摘要:

THE FORMATION AND REACTIONS OF IMINO-COMPOUNDS. 1465 CLXII1.-The Formation and Reactions of Imino-compounds. Part X X . The Condensatiora of Aldehydes with Cyanoacetarnidc. By JAMES NELSON EDMUND DAY and JOCELYN FIELD THORPE. IN a series of papers dealing with tlhe condensadion of ketmnea with cyamamtmide (T. 1911 99 422; 1913 103 1586; 1919 115, 686) it has been shown that) the readion between thew substan-in tbe presence of a condensing agent lelads to the foilmatlion of cis-VOL. CXVII. 3 1466 DAY AND THORPE THX FORMATION AND and truns-additive! products and that ring-formation then ensuea, yielding two different typa of heterocyclic six-membered systems. Thus t,hel trans-condensakion proceeds : whereas the cis-aoadeascttion yields : CN *CH*CO*N H2 CN*(?H*C*ON H CN*CH*C*OK I R2{j N n R * i + H2r 6 4 CN*UH *CO*NH2 CN*UH*t!o I CN*OH*bO (cis.) (11.) the compounds formed in this case (11) being the same as those produced by the well-known reaction disaoverd by Guareschi, which involvlves t3he intaraction of ethyl oyanoac&ate t-he ketone, and ammonia. As both types (I) and (11) yield the p&disubsti-tated gluhrio acid on complete hydrolysis the method servee as a useful one for the preparation on€ these impolrtant acids in quantity. In the course of the work which is now being carried out at this College in mnnexion with the formation and properties of aarbn ring structure5 it became evident that considerable quantities of tlhe glutaria acids halving a single substitumt group in the &position would be required and search was therefore made f u r a similar general metlhod which could be used for their production.Ob-viously the use of an aldehyde in place of a ketone in the above reaction suggested itmll but unfortunately Guareschi has already shown that by his method aldehydes lead t o t4he fmmation of stable pyridine derivatives whiah cannot be hydrolysed to the nitrogen-frm acid : R*CHO CH2( CN) CO Et NH 4 C H2( CN ) COsE t R'CqC(CN):C(OH) C(CN)*C(oH)>N + H2 + etc. (111.) 1% was therefore gratifying to find that the condensations between aliphatio aldehydes and cymoacetamida proceeded very smoothly in the presence of a trace a€ alkali hydroxide that yields 04 90 per cent. or more wetre obtained and that the condensation produats could be quickly and armpletdy hydsolysed ta the mmpmding &substituted glutaria acid by means of dilute hydrolablone acid REACTIONS OF IMINO-COMPOUNDS.PART xx. 1467 Mormver tha acid5 obtainad were in a high %tatel of purity and did not require1 further trelatmelntl before uw. Evidsntly therefore the method is the best m e atl present known for the preparation of these acids. Investigation quickly shotwed however that the condensation products formed in thits way were of a different type from thme prolduced in the ketone reactions. They were for axample insduble in dilute mineral acids and were without basia properties. They did not form platinichlorides and weIra not hydrolysed to1 the imide by boiling with mineral acids a relaction characteristic of the ring iminoccolmpounds of type I.They werel moamer very much more readily hydrolysed to the nitIrogm-free acid than the compounds od either type I o r 11 and were in fact undcvubteldly open-chain cyaiioamides formed in accordance witlh the sahema : This type osf condensation product formed in ewry case investi-gafed approlximaf'ely 99 per centl. of the tot'a.1 solid obtained. The remainder compriseld a.bolu t equal qua,ntities of tlhel iminol-imide of type I a.nd the Guaseschi colmpound of type1 111. A coasiderafdm of these data seems to1 1ea.d t801 the conclusion t8ha.tl the.rel is a greator t,ende,ncy t,a form six-membered hete~ro~cyclic st,ruct,ures when tlwol alkyl grolups are a.ttlached to the1 centtra.l carbon atom tha.n when only olnel sub&ituting gronp is in this position.If this were t,rue and coluld be applield t'ol homocyclia carbon systems of similar type it wo'uld account for maay o'f the peculiar proper-ti= which a.rel possesseld by compounds having t,wo alkyl groups a.tlt.a.che;d to the 38,1116 carbon atom. On the1 ot'hes ha8nd it is possiblel that the physical properties o'f t,hel condensatbon pro'ducts may det,ermine the osdelr and a.niolunt of t'helir formamtion. I n other words that whilst the normal co'mpound of type IV is in every ca,se t'he one first produceid itls actual separatdoln a,s the final product may be influelnmd by it8 solubility in t'ho solvent! used. Ring-forma-tion may therefore ensue i f t'he solubility of t'he initJal compo,und prelve.nts it from being remo'ved by precipitation a.nd if the ring-compound ha.ppeas to be the1 le,ss sodublet od the1 t.wol.I n support of t'his view i t is t,ol be not,ed as already mentioneld tahatl there is delfinite e.vic'lence of ring-fo,rma.tion of bolt'h types I and I1 in the aldehyde1 colndelnsa.tions. AgaJnst it must be1 phcetd tbe. fact that,, a.lt.hoagh repea.t'eld a.ttelmpts have be.en made by varying t,he solvent^ 1468 DAY AND THORPE THE FORMATION AND no variation in the stlru&ure of tlhe product hm been detected, except>ing in the uase of benzaldehyde quoted below whiuh how-ever oannot be regarded as being in any way analogous. It is,, marelover signifiaant that in every case investigated the aldehydes gave open-chain amides and the keltonas ring-compounds. It is clear that tlhe mathr requires further investigation.We were unable tor induce aromatiu aldehydea ta yield derivatives of glutaria acid by condensing them with cyanoamtmida. Guarmuhi who has applied his readion ta a number of them alde-hyea found that the usual pyridine derivative (V) was formed a t the expense of the1 normal colndensatdon product (VI) whiuh was itself rednceld tlol tlhe substlance V I I : Cph<C(CN):C(oH)>N C(CN).C(OH) CHPh:C( CN)*CO*NH, (V. 1 (VI * ) CH,Ph*CH(CN)*CO*NH, (VII.1 As a matlbr of faot tihe produds in the case of benzaldehyde and cyanoamtamide depend an the mnditions. Thus if alcohol is used and a dear solution is maintained throughout the products V and V I I are formed in molelcular proportions. If however no alcohol is used and the aldehyde is shaken with an aqueous solution o t t'he amide the sode product is the unsaturated cmmpmnd (VI).Com-pound V I is also the sole prduut if alcohol is used and if the mixture is first seeded with a crystlal of the unsaturated amide. There appears to be no tlendency whatever for an arolmatiu alde-hyde to combine witlh two1 moleuules of ayanoaoetlamide amd the glutariu acids ha;ving an arolmatiu group in the B-poeitim uannot therelfore be prepared by this method. E X P E R I M E N T A L . Geiteral Remarks.-Cyanoacetamide was prelpared by the method described by Thole and Tholrpe (T. 1911 99 429). After reurystal-lisation from alcohol it waa dried in the steam-oven f o r three hours in order to remove t r a m of ammonia a substance whioh has been found tor have a marked hindming effect oln condensations of this oharaakr.The mndensatkms were oarrkd out in. wide-mouthed glass-stoppered bottles the cyanolacetamide beling dissolved in five times i b wtGght 04 water. In some casm in whioh the heat generated liy the reaction nemssitated cooling in icewater thus oausing the pre-cipitation of some cyanoacetamide a little mare water was added i REACTIONS OF IMINO-COMPOUNDS. PART XX. 1469 order to elffed complete solution. The aldehydes were fra8atimatd immediatetly before use and were added tIa the cmled solution of cyano~aceItamide sufficient alcohol being added when necessary to form it clea+r sollution. The condensing agents used were piperidine, diethylamine and aqueoius poltamium hydroxide. No difference was noticeld beltlween tlhem relagelnts when colmpa,rative elxperimenb were carried out under similar conditions and therefore a small quan-t'ity of a 50 pelr cent.aqueous solution of potassium hydroxide was invarkbly useid. A cetaldehyde. CHMe[CH (CN)*CO*NH&.-This substlance is produced in a yield approximating to 95 per cent. of thatl theocetlieally possible when 25.2 grams of cyanolacetamide dissolveld in 126 C.C. od water are mixed with 6.6 grams of acetalde hyde and 0.3 C.C. of a 50 per cent. aqueous solution of potassium hydrolxide added. Precipitatlion colmmeinces after about ten minutles and is complete a t the end of three hours when the m a t k a l can be colllected. The white crystalline substance melts in the crude mn-ditioln a t 150-155O to a* clear yellolw liquid but owing to its insolu-bility i t cennolt be recrystlallisd from any olf the usual solvents.The spaurnen foir analysis was purified by being first ground with dilute hydrochloric acid and then washed with hoti absolute alcohol. It mellted sharply a t 161O (Found C=49*60; H=5.34; N=28.92. C,H,,O,N requires C = 49.48 ; H = 5-19 ; N = 28-87 per cent.). j3-Methylylutaric Acid.-This acid is praduced from the amide in practically quantitative yield when 20 grams of the latter are warmed with 50 C.C. of concentrateld hydrochloric; acid and the clear solution after being diluted with an equal volume of water is boiled for five hours. The acid in a very pure condition aan bei extracted from the coolled sollution by means of ethelr and meltsl a t 8 7 O after be@ recrystallised f rorn benzene or from dilute hydrolchlolric aaid (Knotevenagel Ber.1898 31 2585) (Found C=49*17; H=6*93. Calc. C =49-3 ; H = 6.9 per cent. Silver saltl Found Ag= 59-87. Calc. Ag=.59.95 per cent.). aaI-DicynnoLP-mc t h y lglu tarumide, 6-Imin 0-3 - cyano-5-car b am?/l-4-m et hyL2-piperidme , CH( C s )-- c o > ~ ~ CHMe<CH(c**N H,)*C(:NH) can be1 obtained in small amount (about 0.25 peir cent..) when the hydroohloiria acid washings from the amide ara trelateid wit$ sodium aaetate sollutdcm. It separates from water in small coloarless prisms, melts and decomposes a t %35O and is rela,dily soluble in dilute hydrochloric acid. Crystallisation has to be effected rapidly other 1470 DAY AND THORPE THE FORMATION AND wise soma hydrolysis ensues (Found C = 49.72 ; H = 5.39 ; N,= 28-77.C,H,,02N4 requires C = 49.5 ; H = 5.2 ; N = 28.9 par cent.). The compound is hydrolysd to B-mekhylgluttaric acid by means olf sulphurio acid (compare T. 1911 99 431). 3-Cyan 0-2 6-CliA e t o -4-m e t h y lpiperidine -5 -car 6 oxy lamide, is formed by the1 adioln of hot dilute hydrochloria acid on the imino-cobmpound (Zoc. cit.). It crystallises from water in calmrleas prisms which melltl and decompose atl 245O (Found N=21.44. C8H,03N, requires N = 21.5 per cent.). The compound is colmpletlely converted into &metlhylglutaria acid o a hydrolysis with sulphuric acid. When tIhe original filtrate from tlhs above! ooadensattoa products is acidified by mixing i t with one&ird of its volume of concen-trated hydrochloria acid a crystalline precipitate is farmed which melts after recrystallisation from dilute hydroshlolric acid atl 252O, decomposing a t 255O (Foand N = 24.1.C,H,02N3 requires N= 24.0 per cent.). The yielld of this substlaace was not morel than 0.3 per cent,. It is evidentlly 3 5-diayano-2 6-dihydroxy-4-meithylpyridine, C M e < ~ [ ~ ~ \ ~ ~ [ ~ ~ { > N described by Quelnda ( A t t i R. Accad. Sci. Torino 1896-1897 32 415). Propaldehyde. aa’-Dicyano - B - ethyZglutaramide CHEtl[CH(CN)*C0*NH&.-This substanm separates in a cryst(a1line wnditioa when an aqueous solution containing 16.8 grams of cyanolacetamide 120 C.O. of watelr, and 5.8 grams of propaldehyde is treated with 0.3 C.C. od a 50 per cent. sollution of potassium hydroxide.The yield oC the crude product is 90 per centl. od that thearetieally powible. When purified by grinding wit$h hydrochlorio acid and recrystallisatlion from a mixtare of alcolhol and benzene itl forms dourless neeldle clusters which mellt a t 147O. The1 compound is insoluble in dilute hydro-chlolric acid and is only spa,ringly solluble in tlhei usual olrganic sol-vents (Found C = 52-67 ; H = 5.63 ; N = 26.95. C,H,,O,N require? C=51-9; H=5-8; N=26.9 per cent.). 6-Etlzylglwtnm’c Acid.-The above amids is mnverted into this acid on being boiled for five hours with dilute hydrochlolria acid. It! melts a t 73O after recrystallisat(ion from dilute hydroiahloric acid (Emetry Annalert 1897,. 295 94) (Found C=52*71; H=7*64. Calo. C= 52.5 ; H = 7.6 per cent,. Silver salt Folund Ag =57*55.Calc. Ag=57*7 peir oent.) REAC'TIONS O F IMINO-COMPOUNDS. PART XX. 1471 6 -1nz in 0-3 -c:yu n 0- 5 -carb anty l-4-e t Jbyl-Z-piperidon e, CH Et<CH(CN)-- CEI(C0.N H,)*C( NH) co>NH, occurs to the estent ol€ about 0.5 per cent'. in the original mndeasa-tion and can be isotlatetd froin the hydrochlorio acid washings from the main prolduct on treatment wit\h aquelous sodium aceitate. It separatlee from water in small crystals meltling and decomposing at 2 1 4 O (Found N = 26.86. C,H,,O,N requires N=26*9 peir cent.). The compound is readily soluble in dilute1 hydrochloric acid. 3-Gym10-2 6-diJceto-4-etIiyl;uiperid~~e-5-carboxylumicle, is prolduced in a crystalline mndition whezi the above piperidone base is dissolved in dilute hydrochloric acid and the solutJon boiled for a feiw minutes.It; separafw i n small colourless prisms whioh, w h m recryst,allised from water melt and evolve1 gas at 2 3 6 O (Found, N = 20.06. Both the above compotuiids a m convelrtle~d into /3-eltlhylglutario acid an hydrolysis. C9H,,O,N3 requires N = 20.1 per cent.). n-Bu t a 1 d e h y de . aaJ-Dicyano~/3-propylgZzctaramicZe CHPra[CH( CN) *CO * NH,],.-A yield of tthis substlanae representing 90 pelr oent,. of that theo-retically possible is produced when a solution containing 25.2 grams of ayanoamtCamide~ 180 C.C. od water and 10.8 grams of n-butalde-hydel is treated with 0.3 C.C. of an aqueous solution of potassium hydroxide. Precipitation is complet8e intlhe course olf three hours, and purificTa,tion can be effected by grinding with dilute hydro(-chlolria acid and cryst(a1lising from a mixture of alcohol and benzene.It forms a white microcrystdine powder which melts ab 1 3 6 O (Found C=54-17; H=6.30; N=25.35. C,,H,,O,N requires C = 54.00 ; H = 6.4 ; N = 25.2 per cent.). The colmpmnd is inso;luble in hydrochloria acid. fl-PropyZglutaric Acid CHPP(CH,*CO,H),.-T~~ hydrolysis of the amide (25 grams) is best effected by means of a solution contain-ing 70 O.C. of conoentrated hydrochloric acid dilutled wibh 100 C.C. olf water and is completel after having besen boiled for five hours. The acid can be isolated by extrachion with ether and purified by recrystallisation from hydrochloric acid when it is obtained in small, nedlmhaped crystah melting at 5 2 O (Folund C = 56.04 ; H = 8.22.08H[,,0 requiree C=55.2; R=8*1 per am&). ?"ha acid is frwly soluble1 in all the usha1 orga8aia solvents an 1472 DAY AND THORPE THE FORMATION AND in water. The siher salt is a white apparelntly amorphous polwder (Found Ag=55.55. C8H120,Ag requires Ag=55*6 per cent,.). The anhydride H:.CO>O prepared from the acid throlugh the agency od aoetyl chloride is a collolurlem molbilel liquid boliling a t 180°/20 mm. (Folund C = 61.24 ; H = 7.68. C8H1203 requires C==61*5; H=7*8 per cent.). The semianilide CHPra(CH,*CO*NHPh)*CH,*CO,H from a benzelne sollutlioin oif the anhydride! and aniline( crystdlises from benzene in small collonrless plata meltling atl 128' (Found, N = 5.86. C,,H1903N requires N = 5.6 pelr cent.). The diethyl estelr CHP~Q(CH,*CO,E~~), prepared frojm the1 acid by melaas of alcohol and aulphuria acid is a colloarlws oil which boils at 132O/10 mm (Foand C=62.81; H=9.62.C,2H220, requires C=62*6; H=9*6 pelr cent.). CH *GO 6 -1mino-3 -cyano-5-carbamyE-4-propyt-2-pipe~&me, -This substance is prelcipita,t#ed i n a crystalline colndition when t<he hydrochloric acid washings from the amide (p. 1471) are treated with sodium acetlate solution. It separat<w f r m alcohol in smdl, prkmatia crystals melting and decomposing ab 208O (Found, N = 25.95. CloH140,N4 requiree N = 25.2 per celnt.). The colmpoancl is readily solubler in dilute hydrochloric aaid. 3 - Cyano-2 6 -dike t 0-4 -propyIpiperidine-5-carb 0x9 Zamide, separatm on cooling from a solut'ion off the1 piperidone derivative in dilutle hydrodoria acid after it has beleln boiled folr five minutss.It separahes frojm water in small cotlourless nedlee melting a t 229' witlh efFerveiwetnce (Foand N = 18.62. C1oH1@3N3 requires N = 18.8 per cmt.). The two last-named substlances are eaah converted inta P-prolpyl-glutaric a8cid on colmplelte hydrolysis with sulphuria acid. Benzaldehyde. The conditions governing the coIurw of the rela,dioln betweea cyanoacetamide and benzaldehyde are discussed on p. 1468. The practical details are rn follows. (1) Condensation. in the Presence of Alcohol$ without Seeding.-Ccyanoacetamide (25 grams) dissolved in 126 c.a. of water is mixed with 16 grams of benzaldQhyde1 and sufficient alcohol added (usuall REACTIONS OF IMINO-COMPOUNDS. PART XX.1473 about 90 c.c.) to give a clear solution. The addition of the usual amount of concentrated aqueous potassium hydroxide failed t o produce any precipitation and the solution WM therefore kept for three days at 38-40°. Extractioln with ether then yielded a solid matelrial which crystallised from dilute alcohol in needles melting at 129-130O (Foaud C = 68-77 ; H = 5-80 ; N = 16.29. Calc. C = 68.9; H=5*7; N=16.1 per centl.). The1 compound was proveld to be idemticad with a-ayano-/3-phcmyl-propionamide CH,Ph*C€€(CN)*CO*Nq by direct comparison with a specimen olf this substlance( prepared by Hessler's method (Amer. Chem. J. 1899 22 169) by the1 action 09 benzyl chloride m the dry soldium compoand of ethyl ayanoacet'ate. When the aqueoas solutioln leftl aftelr wtsadion with ether in the above experiment is acidified witlh hydrolchloric acid a white pre-cipitate is formed whioh crystlallisea frolm alcohol1 or better from dilute hydroshlodc acid in needle dusters melltling and demmposing a t 245O (Found C=65*6; H=3*28; N=17.93.Calc. C=65*8; H=2*9; N=17*7 per cent.). The colmpound is evidently 3:5-di-cyano-6-hydroxy-4-phenyl-A3~ 6-dihydro-2-pyridone, originally prepared by Guareschi (Atti R. Accad. Sci. Torino, 1898-1899 34 565) by tlhe actioln of ammoaia on a mixture of belnzald&yde and ethyl cyanolacetatel. Guaremhi desaribes his wm-pound as qstallising with 3H,o but a direct comparison of the two mmpoands left no doubt as to their identity. The substance is remarkable in that it is frwly soluble in cold wa,ter and will arystal-lise from this solvent in tlhe hydrated form described by Guarwohi if the solution is suffrcient(1y concelntrated.If however a small quantdty of hydrolchlolrio acid is added to the aqueous solution the compound immediately separates in tlhe anhy-drous condition. The rellativet amoantx of the two compounds formed in the above condensation are approximately in the propor-tion of their molecular weights namely 10 grams of the a i d e to 16.5 grams of the pyridine derivahive. (2) Condensation without Alcohol.-The same1 quantities were used as in the previous eixpelriment only in this instance no alcohol was added. Vigorous shaking was necessary in the initial stages of the reaction. but the condensation product soon began to form and the precipitation was complelt<e after two hours. The compound produced in this way crystallid from benzene in dusters of silky needles melting at 123O (Found C= 69-55 ; H = 4.73 ; N = 16.63. VOL. CXVII. 3 1474 IRVINE AND STEELE: Calc. C=69-7; H = 4 * 7 ; N = 1 6 * 3 per cent.) ahd was proved by direct comparison to be a-cyanocinnamamide, CHP h C (CN) CO *NH,, and to be the same substance as that prepared by Heuck (Ber., 1895 28 2252). ( 3 ) Condensation in the Presence of Alcohol with Seeding.-A yield of 80 pelr mnt. of a-cyanounnama,mide in a purel urystslline cmditlioln can be obtained in the CO~UI-SB olf tbwo hours when a solu-tion containing 16 grams of cyanoacetamide 21 grams of beinzalde-hyde 70 C.C. of alcoholl and 84 c.a. o t water which has bean mixed with 0.3 C.O. of a 50 por oent. solluticm of potassium hydroxide in water is seeded with a urystal of the unsaturated amide. THE IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY, Soom KENSINGTON. [Received October 26th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701465

