor-2 : 6-dimethylp'perazine,The cis-4-d-methylenecamphor - 2 : 6 - dimethylpiperazine hydro-chloride described above is dissolved in water, and the equivalentquantity of sodium hydroxide solution added ; after acidifying withdilute acetic acid one molecular proportion of Z-oxymethylene-camphor is added in alcoholic solution.After warming on thewater-bath the mixture is diluted with water and extracted withbenzene; the benzene solution is extracted once with dilute hydro-chloric acid and several times with dilute sodium hydroxide solu-tion, and then evaporated to dryness. The crystalline residue isreadily soluble in most organic solvents, and separates from aqueousalcohol in fine, glistening scales, melting a t 259-260O ; fractionalcrystallisation showed it t o be a homogeneous substance SUPPOSED /3-2 : 5-DIMETHYLPIPERAZINE. 2450.1068 gave 0.2990 CO, and 0.0904 H,O. C=76.35; H=9*47.CBH,,Oa, requires C= 76.64 ; H = 9.66 per cent.0.2020 gram in alcohol.Hg, 5461.~ g , m o . Na, 5893.a ........... t 2.18" + 1 '84" + 1 '74"[u] ........... -t 81 -0 t 6 8 . 3 + 64.6[-\I] ............ -t355*O f299.0 + 283.0Hg, 5461/N~,, 5893= 1 *253. Hg, 57SO/Ka, 5593=l 057.The fact that this substance, although containing d- andE-camphor residues in equal amount, is strongly optically active,furnishes a strong proof that the 1- and 4-positions in the moleculeof the parent base are not identically similar. It is interesting tonote that the d-camphor residue, which is apparently present inthe lighter end of the molecule, exercises a much greater opticaleffect than does the Z-camphor residue, the di-derivative being verystrongly dextrorotatory.We have previously described the isomericcompound, in which two d-camphor residues are present (T., 1912,101, 2335).cis-1 : 4-Dinaph thalene-a-sulphonyl-2 : 6-dime thylpiperasine,C6H12N2(S02*CIOH7)2.This substance was prepared by the Schott'en-Baumann reactionfor comparison with the isomeride formed from the trans-2 : 5-di-methylpiperazine as described below. It crystallises from aqueousalcohol in minute, colourless needles, melting at about 97O in theirwater of crystallisation; after drying at looo the substance meltsa t 117-118°:0.4112 lost 0.0224 a t looo. H,O=5*45.0.1165 gave 0.2556 CO, and 0.0720 H,O. C= 59-84; H = 6.94.C,H260,N,S,,1.5H,0 requires C=59*85 ; H= 5-61 ;H,O = 5.18 per cent.Yrepara t i o n of d-Chlorom e t h ylenecamphor.d-Chloromethylenecamphor was first prepared by Bishop, Claisen,and Sinclair (A~znalen, 1894, 281, 361) by treating d-oxymethylene-camphor with phosphorus trichloride ; as these authors remarked,the yield is small because of the production of considerable quanti-ties of a phosphorus ester of methylenecamphor. We find that thisdisadvantage may be avoided by preparing the substance with theaid of phosphorus pentachloride. d-Oxymethylenecamphor isground in a mortar with an equal weight of phosphorus penta-chloride ; when the evolution of hydrogen chloride has ceased an246 IDENTITY OF THE SUPPOSED s-2 : 5-DIMETHYLPIPERAZINE.the whole mass has become liquid, the product is poured intocrushed ice. The chloro-derivative is then extracted with ether,and its subsequent purification effected in the manner describedby Claiser and his pupils; the yield is very satisfactory.trans-2 : 5-Dim e t h ylpiperasin e.For the reasons detailed in the early pagm of this paper wenow regard the a-2 : 5-dimethylpiperszine of Stoehr as the tram-2 : 5-dimethylpiperazine ; in the molecule the two nitrogen atomsoccupying t'he 1- and 4-positions are constitutionally similar inenvironment. It was consequently of interest to attempt thepreparation of the monoacidic derivatives of the trans-2 : 5-base inthe same manner as we have effected that of the correspondingderivatives of the cis-3 : 6-isomeride ; the methods applicable t othe latter case, however, fail completely in the former one.On treating trans-3 : 5-dimethylpiperazine, melting at 115-1 16O,with Eenzoyl chloride in acetone solution under the conditionsdescribed above, a copious precipitate results ; part of this dissolvesin water aiid is the hydrochloride of the dismine, whilst theremainder proves t o be the dibenzoyl derivative melting at 226O.Several lnodified methods of applying the reagent were adopted,but always with the same results as just mentioned.On applying a-naphthalenesnlphonyl chloride to the trans-2 : 5-base under similar conditions a mixture of the hydrochloride ofthe original base with trans-1 : 4-dinaphthalene-a-sulphonyl-2 : 5-dimethylpiperazine is obtained ; the new derivative is sparinglysoluble in the ordinary organic solvents, and separates from chloro-form in minute, colourless needles, melting at 269-270° :0.1083 gave 0.2512 CO, and 0.0591 H,O.C26H260,N,S, requires C = 63.11 ; H= 5.30 per cent.Similarly, on treating the tram-2 : 5-base with d-chloromethylene-camphor in the manner which, with the cis-2 : 6-isomeride, yields themonomethylenecamphor derivative, only the hydrochloride ofunchanged base can be isolated, together with the dimethylene-camphor derivative previously described.It is thus clear that the methods by aid of which the 4-mono-substituted acidic derivatives of cis-2 : 6-dimethylpiperazine can beprepared fail when applied to the trans-2 : 5-base; it is suggestedthat this is due t o the similarity of the 1- and 4-positions in theconstitutional formula of the latter substance.C=63*27; H=6*11.THE CHEMICAL LABORATORY,TIT E UNIVERSITY, CAM R ti I DGE

ISSN:0368-1645    

DOI:10.1039/CT9140500219

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

FLECK: THE RELATION OF URANOUS SALTS TO THORIUM. 247XXVIL- The Relation of Uranous Salts to Thorium.By ALEXANDER FLECK.IN the beginning of 1913 the law governing the evolution of theradio-elements through the periodic table was formulated, and itwas then shown that when an element gave off an a-ray, the numberof the group of the periodic system t o which the resulting productbelonged was diminished by two units, and that when an elementgave off a &ray the number of the group was increased by oneunit. It was further shown that when any number of radioactiveelements occupied one place of the periodic table these elementswere non-separable from one another (Russell, Chem. News, 1913,107, 49; Fajans, Physikal. Zeitsch., 1913, 14, 131; Ber., 1913,47, 422; Soddy, Chem.News, 1913, 107, 97; Juhrb. Badioaktiv.Elektronik., 1913, 10, 188). Thus mesothorium-1 gives off two8-particles and then one a-particle to become thorium-X. Thesetwo substances cannot be separated from one another once theyhave been mixea fogether in solution, although they have a differentatomic weight. Such non-separable elements have been termed“ isotopic elements ” or “ isotopes ” (Soddy, Nature, 1913, 92, 399).So far as radioactive changes show, the successive places betweenthallium and uranium correspond with unit difference of chargein the atomic constitution, as has been proposed generally for thewhole table h y Van der Broek (iVature, 1913, 92, 372), andrecently verified for the elements calcium t o zinc by the experimentsof Moseley (Phil.Mug., 1913, [vi], 26, 1024). The point hereexperimentally tested was whether the change of atomic chargein ordinary electrochemical change of valency in one element wouldproduce changes of chemical character indistinguishable from thoseobserved in radioactive changes. The oxidation of quadrivalenturanium (uranous compounds) t o sexavalent uranium (uranylcompounds) may be regarded as a process in which the uraniumatom loses two electrons, and it is analogous t o the process in whichuranium-X, isotopic with thorium, loses tpio 8-particles, and formsuranium-2, isotopic with uranium. The point examined was there-fore whether uranous salts, so long as their valency is not allowedto change, would prove to be non-separable from thorium-salts.If so, it might reasonably be concluded that the electrons concernedin the two cases came from t.he same part of the atom, the outershell rather than the central nucleus on Rutherford’s theory.When the literature concerning thorium and uranous compoundswas examined, it was seen that, apart from their differences ofcolour, both possessed chemical properties very much alike.Ther248 FLECK: THE RELATION OF URANOUS SAT,TS TO THORIUM.did not appear to be any reaction in which it was definitely provedthat thorium could be completely separated from uranous com-pounds by one operation. It was therefore decided t o try some ofthese reactions which precipitated thorium and uranous com-pounds in a fractional manner, and then to examine the relativeproportions of uranium and thorium in the various precipitates.Ifthorium and uranous salts are chemically non-separable, then theratio of the quantity of thorium to the quantity of uranium willbe constant throughout one experiment. This ratio will, of course,not be affected by estimating the uranium in the uranyl condition.Uranous compounds are easily oxidised to uranyl compounds ifallowed to come into contact with the air. It was thereforeessential that the various precipitates should be collected, and thefiltrate again treated with a further quantity of the reagentwithout permitting the entrance of air into the mixture of thoriumand uranium in the lower state of oxidation.The principle employed in operating an apparatus for this purposewas to use differences of gas pressure t o move the liquid, eitherclear or holding a precipitate in suspension, from a vessel into thefilter pump and back again to the vessel.I n the case of the firstapparatus that was constructed, the air was exhausted by meansof a water-pump, and any gas required t o give a difference ofpressure to force the liquid from the reaction vessel or back againinto it was obtained from a Kipp’s carbon dioxide apparatus. Theliquid was thus during the progress of the experiment a t a pressureof only a few centimetres of mercury. This first apparatus wasopen to the objection that through any small leak air would travelinwards and come into contact) with the mixture of thorium anduranous salts.Two reactions were used with this apparatus,namely, the fractional precipitation of a mixture of thorium anduranous salts, (1) by gradually decomposing by boiling the excessof ammonium carbonate holding these salts in solution, and (2) bythe addition of successive small quantities of oxalic acid to anacid solution of the mixed salts. I n both of these experiments theprecipitates were treated with nitric acid and the uranous saltsthus oxidised to the uranyl condition before the quantities ofthorium and uranium were estimated by the usual well-knowngravimetrical methods. I n the first case it was found that uranouscarbonate is more insoluble than thorium carbonate, that is, thefirst fractions that were precipitated contained more uranium thanthe latter fractions.In the oxalic acid experiment the contrarywas found to be the case, and it was seen that uranous oxalate wasmore soluble than thorium oxalate.I n both of these experiments it was noticed that after no furtheFLECK: THE RELATION OF URAKOUS SALTS TO THORIUM. 249precipitates were obtained the solution that remained possessed thecharacteristic green coloration of uranyl compounds. The reactionswere carried out in a partial vacuum a t a temperature approaching100°, and there were present large amounts of compounds con-taining oxygen. Under these conditions these compounds mightvery readily be reduced, oxidising some of the uranous salts in theprocess. Thif, oxidation process will be continuous during theprogress of the experiment, and consequently, even if thorium anduranous salts are chemically identical, the ratios of the quantitiesof the two elements will vary in different precipitates.Neitherof these two experiments can therefore be regarded as conclusivethat thorium and uranous ions have different chemical properties.KIjIn order t o overcome the objections mentioned above t o thoseexperiments, it was decided t o precipitate fractionally a mixtureof thorium and uranous salts in the cold, and so decrease thereadiness with which oxidation would take place. For this purposea cold solution of potassium fluoride was used as the precipitant.The experiment was also conducted in an apparatus free from airand containing carbon dioxide a t a pressure greater than atmo-spheric.In this way, if there was any leak in the apparatus, gaswould force its passage outwards, allowing no air t o come in. Theapparatus shown in the figure was constructed. Excess of pressureis obtained from a carbon dioxide cylinder, and a safety valve isformed by dipping the long limb of a T-tube below four feet ofwater. By means of a three-way tap a pressure can be applie250 FLECK: THE RELATION O F URANOUS SALTS TO THORIUM.to the liquid in the tap funnel to force it into the reaction vessel A ,or to the liquid in the reaction vessel t o force i t into the filterpump. By exerting a pressure on the liquid in A , and openingthe taps 31 and N , the liquid is forced into the Buchner funnel,and passes into B in a clear condition.The taps ill and N areclosed, and the three-way taps a t K turned so that pressure isexerted on the liquid in B. The tap €2 is opened in the properdirection, and the liquid in B flows back into the vessel A , whereit can be subjected t o a further treatment with the reagent. Awooden collar is used t o clamp the ground glass to the top of thefilter filnnel. The mixture of uranium and thorium salts is placedin A and reduced there by means of pure zinc and sulphuric acid,a considerable evolution of hydrogen being maintained for one toone and a-half hours. The reduced liquid is then forced into B,and excess of sulphuric acid added to the vessel A . When all thezinc is dissolved, the tube entering the filter funnel is momentarilydisconnected, and the zinc sulphate solution blown out.This tubeis then replaced, and the reduced solutions forced back into thevessel A by applying a presssure on t o the top of the liquid in B.Small quantities of the precipitant are forced into this vessel fromthe tap funnel, the liquid being filtered between the addition ofeach quantity of the reagent. After the liquid is filtered it isforced back into the vessel A , and all the taps closed before thecover of the filter funnel is lifted to take out and to replace thefilter paper. I n this way, by rxsing a cold solution of potassiumfluoride, a number of successive fractions-usually five-of amixture of thorium and uranous fluorides was obtained. Thoriumfluoride is a very insoluble substance, and it was found that con-centrated nitric acid had no effect, and that sometimes even a largeexcess of aqua regia failed t o dissolve completely the uranium whenan attempt 1778s made to convert the uranous fluoride into asexavalent condition.The method that was subsequently adoptedto obtain both the thorium and uranous fluorides in solution wasto treat the precipitate with concentrated ammonium carbonatesolution and a few C.C. of 10 per cent. solution of hydrogenperoxide. On warming the zolution the whole of the mixed pre-cipitates was dissolved. The quantities of thorium and uraniumcould then be estimated in the usual way. The result of oneexperiment is as followsPOPE : FLUORONE DERIVATIVES. PART Ir. 251Potassium Fluoride Experiment.Number of Weight of Weight of Ratio ofprecipitate.uranium oxide. thorium oxide. UsO$ThO,.1 0’0201 0.1230 0.16342 0.1242 o m 5 7 0.1813 0,2841 1.0392 0 2744 0‘4586 0.2744 1-675 1.1501 0’1417 8-12A t the conclusion of this experiment the solution which remainedin the flask was quite colourless, showing that no oxidation hadgone on during the progress of the experiment. None of theobjections that were raised t o the former experiments could there-fore be applied to this one.It is quite evident that although the properties of the uranousand thorium ions are similar, yet there is a distinct difference, andthat they can be separated chemically from one another. Thismeans, then, that, there is an essential difference between the lossof two electrons by means of electrochemical change and the lossof two electrons expelled as two successive &rays. The theoreticalconsiderations involved have been discussed by Soddy in a letterto Nafure (1913, 92, 399) on “Intra-atomic Charge,” and allthat requires to be said here is that so far as these experimentsare concerned one must definitely regard the electrons expelled inP-ray changes as coming from the central nucleus of the atom, onRutherford’s theory, and not from its external ring. The electronsof the external ring can either give up or receive other electronsfrom the exterior as in ordinary electrochemical change of valency.There are electrons in the nucleus, but in chemical changes thereis no transference of them t o the outer ring.I desire to thank Mr. Soddy for suggesting this research, andfor his advice in connexion with itPHYSICAL CHEMISTRY DEPARTMENT,GLASGOW UNIVERSITY