出版商:RSC    

年代:1920

数据来源: RSC

摘要:

1474 IRVINE AND STEELE: CLX1V.-The Constitution of Polysaccharides. Part I . The Relationship of -Inulin to Fyuctose. By JAMES COLQUHOUN IRVINE and ETTIE STEWART STEELE. IT has been shown by one of us in the course of previous publica-tions* that a general method for determining the structure of both di- and poly-saccharides is opened out through the constitu-tional study of methylated sugars. Although the programme of research contemplated in this laboratory has been definitely stated on more than one occasion, we are aware of the fact that other workers have entered this field. It is thus necessary again to point out that the systematic investi-gations on methylated sugars which have been carried out here for the past twenty years were conducted essentially with the object of rendering possible the extension of our work on obvious lines.to the more attractive problems presented by the complex carbohydrates. The preparation of as large a variety as possible of alkylated aldoses and ketoses and the elucidation of their struc-ture provided for purposes of identification the substances which we anticipated would be encountered in solving the constitution of the compound sugars. The principle involved is a simple one in that it is generally possible to substitute all the free hydroxyl groups in a carbo-hydrate or its derivatives by stable methoxyl groups and sub-* References to the use of elkylated sugars are given in the bibliography attached to “The Simple Carbohydrates and the Glucosides” (E. F. Armstrong 3rd edition) and the principles involved are fully described in the Biochemische Zeitschrift 1909 22 357 THE CONSTITUTION OE’ POLYSACCHARIDES.PART I. 1475 sequent hydrolysis yields a methylated sugar or sugars. Deter-mination of the number and position of the alkyl groups in each of the hydrolytic products thus gives direct evidence as to the linkage of the constituents in the parent complex. The general method has already been applied in this laboratory t o the con-stitution of natural and synthetic glucosides (Purdie and Irvine, T. 1903 83 1021; Irvine and Rose T. 1906 8.9 814) to disaccharides (Purdie and Irvine Zoc. cit. and T. 1905 87 1022; Irvine and Dick T. 1919 115 593; Haworth and Law T. 1916, 109 1314; Haworth and Leitch T. 1919 115 809) and also to a typical polysaccharide (Denham and Woodhouse T.1913 103, 1735; 1914 105 2357). Recent developments in the cheinistry of the sugars have added greatly to the complexities involved and incidentally have furnished ample justification of the policy which restrained us from the premature study of the polysaccharides. It is now recognised that a hexose can react n o t only as a butylene-oxide, but also in the more reactive forms provisionally termed “ y-sugars” (Fischer Ber. 1914 47 1980; Irvine Fyfe and Hogg T. 1915 107 524; Irvine and Robertson T. 1916 109, 1305; Cunningham T. 1918 113 596). The chief weight of evidence is in favour of the idea that these isomeric forms of the hexoses possess an ethylene-oxide structure but no rigid formula can yet be applied to all examples and the possibility that an aldo-hexose may react as a propylene- amylene- or hexylene-oxide must also be kept in view.Evidently the constituent sugars of a di- or poly-saccharide may be present in any of the structural forms mentioned above and thus the evidence afforded by the hydrolysis of the unsubstituted complex may be misleading. The case of sucrose may be quoted in illustration. The sugar on hydrolysis yields glucose and fructose of the ordinary type but it has been shown from the study of octamethyl sucrose that the fructose constituent is present in the ‘‘ y-form ” (Haworth and Law loc. cit.). It follows that the complete constitution of a compound sugar, from the disaccharides up to the polysaccharides must include the identification of (1) the constituent sugars (2) their stereochemical form (a or fl) (3) the hydroxyl groups involved in the coupling of the constituents and (4) the position of the internal oxygen ring in each sugar.Determination of factors (3) and (4) demands the introduction of non-hydrolysable residues into the molecule, and it is in this connexion that alkylated sugars play their most useful part. Taking tbe above considerations into account we have resumed 3 1 1476 IRVINE AND STEELE: the study of the constitution of cellulose and have also extended our work to starch and inulin t h e results obtained in the last example being now submitted. The experimental methods employed follow closely the lines already laid down in the methylation of cellulose. It will be recalled that by subjecting cotton cellulose to the action of methyl sulphate and sodium hydroxide solution Denham and Woodhouse (loc.c i t . ) obtained a substance possessing the composition of a trimethyl cellulose from which they isolated a well-defined crystal-line trimethyl glucose as one of the hydrolytic products. The research in question is important as it showed that complete methylation can be effected by means of methyl sulphate in cases where the insolubility of the carbohydrate under examination prohibits the use of methyl iodide and silver oxide as the iii et hyla t ing reagents. Although inulin as the most widely distributed reserve material derived solely from fructose is a compound of considerable import-ance nothing is kno'wn regarding its exact constitution beyond the fact that it is non-reducing and yields fructose on hydrolysis.Even the question of its empirical composition has been debated, as the results of elementary analysis do not agree exactly with the figures required for a compound (C6HI00&. A review of the literature shows that these variations in composition are small, and are doubtless to be attributed to imperfect washing of the samples and the method' of drying adopted. It is now shown that inulin purified and dehydrated as described in the experi-mental part is essentially a polyanhydrofructose with the formula given above. This view does not ignore the presence of the small quantities of inorganic constituents usually associated with inulin, the removal of which is sol difficult as to suggest that they form a minute but definite part of the molecular complex.As it is possible that in the past several closely related poly-saccharides have been included under the general name of inulin, it is necessary t o specify the origin and treatment of the material used in the course of the present research. The inulin employed was prepared from dahlia tubers the standards of purity adopted being that the compound should be white should give less than 0.2 per cent. of ash on ignition be free from any action on Fehling's solution and display the constant' specific rotation of - 35.0° on successive " crystallisation " from water. So far as the methylation process is concerned inulin possesses a marked advantage over celluloss or starch in that it is soluble in aqueous sodium hydroxide.When this solution was treated with methyl sulphate methylation proceeded normally but did no THE CONSTITUTION b~ POLYSACCHARIDES. PART I. 1477 extend beyond the stage at which dimethyl inulin was the essential product. A second treatment with the methylating mixture had very little effect on the iiiethosyl content of the syrup thus obtained and judging from the consistent physical constants dis-played by the product of different preparations it was evident that dimethyl inulin [C,H,O,(OMe),], is a definite compound. I n order to substitute the remaining hydroxyl group recourse was had to the silver oxide method of alkylation. Dimethyl inulin mixes freely with methyl or ethyl alcohols giving a colloidal solution, which is not coagulated by the addition of methyl iodide.By warming such a solution with silver oxide further methylation was effected but the process was tedious owing to the colloidal nature of the material being manipulated. The final alkyl-ations were as usual conducted in methyl iodide solution, and in this way trimethyl inzclin [C6H,O2(OMe)& was obtained. It was not found possible to increase the methoxyl content beyond this stage a result which shows that the series of processes did not result in appreciable degradation, hydrolysis or oxidation of the polysaccharide. Trimethyl inulin is a viscous colourless syrup soluble in organic solvents generally and behaving like a glucoside towards Fehling’s solution. The com-pound could not be crystallised and although in small quantities it may be distilled from a metal-bath at 1960/0.15 mm.the process is wasteful and the further examination was conducted on undistilled material. As in the case of dimethyl iiiulin there can be little doubt that the substance is a definite chemical individual, the protduct of different preparations in which the experimental procedure was varied showing identical physical constants. It is important to note the marked alteration in optical activity which occurs during successive methylation. Whereas dimethyl inulin, like inulin itself is lzevorotatory the introduction of a third methyl group alters the sign and trimethyl inulin is dextrorotatory ([a]’; + 55.6O in chloroform). On hydrolysis by heating a t looo with 1 per cent.oxalic acid, trimethyl inulin was converted into trimethyl fructose the polari-metric record of the change showing a smooth unbroken curve. When the methylated ketose was isolated and purified by vacuum distillation it was a t once evident that the product belonged to the y-series. The sugar was dextrorotatory ([a] + 30.5O in water), reducedl potassium permanganate instantaneously in the cold and also although more slowly Fehling’s solution and an ammoniacal solution of silver nitrate. As this is the first occasion on which a trimethyl y-fructose has been obtained it was necessary for the purposes of identification to convert the compound into 1478 IRVINE AND STEELE: methylated sugar already known and characterised. This was effected by condensing the compound a t 30° with methyl alcohol containing 0.25 per cent.of hydrogen chloride and niethylating the trimethyl y -methylf ructoside thus produced by means of the silver oxide reaction. It is to be noted that the above process gives a mixture in unknown proportions of the a- and P-forms of tetra-methyl y-methylfructoside so that direct comparison with other preparations of the same compound was a t this stage impossible. By hydrolysis however tetramethyl y-fructose was produced and this proved to be identical with the form of tetramethyl fructose isolated from sucrose (Toc. cit.). As the sugar is a liquid and so far as known gives no crystalline derivatives the identification rests primarily on the physical constants determined. These are quoted in the following table and compared with the values given by the two forms of tetramethyl fructose already known Compnriso?z of Tet m m e t ltyl Fru c t oses.A . R. C. From inulin. From sucrose. fructoside. From @-methyl-Liquid b. p. 148*5"/10 mm. Liquid b. p. 154"/13 mm. Solid m. p. 98-99' 1 -4554. no 1.4545. -[a];5 (permanent) + 15.6'. .. + 14.04' ..................... - 20.2" in ethyl alcohol , +32.gg*.. + 31.7" ..................... - 20.9" in water. Reduces KMnO,. Reduces KMnO,. Stable towards KMn04. There can be no doubt as to the identity of products -4 and B and their differentiation from C. In confirmation samples of tetramethyl y-fructose from inulin and from sucrose were dissolved in methyl alcohol containing 0.25 per cent. of hydrogen chloride, and the changes in rotation observed at frequent intervals as the formation of the corresponding methylfructoside proceeded.The speed of reaction in these parallel experinients was idenEica1 a t 30° and the end-points coincided thus confirming the identity of the sugars used. Discussion of Results. The bearing of our combined results on the constitution of inulin may be seen from a survey of the reactions described in the present and related researches (p. 1479). I n series A and G the y-fructose component remains throughout in the y-form whilst in B and D the stable types alone are omr ative . It is evident from the above that the structural relationshi THE CONSTITUTION OF POLYSACCHARIDES. PART I. 1479 J. A . B. C. D. J. J. J. J. inulin fructose sucrose (a or P ) + + J/ + INULIN + Fr?cctose +- SUCROSE + Glucose Tetra-acetyl Reptamethyl Methylglucoside Dime t h y 1 Trime thy1 Tetra-ace tyl Oc tame t h yl Te t rame t h yl inulin methyl f ruct oside sucrose me thylglucoside J.4. J. Trimethyl y-fructose Trimethyl y-methylfr uctoside Tetramethyl y-me th ylfructoside J. J. J. Methyl-fructoside Tetramethyl methylfructoside Tetramet h y 1 fructose between sucrose and inulin is a close one. Both compounds are non-reducing undergo hydrolysis with extreme ease and under ordinary conditions yield the form of fructose melting at 112-114O' and displaying [a] - 93O after mutarotation. We have carried out test hydrolysis of the inulin used in our experiments, and were able to isolate a yield of 66 per cent.of the theoretical amount of crystalline fructose showing the above constants. This result is however utterly misleading from the structural point of view as the fructose component is present in the isomeric y-form. Moreover the yields obtained in the first three stages of A and the complete uniformity of the tetramethyl fructoses pro-duced in pracesses A and C show that all t h e fructose residues in inulin belong to t h e y-series. Again the hydrolysis of trimethyl inulin gives an excellent yield of trimethyl fructose the weight of lower-boiling distillate then isolated being less than 4 per cent. of the material treated. This leads to the second conclusion that i n u l i n i s an aggregate of y-fructose residues each lzetose molecule having lost two hydroxyl groups in t h e formation of t h e poly-saccharide.I f this were not the case the hydrolysis of trimethyl inulin would have given a mixture of sugars ranging from dimethyl to tetramethyl fructoses in place of a trimethyl fructose alone. According to one alternative the polysaccharide may be regarded as a poly-merised anhydrocy-fructose in the formation of which the reducing The above conception admits oft two interpretations 1480 IRVINE AND STEELE: group of the fructose residue takes part in the dehydration and is thus eliminated. c6H1206 C6H1005 (C6H1005)~ y-Fructose. Pol ymerised anhydro-y -fructose. The combined results of several researches so far unpublished, show that the most probable formula for anhydro-y-fructose is either CH,*OH /c5! I 0' I \ 'C-AH~OH \ AH.OH/ ~ H - O H / dH,-/ CH2- ' / 04-\ \CH \ 6H*OH ) O 6H-OR >.(1.) (11.1 or Both structurw admit' of polymerisation on the lines suggested by Pictet and his collaborators to give a comphx carbohydrate, and although the formuke need not be further discussed a t this stage it may be mentioned that I is regarded as more probable than 11. The alternative view of the structure of inulin involves the idea that y -fructose molecules are condensed together in such manner that each ketose component loses two hydroxyl groups one of which is the reducing group in the condensation. CH,*OH j CH,*OH I I ~ H ~ O H j &H.OH 1 ~ H - O H I bH*OH I CH2 ; CH, / i CH CH, ~ H - O H ~ H ~ O H ~ H ~ O H ~ H - O H \C--@j- C- ' >o 0 1 PH ~H,*OH j ~H,*OH A ....o/ . . . . . . . - - ..... - . . . ; . . . \o .._._._..._... \ I bH (The dotted lines indicate the cleavage of the molecule on hydrolysis. THE CONSTITUTION OF POLYSACCHARIDES. PART I. 1481 In order to satisfy all the conditions including the fact now established that inulin contains three hpdroxyl groups in each unit of six carbon atoms the number of ketose residues necessary to form a symmetrical molecule must be a multiple of two. The physical properties of inulin show that the compound is not a, disaccharide and taking the next simplest case our results would be explained by the formula shown on p. 1480 which permits of expansion to a hexa- or octa-saccharide by the addition of coupled ketose residuesl a t the etheric linkages marked A and B .The formula on p. 1480 equally with the first alternative dis-cussed involves that! in each c unit of inulin the same hydroxyl groups are unsubstituted and that two of these groups are different from t3he third. This is consistent with the methylation of the com-pound in definite steps. It also demands that only one form of trimethyl fructose should be produced from trimethyl inulin and this is again in agreement with the experimental evidence. The formula suggmted is of course capable of considerable modifica-tion as any part of the carbohydrate chain may be lengthened by coupling the reducing group of one ketose residue with one of the primary alcohol groups of the next. Part of the inulin molecule would in such case contain the system OR *CH2*C- -CH* [C H*OH],- CH,*O*C-CH [CH*OH],* CH,*O* I'd C'H,*OH I'd 0 I It is of course unlikely that inulin possesses a structure so simple as that of a tetrasaccharide but the fact that trimethyl inulin is perceptibly volatile a t 196O/0*15 mm.suggests that the molecular weight of the polysaccharide is much smaller than is generally imagined to be the case. The high molecular weights quoted in the literature are discordant and can have little significance. At the present stage it is premature to give a decided opinion on the relative merits of tbe two alternative formuh for inulin now proposed and the research is being continued. It is also our intention to attempt the synthesis of sucrose from the form of fructose now shown to be present in inulin.E x P E R I M E N T A L . Purification of Inulin. Crude inulin prepared from dahlia tubers was boiled with char-coal until colourless and separated from the filtrate by freezing. 