ISSN:0368-1645    

DOI:10.1039/CT9140500247

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

251 POPE : FLUORONE DERIVATIVES. PART Ir.XXVI I I .-Flu or one Derivatives. Part ]I. Resorcinol-benxein.By FRANK GEORGE POPE.RESORCINOL-BENZEIN is the name which was originally given byDoebner t o the compound he obtained by the condensation ofresorcinol with benzotrichloride, when the reacting components wereheated together for some hours a t 180-190° (Annalen, 1883, 217252 POPE : FLUORONE DERIVATlVES. PART IT.234). The empirical formula C,,H,,OQ was assigned t o the benzein,and the reaction was considered t o take place in the followingmanner :C7H5C13 + 2C6H602 = 2HCl+ C,9H1504Cl,the intermediate chloro-derivative so formed being expected t oyield, by exchange of its chlorine atom f o r a hydroxyl group, atetrahydroxytriphenylcarbinol :C19H1504C1 + HOH = HCl + CI,H,,05.Apparently, however, anhydride f orination takes glace, andresorcinol-benzein is produced :2ClQH,504C1 + H 2 0 = 2HC1+ C3SH3009,and Doebner considers that structurally i t may be represented bythe expanded formula :[CI$%(OH)~’C(OH) (G3Hd *C&%(OH)]2O*The benzein was described as crystallising from a mixture ofalcohol and glacial acetic acid in large crystals, exhibiting a violet-red reflex.They remained unaffected when heated to looo, but onraising the temperature to 130°, two molecules of water were lost,and analysis of the residual compound pointed to the compositionC3,H,,07. No definite results were obtained either on acetylationor bromination.Somewhat later, Cohn ( B e y . , 1891, 24, 2064; J . p r .Chem., 1893,[ii], 48, 387) obtained the same compound by the condensation ofbenzoic acid with resorcinol in the presence of zinc chloride, andstated that it formed an unstable compound with hydrochloricacid, and yielded with bromine a series of different bromo-derivatives, according to the amount of halogen employed andthe temperature a t which the reaction was carried out.Here the matter rested for some time, until Kehrmann (Ber.,1908, 41, 3442; 1909, 42, 873) pointed out that resorcinol-benzeinwas probably identical with the 3-hydroxy-9-phenylfluorone that hehad obtained from the product of the action of benzotrichloride onacetyl-m ~aminophenol in nitroberizene solution. I n confirmationof this idea he prepared the benzein by Doebner’s method, andworking with a highly purified product showed that its molecularweight agreed with that of 3-hydroxy-9-phenylfluorone (C,gH1203),and that on methylation with methyl sulphate, the methyl etherof the Auorone was obtained.Pope and Howard (T., 1910, 97,1025) also drew attention t o the fact that the benzein might beconsidered as ideghical with Kehrmann’s 3-hydroxy-9-phenyl-fluorone.H. v. Liebig (J. pr. Chem., 1908, [ii], 78, 534) has, however,objected to Kehrmann’s views, and supports the older DoebnePOPE : FLUORONE DERIVATIVES. PART 11. 253view, considering that in the preparation of the benzein frombenzoic acid and resorcinol, benzoic anhydride may be used inplace of the acid, the reaction then proceeding:the compound thus obtained being Doebner's C3,H2,07.Numerousfresh derivatives of the benzein were described, amongst othersbeing an anhydro-compound, C,6H520,3,C2H,*OH, formed by theaction of ammonia on the benzein, a second anhydro-compound,C,6H,,0,4,CH3*C02H, obtained by heating the benzein with glacialacetic acid, a barium salt, C7,H4,0,,Ba,, a hydrochloride,C7,H,,0,,,4HC1, a compound, C3,H,,0g (m. p. 147*), formed byfusion of the benzein with an alkali hydroxide, an acetyl derivative,C,gH,20(O~CO*CH3)2,C2H5*OH, and a second acetyl compound,C3sH2,03(O*CO*CH3)4, prepared when the acetylation was carriedout in the presence of zinc dust.In 1912 v. Liebig (J. pr. Chem., 1912, [ii], 85, 97, 241) publishedtwo further communications dealing with the benzein, in whichno reference is made to the two different anhydro-compoundsobtained previously.Using the Doebner method of synthesis, heconcludes that the reaction mixture contains a-resorcinol-benzein, C19H1203, @-resorcinol-benzein, (C19H1203)3,C2H5*OH, andy-resorcinol-benzeh, (ClgHl,03)4,H20,C2H,*OH, and the dihydroxy-benzophenone compound of the y-benzein, of the compositionThe a-compound is considered as identical with Kehrmann's3-hydroxy-9-phenylfluorone, whilst the P- and y-benzeins are formu-lated respectively as :~ C ~ 9 ~ 1 2 0 ~ ~ 2 ~ H 2 0 ~ C 1 ~ H 1 ~ 0 ~ ~OH0/\/\/\OH/\B.Ph OEtOH OH0 0 0Using the Cohn method of synthesis, a 8-benzein, ( C,9E1203,R20)z,is also described, whilst the compound C38H3oOg (m. p. 147O),mentioned in the earlier paper, is now recognised as 2 : 4-dihydroxy-benzophenone254 POPE : FLUORONE DERIVATIVES. PART IT.I n the portion of v.Liebig’s paper dealing with his practicaldetails, the term resorcinol-benzein is used very indiscriminatelywithout reference to whether it applies to the a-, p-, y-, o r $-forms,and it is described as crystallising from nitrobenzene in red needles,having the composition (C,gH1203)4,3H20,C,H,*N02, and fromaniline in dark red needles with a blue reflex, having the com-position (C,9H,20,)4,C6H,*NH2. These two compounds containrespectively 1-05 and 1.12 per cent. of nitrogen, and the followinganalytical data are given:0*1128 gave 1.1 C.C. N, a t 21° and 722 mm.0.1092 gave 1.5 C.C. N, a t 15O and 724 mm.N=1*07.N=1*55.N (calc.) = 1-05.N (calc.) = 1.12.results which, seeing the small quantity of substance taken, and theconsequent amount of nitrogen obtainable, may be considered asopen to a considerable amount of doubt, whilst the origin of thewater of crystallisation ( !) is not apparent.Various hydrochlorides are also described, the a-benzein yieldingone of the composition C,gH,203,HCI; the p-, one of the composition(C,SH,20,)3,3HCl,C,H5*OH ; and the y-, one of the composition(C,g13[,203)4,4HC1,H20. The following observations may perhapsbe offered with regard to the /3- and y-benzeins.The 8-form havingthe composition (C,gH,203)3,3C2H,*OH, when heated t o 140°, losestwo molecules of aTcohol, and since the third molecule is difficult t oremove, the product obtained is considered as an ether-like com-bination of the benzein and alcohol, namely :OH 0 EX0 10 0 0 1 0OH/\/\/\CPh C CPh/\P h OEtbut it is difficult to see why the ethoxy-group should be attachedin this way, and no reason is given for affixing it in the positionshown.When heated with alcoholic ammonia and the excess ofammonia is subsequently removed, it is said to yield a compoundof the composition (ClgH,203)3,H,0,2C2H5*OH, which a t 140° loseswater and alcohol, giving (C19H1203)3,C2H5*OH, finally passing at240° into (c1gH&3)3.With regard to the y-benzein, obtained by the action of alcoholicammonia on dihydroxybenzophenone-y-resorcinol-benzein, this iPOPE : FLUORONE DERIVATIVES. PART 11. 