3 I 1482 IRVINE AND STEELE: Thereafter the material was ‘‘ recrystallised ” several times until the action on Fehling’s solution had entirely disappeared after which it was transferred to tall cylinders and shaken with cold distilled water. When the inulin settled the wash-water was syphoned off and the treatment repeated the process being con-tinued for a week. This method of washing proved to be quite as effective as dialysis in yielding a product giving the minimum of ash on ignition. After filtration the moist inulin was spread on plates to ensure that uniform hydration was obtained before commencing the dry-ing process.In this condition the material contained 60 per cent. of water and in quantities of 200 grams was shaken with 25 per cent. aqueous alcohol. After settling the dilute alcohol was poured away and 50 per cent. alcohol substituted. This in turn, was successively replaced by 84 96 and 98 per cent. alcohol. Exactly similar treatment was then given with mixtures of absolute alcohol and ether until finally pure ether was used as the washing agent. After filtration the inulin was kept in a high vacuum until constant in weight. This somewhat elaborate method of dehydra-tion appears to be necessary in order to obtain inulin as a fine, white mass of uniform microscopic appearance. The compound was dried at 50°/80 mm.elver phosphoric oxide but it was found that owing to surface attraction of moisture it was extremely difficult to obtain constant weighings. A dry sample gave for c = 2.7624 [a] - 34*21° in water. Hydrolysis of Inulin. This reaction was repeated for reasons stated in the introduc-tion. Using Wohl’s methbd (Ber. 1890 25 2107) in which inulin is heated with very dilute hydrochloric acid the yield of solid fructose varied considerably but the average result of a series of experiments was that 200 grams of dry inulin gave directly 45 grams of crystalline fructose and a further 11.5 grams were obtained from the syrupy by-products. On the other hand when the hydrolysis was effected by dilute oxalic acid the proportion of crystalline fructose was greatly increased the mean result being a yield of 132 grams of crystallisable sugar from 200 grams of inulin.Preparation of Dime t h y l Inulin. As the methylation of inulin presents some unusual features, an account is given of a typical experiment. Thirty-two grams of finely powdered pure inulin (2 mols.) were dissolved in 40 C.C. o THE CONSTITUTION OF POLYSACCHARIDES. PART I. 1483 45 per cent. sodium hydroxide by heating in water a t 60-'70°, and after cooling 80 C.C. of methyl sulphate (3 mols.) and 140 C.C. of 50 per cent. sodium hydroxide (total 6 mols.) were run simultaneously into the solution which was maintained a t 3 5 O . This addition extended over three hours the mixture meanwhile being vigorously stirred and the alkali kept in excess.There-after the temperature was slowly raised to 7 5 O and finally to looo for thirty minutes. Carbon dioxide was then passed through the liquid for a prolonged period in order to destroy the bulk of the sodium hydroxide and without removing the suspended solids an approximately equal volume of 88 per cent. alcohol was added. After again passing carbon dioxide and allow-ing to stand it. further quantity of inorganic salts was deposited. These were separated by filtration drained and washed with rectified spirit. Dilute sulphuric acid was then added to the filtrate until it was exactly neutral when the aqueous alcohol was distilled off under diminished pressure. The bulk of the product was contained in the residue but some remained behind with the inorganic salts so that both portions were extracted several times with boiling absolute alcohol.This solvent however takes up sodium inethyl sulphate which is formed in considerable amount as a by-product of the reaction and consequently an extraction with boiling chloroform was carried out thus leaving the sodium salt undissolved. On concentration an amber-coloured syrup was obtained which was subjected to a second methylation. The same proportions of reagents were used and the crude syrup was isolated in the manner just described. Thereafter it was further purified by boiling repeatedly with ether to dissolve any niethylated fructose which might have been formed owing to hydrolysis. The undissolved syrup was then boiled in chloroform solution for three hours with decolorising charcoal.The clarified solution when dried over magnesium sulphate gave on removal of the solvent a clear amber syrup amounting to 78 per cent. of ths weight of inulin taken. This on further drying in a vacuum-oven a t looo, became so brittle that it could be powdered (Found (3-50.55; H=7.51; OMe=35-8; ash=1*76. [C,H,O,(OMe),~ requires C = 50.53 ; H =7*37 ; OMe =z 32.7 per cent.). Dimethyl inulin although sparingly soluble in cold water gives a faintly opalescent solution in hot water. The aqueous solution behaved as a glucoside towards Fehling's solution and reduced aqueous potassium permanganate rapidly but not so quickly as a true y-sugar. For c = 1.845 [a]; - 42.1" in chloroform. 3 I* 1484 IRVINE AND STEELE: I’reparatioit of Trimethyl I?LuZin.I n tha further methylation of dimethyl inulin it was found necessary to adjust the procedure according to small variations in the composition of the material used. When the methoxyl con-tent corresponded exactly with that required for a dimethyl inulin the compound gave a clear solution in methyl iodide. The presence however of even small quantities of lower methylated compounds affected this solubility to such an extent that the addition of methyl alcohol was necessary. I n this event the alkyl-ation was conducted in methyl-alcoholic solution by the addition of methyl iodide and subsequently silver oxide the process being repeated until the product was freely soluble in methyl iodide alone. The final alkylation was then carried out in the absence of any extraneous solvent.On the other hand when a niethylated inulin contained more than 32 per cent. of methoxyl the compound was soluble in methyl iodide and one methylation was then suacient to give a trimethyl inulin. Twenty-five grains (1 mol.) of dimethyl inulin were dis-solved in 100 grams of methyl iodide at the boiling point. When a clear solution was obtained 63 grams (2 mols.) of silver oxide were gradually added and the alkylation continued by boiling under reflux for eight hours. The product was isolated by extract-ing with hot alcohol the soslvent removed and the residue extracted with a large excess of boiling ether. The ethereal solution was heated with charcoal to remove traces of dissolved silver dried Over anhydrous sodium carbonate and the solvent removed, teaving a clear viscous syrup.Even after two further methyl-ations in methyl iodide solution the methoxyl content did not ncrease above the value quoted below so that the formation of trimethyl inulin represents the liinit of the reaction. The cpm-plete drying of the product presented difficulties. When heated at 80°/8 mm. the syrup darkened and developed acidity which resulted in hydrolysis. It was thus necessary to dehydrate the material slowly at 65O/ 150 min. (Found C = 53.05 ; H = 7.64 ; OMe =43*83. [C6H,0,(OMe),] requires C =52’94 ; H = 7.84 ; Trimet hyl in din is a colourless syrup resembling in appearance anhydrous glycerol a t loo. The compound mixes freely with alcohol chloroform or acetone but is sparingly soluble in ether or in water.A significant fact is that solution of inethylated inulin in organic solvents removed all associated mineral matter so that. the compound then left no ash on ignition. Trimethyl inulin has no effect on boiling Fehling’s solution but like the parent OMe= 45.5 per cent.). THE CONSTITUTION OF POLYSACCRARIDES. PART I. 1485 polysaccharide is very readily hydrolysecl by heating with dilute acids and it is likewise unaffected by potassium permanganate solution. NO crystallising medium could be found for the com-pound and it is doubtful if it forms true solutions in any solvent. For c=1*980 [u] +55*6O in chloroform; c=1*3707, [u] +50a340 in ethyl alcohol. Experiments on a small scale showed that trimethyl inulin can be distilled under low pressures but the process is wasteful owing to the ready tendency of the compound to generate traces of organic acids.This occasions some hydrolysis and trimethyl y-fructose thus contaminates the distillate. The first material to distil boiled a t 126-132°/0.15 mm. was acid to litmus and reduced Fehling’s solution in the cold. These properties together with the mobility of the syrup and its action on potassium per-manganate solution which it reduced instantaneously showed that the product was trimethyl y-fructose (Found OMe= 4 2.92. Calc. OMe=41.88 per cent.). For c=2*58 [u] + 31*01° i,n ethyl alcohol. The fraction of higher boiling point (b. p. 196O/0*15 mm.) was a viscous syrup soluble in water and organic solvents! generally. Although the material effected some reduction of Fehling’s solution on heating the behaviour of the compound towards this reagent was essentially that of a glucoside (Found C=51*09; H=7-62; OMe=41*8.[C,H,O,(OMe),] requires C =52*94 ; H = 7.84 ; OMe=45*5 per cent.). The lack of exact agreement with the calculated figures is readily explained by the presence of a small quantity of dimethyl fructose, and the properties of the distillate show that this is the case. The compound was slowly hydrolysed a t 1 5 O by N / 10-hydrochloric acid, the specific rotation falling during the reaction to +42*4O. Recalculation of the end-value for the weight of hexose formed gives [~t]g+37*8~ which is in fair agreement with the rotatory power of trimethyl y-fructose. Hydrolysis of Trimethyl J n t t l i n .Trimethyl y-Fructose. A 10 per cent. solution of undistilled trimethyl inulin in 1 per cent. aqueous oxalic acid was heated a t looo the progress of the hydrolysis being ascertained polarimetrically . The optical changes observed were regular the specific rotation diminishing frcn +53*5O to 40-9O in eight hours. After neutralising the solu-tion with calcium carbonate the filtrate was decolorised with charcoal and evaporated to dryness under diminished pressure. The rwidue was extracted with ether the solution dried ove 1486 IRVINE AND STEELE: anhydrous sodium carbonate and the solvent removed. A colour-less syrup then remained which was distilled under diminished pressure. A small first fraction was collected a t 127-129O/0*25 mm. but the main fraction which weighed 76 per cent of the trimethyl inulin taken boiled steadily a t 146O/0*37 mm.This proved to be trimethyl fructose [Found C =48’*90 ; H = 7.94 ; OMe=41*49. C,H,O,(OMe) requires C=48.75; H=8.11; OMe=41.88 per cent.]. Trimethyl fructose is a viscid syrup resembling glycerol in appearance and has nD 1.4689. The aqueous solution reduces neutral potassium permanganate solution instantaneously and also Fehling’s solution in the cold giving bright red cuprous oxide. Although the sugar likewise reduces ammoniacal silver nitrate at the ordinary temperature it does not affect mercuric chloride and fails to give Schiff’s reaction. On treatment with phenylhydrazine and acetic acid it yielded a reddish-brown syrup which could not be crystallised and it is impossible to say if the product is a hydrazone or an osazone.Trimethyl y-fructose is dextrorotatory in all the solvents examined : For c = 1.016 [a] + 30*51° in water. c = 1.029 [a] -t 28’18O in ethyl alcohol. c = 1.052 [u]g + 2 6 ~ 6 1 ~ in chloroform. c = 1.084 [a] + 2‘7’77O + + 22’14O in acetone. The above optical values were permanent except in acetone solu-tion and in this case it would appear that the sugar reacted slowly with the solvent. This was supported by the observation that when the compound was dissolved in acetone containing 0.05 per cent. of hydrogen chloride the rotation a t first diminished and then increased rapidly until the final value [a]’,”+60*0° was recorded. This capacity to react with acetone is of importance in giving a clue to the constitution of trim ethyl y - f ructose.Conversion of Trimethyl y-Fructose into Tetramethyl y-Met hylfr imt oside . The formation of the corresponding methylfructoside from tri-methyl fructose takes place at the ordinary temperature. A 2 per cent. soIution of the sugar in methyl alcohol containing 0.25 per cent. of hydrogen chloride was kept for forty hours at 17O. In this time the reducing action on Fehling’s solution disappeared THE CONSTITUTION OF POLYSACCHARIDES. PART I. 1487 whilst the specific rotation a t first diminished and then increased to a constant. The following selected observations show that the speed of condensation is of the same order as that exhibited by y-fructose derivatives generally. Time from contact of solvent and solute.Specific rotation. 1 minute + 18.7" 6 minutes 18-2 60 Y9 24'0 120 1 9 26-1 24 hours 50.3 60 ,9 57-0 (constant) A t 30° the reaction is much accelerated and is complete in nine hours. The acid was neutralised by means of silver carbonate the filtrate evaporated to dryness under diminished pressure and the residual syrup dissolved in alcohol. After treatment with char-coal to eliminate traces of silver compounds the solvent was again evaporated the product extracted with ether and the extract dried with magnesium sulphate. On removal of the solvent, trimethyl methylfructoside remained as a clear syrup which with-out further purification was dissolved in methyl iodide (4 mols.) and methylated by the addition of silver oxide (2 mols.). The alkylation was continued for eight hours and the product was extracted and isolated in the usual manner.On distillation tetra-methyl y-methylfructoside was obtained as a colourless syrup (b. p. 134-135O/12 min. n, 1.4469). After a second methylation under the same conditions the boiling point was 137-138'5O/ 12 mm. and refractive1 index 1.4472. The yield was 80 per cent. of the theoretical amount and evidence was obtained that the undistillable by-product consisted of a polymerised trimethyl fructose or of a methylated difructose. The tetramethyl y-methylfructoside isolated as described was a neutral colourless syrup which reduced potassium permanganat e vigorously. Although the material behaved essentially as a glucoside towards Fehling's solution some reducing compound (probably tetramethyl fructose) was present and as repeated dis-tillation failed to' remove this impurity the analytical figures were affected [Found (after two fractionations) C=52.31; H=8-66; OMe= 60.6 ; nD 1.4470 ; (after three fractionations) C = 52.33 ; H= 8-47 ; mD 1.4471.C,H,O(OMe) requires C = 52.80 ; H = 8.80 ; OMe = 62-0 per cent.]. Considering the method of preparation two stereoisomerides would be present in unknown proportion and thus the specific rotation cannot be compared with previous determinations. For c=1-192 [a] + 20'98O in ethyl alcohol 1488 THE CONSTITUTION OF POLYSACCHARIDES. PART I. In preparing tetramethyl y -methyl€ructoside by the above method about 20 per cent. of the crude syrup coluld not be dis-tilled although the reactions were conducted on trimethyl y-fructose which had been subjected to repeated distillation.This residue consisting of a viscous clear syrup was further examined. The material was glucosidic and gave on hydrolysis trimethyl y-fructose which was in turn converted into' tetramethyl y-methyl-fructoside. It woald appear that during the condensation with methyl alcohol some of the trimethyl y -fructose had undergone an extraneous change which is probably auto-condensation or polymerisation. Tetrarnet hyl y -Fruc tose. The hydrolysis of tetramethyl y-methylfructoside was carried out in 0.25 per cent. aqueous hydrochloric acid the concentration of the fructbside being adjusted to 1-0684 so as to render possible comparison with the results obtained in parallel work on the same compound prepared from sucrose.At the temperature of the room the reaction was slow and occasioned a fall in rotation. On continuing the hydrolysis a t looo the activity measured a t 15O increased from +24.30 to +30.7O in thirty minutes but the end-point was difficult to detect, on account of the extreme sensitiveness of the rotation with small fluctuations in temperature. I n a control experiment conducted on the same compound derived from sucrose the permanent value [a] The usual procedure was followed in isolating the sugar which boiled a t 148*5O/ 10 mm. (Found C = 50.88 ; H = 8.57 ; OMe = 53.2 ; n 1.4554. Calc. C=50*85; H=8*47; OMe=52.5 per cent.; n 1.4545). In every respect the sugar showed identical properties and physical constants with the tetramethyl y-fructose obtained from sucrose.After distillation the compound displayed slight down-ward mutarotation the permanent values in water and alcohol, respectively being [a] + 32.9O and 15.5'. + 29.6O was recorded so that the agreement is close. Speed of Condensation of Tetramethyl y-Fructose with Methyl A Icohol. The condensation with methyl alcohol was carried out in conjunc-tion with a duplicate experiment in which tetramethyl y-fructose from sucrose was used. A 1 per cent. solution of the sugar was dissolved in methyl alcohol containing 0.25 per cent. of hydroge THE CONSTITUTION OF POLYSACCHARIDES. PART 11. 1489 chloride and preserved a t 15O polarimetric readings being taken a t regular intervals. Typical observations are given. Time from contact of solvent and solute. Specific rotation. 21.9 Fall 80 9 9 26.3 }Rise Thereafter the solution was heated at 30-40° to complete the reaction the end-point being [a] + 59'9O. With tetramethyl y-fructose from sucrose the minimum rotation recorded is +19-So as compared with +19*l0 above whilst the end-point is [a] + 5 7 * 6 O compared with + 59'9O. Moreover on plotting the specific rotations graphically the curves representing the two parallel reactions were identical within the limits of experiment a1 err or. + 1 minute 4 minutes 14 9 19.1 1024 , 27.9 The above investigation was carried out in connexion with the Carnegie Trust Research Scheme and we desire to express our thanks to the Trust. We are also much indebted to Professor W. N. Haworth and Mr. J. G. Mitchell for access to results recently obtained by them in the study of the tetramethyl y-fructose present in sucrose. UNITED COLLEGE OF ST. SALVATOR AND ST. LEONARD, CHEMICAL RESEARCH LABORATORY, UNIVERSITY OF ST. ANDREWS. [Received October 18th 1 920.

ISSN:0368-1645    

DOI:10.1039/CT9201701474

出版商:RSC    

年代:1920

数据来源: RSC

摘要:

THE CONSTITUTION OF POLYSACCHARIDES. PART 11. 1459 CLXV.-The Constitution of Polysaccharides. Part 11. The Conversion of Cellulose into Glucose. By JAMES COLQUHOUN IRVINE and CHARLES WILLIAM SOUTAR. IN the seriw of investigations on the constitution of pollysaaahasides with which we are elngaged in tlhis laboratory a prominent pla,w is naturally assigned to the more! definite varieties of cellulosel. The original literature on the reactions and colnstitutioln of celluloae is voluminous but it aa.nnoh be claimed that views regarding even tlhe fundamental nature of the omplex are by any means establisheld. This obscurity is not surprising considering the special difficulties which surround constitutional studies of this type. Even if wllu-lose aan be regarded 8,s a chemical individual in t'hs ordinary sew 1490 LRVINE AND SOUTAR: t3he customary methods of sohh,g problems of structure are of little ava.il in view of the insolubility of the oompound the dubiety attending its molemla,r magnitude its behaviour as a.codloid a,nd t>he probability tbatl a fibrous structure is not chmica,lly homo+ geneous. As a result ma,ny of t)he st'at'emenb which find a place in tlhe permanentl litetmture a,re bamd on very insecure evidence, and a(re even contradictory. In reviewing brielfly the premnt posi-tion of the subject? reference may at tlhis stage be limitled to recen.t papers whioh have a belaring on fundament,aJ questions. A normad cofton cdlulose is represented by the formula (C6HlOO& an.d idem a,s t'o the molecular st>ruoture ham been formed largely oan the evidenm afforded by hydrolysis.It is impor-tarntl to1 note t,hatl in this particular case hydrolysis is not rea,dily effected and invollves the use of somewhat drastJc relagent.s so thah baking into aacount the unsta.ble nature of the hydrolysis p r d u d e , semn.da.ry rea,ctdons are inevitable[. The fact that numerous and complelx degra8dation colmpoands are formed has thus given rise1 t'o conflictsing opinions on the chemical nature of celluloge butl itl is unnecessary in the present pape:r to discuss theset rival theories in detlail. Appareat,ly tlhe view which finds most acueptanm is that) cellulose, like starch is essentidly a polyglucoae anhydride and it may be weill to state at once that this conception admi.ts of a double inter-preta,tion; The complex may consist of the simple units C,H,,O, (derived from a hexose by molmular loss of wa,te;r) pdymerisd in unknown numbers.On the othelr hand n molecules of as hexose may be direatly connested together through the elimin.ation of molsmles olf Walter or where n is a la.rge fa8ctlor of m- 1 molemulee. I n either ca,se t,he first point which must be seltltled is to ascertain bey0n.d doubt if glucolss is a.atua,lly tlhe hexme folrmed by the hydro!-lysb oif cslluloue and if sol t.o determine exactly the amountl of sugar tlhus produmd. The inquiry becolmea muah more definite if it can be shown tlha,tl, witahin the1 limits of reasonable experiment(a1 error cellulose can be converted in.tol gluc;ms in terms of the equafdoa : (CGH1O05)n f nH,O * mC6H,,O6* 100 parrtrt.s + 111.11 pasts.From timet to time wnfidelnt statements appear in tjhe literature that practliaaJly quantitIative yields of glucose have been obta.ined from oellulm but the grounds upon which suah claims ar0 made are by no means convincing to workers in the sugar group. Praoti-cally speaking the only experimentad methods available for degrad-ing ~lluloae depend upm the use of mineral acids either alon THE CONSTITUTION OF POLYSACCHARIDES. PART II. 1491 or in colnjundlion with a,wtic anhydride and it is evident that any sugar t'hus liberated must undergo profound alteratioln when kept in contad wit,h these reagents. This no doubt) a,ocounts f o r the fact that hitheirto pure crystdine glucose has nevelr been obtained from t,his polys,accha.ride.Nevertheless Flechsig (Zeitsch. physioZ. Chem., 1883 7 523) claimed that a yield of 95-98 per cent. of the thee r e t i d ammint of glucose wits fmeld by t)he adim of sulphuric acid on cellulose but the stlatmelnt i,s based solely on the reducing power of a complex mixtlure and has little significance. Sahwalbe and Schultz (Ber. 1910 43 913) supplemented Flechsig's experiments by isolating the produo& of hydrolysis and obtained a se,mi-oryst,al-line suga,r amounting only to 20 per cent. of the tlheoretlical yield. Working on similar lines Ost atnd Wilkelning (Chem. Zeit. 1910, 34 461) ma,de t,he importmantl claim tha,tl the yield of glucose was a.lmostl quantitative but it may be remaskeld t$ha,t they exa,mined the1 produds otf hydrolysis po,lasimet,rically and reported specific rotatboas ra.nging from + 29'4O to + 44'8O whea-eas the equilibrium value for glucose is + 5 2 * 5 O .As a furtlher mea,ns of estima,ting the amount of sugar farmed tahq adopteld melthods depending on the reduction of copper so11utioq but in this case a h irregularit*iee were experienced and the results indicated yields of glucose varying from 73.4 to 113.5 per centl. of the welight of cellulose tlreated. The we of hydrochloric a'uid for degrading cellulose is even less satisfactory. As is well known Willstiitter and Zwhmeister (Ber., 1913 46 2401) dissolved coltltan-wooll in 40-41 per cent;. aqueous hydrolchloric acid and allowed the hydrolysis to protoeled in the cold. 'The oouw of the rea.dion wats followed polarimetlrically and, by data obtained from control experiments in which glucose was dissolved in the same acid medium they ca410ula.ted tha't the yield od tIhe hecmse formed from cellulose a,moiunted bo 96.3 per cent!.of the theoretical value. This mnclusion was appa8reatlly colnfirmed by the results of titrations which indicated the forma.tion oif 94 per ce8nt4. of the theoretical weight of glucme. The results appmr mn-vincing untJl th&y are wnsidered in mnjunct'ion with the known effects of hydrochloric acid upon glucose. %illstlatter and Zech-melister were of the opinion tha,t, owing to the l m mnmntration of sugar in the aoid mlutim no isomalbe was f o m d butl it has been shown (Davis J . SOC. Dyers m d Col. 1914 30 249) tlhat the action of hydrochloric acid in prolmating the antmcoindeasamtlion of glucose extbnds t,a solutions containing as lit'tle as 1 per mat.of the sugar. In addition few reagenta effect more fundamentad changes in reduhg hexoees than hydrochloric acid in either dilute or con-centrated solution. Thus traces of the acid convert the butylene-oxide forms of glucose into the ethylene-oxide isomerides. I n highe 1492 IRVINE AND SOTJTAR: concentrations of acid complex changes are therefore to be expected, 501 that when glucose is dissolved in 44.5 per cent,. hydrochloric acid t.hel specific rotation is + 164*6O a.nd thus exceeds the maximum value for a-gluc!osel by a,pproxima,t,elly 50°. Tha,t Willstatqtelr's prolcew has velry lithlel bearing on the prima,ry constitution of celllulolse is further showfi (Cunningham T.1918 113 173) by t,hel famothat both coft't80n and elspasto mlluloms give praatically idelntioal rot'a,tion curves wheln hydrolysed with coaceatsatleid hydrochloric a,cid undelr t,he colnditiolns described by him. I n fact the evidence of speufifio rot,atioln and reducing polwelr emn when apparently consistentl, caa,nnolt be held to chara.at,eirisel an uncrysta~llisable~ syrup as a definite sugar. A colnsidelrablel a,dvance oln ths use ob minera,l a,cids is marked by the; coinveirsioln olf mllulose~ into glucose a,cet,at es as elaborated in the exha;us;tiive reseasches of Ost and his pupils. Recopisable crystal-h e products coaslisting of cedlobiolsei oIct,a,-aceltatee a.nd glucolsel pentam-acetates are thus obtained ro that i t is possible to ascribe t,rustr worthy va,lues to the yields.By using amltic anhydride1 conta,ining a8pprolxima.tdy 10 per centl. od sulphuric acid as tlhe hydrollytio reagent Ostl (Chem. Zeit. 1912 36 1099) i,sola.ted a mixture off solid acetates amounting to 60.6 per cent,. of the1 theoretical quan-tity the rema.ining prolducta being uncrystallisable syrups. It. is very doubtful if the latter can be inoluded in cra3culatJng the! t'oltal yielld oc if poda,rimelt(ric mehholds a8re a8dmi.ssible in wtimating hexose aue,t,atee as many factors comb,inei ta render suoh a method uncer-tain (Hudson and Pa,rkm J . Amer. Chem. SOC. 1915 37 1589; Hudson ibid. 1591; Hudson and Johnson ihid. 1916 38 1223). Up to1 the1 preiwnt time in no reaelasch on t'he hydrolysis oif cellu-lorn where] a yield of glucose even approlxima,ti.ng tol the theoretical amount has been claimed ha,ve tlhe results been based oln t'hei quan-tity of the s;ugar or of a crharackeristia derivahivel amdually isolabd.In the1 work nolw described we0 a.dhere1d to the prinuple tlhatl the yield of hexose should be ascert.ained from the weight of crystalline mmpolunds obtained in a mndi,tioln of a.nadytlical purity and in well-defined sterelolahemiclad forms. Adolpting tlhis standard we have been able t,ol sholw t,hat as a minimum the yielld od glucose obt<ained from cellulose is 85 per cent. olf the theloreitid amoant. The melt,hold used by us elmbodies the same principle as amtolysis in that it involved hydrolysis of cellulose and simultaneous con-densation of the sugar liberated so as to give a &able derivafive which t8helre.a9t,er relmained una.ff eldeld.I n this way the1 glucose wa's proteobd from the destructive effect of the hydrolytic agenk. The material employed was a normal cot,tm celluloee for a supply of which we are indebted to Mr. Wm. Rintoul of Nobel's Explosive THE CONSTITUTION O F POLYSACCHARIDES. PART 11. 1493 Co. This was treated as described in the experimental part, with a 1a.rge excetw of acelt4ic a,nhydride containing acelttia aad snlphuric wids. Wheln thel fibrous stlructare ha,d diaappelare:d tlhet produatl was poured intlol Walter and the precipitlatetd solid ,setpasated. The filt,ratle t'hen cont'aineld t'hs lower acetyla.te,d glucwes t,oIgelther with amtosulpha,tea and other soluble degrada,tion productx whilst the insoluble1 residue1 colnskteld of polysa,cahafidel ammtlattes.On heating the la,tt,elr in an a.utoclavve a,t looo with mstlhyl alcohol1 aolntaining 0.5 pelr cent'. of dry hydrogen chloride the first e$e& was ts remolve the acetyl groups which were converted into methyl acetate (Perkin, T. 1905 87 107; Fentoa and Beirry Proc. Camb. Phd. Soc., 1920 20 1 16). Thelreaf tsr simultlaneoas hydrolysis and coln-densat,ion witlh the sollvetntI ensued the process thea being pa,rallel witlh tlhe conversion of stlarch iatol metlhylglucoside (Pisoher Ber., 1895 28 1151). The main productl of the relaction consisted of arystlalliae methylglucolsideA but a,boutl 25 per cent. od t.he maltelrial persistled aad remained pra8ctbcally unafiected on relpelati.ng tlhe ttrea,tlment4 with the a.cid alcohol.This anmrphous relsidue was t8herefolre hydrollysed by melans olf dilute1 aqueous hydrochloric acid, and the product aga,ip brolught into rea,dio'n witlh acid methyl a.lcoho1. In this way the tot.a.1 yield of metIhylglucoside froim the fra.&ioln insoluble in water was ascertained. Owing to the large volumes which had to be manipulated the t8relat8ment od the products soluble in water was laborious. After removal of t4he free a,cids t4he solveint was eva.polra8tle.d a'nd the s u p converted into mettIhylglucoside in the usua.1 way. In every case bhhs rnet8hylgluemide wa,s cYbt,aJned as a co~lourless syrup which rapidly solidifid tol a hasd mass of cayst.als. On hydrolysis wit,h acid no difficulty was experietnced in obt.aining pure crystalline glucoael frolm the1 glucoside.Stutement 01 Yields Obtained. Two1 melt4hds ob estimating the yields of melt,hylglucosidet wetre employed. The weights reported refer tlol pure crystallinel material drietd in a vaauum weln until comtlantj and as an additiolnal ahecrk, the olptiaal activity ob eaah sollution whioh yielded methylglucmide was datelrmineld. During the glucolsidel folrmattioin heating with acid mehhyl alcohol was coatinued untlil equilibrium had belen esta(b1ishetd between tlhef a- and P-folrms and under the conditions adopted the propmtboln in which kheae modifications are present is respectively a = 77 fi = 23 per cent. (Jungius Proc. K . Akacl. 1T'efemch. Amsterdam 1903 6 99). The mnstantI spedfic roltatioii attained when sollutims of melthylglucwidel in acid methyl alcoho 1494 IRVINE AND SOUTAR: a're heatled is thus of the ordea of + 1 1 4 O so that we w m able t,o check our gravimetlriria r e d & pdarimetriaally.As we rely exclu-sively oa our gravimetlri.a data, this prelca!utlioln may swm unneces-sary butl it8 a,doptioa selaured t,haat expelrinietntal conditions were weld whiah predudd a.ny possibility off the yields being af€elct,ed by t,he fo;rma,tioa sf y-metlhylglucoaide. The combined rtzsults of one typical experiment are shown in the' follolwing chart the weight of celllulosel t,a.keln (70 grams) being cotrrected for tlhe moistlure and ash content,. 112.0141 graiiis f i solid acetylated \-prod u c t . ,/ \ \ ,/" x I 3fe thylglucoside.I Cellulose J. 34.0513 grams 65.0614 grams 29.0830 grams -+ 25.9639 ,, resistant deacetylated 6.2340 ,, prod uc t . fl- -- - -\ /' 66 2493 grams = Total \ '., li i \ 10 litres aqueous acid solution. Expressing t'hel resultl in perwnta>ges : Cellulose -+ M e thylglucoside -+ Glucose 100 parts gave 101.8257 parts equivalent to 94.4775 parts. If the celluloael mollelmlel is composed entirely of glucose residues, 100 parts oif the podysacaharide should give 111.11 pasts olf glucose, so tihast the1 opeiration olf the above scheme gives a yield od methyl-glucmider (and thereforel od glucosel) of 85.03 per cent. of t>hs theof-retical amountl. Although the1 manipulations were conducted with a standard of accuracy comparable with that employed in gravi-metric analysis itl is obvioas that the above result is a minimum value.The preparation of methylglumside from glumel although a smooth reiaotion is not quantitlatlive owing to inevitable experi-mental 101% in isolating and crystallising the product. We do not propose however to introduce any correction in whiah allowmce is made for expwimental law a d our future work will inolude an attempt to alcwunt2 for this diveirgeizce of 15 per mnt. from the thesretiical value THE CONSTITUTION OF POLYSACCHARIDES. PART 11. 1495 Discwsion of Results. Althofugh the1 'main objectl of the presentl research did not involve the deltadd Colnstitution of wllulmel solme of the results obtained have1 a. dire& bearing on tlhe problem and may be disoussed. As a rule i t is an unoommo1n experielnm in the sugar group to1 obtain crystlalline derivatives in yields which exceed 80 per cent.and the figurw now submitked thus afford strong evidence that cotton oelllu-lose is composed essentially olf glumel rmidues condensed together. It is to1 be noted however thatl the processes adopted by us would noit serve to isolate any ketwe constituent should such be preisentl. I n view of the fact that cellulose yields bromomethylfurfuraldehyde (Fenton and Gostling T. 1901 79 361) itt is conceivable that the unexplained margin of 15 per celnt. may be amounted for by the presence of a nucleius in the cellulose molemle which is resolved into a keltmel on hydrolysis. It is possiblel although somewhat improb-able that the hexme units in mllulose are symmetricadly disposed as in inulin (Irvine and Steele this vol.p. 1474) and the alterna-tlive has to be kept in view tlhat two three or four hydrolxyl groups of individual glucose molecules may be involved in the coupling. Should tlhis be the1 oae the hydrolxyl content od cedlulose may still be regarded as three but this would be an average value and would not imply thatl as in inulin three hydroxyl grolups are present in eiery C unit. Evidelnce in support of this secolnd vielw has been colntsibutleld by Delnham and Woodhoasel (T. 1917 111 244) from the study of trimethyl cellulose and we hope in consultation with these uwkers to elxtlend tlhe investigation on melthylated wlluloses. Further evidence of the non-uniformity of the glucose linkages in cellulose1 is aflordad by the remarkable variatioln in the ease with which the oomponent parts of the modecrule undergo acid hydro-lysis.Another signifioanto faotolr is tlhatl the1 yield of cellobiose obtained from cellulose although varying greatly with the condi-tioiis of hydrolysis has never exceeded the maximum quoted by Klein (Zeitsch. cmgezo. Chem. 1912 25 1409). His figures are: Cellulose + Cellobiose octa-acetate -+ Glucose 100 parts gave 60 parts equivalent to 31.9 parts. From thme rmult,s it would appear that at least one-third of the cellulmel molecule mntains the linkage characteristic of celloibime. Now cellobiose contains eight hydroxyl groups one of which is a reducing group and therefore terminal. It follows that one of the reimaining hydroivy1 groups of the reduuing o p o n e n t must be attached to t4he reducing group of the1 second glucose residue.9310 position of this linkage may be fixd from among other factors 1496 IRVINE AND SOUTAR: tJhe constdtlutlion assigne.d to trimet,hyl glucose and f o'rmula I may t'hus bet deduced for oelllobiose : .CH*OH OH-0-G 'AH C!lH*O*CH.[CH*OH],*CH*CH(OH)*CK,~OH / \ UH-0-GI I I CH,*OR bB,*OH The! expanded stlrudare 11 in whiah G aad G relpresent glucose raidurn aan thus be delduced for a fragment olf the celllulose mm-plelx. Of the tIwo groups G and G, the latter i& the molre stable to hydrollyste and the systelm indicated in formula I1 evidentlly relpre-seats the mostl resistant portion of the cellulose mollede. It is significant that in olur wolrk we! encountelred tlhe same prolgrmive diaculty in eliminating the glucose residues f r m cellulow.The melthylglumside obtaineld was isolated from three1 groups of aaetollysis prolduc;ts : (1.1 (11.) A. Soluble in water. B. Insoluble in water and hydrolysed by acid melthyl dcmhol. C. Insoluble in water and resista.ntl to acid methyl dmhol. Our rwultsl tlhus show that tlhe cmlluloaa modeloule may be1 dis-sected into three1 portions and the a,pproximate ratliol in which the grcups A B and C are presentl is displayed below. Methylglucoside. Glucose. C,H,,05. cellulose /"-4 gave 9.5817 equivalent to 8.9 equivalent to 8-0 100 parts <+ $ 9 52.3372 9 7 48-6 Y Y 43.7 , 39.9068 99 37.0 9 9 33.3 - -94.6 85.0 It) will be1 wen tha,tl tlhe prolposrtioln olf C agreea approlxirna-tedy with the figure indicated by the maximum yield of cellolbiow oota-acet'ate obtlained from cellulose and it is our intlentlioliz to continue the investigation by tracing the structural distinction between the units A B and C.In addittion we hope to ascertain whether the glucose belongs to the ethylene-oxide or butylene-oxide types as the fundamental difference between cellulose and starch may depend on the nature of the oxidic linkage in the constituent hmose residues. E X P E R I M E N T A L . The material employed wit8 a normal mtlton cellulosel suppliefd by So the ReBearch Department of Nobel's Explosives Co. Ardeer THE CONSTITUTION OF POLYSACCHARIDES. PART 11. 1497 f a,r as the1 ultima8tet yields of met~hylglucoside are m~n.mtrned simila'r reaulte were1 obtaineld with filter paper which ww more resdily disintograt(d by the relagents.I n quoting yields allolwa,nce has been made f o r the moktarel content (6.7 per cent.) and the1 ash lelft on ignition (0.355 per cent.). Seventy g r a m o€ the1 mllulow cutq inta mad1 pieces 2 cm. by 1 cm. were placed in an enamelled iron beaker surrounded by a ba,t.h cooled wit,h running watelr. A mixture1 of 350 C.C. of amtic a>nhydride cont,aining 6-25 per celnt'. oC a.celtic a,cid a'nd 20 C.C. od conceatrated sulphuric acid was mo;leld to 1 5 O aad qui.ckly a,ddeld tlhe mass being rapidly agita,t,ed with a polwerful stirrer. The best retsults were obtadned when the maximum telmperatnre did not e l x d 75O and in twelnt~ minut'es the fluid mixture was poured into imcold water with continuous stirring during the dilution.After twenty-four hours the white precipi,tafe which had setltled became brittdel and was filtelreid a,nd washed until free from a.cid. The t,olttatl volume 04 iilt'rafe and wa.shings was 10 lit'ree a.nd tlhe insoluble aaeltlates after drying ah 40-50°/25 mm. weigheld 112 grams. The1 mat'eirial was sepa,ra,tled into tlhrea portlions a,coording to1 the1 solubility in. 95 pelr cent,. aJco.holl (1) soluble1 in the cold (2) soluble! only a t the boiling point, (3) insoluble. As each f ra,ctioa was mave1rt:ible into1 methyl-glu cmidel tlhis sepasa.tion was not' oarrield o u t in t'he 1a.rget-scale elxpelrim elnta. The following is a,n account of a tlypiaal experimelnt. Simultaneous Deacetylatz'on Hydrolysis and Xeth,ytation of t h e Inso Zub I e A c e t a t es.The mixed a.ceta,tes were disolveld in methyl alcohol containing 0.5 per cent. of hydrogen chloride m as to give a 5 per cantl. solu-tion and heated a t looo for seventy hours. On opening the auto-clave tlhe odour off methyl acetate was noted a8nd a white amor-phous precipitate was found to have collledd. This was filtered (Filtrate A); washed and d r i d (Residua B). Examination of Residue B.-The materia,l a?mounting fo 29 grams was a white amorphous powdelr insoluble in water, chloroform ether alcohol or dilute! hydroohloria acid but readily soluble in dilute sodium hydroxide solution. It melted and decom-pwed a t 237O and reached as a glucoside towards Fehling's mlu-tion beling hydrolysed on boiling with dilute acid.No chlorine was present and a mekholxyl determinatim gave a blank r e d t (Found, C = 44.0 ; H = 6-24 ; OMe= 0. C,H,,O requires C = 44.4 ; H= 6.20 ; OMe=O pelr cent.) 1498 IRVINE AND SOUTAR: Con.version of Besidue €3 into Methtylglucoside. On boiling under a condenser with 3.75 per cent. aqumus hydrm chlo,rio a'cid the white solid gra8duadly dissolved witlh the exwpt,ion of a small residue which in a. separate experiment was hydrolysed by means od 8 per cent. a$cid. Wheln the activity of the solutions was colmtant indiaatdng %hat hydrolysis was complete the liquids were unitled neutlradised wit'h barium ca,rbonate and evaporatd to drynegs under diminished pressure. A pale brown syrup remain&, which was extsa.&d five times with boiling methyl alcohol1 contain-ing 0.5 per cent.of hydrogen ahloride and the solution was heated aft looo untJl the1 optica.1 a<otivity remained const8ant ([aID + logo, cadculattleld oln the1 weightl of glucoside ischted). The amaid was then neutlraliseld by shaking the solution sucawsively with 1ela.d m d silver carbmmtes a.ftees which the filtrate wm boiled for some hours with cha,rmsl. A colourlew solution was thus obttained whioh 0.n concelntrafioln undelr diminished pressure gave a clear syrup. T'his3 rapidly crystallised t o a compact hard mass on the addition of a nucleus oif a-methylglucoside. The cryst'als were extracted five times with a large excess otf boiling ethyl acetate and the pure glucolside isolaf,ed in one crop from the united liquors.The product colnsisted otf t,he equilibrium mixture ot a- and P-methylglucosides. Yield, 25.9 grams. (Found C = 43-20 ; H = 7.41 ; ORXa = 15.31. Cak., C=43*30; H=7.22; OMe=16-98 per cent.) The specific roltatioa in wa.t'er (mean of t'wo detmmina.tdons) was + 114.B0 in place of the calcula,tled value + 114.0°. The compound behaved sha.rply as a glucoside towards Fehling's solution a,nd showed tche usual range of melting point (125-154O) for the mixed glu cornsides. Examination of Filtrate A .-This solutdon contained the equili-brium mixture8 of a- aad &methylglucosides in acid melthyl alaohol and showe'd [aIn + 113'8O (calculadad o'n the weight od glucoside obt,ained). It was neut,ra.lised as described above with lead and silver ca,rbonates the further treatmentl involved in removing CQ~-loidal silvelr aad in isolating the products being also identkal.As beforei no1 diffioulty was experienced in obtlaining the methylglum-sides in the crystalline condition. The product was free from halogen o'r sulphur and had no adtion on Fehling's sdutJoln untlil hydrollysed (m. p. 123-162O) (Found C = 43-30 ; H =7*15 ; OMe= 15.56. Calc. C=43'30; H=7.22; OMe=15.98 per oeatl.). The constant weight of pure glumside was determined by hea.ting atl 50° under diminisheld presure a currentl ogf air dried over phos-phori.a orxide being led tlhroagh t'he apparatus. A trap containin THE CONSTITUTION OF POLYSACCHARIDES. PART 11. 1499 tlhe sa,me dehydrahing agemt was placed between the receiver and the water-pump.Yield 34 grams. Preparation of Methylglucoside from 4 cetolysis Products Soluble in TVater. The aquelous acid filtxratle obtaineid in removing the insoluble acet,ates was distinctly dextlrmo8tatolry a.nd amoantled with wash-ings t.a 10 lit'res. This was subjeated to distilla,tion in &earn the voilume being kept constant, to remove the excess of amtic a8cid, a,nd the sulphuria a,ud present waa then precipitla8t.ed by shaking with barium carbonate. The filt,e,red solution was evaporated to dryness unde,r diminished pressure. A white crgsta.lline reaidue remaineld tsgethar with a yellow syrup which was elxtracted five times with boiling meithyl alcohol containing 0-5 per cent. of hydro-gen chloride( the elxtmction process extending over ten hours. The unit,ed extracts (Solution C) were separated from the semi-arystal-line undisso2lved solid (Rwiduei D).Examination of Residue D .-Alt(haugh largely inorganic Ohis residue contlaineld some orgaaia ma.tt8er delrived eiit,he,r from soluble acetmulphatels or from collolidad cellulose1 aceltatea. It was accord-ingly tlrelateld in exa'ctly the1 same mannelr as Residue B and the hydrolysis proldud isoIla.ted as a syrup. This was eixtaact\ed six tJmea with boiling methyl alcohol1 coatlaining 0-5 per celnt,. olf hydro-gen chloride and the solutions were united with Solutio'n C. Examination of Solution G.-This ext,ract tagethes with that from Residue D, was hea,ted a t looo until the robtion became const,ant after which the equilibrium mixture of the methylgluco-sides was isohted in the usual mannelr.Somelwha.t greater difficulty was experienceld in obtaining the produat in a. pure1 condit'ion and a.lthough the material beihaved shasply a,s a glucoside t,oIwards Felhling's wht,ion the melting point sholweid a wider range' than usual (105-140°). The specific ro'tahion was also slight'ly low ([a], + 111.5O in place of + 114O). Yi.edd 6.2 gra.ms (Found, OM@= 15-98 per cent.). C=43.17; H=7*16; OMe=15.22. C ~ C . C=43.30; H=7*22; Isolation of Crystalline Glucose from Cellulose. The preparations of crystlalline melt'hylglucmide olbtained it5 described were mixtures of the a- aad P-forms in equilibrium. This was confirmed by cryshllising a sample slowly from methyl alcohol. The B-form was then retrained in solution and the u-iw 1500 THE CONSTITUTION OF POLYSACCHARTDES.PART 11. meride which separated showed after drying a t 50°/25 mm., La], + 157*53 in watelr. This agrees elxactdy witlh the standard value (+ 157.6O). Moreover the material melted at 1GFi0 the melting polint being unaflelctd by admixture witlh pure1 a-methylglucosidet. Furkher proof of the stlandard of purity attltlained was aflolrded by the hydrolysis olf the mixed glumides. A 5 per cent. solution in 4 per cent(. hydrolchlotria acid was heateid at looo polarimetria reladings being tlaken ewery fifteen minutes. The permanent vdue observed when calculated for the1 weight od glucow farmed was +-53*Oo in place o t -+52*5O. After neutlralisatiom with barium arbanate and evaporation to dryness under diminished pressure it syrup mixed with barium chloride remained. This was extraded with boiliqg absolute aIcohot1 the sollutjion demlolrised f i l b r d and slowly canaent,rated at a lolw tempelratlure. On nudelatian and stirring crystalline glucose readily separated After a second crystallisation from absolute alcohol the yield olf dry sugar amoanted to 60 per cent. 09 thatl required by theory. The! glucose melted at 145O and gave glucosephenylosazone (m. p. 204-205O uncarr.) Calc. c = 40.00 ; H=6.67; OMe=O p a ct4nt.). When dissolveid in water the initial spe:cific rotation od +100*8O was relcmded and tlhis diminished to the canstlantl value1 of + 52.37O. The abwe result prolveisl conclusively that the methylglumside employed did noit contain any isomeria methylheaoside~ and that! consequeintly no mannow or gdadms residues are prewnt in celllulose. (Found C = 39.97 ; H = 6-54 ; OMe= 0. We dwim to record our tihadcs to the Royal Cbmmissionws for the 1851 Exhibition far a. Re'search SchoZa,mhip held by one of us during the progress od the above remarah. CHEMICAL RESEARCH LABORATORY, UNIVERSITY OF ST. ANDREWS. UNITED COLLEGE OF ST. SALVATOR AND ST. LEONARD, [Received November 4th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701489