255represented as (ClgHlZO3),,2HzO,C,H5~OH.A t water-bath tem-perature, by loss of water, i t passes into the compoundwhich loses alcohol when heated to 140°, yielding (C,,H120,),,H,0or0 0 0 0 0 0(C,,H,20,)4,H,0,CZH5'0H,OH OHI I I I I I I l l v\<y V>Q/ PhC--0---and finally, a t 240°, the last molecule of water is removed, and theanhydrous product, C19H1203, results. It seems curious that, onheating, the water molecule should be removed before the alcoholmolecule, and that v. Liebig in this instance does not make use ofan ether formulation t o explain the tenacity with which the alcoholmolecule is held, whereas such a method was adopted with the&compound.With the object of trying to decide between the conflictingopinions of Kehrmann and v.Liebig, resorcinol-benzein was pre-pared by the Doebner method, and the following results wereobtained. The crude product, when boiled with water, yielded anaqueous extract containing benzoic acid, some 2 : 4-dihydroxybenzo-phenone, unchanged resorcinol, and a small quantity of a redcolouring matter which was not further examined. The residualsolid was digested with dilute ammonia and the mixture filtered,when a reddish-coloured residue was left. This is apparently thebenzoyl derivative of the benzein, since it is insoluble in coldalkali, and on hydrolysis by means of mineral acid is decomposedvery slowly with formation of benzoic acid.The ammoniacal filtrate was acidified with acetic acid, and theprecipitated solid purified by conversion into its hydrochloride.The hydrochloride was dissolved in ammonia, the base then pre-cipitated by the addition of acetic acid, and finally recrystallisedfrom a suitable solvent.It was a t first thought that by fractional crystallisation of thehydrochloride, two isomerides were obtained, but on liberation ofthe base from the two specimens, compounds of identical meltingpoints were produced, and when a mixed melting point of the twospecimens was taken, no depression was observed.Moreover, onfusion of the two specimens wifh an alkali hydroxide, both yielded2 : 4-dihydroxybenzophenone, and thus apparently only one productof reaction is produced.The resorcinol-benzein so prepared is identical with Kehrmann's3-hydroxy-9-phenylfluorone, as is shown by the analytical dat256 POPE : FLTJOROKE DERIVATIVES. PART 11.obtained from the base, its hydrochloride, the sodium and bariumsalts, the acetyl derivative, and the acetyl derivative obtained onacetylation in presence of zinc dust.No trace of v. Liebig's varioushydrochlorides was observed, and the same analytical results wereproduced whatever solvents were used for recrystallising thebenzein. Liebig's anhydro-compounds could not be obtained eitherby the action of alcoholic ammonia or acetic acid; in each case theproduct formed gave tEa melting point of the unchanged benzeinand furnished correspmding data on analysis, whi1,st no depressionof melting point was observed on mixing the so-called anhydro-compounds with a specimen of the benzein.I n order to obtain confirmatory evidence of the fluorone structureof the benzeiD, i t was subjected to the action of phosphorus penta-chloride,, when the 3 : 6-dichloro-9-phenylxanthonium chlorideobt,ained by Howard and Pope (T., 1911, 99, 550) from the actionof the pentachloride on 3-hydroxy-9-phenylfluorone was produced,the identity being further established by the conversion of thexanthonium chloride into 3 : 6-dianilino-9-phenylxanthenyl chlorideand the corresponding 3 : 6-di-~-naphthylamino-compound on con-densation with aniline and P-naphthylamine respectively.These facts would seem to justify Kehrmann's view as to thestructure of resorcinol-benzein, and in the annexed table theformulze of the variousauthor are contrasted.Resorcinol- henzein ............a- Kesorcinol-benzein ............B-Elesorcinol- benzein .............y-Kehol.ciilol-l-lenzAin ............8-Resoi ci ri ol-be1 t zein ............Anhydroresorcinol-bcnzein (I)9 9 9' (11)Hydrochlorides :a ..............................8 ..............................y ..............................Barium salt ........................Acetyl derivative ..............Reduced acetate ...............Alkali fusion .....................products obtained by v.Liebig and theH. v. Liebig. F. G . Pope. I 'OH jIEXPERIMENTAL.For the preparation of resorcinol-benzein, the method adopted byKehrmann and Dengler (Ber., 1909, 42, 873) was used, and theproduct obtained was purified by means of its hydrochloride.It was thought that possibly the hydrochloric acid solution fromwhich the hydrochloride of 3-hydroxy-9-phenylfluorone waFOPE : FLUORONE DERIVATIVES.PART 11. 257originally obtained might contain an isomeride, conceivably of thestructure :0and with the object of ascertaining whether such were the case orno, the acid solution wap concentrated, and the crystalline residueobtained subjected t o purification by Kehrmann's method. Thebase obtained was, however, identical with 3-hyclroxy-9-plienyl-fluorone, and when the two were mixed, no depression of maitingpoint could be noticed, so that apparently only one product of thefluorone type is formed.Resorcinol-benzein is readily soluble in hot nitrobenzene, aniline,or pyridine, but sparingly so in alcohol. From the three formersolvents it crystallises in small, red needles, which melt at 330-331O(Found, C=79*29; H=4.25.Calc., C=79.17; H=4*17 per cent.).The hydrochloride, C19H120,,HC1, is obtained by dissolving thebase in alcohol and adding concentrated hydrochloric acid to thesolution (see above). It crystallises froin alcoholic hydrochloricacid in golden-yellow needles :0.2240 gave 0.5748 CO, and 0.0826 H20.0.1747 ,, 0.077 AgC1. C=70*0; H=4*09; C1=10*90.C19H,,03,HC1 requires C = 70.25 ; H = 4.01 ; C1= 10-94 per cent.The sodium salt is prepared by suspending the base in s;ater,and adding to the suspension one equivalent of sodium hydroxidealso dissolved in water. A deep red solution, showing a yellowfluorescence, is produced, and on concentration the sodium saltseparates in very small, red needles:0.2838 gave 0.0652 Na,SO,.Cl,Hl103Na requires Na = 7-42 per cent.v.Liebig states that a soluble barium salt, C,,H,,O1,Ba,(Ba = 32.35 per cent.), is formed when resorcinol-benzein is heatedwith baryta solution. On repeating this experiment it was foundthat the benzein is almost insoluble in cold baryta solution, butthat on boiling it appears t o dissolve, and a barium salt, in animpure condition, or possibly a basic salt, is formed. If, however,the sodium salt is first prepared and barium chloride added t o itsaqueous solution, a bright red precipitate of the barium salt of thefluorone is immediately produced. This was collected, well washedwith hot water, and dried:Na = 7.44.VOL. cv.258 POPE : FLUORONE DERIVATIVES. PART 11.0.1253 gave 0.0408 BaS04.(C19H,,03),Ba requires Ba = 19.27 per cent.The acetyl derivative, C,gH,,02-O*CO*CH,, was prepared byheating 5 grams of the benzein with 20 grams of acetic anhydrideand 5 grams of anhydrous sodium acetate for four hours. Themixture was then poured into cold dilute alcohol, and warmedon the water-bath until the excess of the anhydride was destroyed.The residue was collected, washed, dried, and crystallised fromalcohol or acetic acid, separating from the solvent in red needles:Ba = 19.14.0.1449 gave 0.4046 CO, and 0.057 H,O.By carrying out the acetylation in the presence of zinc dust, theC=76*15; H=4*37.C,,R,,O, requires C = 76.31 ; H = 4.27' per cent.colourless 3 : 6-dihydrozy-9-phenylzanthen diacetate is obtained :0and on crystallisation from alcohol, separates in colourless needles,which melt a t 175O:0.1048 gave 0.2840 CO, and 0.0436 H20.C,,H,,O, requires C = 73-80 ; H = 4-81 per cent.According to v.Liebig, a compound which he designates asanhydroresorcinol-benzein, C,,H,,O,,,C,H,*OH, is obtained whenthe parent substance is heated with alcoholic ammonia. In orderto test this statement, 4 gram? of the benzein were heated on thewater-bath for two days with successive quantities of alcoholicammonia, the product thoroughly dried, and compared with theoriginal benzein, with the following results :C = 73.91 ; H =4*62.Besominol- benzcin.Red needles, m. p. 330-3.31".Hydrochloride, yellow.A nh ydroreso rciii o 1 - benze in.Red needles, m.p. 330-331".No depression of m. p. on inixiiigwith original substancc.Hydrochloride, yellow.Analysis of the so-called anhyclro-compound gave the following0.1758 gave 0.5084 CO, and 0.0652 H,O.v. Liebig's anhydro-compound would require C = 74.88 ; H = 4*64per cent. It would thus seem apparent that alcoholic ammoniais without action on resorcinol-benzein a t water-bath temperature.Again, a second anhydro-compound, C,,H,O,,,CH,*CO,R, is saidto be formed on heating the benzein with glacial acetic acid. Thisexperiment was repeated by heating the benzein for twelve hoursdata :C=78.88; H=4*12.C1gHI2O, requires C = 79.17 ; H = 4-17 per centPOPE : FLUORONE DERIVATIVES.PART 11. 259with the acid. Itmelted a t 330-331°, and was in all respects identical with theunchanged benzein :The product obtained was collected and dried.0.2667 gave 0‘7691 CO, and 0*1006 H,O. C=78.65; H=4.19.C1,H,,O3 requires C = 79.17 ; H = 4.17 per cent.C,,H,Ol,,CH,*CO,H requires C = 74-88 ; H =4.64 per cent.In order further to establish the identity of the benzein with3-hydroxy-9-phenylfluorone, the reaction between the benzein andphosphorus pentachloride was examined. For this purpose 5 gramsof the benzein were dissolved in 20 grams of phosphoryl chlorideand warmed on the water-bath, with the gradual addition of 10grams of phosphorus pentachloride. The blood-red liquid obtainedwas warmed until all the pentachloride dissolved, allowed to remainfor five minutes, and then poured into 300 C.C.of light petroleum.The yellow precipitate obtained was collected, well washed withlight petroleum, and dried in a vacuum. It is insoluble in non-hydroxylic solvents, but readily decomposes in the presence ofhydroxylic solvents. A chlorine estimation served to establish itsidentity with the 3 : 6-dichloro-9-phenylxanthonium chloridedescribed by Howard and Pope (T., 1911, 99, 550) (Found,C1= 29.06.Confirmation of this result is seen in the reaction of the abovechloro-derivative when brought into contact with aniline and with8-naphthylamine. I n the first case 5 grams of the dichlorophenyl-xanthonium chloride were heated for five minutes with 25 C.C. ofaniline, and the resulting paste was added t o 200 C.C.of water, thewhole rendered alkaline, and distilled in a current of steam t oremove the excess of aniline. The residue was acidified, the pre-cipitate collected, well washed with water, and dried. For purifi-cation, the bluish-purple solid was recrystallised from alcohol,separating from the solvent in very small needles, which dissolvein alcohol to a purple solution. Analysis showed that the substanceobtained wa3 identical in composition with the dianilinophenyl-xanthenyl chloride obtained fsom 3-hydroxy-9-plienylfluorone(Found, C = 78.60 ; H = 4.6 ; C1= 7.28. Calc., C = 78-39 ; H = 4-84 ;Cl=7.48 per cent.).Similar results were obtained by the condensation of the dichloro-xanthonium chloride with B-naphthylamine, the xanthenyl chlorideformed recrystallising from nitrobenzene in small crystals showinga fine bronze reflex, and giving analytical data corresponding withthe xanthenyl chloride obtained similarly from 3-hydroxy-9-phenyl-fluorone (Found, C1= 5.97.From the above results it thus appears that resorcinol-benzeinas obtained by Doebner method is identical with Kehrmann’sCalc., C1= 29.49 per cent.).Calc., Cl = 6-18 per cent.).s 260 WORLEY: THE SURFACE TENSION OF MIXrURES.PART I.3-hydroxy-9-pl1enylfluorone, and is not a mixture of various forms,since the derivatives obtained by working with the two compoundsare the same in both cases.On fusion with alkali hydroxides, or on boiling with a moderatelyconcentrated solution of potassium hydroxide, the benzein yieldsresorcinol and 2 : 4-dihydroxybenzophenone. To recover the latcer,the fusion was acidified with hydrochloric acid and filtered. Theprecipitated matter was extracted with cold alcohol, the alcoholicsolution evaporated to dryness, and the residue repeatedly re-crystallised from hot water. I n this manner, pale yellow needles,melting a t 143-144O, are obtained. This is the melting point of2 : 4-dihydroxybenzophenone, and analysis furnished data confirm-ing this conclusion (Found, C = 72.98 ; H = 4.7. Calc., C = 72.90 ;H=4.7 per cent.)."I n conclusion, I desire to express my thanks to Mr. E. Turner,B.Sc., for his help in the practical work, and to the Research FundCommittee of the East London College for a grant to defrayexpenses.EAST LONDON COLLEQE