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年代:1920

数据来源: RSC

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IMAXTED THE INFLUENCE OF LEAD ETC. 1501 CLXV1.-The rnfluence of Lead on the Catalytic Activity of Platinum . By EDWARD BRADFORD MUTED. IN a recent investigation (T. 1919 115 1050; this vol. p. 1280) dealing with the inhibitive effect of hydrogen sulphide on the occlizsive power of palladium for hydrogen it has been found that a linear relationship exists between the mass of poison absorbed by the palladium and the resulting depression in its occlusive power for hydrogen. In view of the intimate connexion which undoubtedly exists between the occlusive power of a preparation for hydrogen and its activity for catalytic hydrogenation work has now been undertaken with the object of following quantitatively the influence of the addition of successive small increments of a catalyst poison on the subsequent activity of a catalyst for catalytic hydrog ena tion.In the measurements described in the present paper lead has been chosen as a typical non-volatile catalyst poison finely divided platinum being employed as a catalyst. From the results obtained, t,he catalytic activity of platinum would appear to be a linear function of the lead present this relationship being analogous to that obtained for the influence of a poison on the occlusive power. E X P E R I M E N T A L . The method adopted consisted in measuring the velocity of absorption of hydrogen by a given weight of oleic acid under standard conditions in the presence of a fixed amount of finely divided platinum to which was added a variable proportion of a lead salt.The shaker and measuring apparatus employed were similar to that previously used for measurements of the velocity of hydrogenation in the presence of varying amounts of carbon monoxide (Tmrrs. Fur~tduy Soc. 1917 13 36). In order to avoid the presence of more than one liquid phase both the oleic acid and the lead salt were dissolved in glacial acetic acid the lead being employed in the form of acetate. For the preparation of a platinum catalyst of approximately uniform activity a weighed quantity of hydrated platinic oxide was suspended in stearic acid and reduced in this medium by means of pure hydrogen. The suspension was agitated during cooling in order t o obtain a solid product containing an approximately uniform concentration of platinum. Each gram of this stoc 1502 MAXTED THE INFLUENCE OF LEAD ON THE catalyst was found on analysis to contain 0.0634 gram of platinum 0.1653 gram of the catalyst corresponding with OmO105 gram of platinum being taken for each experiment.For the standard solution of lead acetate 0.2 gram of pure lead, prepared by the electrolysis of lead borofluoride (Zeitsch. anorg. Chenz. 1910 67 339) was dissolved in nitric acid and converted into oxide by ignition. The lead oxide was subsequently dissolved in glacial acetic acid in which however lead acetate is only sparingly soluble and was made up to 1 litre with the same solvent. Careful analysis of the filtered liquid showed that each C.C. of the solution contained 0-00017 gram of lead. In order to ensure uniformity the oleic acid and glacial acetic acid employed were each taken from a stock bottle containing sufficient for the whole of the measurements.For convenience in working both acetic and oleic acid were measured by volume by means of a graduated pipette 3 C.C. of the latter being in each case disso'lved in sufficient acetic acid to total with the acetic acid subsequently added with the lead 9 C.C. of acetic acid in all. The hydrogenation reaction was carried out in a thermostat at 50° the desired quantity of standard lead acetate solution being previously added to the reaction mixture which was allowed to remain in the thermostat for about half an hour before starting the shaker. Table I summarises the results of a series of experiments carried out under the above conditions.TABLE I. C.C. of Ratio gram-standard atoms Pb leadsolutiori t o gram-added. atoms Pt. 0.0 0.0 0.0 0.0 0.5 0.0076 1.5 0.023 2.5 0.038 3.0 0.046 4.0 0.061 5.0 0.076 5-0 0.076 6-0 0-916 7.0 0,107 7.5 0.114 7 1 min. 10.9 11.0 9.4 7.5 7.0 6.6 5-0 2.9 2.8 2.2 nil nil Hydrogen absorption in C.C. after -4 2 mins. 4 mins. 6 mins. 8 mins. 10 mins. 21.6 40.8 58.4 74.1 88.6 20.8 38.5 64.2 67.5 82.8 17.2 30.8 42.6 52.0 58.9 14.0 25.5 35.4 43.5 49.0 12.2 21.6 29.8 36.5 42.1 9.9 17.0 82.3 26.4 29.4 5.4 9.4 12.6 15.2 16.9 4.9 8.2 10.9 12.8 14.3 4.2 7.3 9.5 10.6 11.4 13.0 23.0 31.0 37.6 42.8 - nil ni 1 - - -I I - -_ It would appear to be justifiable to take as a measure af the activity of a given catalyst the intensity of the effect produced by it this effect being in the present instance the velocity of the absorption of hydrogen induced by a given weightl of platinum under standard conditions.Since however this velocity change CATALYTIC ACTIVITY OF PLATINUM. 1503 as saturation proceeds it becomes necessary to choose an equivalent point on the absorption curve a t which the velocity induced by the various catalysts becomes comparable. Armstrong and Hilditch (Proc. Roy. Soc. 1919 [ A ] 96 137 322) have shown that with pure substances the velocity of absorption in place of following the unimolecular formula as was formerly supposed does not change appreciably as hydrogenation proceeds until a certain point of inflexion is reached when it rapidly decreases.These authors consider that the regular curves usually obtained with materials of ordinary purity are due to the presence of impurities, possibly in the present case to' " clogging " poisons of an albuminoid nature. It is not proposed in the present paper to discuss further this most interesting point and for the sake of simplicity the progress of the absorption with the time may be expressed in a form independent of any general theory by an expression of the conventional algebraic type V =at + bt2+ ct3 in which a b and c are constants and V is the volume in C.C. of hydrogen absorbed after t minutes. From the absorption curve expressed in this form the initial velocity of absorption induced by the platinum may readily be obtained by differentiation. This initial induced velocity represents the rate a t which hydrogen would continue to be absolrbed in the presence of the given catalyst if no disturbing factors due either to the presence of impurities or to the nature of the reaction were present and affords a simple means of express-ing numerically the activity of the catalyst promoting the reaction.I n table 11 ths curves corresponding with the figures of table I have been expressed in the form indicated above the* absorption at one minute four minutes and ten minutes being taken as the basis of the expressions which correspond well with the entire curve. TABLE 11. Values of C.C. of lead solution added. 0.0 0.0 0.5 1.5 2.5 3.0 4.0 5.0 5.0 6-0 7.0 7-6 a. 11.14 11-56 10.1 7-94 749 7.10 5.26 3-12 3-11 2-33 0.0 0-0 b.- 0.238 - 0.588 - 0.714 - 0.447 - 0.511 - 0.512 - 0.207 - 0.224 - 0.332 - 0.131 -C. 0.00 1 1 0.0260 0.0295 0.0144 0.0191 0.0224 0.0035 0-0082 0.0163 0.0012 1504 MAXTED THE INFLUENCE OB LEAD ON THE On differentiating these equations in order to obtain the initial induced velocity the interesting result is obtained that the depression of the catalytic activity of the platinum due to the presence of increasing proportions of lead follows a linear law analogous t;o that observed for t’he inhibition of occlusion. This point is strikingly illustrated in graph (1) of the figure in which catalytic activity measured by the initial induced velocity of reaction has been plotted against the lead content of the system.The constants b and c of table 11 representing the decrease in the velocity of absorption with the time do not change regularly Milligrams 0; platinum (11). 3 4 6 8 10 12 Lead content in milligrams ( I ) . with increasing lead content but vary somewhat widely from experiment to experiment round a mean value the deviation from this mean being probably caused by the difficulty in producing exactly corresponding conditions of experiment and being observed also during a number of measurements carried out with platinum alone in the absence of a poison. It would appear that the action of lead is to inhibit completely the catalytic activity of a certain proportion of the catalyst each milligram of lead rendering inactive about 8.8 milligrams of platinum whilst the residual platinum remains capable of function-ing normally.This conclusion was further strengthened b CATALYTIC ACTIVITY OF PLATINUM. 1505 experiment 3 of table I which although included in the general results was carried out under somewhat different conditions from the other measurements. l n this case whilst the weight of oleic acid and acetic acid remained that usually taken the platinum catalyst corresponded with 50 per cent. more platinum than that normally employed namely to 0.0157 gram in place of 0.0105 gram. To this 4 C.C. of the standard lead solution were added. If the conclusion just stated is correct the result should be equi-valent to a normal experiment with 0.0105 gram of platinum in which 0.5 C.C.of lead solution has been added. That this is the case is well shown by the manner in which the initial absorption corresponds with the poisoning line a t the point required by 0.5 C.C. of lead solution and the measurement has therefore for the sake of brevity been included in table I under this heading. The view that a certain proportion of the catalyst is poisoned by each milligram of lead added the remaining catalyst function-ing normally involves the tacit assumption that the initial velocity of absorption induced by varying weights of catalyst under other-wise identical conditions varies directly with the weight of platinum available for hydrogenation. That this is actually the case was shown by means of a series of experiments with platinum alone in which the weight of this metal was reduced to three quarters one-half and one-quarter of that taken for the experi-ments of table I.The results obtained are summarisecl in table 111. TABLE 111. Wt. of Hydrogen absorption in C.C. after Pt in 4 \ 10.5 10.9 21.6 40.8 58.4 74.1 88.6 10.5 11.0 20.8 39.5 54.2 69.5 82-8 7.9 7.4 14.3 26.6 37.2 46.4 53.6 5.2 5.5 10.4 17.3 22.5 26.6 29.1 2.6 2.3 4.2 6.8 9.0 10-5 11.3 milligrams. 1 min. 2 mins. 4 mins. 6mins. 8 mins. 10 mins. Table 1V contains the coefficients a b and c of the absorption curves corresponding with the figures of table 111 expressed in the conventional algebraic form previously employed and in graph (11) of the figure the initial velocity of absorption obtained, as before from these curves by differentiation has been plotted against the weight of platinum taken the linear relationship between these quantities being clearly marked. The conditions, other than the constancy of the weight of platinum taken and the absenc2 of lead were similar to those employed above. VOL. cxm. 3 1506 LUNG AND MCBASN THE INVESTIGATION OF TABLE IV. Wt. of Pt in milligrams. 10.5 10.5 7.9 6.2 2.6 Value of a. b. C. 11.14 - 0.238 0.001 1 11.56 - 0.588 0,0260 7.66 - 0.270 0*0040 5.96 - 0.478 0.0173 2.66 - 0.381 0.0228 F I CHARLES STREET, WALSALL STAFFS. [Received October 26th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701501