ISSN:0368-1645    

DOI:10.1039/CT9140500251

出版商:RSC    

年代:1914

数据来源: RSC

摘要:

260 WORLEY: THE SURFACE TENSION OF MIXrURES. PART I.XXIX.-The Surface Tension of Mixtures. Part 1.Mixtures of Pal-tly Miscible Liquids and theInjueizce of Solubility.By RALPH PALLISER WORLEY.THE most marked peculiarities of the surface tension of mixturesof liquids are, first, the lowness of the surface tension of aqueoussolutions of liquids which are only partly miscible with water,and, secondly, the divergence of the surf ace tension-compositioncurves, in the case of liquids, which are perfectly miscible, fromthe straight line that would express the relationship between surfacetension and composition if the former were merely an additiveproperty; that is to say, by what is generally called the admixturerule. The following investigations were carried out in order t othrow more light, if possible, on these phenomena, and in the* While this paper was being written, I have been in communication with Prof.Kehrmann, who has forwarded me a dissertation of one of hie students. Confirma-tion of v.Liebig's results as to the different varieties of resorcinol-benzeiu was notobtainedWORLEY: THE SURFACE TENSION OF MIXTURES. PART I. 261present paper will be found the results of the study of the surfacetension of mixtures of partly miscible liquids. The case of mixturesof perfectly miscible liquids is dealt with in the succeeding paper.Before proceeding to a description of the experiments carriedout, a short account of the results obcained by some other observersis necessary to show wherein the peculiarities lie.Duclaux (Ann.Chim. Phys.; 1878, [v], 13, 76) carried out aseries of experiments on the surface tension of mixtures of thehomologous series of alcohols and fatty acids with water in varyingproportions. His measurements were made by means of the droppipette. He pointed out that a considerable drop in surfacetension occurred on passing from pure water to a weak alcoholicsolution, and that this drop increased in magnitude as the molecularweight of the alcohol increased. The following numbers are takenfrom his tables, and represent the surface tensions of 1 per cent.solutions by volume, that of pure water being taken as unity:bIeth3 1 alcohtll and water .......................... 0.962Ethyl , , ,, , ..........................0 -933isoProlly1 ), ,) ) ) ........................... 0 900isoButy1 ) ) ,) ,, ......................... 0-742Amy1 ,, ,, ) ) .......................... 0.594He pointed out, moreover, that the surf ace tension-compositioncurves were of the form of hyperbolas, and the following formulawas proposed to express the curves:y = k(ez - l),where y =surface tension, and x =percentage composition of themixture by weight.J. Traube (Ber., 1884, 17, 2294) determined the capillaryheights of mixtures of the alcohols, fatty acids, and isomeric esterswith water. Unfortunately he did not find the densities of themixtures, so it is impossible to convert his results into surfacetension expressed as dynes per centimetre. However, the numbersobtained agree relatively with those found by Duclaux.He alsonoticed the decreasing value of the surface tension of a solution ofgiven strength with increasing molecular weight of the solvent, andhe formulated the following expression to represent the relationshipbetween the two:where ha and hfl represent the heights to which solutions of thesame concentration of two substances the molecular weights ofwhich are Ma and Mp respectively will rise in a given capillarytube, and h', and Id, the heights corresponding with another equalconcentration of the same two liquids262 WORLEY: THE SURFACE TENSION OF MIXTURES. PART I.What neither of these investigators * pointed out, however, andwhat has hitherto escaped attention is that there is a marked fallin the surface tension of a solution of given strength on passingfrom the members of a homologous series which are miscible withwater in all proportions to those members which are only partlymiscible a t the ordinary temperature.This fact is clearly shown inthe above table. It seems remarkable, too, that such a weaksolution of amyl alcohol as 1 per cent. should have a surface tensiononly one-half as great as that of water, whilst a solution of ethylalcohol of the same composition has a surface tension almost asgreat as that of water itself. It seemed probable from such con-siderations as the above that a relationship exists between thesolubility of the solute and the surface tension of its solutions.With a view, therefore, to learn more concerning the relationof surf ace tension to mutual miscibility, experiments were madewith aniline, phenol, and isobutyl alcohol, the approximate solu-bilities a t 1 5 O being f o r aniline 1 part in 30, for phenol 1 part in 15,and for isobutyl alcohol 1 part in 10.The method adopted of measuring the surface tension was themethod of capillary rise, the surface tension being calculated fromthe formula :S = $rghd,where S =surface tension in dynes per centimetre ;T = radius of capinary tube in centimetres ;g=981 dynes;h = capillary rise in centimetres;d = density of liquid.Two factors have been neglected in the above formula, d’ thedensity of the vapour above the liquid which ought to be sub-tracted from d, and JT, which ought to be added to the capillaryheight h.Both of these quantities are, however, so small that noappreciable errors have been introduced in omitting them.The apparatus consisted of a tube 25 cm. long and 2 cm. wide,which contained the liquid to be examined. It was sealed off a tthe lower end, and closed by means of a rubber stopper at theupper end. The stopper was perforated to hold a glass rod whichpassed down into the tube, and to this rod the capillary tube wasfastened by means of fine platinum wire. By the vertical motion* The’ following investigators may also be referred to : Rodenbeck ( D i m ,Bonn, 1879) ; Whatmough (Zeitsch. physiknl. Chem., 1902, 39, 158) ; Volkmanii(Ann. Phys. Clmn., 1882, [iii]. 16, 321 ; Torch (Ann. Physik, 1905, [iv], 17, 744) ;Lewi3 (Phil.i M q . , 1908, [vi], 15, 499) ; Lqlinstein (Ann. Physik, 1906, [iv], 20,614) ; Ramsden (Pmc. Any. Soc., 1903, 72, 156) ; Drucker (Zeitsch. physikal.Chem., 1905, 52, 678) ; Milner (Phil. Mag., 1907, [vi], 13, 96)WORLEY: THE SURFACE TENSION OF MIXTURES. PART I. 263of the rod, therefore, the capillary tube could be raised or loweredin respect to the surface of the liquid. In order t o obtain accurateresults, it is absolutely necessary that the liquid be made to flowover the end of the capillary tube before each reading to ensurethe walls of the tube above the meniscus being wet, and the surfaceof the liquid fresh. The whole was contained in a jacket made ofglass tubing of wide bore. Water a t various constant temperatureswas passed through this jacket, the temperature being adjusted byincreasing or decreasing the rate of flow of the water.The diameters of the capillaries were measured by means of amicroscope furnished with a micrometer eyepiece.Measurementswere taken in four directions, and unless these agreed the tubeswere rejected.The tubes -were cleaned and dried by drawing through themboiling chromic acid, distilled water, alcohol, and dry ether in theorder named.The capillary heights were measured by means of a cathetometerwhich read to a hundredth of a millimetre. Four readings weretaken in each case, the tube being lowered and raised again bymeans of the glass rod before each observation. The rod wasadjusted each time so that the meniscus fell to a point 1 cm.fromthe top of the capillary tube. The capillary heights contained inthe tables are the means of the four observations.*The densities were measured by means of a 25 C.C. Sprengel tube.Effect on the Surface Tension of Decreasing the Solubility ofAniline in Water by the Addition of Common Salt.The solubility of aniline in water is greatly diminished by theaddition of salt. The effect of this change of solubility on thesurface tension of the mixture was the first thing to be investigated.Twenty-five C.C. of a solution of aniline in water (containing 1 partin 60) were taken, and salt was added in quantities of 1 gram a ta time until the eolution became turbid. #The capillary height andthe density were measured after each addition of salt, and theresults obtained are contained in table I.The symbols a t the headof each column refer to the quantities above mentioned, whilstG=number of grams of salt added. The temperature was 20°.* A tube of different diameter was always used in addition so as to keep a checkThe two tubes gave results which never differed by more thanThe results obtained from the second tube are not containedon the results.one-tenth of a dyne.in the tables264 WORLEY: THE SURFACE TENSIOX OF MIXTURES. PART I.TABLE r.G. T (cm.). d. h (cm.). x.0 0 02154 1 -000 5.1 91 54.8341 0'021 54 1.026 4'780 51.8162 0.02154 1.051 4.470 49'5903 0'02'154 1.070 4'222 47'7524 0.02154 1.094 3.989 45'9405 0.021 54 1-119 3*P75 45'803T i 3 solution became turbid when the fourth gram had beenadded, and the fifth gram had very little further effect.Thesurface tension of pure aniline a t 20° is 42.The change in surface tension brought about by the additionof salt to water is very small, and consists, moreover, in an increaseof the tension. Thus, according to Whatmough (Zeitsch. ph ysiknl.Chem., 1902, 39, 149), the surface tension of a 2N-solution ofsodium chloride is 79.35, that of water being 75.57. The coil-siderable fall in surface tension shown in the above table cannottherefore be due to the mere addition of the salt, but most probablyi t may be due t o the diminution of the solubility of the aniline inwater. The evidence, however, is not conclusive, and the followingfurther investigations were therefore carried out.The EfJect of Temperature and the Accompanying Changes inSolubility on the Surface Tension.Since the mutual miscibility of such liquids as aniline, phenol,and isobutyl alcohol with water is greatly dependent on the tem-perature, the liquids becoming soluble in all proportions a t hightemperatures, it seemed necessary t o find out how the surfacetension of these mixtures varied when the temperature wasincreased.A series of experiments was therefore made withaqueous solutions of varying strength of the three liquids men-tioned, and the surface tension was found a t several temperaturesfrom the room temperature up t o looo. The surface tension ofthe distilled water used t o make up the solutions was measured a tfour different temperatures.1.-Aniline and Water.The aniline used was of conrkant bciling point. Solutions ofdifferent concentration were made up, and the surface tensionwas determined a t various temperatures.The results are set forthin the following tablesWORLEY: THE SURFACE TENSION OF MIXTURES. PART I. 265TABLE 11.3-33 C.C. of Aniline and 100 C.C. of Water.t. r (cm.). d. h (cm.).15" 0.0250 1.0028 3.88755 0'0250 0.9920 4.07795 0.0250 0.9665 4'274TABLE 111.2.5 C.C. of Aniline and 100 C.C. of Water.11" 0 *0250 1.0027 4.10621 0.0250 3'0016 4.13132 0.0250 0.9997 4.16946 0'0250 0-9927 4.23161 0 0250 0'9850 4,28380 0.0250 0.9761 4.364100 0'0250 0-9656 4-455TABLE IV.2 C.C. of Aniline and 100 C.C. of Water.16" 0,02154 1 -001 8 5.06438 0.021 54 0.9942 5.10560 0,02154 0.9915 5.15680 0.02154 0.9747 5.273TABLE V.1.5 C.C. of Aniline and 100 C.C.of Water.16" 0.02154 1.0013 5.36438 0.02154 0'9925 5 *38960 0'02154 0.9900 5-35590 0.02154 0.9746 5.389TABLE VI.1 C.C. of Aniline and 100 C.C. of Water.15" 0.02154 1.0012 5.72053 0.02154 0'9904 5-54585 0'02154 0.9741 5.563TABLE VII.0.5 C.C. of Aniline and 100 C.C. of Water.0'02154 1 0011 6.21730 15" 0.06154 0.9978 6.119(Cu,rve 6.)S.48.20649'22250.729(Curve 5.)50.49650'70151.11151.50451'73252.23052'754(Curve 4.)53.59653.62354.01 254.300(Curve 3.)56.74456.51456.01255.499(Curve 2.)60.50558 02357'254(Curve 1.)65.75364'50556 0'021 54 0,9880 5 915 61.73380 0.02154 0 9758 5'724 59'00266 WORLEY: THE SURFACE TENSION OF MIXTURES.PART J.TABLE VIII.Surface Tension of Distilled Water.17" 0.0297 0.9988 7.188 72.88641 0'0207 0'9922 6.878 69.28359 0'0207 0.9840 6 666 66 57377 0.0207 0.9737 6.441 63.256f. r (cm.). d. h (em.). S.F I G . 1.45 -35 '-20" 40" 60' 80" 100" 120" 140"Temperatzcre.The above results are shown graphically in Fig. 1. It will beseen that increase of temperature has a very different effect fromthat observed in the case of pure liquids. The curves representingdilute solutions fall with rising temperature but less rapidly thanthe water curve. At higher concentrations the rate of decrease ofsurface tension becomes markedly less, until in the case of solutionswhich are nearly saturated the interesting fact is exhibited thaWORLEY: THE SURFACE TENSION OF MIXTURES.PART I. 267with increase of temperature the surface tension even rises. Atall concentrations increasing the temperature reduces theabnormally large difference between the surface tension of thesolutions and that of the solvent, and the surface tension of thesolutions tend to approach the value they would be expected tohave if the liquids were miscible in all proportions. A t lowtemperatures the surf ace tension of nearly saturated solutions isnot much greater than that of pure aniline, whilst a t high tem-peratures it becomes nearly as great as that of water.2.-Phenol and Water.The phenol was '' pure crystallised phenol " and was recrystallisedThe solutions were made up as before, but by weightThe surface tension of phenol above itsThe results of the experimentsbefore use.instead of by volume.melting point was also determined.were as follows:TABLE IX.Supface Tension of Phenol above its Melting Point.to. r (cm.).d. h (cm.).49" 0.01528 1.0514 4'63766 0.01528 1.0387 4'46181 0.01528 1.0264 4.311100 0 '01 528 1.0121 4'101TABLE X.6-66 grams of Phenol artd 100 C.C. of Water.15" 0.02038 1'0069 4.06535 0 *02038 1'0011 4.02857 0-02038 0.9931 4.06676 0?)2038 0.9840 4'11090 0*02038 0.9767 4-249TABLE XI.3-33 grams of Phenol and 100 C.C. of Water.15" 0.02038 1.0054 4'74835 0 -02038 0.9997 470253 0.02038 0.9925 4-72675 0 *02038 0.9825 4.77090 0.02038 0.9730 4'827TABLE XII.2 grams of Phenol and 100 C.C.of Water.14" 0.02038 1 '0028 5.36236 0 -0 2038 0-9976 5-28755 0.02038 0'9919 5302s.36.54034'72833'15931 -098(Curve 5.)40.88940.30040.36540'42541 '485(Curve 4.)47.70346.94146.88846'85046.945(Curve 3.)53.74852 71252.56652.048 75 0.02038 0.9815 5.30588 0 '02038 0.9729 5.285 51 '40268 WORLEY: THE SURFACE TENSION OF MIXTURES. PART I.TABLE XIII.1 gram of Phenol aizd 100 C.C. of Water. (Curve 2.)to. T (cm.). d. h (cin.). S.15" 0.02038 1.0018 6-029 60.36837 0.02038 0.9961 5-916 58.91160 0.02038 0.9897 5.888 58'14680 0 *02038 0.9776 5.815 56,82490 0.02038 0 9711 5.717 55.500TABLE XIV.0.5 gram of Phenol and 100 C.C. of Water. (Curve 1.)16" 0-02038 1.0017 6.583 65.84540 0.02038 0-9955 6'41 1 63 *79861 0.02038 0.9827 6.277 61.66081 0.02038 0.9760 6'112 59.662The above results are set forth graphically in Fig.2, and hereagain the same peculiarities as those shown by aniline are exhibited,FIQ. 2.20" 40" 60" 80" 100" 120"TemperatureWORLEY: THE SURFACE TENSION OF MIXTURES. PART I. 269although the curves do not show such a marked tendency to rise.The surface tension of the saturated solution is approximately thesame as that which would be obtained for phenol alone byextrapolation a t room temperature.isoBzcty1 Alcohol and Water.Unfortunately no pure isobutyl alcohol could be procured, butsome was prepared by saponifying isobutyl acetate. The latter witsKahlbaum's, and before use was redistilled.The alcohol kept forthe following experiments distilled a t 105-107*. Solutions of fourdifferent concentrations were made up, and their surface tensionsdetermined a t different temperatures. The surface tension of thepure alcohol was found a t one temperature only, the result agreeingwell with that found by other observers. The following tablescon taiii the results of the experiments.TABLE XV.Surface Tension of isoButyl Alcohol. (Curve 5.)to. r (ctn.). &. h (cm.). S.15" 0 01528 0.8094 3.073 22.919TABLE XVI.10 C.C. of isoButyl Alcohol and 100 C . C . of Water. (Curve 4.)15" 0.01528 0.9870 3 651 27 -01 144 0.01528 0'9785 3 205 23.51076 0.01528 0 9656 2.768 20.029TABLE XVII.6 C.C. of isoButyl Alcohol arm? 100 C.C. of Water.