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年代:1920

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1506 LAING AND McBAIN' THE INVESTIGATION O F CLXVI1.- The Investigation of Sodium Oleate Solutions in the Three PhysicaZ States of Curd Gel and Sol. By MARY EVELYN LAING and JAMES WILLIAM MCBAIN. ONE of us (M.E.L.) in continuing previous work (l'. 1919 115, 1280) has now found that aqueous sodium oleate a t temperatures between Oo and 25O can be bronght at' will into any one of three typical states namely clear oily liquid sol clear transparent elastic gel or white opaque solid curd all at one and the same concentration and temper a tur e. Hitherto the last two types have not been differentiated, althciugh as will be shown they are wholly independent and exhibit very different properties. Probably nearly all of the observations on solidified soap systems recorded in the literature refer to what we have here defined as soap curd and some con-fusion would have been avoided if the existence of these two separate types had been recognised (see for example the con-troversy bet'weeln Zsigmondy Bachmann and von Weimarn with regard to whether or not soaps are "gels").The real soap gels are unmistakable since they resemble gels of gelatin. It has become evident that under suitable conditions all soaps may exist in these three forms and each form is important both for the theory and manufacture of soaps. The chief experimental discovery described in this paper is that soap sol and soap gel are identical in all respects with the excep-tion of elasticity and rigidity which are characteristic of ihe gel form alone. The following properties are all identical in sol an SODIUM OLEATE SOLUTIONS ETC.1507 gel (i) electrical conductivity; * (ii) lowering of vapour pressure, which measures the amount of substance in true solution; (iii) refractive index; and (iv) as Salmon has recently shown in this laboratory (this vol. p. 536) the concentration of the sodium ion. A soap curd on the contrary is a sol or gel from which a part or nearly all of the soap has been abstracted through the formation of white curd fibres as Darke McBain and Salmon have shown in another communication. The distinctive structural feature of soap curd is the separation of hydrated soap as a felt of long, white fibres these fibres being of barely microscopic diameter. Zsigmondy maintained that the formation of the soap curds which he studied was essentially a process of crystallisation; the analogy is certainly close.It would seem an unavoidable conclusion from the observed identity of so many properties of the sol and gel of soap that the chemical equilibria are the same and that therefore the colloidal particles present in the two are identical both in nature and amount. It is evident that this is of direct significance in the general theory of the structure of gels, .It has long been known that salt solutions retain the greater part of their conductivity and diffusibility when gelatinised by the addition of gelatin. This was however less surprising since the conductivity could be largely ascribed to the electrolyte and to this extent it was a mattea. of indifference what happened to the gelatin on gelatinisation.To those who regarded the gelatin solu-tion as heterogeneous whether in the form of sol or gel any alteration in the degree of dispersion even amounting to removal of the gelatin from solution need not necessitate any great change in the conductivity of the dissolved salt. No such explanation is possible in the case of soap solutions where no extraneous chemical is present and where the colloid arises from and is in true equilibrium with the crystalloidal con-stituents. Any essential alteration in amount or degree of dispersion of the soap colloid would have been instantly reflected in changed conductivity well illustrated in the behaviour of curds. A further point to be mentioned here is that the gel in its genesis is much more closely related to the curd than to the sol.With the less concentrated solutions i t was found almost impossible * Since this paper was submitted for publication i t has been pointed out t o us that Arrhenius so long ago as 1887 (Oefvers. Stockholm Akad. 6 121) showed that the conductivity of gelatin-water-salt systems is the same whether in the sol or gel condition. This was quite unknown to LIB and, so far as we know this important observation has been overlooked. 3 9 1508 LAMG AND McBAIN THE INVESTIGATION O F to prepare a gel except through formation of a curd which was then gently warmed until it became clear. On careful cooling it could be retained in the form of gel. This is a t complete variance with the emulsion conception of gelatinisation as involving merely a large increase in viscosity on lojwering through a small zone of temperature.It would seem necessary throughout the discussion of colloids to distinguish clearly between gelatinisation and coagulation that is, between the formation of a gel and a curd or coagulum whether the latter is irreversible as in the case of a boiled egg or reversible, as in the case of a soap curd. The experimental data here presented include first systematic measurements of the conductivity of sol gel and curd of sodium oleate over the whole range of temperature 0-28O a t which it is posible to obtain gel or curd. These are supplemented by measurements of refractive index and of vapour tension and by direct analyses. Finally some observations on the behaviour of curds of mixtures of soaps are recorded.EX P E R I Y E N TAL. The earlier experiments had to be carried out with a Eohlrausch (Kohler) apparatus whereas with the final work a set of Washburn (Leeds and Northrup) apparatus was available. Even when not using the pure sine wave current from the Siemens high-frequency machine or the Vreeland oscillator but with an ordinary induction coil the position of the minimum was defined with an eight-fold accuracy by the Washburn set as com-pared with the Kohler apparatus. This is important. for it means that even small differences in conductivity between gel and sol had they existed would have been measurable on such a bridge even if they would not have been detected on the ordinary metre wire. All resistances bridge wires thermometers etc.were carefully calibrated. The thermostat temperatures were constant within O - O l O . The special conductivity cells of borosilicate glass have already been described (see McBain Laing and Titley T. 1919, 115 1279). The cell constants a t Oo were 13.06 and 0.1664 and a t ZOO' 13.20 and 0-1690 (co'mpare McBain and Coleman Trans. Faraday SOC. 1917 15 36 who obtained a similar variation with temperature when using Kohlrausch's standard values). Preparation of the Soaps. Apart from more than a year's delay in securing the necessary oleic acid there was unexpected difficulty awing to the lack o SODIUM OLEATE SOLUTIONS ETC. 1509 purity of the materials ultimately obtained. Pending the routine tests soaps were prepared immediately on the arrival of various specimens which had proved satisfactory in pre-war work.Table I contains some of the iodine values and molecular weights as obtained by titration of specimens supposed to be pure. Speci-mens marked ‘ ( K ” were palmitic and oleic acid “Kahlbaum.” The iodine value was determined by the Wijs method for which pure palmitic and oleic acids should give the values 0 and 90 respectively. TABLE I. Tests of Fnttp -4cids. Specimen. Palmitic ‘‘ K ” pre-war ............ Palmitic “ K ” post-war ......... British ost-war ..................... Oleic “ K ” pre-war sealed.. ....... British post-war sealed ............ Oleic f; ’’ pre-war bottled ...... Oleic “ K ” post-war sealed ...... Iodine value. 1.0 3.0 1Q.O 66.6 90.14 90-14 88.9 Mol.wt. & Titration. Theory. 256.1 256.1 256.9 256.1 262-8 256.1 299.5 282.2 - 282.2 385.5 282.2 286.5 282.2 The soap solutions were prepared from oleic acid and sodium drippings free from carbon dioxide in stoppered bottles of Jena glass in the manner previously described. The hydroxide was standardised against hydrochloric acid (method of Hulett and Bonner J . Amer. Chem. SOC. 1907 31 390) as well as against pure oxalic acid. Concentrations are invariably expressed in weight-normality gram-molecules per 1000 grams of water. In all four series of measurements were carried out with sodium oleate. In series A solutions of good sodium oleate were employed, although they had been kept since the previous communication (T.1919 115 1279). Although the actual data are not here recorded they in themselves sufficed to establish the main conclusions now confirmed and extended. Series B was carried out using the oleic acid of the fourth hori-zontal row of table I. Evidently it had become partly oxi+sed by exposure to air as shown by the iodine and titration values. Here again sol and gel are identical and the values for curd are of interest as showing the high conductivity of a curd which was not more than a few hours old. Series C made with the oleic acid of the sixth horizontal row in table I contained 1.5 per cent. excess of alkali. All the data obtained in this the principal series have been corrected by the 3.8 per cent. predicted from the measurements of McBain and Taylor (Zeitsclt.phtysikal. Chem. 1911 76 178) and it will b 1510 LAINCr AND McBAIN THE INVESTIGATION OF noted that Lh0y agree within a fraction of 1 per cent. with the three measurements already published. Series L) was carried out wit'h the same speciinen of oleic acid, using neutral solutions prepared by taking the experimentally determined quantities of acid required as recorded in table I. Density Meusure me n t s . The density was found for each concentration a t these low temperatures with a 10 C.C. pyknometer. The densities found give straight-line graphs when plotted against concentration the values, except for 0*2N above 18O being only slightly greater than unity. TABLE 11. Densities of Sodium Oleate Solutions. Con centration. . Temperature. 0*2N,,.0.4N,. 0.4N,,,i 0" 1.0012 1-0040 1.00GS 10 1.0005 1.0029 1.0062 18 0.9997 1.0020 1.00 5 0 (Values above 18" extrapolated.) Method of obtaining t h e Curd or Gel. There are definite temperature limits to the existence of each of the states gel and curd. Thus a 0.4N-gel could not be obtained a t Oo or the 0.4N-curd above 2 3 O ; 0.6N-gel and sol were not obtained below Go or the O.6N-curd above 2 5 O . Both Oa4N- and O*GN-gel rapidly liquefied at' 2 5 O . The gel was obtained in almost every case by very slow warming of the curd which gradually lost its opacity first becoming cloudy and then turning to a clear gel of definite shape. I n the case of 0.2N- and O*4N-soap the gel was always surrounded by a film of sol a t least 2 mm. thick in the centre of the cell and for 4-6 mm.above each electrode. The gel column is firmly attached to each electrode and the sol surrounds it. With rising temperature the gel shrinks more and more remaining attached to the electrodes a t each end until there is only a fine diaphanous thread connect-ing the two small masses of gel. The O*GN-solution was always obtained as either sol or gel not having a boundary line as in the other cases mentioned. With this concentration alone a gel was obtained by cooling the sol. With slow cooling the whole viscous sol set to a gel which curded very gradually (that is after two days). The curd formed in each iimb spread towards the centre in long silky fibres which graduall SODIUM OIiEATE SOLUTIONS ETC. 1511 became more and more opaque until the whole mass was white curd with individual fibres no longer distinguishable.The 0-2N- and Om4N-sols when cooled developed large white nuclei in isolated spots and these nuclei grew towards each other by thickening filaments. Thus a clear gel was not obtained in these cases from the cooling side. Whenever the nuclei appeared, the conductivity always dropped appreciably but when a8 in the case of 0-6N-gel the fine fibres appeared it was not until the whole was cloudy that the lowering of conductivity became appreci-able. When the nuclei formed the soap was evidently being removed from the sol in considerable quantities whereas for a few T h e Conductivity Data. TABLE 111. Molecirlar Conductivity of Sodium Oleate. (Series B alkaline see p. 1509.) 0.2.N.0.4N. Tempera- < wk-ture. Sol. Gel. Ckrd. Sol. Gel. Curd.* o*oo 13.42 13-38 5.88 14.16 - 7.19 5.5 14.63 14.82 6.97 16.77 16.78 8.97 11.0 17-54 17.33 9.55 19-70 20.04 10-43 16.0 2 1.25 21-25 - 24.48 24-43 21.32 - - - 26.02 26.04 - 20.0 22.0 - - - 27.00 27.00 -* Fresh curd not more than a few hours old in each case; often a day elapsed between measurement of gel and sol at any one temperature but the order in which these were measured did not affect the result. TABLE IV. Molecular Conductivity of Sodifurn Oleate Solutions. (Series C corrected for alkalinity.) Tempera-ture. 0.0" 5.0 10.0 16.0 18.0 22.0 25.0 7 Sol. 13.94 16.22 19.13 20.95 22.62 25.87 -0*4N,,,. Gel. 13.94 16.22 19-13 20.94 22.62 25.81 1 -0*6N,.- A t- I Curd.* Sol. (3.01. Curd. * 3253 - - 2.547 4-248 18-10 - 3.046 6.015 16.95 16.94 4.341 - 20.37 20.33 6.393 - 21-65 21-65 12.96 - 22.64 22-64 - 25.97 25.97 -* The curds were kept four days at o" and during two subsequent days were gradually warmed t o the ordinary temperature. The temperature was kept constant at each intermediate temperature before the conductivity was noted. Sometimes a week elapsed between the measurements of gel and sol without affecting the constant value obtained before and after such treatment 1612 LAMG AND McBAIN THE INVESTIGATION O F TABLE V. Comparison of Specific Conductivities of Curds and Gels. (Series C.) Curds. Gel (or sol.). Tempera- A- - ture. 04V. 0.6N. 0 4 N . 0.W. 0" 0.01168 0*001304 - -6 0.001 119 0.001555 0.004983 0.007729 10 0.002150 0*002213 0.005805 0.008632 15 0.003169 0.003255 0.00682 1 0.01038 18 0.004529 0.006594 0-007494 0.01101 25 - - 0.009196 0*01320 20 0.005597 - o.on8065 0.01 161 TABLE VI.Specific and Molecular Conductivity of Cwrds of Sodium Oleate at Oo. (Series D neutral.) Days. 1 2 3 7 14 21 28 40 56 05 0.2N. -, k. P* 0'0009661 4.860 0-0008908 4.478 0.0008672 4.362 0-0008339 4.195 0.0008106 4.078 0.0008066 4.057 0.0008028 4.038 0 0008138 (4.094) I - - -0.m. - k. 0.001 171 0.001 137 0.001 114 0.001072 0*001014 0.0009858 0.0009734 0.0039580 0.000941 7 0*0009328 - P. 3.268 3.176 3.111 2.994 2.832 2,754 2.719 2.676 2.630 2.609 0.6N & 0.001162 2.273 0.001 140 2-229 Om0O1135 2.219 0.001126 2.203 0*001114 2.178 0*001112 2.174 k.P* - -- -- -- -TABLE VII. Specific and Molecular Conductivity of ,4ged Curds * of Sodium Oleate from Oo' t o 20° (Series D neutral.) Tempera- - * - ture. P* k. P- k. P-0*2N. 0-41y. 0-6N. 0' 0.0008028 4.038 0.009328 2.609 0.001112 2.174 6 0.0009666 4-867 0*001160 3.243 0.001277 2.479 10 0.001190 6.994 0.00170 4.752 0.00179 3.506 16 0.001930 9.735 0.00282 7-893 0.003146 6.167 18 0.002720 13-11 0.00414 11.32 0.004700 9.217 20 0.003572 18-01 0-005501 15.40 0.006577 12.90 * The ciirds in the thermostat after completion of table VI at O" were allowed to attain the ordinary temperature while these measurements were being taken ; this occupied four more days.Figures 1 and 2 present the conductivity data and show a t a glance the effect of time of temperature and of concentration besides showing the relative magnitudes of the specific conductivities oL sols gels and of aged curds SODIUM OLEATE SOLUTIONS ETC. 1513 faint fibres only very small amounts were being removed. In every case where the gel exhibited a conductivity slightly less than that of the sol this could he directly traced to the presence of a few curd fibres. The sol was always obtained by warming the gel or curd to 20° or 30°. Analysis Refractive Index and Vapour Pressure of Sols and Gels. It was first established that the refractive index of 0-5N-sodium oleate as gel is identical to eight significant figures with that of the same solution as sol.A Zeiss interferometer with 3-em. cell was employed. Into one side was placed some of the sol and, after it had been caused to gelatinise more of the same sol was poured into the other side for direct comparison without causing alteration of more than one division from the position of the zero reading corresponding with a difference in concentration of 10-6A7. This confirms the result of the conductivity measurements and also of Salmon's measurements of sodion concentration using the sodium electrode (Zoc. cit.). A similar result has been obtained for gel and sol of gelatin by Walpole. The identity in properties of sol and gel is shown also by the following measurements of vapour tension," using the dew-point method of McBain and Salmon (Proc.Roy. Soc. 1920 [ A ] 97, 44; J . Amer. Chem. Soc. 1920 42 426). Dew-point Lowering of Sodium Oleate at 18O. Concentration. Gel. 0.6N 0.06" 0.LV 0.04 Sol. 0-06" 0.04 Experiments were next carried out to test whether appreciable segregation of soap occurs during gelatinisation. A 0.4N-curd was introduced into a clean dry test-tube and very gently warmed. The curd very gradually became a column of gel with sol surrounding it. After some time the contents were poured through silver gauze into a dry weighed flask the sol passing through the gel remaining on the gauze. Some of this gel was removed into a second tared vessel and both weighed speci-mens were carefully tested both for sodium and for oleic acid (or oleate) by titration with about iV/4-solutions of aqueous and * Vapour pressure is used as a measure of the concentration of crystalloidal constituents present; the vapour pressure of gels and sols 'containing no crystalloidal material does not possess any such significance since it ie necessarily the 8am0 as that of the solvent itself.3 K 1514 LAING AND McBAIN THE INVESTIGATION OF alcoholic sodium hydroxide standardised against the oleic acid used (molecular weight 286.5 instead of the theoretical 282.2). Two such experiments are recorded below the sodium and oleic acid content being expressed in C.C. of O.2N-acid. Soap Difference Weight Oleic calculated sol/gel taken. Type. Sodium. acid. per 100 grams. per cent. 6.4344 sol 9.43 4.081 4 sol 7-11 7-00 34-56 0-9 0.08 10.55 10.48 33.8 9.42 34.7 1.6.2272 gel 2. 2.2807 gel 3.94 3.93 34.53 It is evident from the above table that the sol and gel have nearly the same composition. Even after allowing considerable time for shrinking and possible syneresis the result expected would be similar to the above since the conductivity of an old gel is the, same as that pf freshly formed gel and as that of the sol into which it turns. A similar experiment was made with 0.5N-sodium oleate using the Zeiss interferometer with 5 cm. cell. The difference in con-centration bettween lumps of gel and the sol in which they were floating was not more than 0.003N. Perhaps even this small difference may have been due to segregation caused by previous curding which could not be equalised again without melting the gel for the purpose.From all the above it is evident that in complete contrast to formation of curd formation of gel takes place without appreciable segregation of the soap. The refractive index of a soap solution is an accurate measure of the total concentration of soap whether as sol or gel. Discztssio?L Theory of Gels. It would appear from the present work that a gel is identical with a sol except for its mechanical properties.* Osmotic activiey, electromotive force and conductivity alike prove that the chemical equilibria are identical in gel and sol. Furthermore since the conductivity of concentrated gel and sol is thus identical the hypothesis of a closeld cellular spongy or honeycomb structure or other similar structure is disproved and even a similar structure with partly open pores is rendered! extremely unlikely [see (1) and (2) below].* Previous communications have indicated that soaps are to be classed with proteins gelatin salts dyes etc, m colloidal electrolytes. The similarity in the behaviour of their sols is so definite that m y general theory must be consistent with the facts of all these cases. Hence the significance of the identity of soap sol and gel must extend to these other systems SODIUM OLEATE SOLUTIONS ETC. 1515 A difficulty in reviewing the various opinions held with regard to the structure of gels is that a definition of the word phase is primarily involved. The old diversity still subsists as to whether typical colloidal sols and gels are to be called one-phase or two-phase systems.Thus whereas most authors are agreed that sols and gels are to be regarded as heterogeneous systems a few such as Proctor Hayes and Brailsford Robertson prefer to call them one-phase systems even where they postulate a molecular network throughout the gel. It was arguable to regard sols and gels of protein salts as one-phase systems containing only molecularly dis-persed matter until the facts with regard to soap sols and gels had been established. I n the case of soap solutions the formula and molecular weight of the chemical substance concerned are known, and it is impossible to ascribe the colloidal properties to the presence of unknown molecules of enormous molecular weight. So long as the soap is in molecular dispersion it behaves as an ordinaq crystalloid.Apart from the above conception of a moleoular network there are four suggestions which have been advanced to account for the properties of gels namely : (1) Closed honeycomb solid-liquid ; Freundlich. (2) The porous but continuous solid cellular framework ; (3) The emulsion liquid-liquid ; Wo. Ostwald. (4) The micellar theory of Nageli Pauli Zsigmondy and the present authors. Various authors whilst adhering to one or other of the above conceptions have argued that the phenomenon of gelatinisation is a process of crystallisation. The evidence here presented is how-ever incompatible with this suggestion if crystallisation is taken to be removal of substance from the colloidal solution (see for instance Levites 1908 ; Zsigmondy and Bachmann 1912 etc.; Bradford Biochem. J. 1913 12 351; 1920 14 91; Bogue 1920; Lloyd Biochem. J . 1920 14 147). Thus coagulation and form-ation of curd are differentiated from gelatinisation. The present data give but little information with regard to the question as to whether the individual colloidal particles of soap gels and sols are to be regarded as (‘ crystalline” or amorphous but the fact remains that in the process of gelatinisation they are not sufficiently removed from solution to disturb the equilibria into which they enter. Since they are identical in sol and gel and since they exhibit properties of aggregation or orientation it is more difficult to conceive of them as liquids. These terms however lose much of their meaning when applied to particles of ultramicroscopic and Hardy and Lloyd.3 K’ 1516 LAINU AND MCBAIN THE~INVESTIGATION OF amicroscopic dimensions such as exist in these typical “ emulsoid ” systems. As a result of the optical observations of Biitschli (1892-1900) and of Hardy (1899) and Quincke an emulsion theory of gels, whether (1) or (2) or (3) above was regarded as finally established (see for instance Freundlich “ Kapillarchemie,” 1909 p. 475). Most authors considered that the emulsion had solidified to a cellular or honeycomb structure a conception which is irrecon-cilable with the definite experimental evidence here presented. Wo. Ostwald (1905) regarded the emulsion as still consisting of two liquids and several authors have suggested that gelatinisation consisted of the inversion of these two liquids the dispersed phase becoming in its turn the dispersion medium.This again is clearly contradicted by the experimental data for soap gels since gelatinisation leaves conductivity quite unaffected. Further, Hatschek (Trans. Faraday SOC. 1916 12 17) showed that the viscosity of a gel does not exhibit the behaviour characteristic of an emulsion of two liquids. The very earliest explanation of gels was the micellar theory of Frankenheim (1835) and Nageli (1858). They considered that gels owe their characteristic propertiw to a loose network or aggrega-tion of ultramicroscopic or amicroscopic solid particles. Zsigmondy and Bachmann resuscitated this theory producing strong experi-msntal evidence in its favour as was pointed out by Pauli a t the time.They showed that the heterogeneity of gels is of a different order of magnitude from that assumed by Biitschli Hardy etc. whose observations were made before the invention of the ultramicro-scope. The heterogeneity is amicroscopic instead of microscopic, involving distances of less than one hundredth of a micron. They emphasised the very important point that in all the positive ex-periments of Butschli and of Hardy some procedure was adopted, or chemical added to produce the structure observed in the micro-scope as had indeed been pointed out by Pauli in 1902. The micellar theory is in harmony with the phenomena of syneresis double refraction swelling peptisation the definite form and elasticity of gels coagulation dehydration and vapour-pressure curves pleocroism optical and ultramicroscopic pheno-mena the behaviour of protected colloids such as gold particles, which retain their identity even after repeated transformations, such as gelatinisation in other words all the characteristic proper-ties of gels.All that is necessary is to assume that the particles become stuck together or oriented into loose aggregates which may be chance granules or more probably threads. This hypothesis i SODIUM OLEATE SOLUTIONS ETC. 1517 supported by many other phenomena such as those observed by Garrett (Phil. Mag. 1903 [vi] 6 374) Shreve (Science 1918, 48 324) Holmes Kaufmann and Nicholas ( J . Amer. Chem. SOC., 1919 41 1329) Shoji (Riochem. J. 1919 13 227) Lloyd (ibid., 1920 14 147) Bogue (Chem. Met. Eng. 1920 23 62) and Lifschitz and Brandt (Rolloid Zeitsch.1918 22 133). The conception of micellar orientation to which the present evidence so directly leads is supported by many other facts such as the following. Thus on heating a gel molecular movement becomes so intensified that the forces holding the particles are overcome and we have the familiar phenomenon of the ‘‘ melting ” of the gel. Again nitrecotton which is completely gelatinised in a minute or so by a urethane is converted into a sol in a period ranging from a week down to a few minutes depending entirely on the degree of mechanical stirring employed which is in accord-ance with our theory that a sol is formed by mechanically breaking the orienting bonds between the particles. The third significant fact for the special case of soap is that we have never observed Brownian movement under the ultramicroscope in a soap which we had reason to believe was in the form of gel.Bachmann (Zeitsch. anorg. Chem. 1912 73 125) has made similar observa-tions with gels of gelatin. This conception explains moreover the fact that the apparent viscosity of a sol frequently depends on its previous treatment and! history. Many sols must be in process of forming such orienta-tions between their particles and hence the viscosity must depend on how far this has gone. Thus for instance a sol of boiled starch, the delicate incipient structure of which had been destroyed by previous shearing exhibited thereafter much lower viscosity (Hatschek Kolloid Zeitsch. 