(Curve 3.)1 6" 0-01 528 0'9906 4.378 32'47046 0.01528 0.9808 3.956 29.07865 0 *O 1528 0.9724 3.708 27.021TABLE XVIII.3 C.C. of isoButyl Alcohol and 100 C.C. of Water. (Curve 2.)14" 0 01528 0 9962 5.410 40.39350 0.01528 0.9804 4.875 35231880 0.01528 0-9684 4.458 32.353TABLE XIX.1.5 C.C. of isoButyZ Alcohol and 100 C . C . of Water. (Curve 1.)14" 0.01528 0.9990 6.912 51.74946 0 '01 528 0'9891 6.449 47.80478 0.01528 0.9716 6.012 43'74270 WORLEY: THE SURFACE TENSION OF MIXTURES. PART I.The graphic representation of these results will be found inFig. 3. It is noticeable that the curves are markedly differentfrom those obtained with solutions of aniline and phenol, therebeing little o r no tendency for the abnormally low value of thesurf ace tension to disappear with rise of temperature.When the changes in solubility which are brought about byincrease of temperature as regards aniline, phenol, and isobutylalcohol are examined in detail, it is found that the changes are byno means the same in each case.I n the following table will beFIG. 3.Tempernt w e .found the percentage solubilities up to the critical solution tem-perature, the numbers f o r aniline and isobutyl alcohol being dueto Alex6ev (Ann. Phys. Chem., 1886, [iii], 28, 305), and those forphenol to Rothmund (Zeitsch. physikal. Chem., 1898, 26, 433):Aniline. - Per cell t.2 0" 3.140 3.360 3.880 6.5100 7-2120 9'1140 13-5167 48.6Phenol.7-l'er cent.209 8-4030 8.9240 9 *7845 10 6255 13.8860 17.1065 22-2668.8 35-90isoButyl alcohol.e-Per ccnt.O0 13.020 9'040 7.560 7.080 7.0100 8.0220 16.0133 40.WORLEY: THE SURFACE TENSION OF MIXTURES. PART I. 211It is seen that whereas the solubility of aniline and phenolincreases up to the critical temperature, that of isobutyl alcoholdecreases up to 70°, and then begins ta increase again until thecritical temperature is reached.On comparing the solubilities of these substances with the surfacetension of their solutions, it is evident that some close connexionexists between the two phenomena, and the ‘abnormally low valuesof the surface tension would appear to be connected with the degreeof immiscibility of the liquids. When the solubility is increasedby raising the temperature, as in the case of aniline and of phenol,the surface tension becomes less and less abnormal, and tends t oapproach the value it might be expected t o have if the liquidswere miscible in all proportions, whereas, when increase of tem-perature is not accompanied by increased solubility, as in the caseof isobutfl alcohol, there is no such tendency (see Fig.3). More-over, it was shown (table I) that on decreasing the solubility ofaniline in water by the addition of salt, the surface tension wasconsiderably diminj shed.It is not surprising that an aqueous solution of a liquid of lowsurface tension, miscible with water only in small proportions,should have an abnormally low surface tension when nearlysaturated. A t the point of saturation there is a tendency for theliquid to separate out, and even below this point it probably existsto some extent as molecular aggregates of low surface tension whichare continually being formed and resolved.Such a condition,however, could not be expected to exist in dilute solutions in whichthe surface tension is also abnormally low. The explanation of thelow values in this case lies in all probability in the fact that thesolute is not uniformly distributed, but is concentrated a t thesurf ace.According to Willard Gibbs ( I ‘ Thermodynamic Studies,” pp.219-300), a solute which increases the surface tension of thesolvent is pushed out of the surface because the molecules tend t oarrange themselves in a system having the least potential energy,and vice versa, a solute which decreases the surface tension isconcentrated in the surface.Various investigators have shown that the surface layer of asolution often has a different composition from the bulk.Most ofthe experiments have been carried out with colloidal substances,but the same phenomenon has been shown to exist in the case oftrue solutions. Reference may be made to the work of Dupr6(Ann. Chim. Phys., 1866, [iv], 7, 409), Rayleigh (Proc. Roy. Znst.,1890-1892, 13, SS), Milner (Phil. Mag., 1908, [vi], 15, 499),Ramsden (PP’oc. Roy. SOC., 1903, 72, 156), Lewis (Phil. Mag., 1908272 WORLEY: THE SURFACE TENSION OF MIXTURES. PART I.[vi], 15, 49; 1909, [vi], 17, 466), and Donnan and Barker (Yroc.Roy. ~'oc., 1911, A , 85, 557).There is thus good reason to believethat solutes act in general in the manner predicted by Gibbs.I n the case of solutions of aniline, phenol, and isobutyric acid,then it is probable that the low values of the surface tension, evenin dilute solutions, are due to the fact that the s01ut0 is concentrateda t the surface, which'is thus much nearer the point of saturationthan is the bulk of the solution. Increase of temperature increasesthe solubility of aniline and phenol, and consequently the surfacelayer, even if its concentration does not fall, becomes less nearlysaturated as the temperature is raised. The increased solubilitywould also possibly cause the concentration of the bulk to becomegreater a t the expense of the surface layer.I n the case of isobutyl alcohol, since increase of temperature isnot accompanied by increased solubility, the surface lay& does notbecome less nearly saturated as the temperature is raised, and,moreover, there is no reason to expect that the concentration ofthe surface layer would diminish.It is thus to be expected thatthe abnormal lowness of the surface tension will not tend todisappear when the temperature is raised. I n this connexionmention may be made of some experiments carried out on theduration of froth upon the different solutions. An aqueous solutionof aniline agitated violently f o r thirty seconds a t 20° formed acopious froth, which had not entirely disappeared after fifteenminutes had elapsed. The same solution when agitated similarly a t70° formed a froth which disappeared entirely in ten seconds. I nthe case of isobutyl alcohol the froth was not so copious. It lastedfor thirty seconds a t 20°, and for thirty-five seconds a t 50°.To conclude, there seems to be little doubt of the correctnessof the view advanced in an earlier part of the paper that the lowsurface tension of the aqueous solutions studied is intimatelyconnected with the comparative insolubility of the solutes. Thereduction of the surface tension of solutions of aniline accompanyinga reduction of solubility brought about by the addition of salt, andthe comparison of the effects of increase of temperature on thesolubilities of the liquids studied and on the surface tensions oftheir solutions ail support this conclusion. There is good reasonto suppose that the lowness of the surface tensions of the lessconcentrakd solutions is due to the concentration of the surfacelayer being greater than that of the bulk of the solution, and thusconsiderably nearer the point af saturation.UKIVERSITY COLLEQE,AUCKLAND, N. Z

ISSN:0368-1645    

DOI:10.1039/CT9140500260

出版商:RSC    

年代:1914

数据来源: RSC