1913 13 881). Again it is quite char why supersaturation and hysteresis with regard to gelatin-isation so frequently occur.Once more this conception links up with the observed facts of liquid crystals. It would seem that there must be some connexion between the orienting forces observed in crystalline liquids and in gels. Indeed one of the typical soaps ammonium oleate is a well-known liquid crystal. Reference may also be made to Sand-qvist ’s b ram op h en an t hr en esul phonic acid which is obviously a1 so a colloidal electrolyte the solutions of which however can be obtained under certain conditions as crystalline liquids. Vorlander has observed that long molecules are required for forming liauid crystals which agrees with Bose’s theory of swarms of long molecules. The same appears to be true of colloidal electro-lytes such as sodium palmitate or hexadecylsulphonio acid.1618 LAING AND McBAIN THE INVESTIGATION OF decoate in concentrated solutions is a colloidal electrolyte; on the other hand sodium and naphthalene-a- and -P-sulphonates and sodium naphthionate with an equal number of carbon atoms, contain only a small amount of colloid if any. The tendency of soaps to form long strings of inolecules* or of colloidal particles is demonstrated by the lung ultramicroscopic fibres which are the characteristic feature of curds (and possibly gels) of sodium soaps (observations of Darke McBain and Salmon). An exceedingly fine filamentous structure may account for the elasticity of gels f and also for the fact that they exhibit more or less clearly oriented properties such for instance as the lenti-cular (that is not isotropic) form of bubbles generated within gels, as described by Hatschek.Freundlich has published an interest-ing study of vanadium pentoxide sols which had been aged many years and in which he found that a t the boundaries or through-out the sol when the sol was set in movement all the anisotropic and other characteristics of a crystalline liquid were exhibited. The theory of gels here deduced also leads to a prediction of the characteristic phenomenon of syneresis. Thus if there is an orienting force between the particles there must necessarily be in that force a component of attraction and hence the gel structure of oriented particles must exhibit a distinct tendency to shrink.Even i f tbis attractive force is only feeble i t must in course of time produce syneresis since in dilute gels itl is opposed only by the viscosity of a fluid. The swelling of gelatin salts is not in conflict with this view because the ionic inicelle of gelatin and proteins unlike that of soap does not become crystalloidal in dilute solution and so continues to be retained within the gel. The question now arises as to what are the colloidal particles which are linked together in the case of soap to form the gel structure. There are but two possibilities neutral colloid and ionic micelle. It is uncertain as to how much of the neutral colloid is included in the ionic micelle and it is just possible, * It might explain the fact that true reversible equilibria obtain in soap solutions if each of the true colloidal particles of soap were essentially composed of strings or even sheets of molecules thus harmonising colloidal behaviour with molecular reactivity and also resolving the problem of the number of phases present in a gel.The mechanical properties of the sols would however require further consideration. Indeed the stable existence of any colloidal aggregate has not yet been explained. t Each of the innumerable threads consisting of colloidal particles stuck together could exhibit mechanical elasticity in itself. Owing to the arnicro-scopic degree of dispersion there would be such great frictional resistance t o their displacement in the liquid that this property of elasticity would be transmitted t o the mass of gel itself for a temporary period; the time of relaxation would be dependent upon the viscosity of the intramioellar liquid SODIUM OLEATE SOLUTIONS ETC.1519 although unlikely that all of i t is so included and that therefore these conducting particles are those the orientation of which gives to the gel its structure. Were this possibility to be entertained it would have to be assumed that the gel structure as a whole would carry half the current the corresponding sodium ions being merely interspersed in the intramicellary liquid of the gel. Much more probably the neutral colloidal particles are thus linked up. An important fact t o remember in the case of soap gels and one that distinguishes them from salt solutions which have gelatinised with gelatin or agar-agar is that here more than half the current is carried by the ionic micelle instead of by ordinary ions.Thus these colloidal particles under the influence of electrical as distinguished from mechanical forces must pass as freely through the open network of the gel as they do through the sol. This is quite consonant with the fact that the neutral colloidal particles in soap sol and gel are identical in nature and amount. It is also supported by the observation of Salmon (Zoc. c i t . ) that t,he diffusion potential of soap against a solution of chloride is the same for a gel as for the sol which indicates that t,he diffusibility of both sodium ion and ionic niicelle are unaffected by gelatinisation. The Theory and Structure of Soap Curds. Whereas sol and gel are identical save for some coherence or orientation of the colloidal particles curds as will be shown are the result of an actual removal of soap from the solution in the form of white fibres the product of a process clcsely related t o crystallisation.Figs. 1 and 2 show that the specific conductivity of gel or sol is nearly proportional to its concentration and that that of the corresponding curd is much smaller and that in the curd it is comparatively independent of the concentration a t any one temperature. The curd fibres therefore enmesh a solution much more dilute than the original sol or gel of concentration which is roughly fixed for any onei temperature. Were curd fibres a true crystalline phase of constant composi-tion it would follow that the solution they enmssh would exhibit a definite saturation concentration for each temperature and this concentration would be the definite solubility of such curd fibres a t that temperature.The specific conductivity of a curd a t any temperature would then be nearly independent of the total original concentration of that curd although only approximately so on account of the mechanical diminution of the cross-section o 1520 LAING AND MCBAIN THE INVESTIGATION OF 0.0015 0*0010 0.0006 o*ooo the electrolyte through the presence of masses of curd fibres in concentrated curds. One would expect for this reason that the conductivity of a concentrated curd would be low as compared with that of a dilute curd. The contrary is however the case. The conductivity of a 0-6N-curd is always distinctly greater than that of a 0-2N-curd and it is sometimes nearly twice as great.Again for a true crystalline phase of constant composition the * - 6.6N. - 0,m a L Q c a * * b C U R 0 5 0.1 rJ -. . . . -3 0.0040 Q 8 0.0030 B 0~0020 " w2 solubility would be independent of time whereas for curd fibres this is not so. The curd falls off rapidly in conductivity during the first twelve hours and the conductivity continues to diminish slowly for some months. As shown in table VI and Fig. 2 the conductivity of 0.2N-curd fell steadily for fourteen days then remained nearly constant up to forty days a t Oo. The 0-6N-curd was altering so slowly that the experiment was discontinued a SODIUM OLEATE SOLUTIONS -" ETC. 1521 twenty-one days but the later experiment with 0.4N-curd where the conductivity was still falling a t sixty-three days shows that changes must extend over a period of months a t least.Hence although formation of curd means the separation of neutral soap from solution in the form of curd fibres and is analogous to crystallisation these fibres constitute a variable phase. For the present case the phase rule assumes the form f'+ F = C + 3 where the extra degree of freedom is the diameter of the component particles of the curd fibre or the diameter of the fibres themselves i f each of these is one solid whole. There are two possible factors of variability namely the FIG. 2 1.6 '"1 I t 0.2 6" lo0 160 2b" 2iY Temperature. Specifl conductivity o j soh gels and curds of sodium oleate at variow c temperatures.diameter of the fibres and their degree of hydration. The first factor ceases to cause appreciable change as soon as the fibres have become microscopic. In any case it can scarcely be the chief factor here concerned for the specific conductivities of fresh 0.2 and O-4N-curds differ too greatly whilst those of 0-4 and 0.6N-curds which a t first nearly coincide diverge on keeping although by hypothesis the mother liquor would be identical in both cases. The general nature of the facts in tables I11 to VII is the same, whether fresh or aged curds are considered whether equilibrium is approached from one side or the other and whether much or but little time has been taken in so1 approaching equilibrium 1522 LAING AND McBAIN THE INVESTIGATION OF It would appear that the important factor involved is degree of hydration and that the more heavily hydrated fibres are the more insoluble and1 the more stable.Taking the last point first it follows from the phase rule that for any definite diameter of fibre (or of component particles) the most stable form is that which is least soluble and in fact the conductivity does diminish with time. As regards degree of hydration a series of investigations in this laboratory using several methods one of which has been published (McBain and Taylor T. 1919 115 1300) has shown that hydra-tion of curd fibres is greatly influenced by the vapour pressure of the mother liquor. Thus in the presence of 3'ON-sodium hydr-oxide the composition of the palmitate fibres was NaP,3*2H20, whilst in the presence of 1-5~~-sodium hydroxide it was NaP,6*5H20.According to this therefore the curd fibres which first separate out from O'GN-oleate sol or gel are less hydrated and also more soluble than fibres which separate from 0.2N-oleate. Such fibres are moreover unstable in that greater hydration is required to correspond with the residual diluted mother liquor with which they are finally in contact. It should be mentioned that concentration, not temperature as such is the chief factor in determining the degree of hydration. Equilibrium in a soap curd can therefore only be attained by a process of recrystallisation with formation of more heavily hydrated fibres a process which requires much time since convec-tion or stirring is impossible and the diffusibility of soap is low (Salmon Zoc.c i t . ) . It seems certain however that the concen-tration of the mother liquor enmeshed in a soap curd kept a t constant temperature would ultimately reach a value independent of its original concentration or previous history. This view receives further support from a comparison of tables I11 or V with VII which show that an aged 0-6N-curd exhibits a lower con-ductivity than a moderately fresh 0-4N-curd ; similarly with 0.4N-and 0.2N-curds. Further a curd which has been well aged at Oo possesses on subsequent keeping at any higher temperature a conductivity which shows no tendency to rise. Discussing conductivity as distinguished from concentration it is a matter for some surprise that the heavy mass of fibrm in a 0-6N-curd does not cause such mechanical obstruction to the passage of the current through reduction of the effective cross-section of the liquid as to reduce the specific conductivity to a much lower value than that of a 0*2N-solution in which only about one-quarter as much fibre is present.The apparent absenc SODIUM OLEATE SOLUTIONS ETC. 1623 of any such effect might possibly be due to electric endosmosis; the study of the problem is being continued with the object of elucidating the phenomena which accompany the passage of current in gels and sols as well as curds. The conductivity data here given suffice to show that if the two effects suggested are appreciable they nearly counterbalance each other. The conductivity curves in Fig.2 show that with rising tempera-ture the solubility of the curd fibres increases and the conductivity rapidly rises towards that of the sol or gel. The conductivity of curd sol and gel will become identical a t the point where the solubility of the soap fibres becomes equal to the gross concentra-tion of soap present where the last fibre just dissolves or where the first fibre just appears. Such a solubility curve is indicated by the line of dashes in Fig. 2 although its exact position varies somewhat with the previous history of the curd fibres present. The rapid increase of the solubility of the curd fibres with rise of temperature is in accordance with that required by thermo-dynamics as deduced from the heat of solidification.The heat evolved on solidification in the case of a soap solution which has been cooled well belojv the temperature of initial solidification results in a noticeable rise of temperature. This conception of the solidification of soap solution as being essentially of the nature of a crystallisation process with separ-ation of curd fibres also explains the observation of McBain and Martin with regard to the increased alkalinity of curds a t low temperaturw as compared with sols a t somewhat higher tempera-tures. They found that the hydrolytic alkalinity of the sol increases within certain limits with decrease of concentration or with rise of temperature. That it is greater when curd has formed is now evidently due to the fact that the residual solution is more dilute and hence more hydrolysed.It is thus not necessary to conclude that the fibres in soap curd are anything but neutral (hydrated) soap whereas previously it might have been suspected that they were very slightly acid soap (see also the analyses below). The behaviour of the sodium oleate systems here investigated is all in agreement with the incidental observations of McBain, Cornish and Bowden on sodium rnyristate (T. 1912 181 2053), only they like all authors hereto confused gels and curds and they did not allow sufficient time in the measurements of curds. They concluded that the formation of a soap curd is not a process continuous with the adjustment of the degree of dispersion of a colloid in the sol since in a sol supersaturated with respect to formation of curd true reversible equilibrium subsists 1524 LAING AND McBAIN TRE INVESTIGATION OF Composition and Solubility of Curd Fibres.In order to obtain a direct experimental control of the deduc-tions made on the preceding section curds and qother liquor were analysed. From curds of O'6N-oleate as much as possible of the enmeshed mother liquor was removed by pressure and suction in an atmosphere free from carbon dioxide and the amounts of sodium and fatty acid radicle were determined. Three specimens thus examined all showed a slight alkalinity the proportion of sodium to fatty acid radicle being 100.4 100.9 100.4 equivalents of sodium to 100 equivalents of oleic radicle. This slight alkalinity may be attributed to oxidation of the oleate. It is thus established that the curd fibres consist essentially of (hydrated) neutral soap; the small amounts of acid soap which correspond with the hydrolytic alkalinity of all soap solutions are evidently completely submerged in these high concentrations of these neutral soap fibres.N o data previously existed with regard to this point, Tor although many authors had analysed the sediments and suspensions from various soap solutions since these always referred to low concentrations of solid they. found acid soaps of varying composition. Analysesi made of the mother liquor of 0-6N-curd a t various temperatures also showed equivalence of the sodium and oleic radicle within a small fraction of 1 per cent. Each of these determinations was carried out in duplicate involvinq four in-dependent analyses for each case.The resulting solubilities thus determined are for 0*590N-curd of sodium oleate about sixteen hours old 0-391N a t 1 8 O and 0-261N a t loo and for 0.1905N-sodium oleate and of about the same age a t 18O 0.0998N. The solubility obtained from a 0-590N-curd after three days a t Oo was 0*114N. These analyses thus substantiate the conclusions of the preceding section and the lack of quantitative agreement with the con-ductivity measurements must partly a t least be attributed to the difference in the age and previous history of the rmpective speci-mens. Further measurements will be undertaken with well-aged curds the conductivity of which will be taken just before analysis. Preliminary Experiments on the Behauiour of Mixed Cwrds of Oleate and Palmitate.In view of the fact that all commercial soaps are made from mixtures of fatty acids it is of importance to. inquire as to whether these different sodium salts separate out independently or whether the individual fibrw are each composed of mixture of soaps. I SODIUM OLEATE SOLUTIONS ETC. 1525 will be seen that although to a large extent the oleate and palmitate remain independent the separation is nevertheless in-complete. Sodium palmitate was chosen because its molecular weight and especially its iodine value differ from those of the oleate and because its solubility is less than N / 4 0 a t 25-30', temperatures a t which sodium oleate does not exist in the form of curd. Equivalent quantities of solutions of the oleate and palmitate were melted together to form a clear sol and then allowed to cool until curd fibres separated out.In the first experiment the snmeshed liquor was withdrawn at 3 5 O by means of a pipette to a tiny piece of filter paper which withheld the soap and allowed the soap solution to pass. The liquor was then weighed for analysis. In the second experiment the mixed soap curd was transferred a t 30° to a vacuum filter and the enmeshed liquor drawn through. Air passing through the soap caused frothing of the withdrawn liquor. This was condensed by warming the flask and weighed f or analysis. In the third experiment the treatment was similar to that in the second except that air deprived of ,carbon dioxide was drawn through the soap the temperature this time being 2 5 O (but see below).In the second and third cases comparative experiments were made with aqueous sodium palmitate of the same concentration as in the mixture to ascertain what concentration of the more insoluble sodium palmitate existed a t that temperature in the enmeshed liquor. The total concentration of soap in the filtrate was determined by decomposing and titrating with aqueous acid as well as with alcoholic hydroxide; the molecular weight of the fatty acid was deduced from its weight and the latter titration and finally the iodine value of the fatty acid was determined. TABLE IX. Analysis of Mother L i p o r in Mixed Curd of Sodium Oleate and Patmitate. Experi- Tempera- Mol. Iodine ment. ture. Concentration. Filtrate. wt.* va1ue.f I...3 6" 0.1680N each 0.1732N 286.9 82.2 2... 30-35 0.1903N each 0.2303N 27993 71.8 2. .. 30 0.191 4N NaP 0.01 778N 256.3 -3. .. 25-17 0'2486N each (0'2152N) 282.7 81.2 3 . . . 25 0.2500N NaP 0.00819N - -* H P=25&1 by theory; H 01=282.3 by theory t H P= 0 0 by theory; H 01= 90.1 by thoory; see table I 1526 LAING AND MCBAIN THE INVESTIGATION 0%’ Table IX shows that most of the oleate remains in the mother liquor and that the palmitate mostly separates out as curd fibres. This is shown by the high iodine values of the mixed fatty acids in the filtrate namely 82 72 and 81 comparable with fairly pure oleic acid as was shown in table I. The separation is however not quite complete for there is some oleate in the curd fibres. This was shoiwn by a continuation of experiment (3) in which the residual curd was washed with pure water and then a sample tested for the molecular weight of the fatty acid in the curd fibres.The result was 263.1 instead of the theoretical value 256.1 for palmitic acid. After about half of the curd had been washed away a sample was taken for determin-ation of the iodine value of the fatty acids present. The result was 11.2 instead of the 3.0 for the original palmitic acid used. Hence the palmitate fibres contained 10-20 per cent. of oleate alsot although unfortunately at the end of this experiment the temperature was low enough for oleate itself to) curd. It is fortunate that the behaviour of a mixture is even so far additive, since in the corresponding sol the behaviour is much more com-plex.Further experiments a t exact temperatures are contem-plated. Characterisation of a Commercial Soap. It is now possible to attempt a definition of a commercial soap. A transparent soap is a gel. All other hard commercial soaps are gels containing a felt of curd fib&. The gelatinisation may be due to the dissolved soaps or it may be partly due to other gelatinking filling agents. Curd fibres enmeshing a sol instead of a gel would probably not have the physical properties required. Thus some of the soap is separated out as curd fibres whilst some is in solution. The latter is absolutely necessary if the soap is to exhibit detergent action at ordinary temperatures. A soap containing only palmitate and stearate would not be a detergent a t ordinary temperatures.The value of the presence of oleate lies not only in its solubility but in the persistence of its colloidal constituents in unusually dilute solutions. A good illustration of the dual qualities required of a com-mercial soap is to be found in the behaviour of remnants of used soaps which have largely lost their detergent properties through extraction of the more soluble constituents. Holde (Chem. Urnschaw F e t t . Ind. 1920 27 56; SeifeiLfabi-., 1920 40 113) in a recent summary of the facts with regard to residues of soap cakes considers the further factor which helps in the accumulation of insoluble matter in these residues namely SODIUM OLXATE SOLUTIONS ETC. 1527 the precipitation of calcium salts through reaction with the impuritie~ in the water.Further interesting corroboration of the views here put forward is observed in the formation of the feathery clusters which separate in a soft soap on keeping known as figging. Soft soaps made froin linseed oil (and therefore containing chiefly very soluble soaps if unsaturated fatty acids show no “fig”). A small proportion of tallow rich in the lass soluble stearate ensures figging. Another example is that mentioned by “ H.A.” (Seifensied. Zed. 1920 47 646). A sodium soap made from coconut oil alone is very hard and very crumbly. Substitution of potassium for some of the sodium together with the addition of some potassium chloride to develop formation of a colloid makes this soap more like ordinary soap sol that it can be stamped out into cakes.For completeness it should be mentioned that many commercial soaps are formed by the curding of a mixture of two liquids. When salt is added tol a soap solution the viscosity rises enormously until suddenly the solution breaks into two layers and the mixture becomes of manageable effective mobility in the soap pan. Thus normally in the process of soap boiling the soap is probably never allowed to be in one homogeneous solution. This statement is the subject of a further communication froin this laboratory to be made by Mr. Buriiett. Summary. (1) We have discovered t’hat a soap solution of one and the same concentration a t any definite temperature may be prepared in three characteristic states ; namely clear fluid sol transparent elastic gel and white1 opaque cnrd.The latter has oiten but erroneously been called a gel. (2) The sol and gel forms of a solution of sodium oleate are identical in osmotic activity concentration of sodium ions con-ductivity and refractive index ; this proves that identical chemical equilibria and constituents are present in the two cases. The sol and gel differ only through the mechanical rigidity and elasticity of the gel form. (3) The quantitative identity of conductivity in sol and gel is irreconcilable with all theories of gel structure hitherto advanced, with the exception of the micellar theory of Nageli which was resuscitated by Zsigmondy and Bachmann in 1912 and is strongly supported by many lines of evidence referred to in the presen 1528 THE INVESTIGATION OF SODIUM OLEATE SOLUTIONS ETC.paper. The colloidal particles in sol and gel are the same but whereas in the former they are independent in a fully formed gel they stick together probably t o form a filamentous structure. It is probably the particles of neutral soap and not of ionic micelle that exhibit this behaviour. (4) The formation of soap curd in clear contradistinction from gelatinisation is analogous to a process of crystallisation neutral soap separating from the solution in the form of curd fibres of microscopic or ultramicroscopic diameter. This is shown by the drop in conductivity and osmotic activity and confirmed by direct and indirect analysis in addition to observations with the ultra-microscope. Coagulation and crystallisation are thus sharply distinguished from gelatinisation. This we consider to be the chief theoretical result of the present paper. (5) The curd fibres consist of hydrated neutral soap the hydra-tion of which depends on their origin and previous history. Within corresponding limits their solubility is definite for each temperature. The so-called melting points of soap curds are the temperatures a t which the solubility curve rises to a value equal to that of the total concentration of the soap and a t which the last curd fibre just dissolves. (6) All the above results are of general applicability both on account of the detailed similarity of soaps to protein and gelatin salts etc. as well as on account of the precision of the methods available in the investigation of these simple systems. (7) I n a curd formed from a mixture of palmitic and oleic acids, the two1 soaps are largely independent. In conclusion our thanks are d m to the Colston Society of the University of Bristol and to the Research Fund of the Chemical Society for their generous grants which enabled this work to be carried out. THE UNIVERSITY, BRISTOL. [Received October 18th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701506

出版商:RSC    

年代:1920

数据来源: RSC

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2 4-DIHYDROXY - AND 2 4 4’-TRIHYDROXY-BENZOPHENONE. 1629 CILXVIIL-A New Method for the Preparation of 2 4-Dihydroxy- and 2 4 4’-Tri?iyd~oxy-benzo-phenone and some Observations relating to the Hoesch Reaction. By HENRY STEPHEN. IN Hoesch’s method (Ber. 1915 48 1122) for the preparation of aromatic hydroxy-ketones by condensing phenolic compounds with nitriles in the presence of hydrogen chloride the formation of an imino-chloride CRCKNH is assumed and this compound con-denses with the phenolic compound to yield the ketimine, CRR’ZNH. The latter yields the corresponding ketone on hydro-lysis. Cyanogen bromide is exceptional in its behaviour towards hydrogen chloride (compare Karrer Helv. Ckinz. Actn 1919 2, 89). References to the formation of additive compounds (imino-haloids) of nitriles and hydrogen haloids are given in the literature (Gauthier Annalen 1869 150 187; Michael and Wing Amer.Chem. J . 1885 7 71) but the most definite evidence of the form-ation of such additive compounds was obtained by Troger and Luning (1. pr. Chem. 1904 [ii] 69 347) who obtained chloro-acetimide chloride CH,Cl-CCl:N€I from chloroacetonitrile and hydrogen chloride. The author has prepared this compound and found that on mixing it with the theoretical amount of resorcinol and warming on the water-bath a t 50-60° hydrogen chloride was evolved o-chlororesacetophenone (needles m. p. 131O) being sub-sequently isolated from the product. Sonn (Ber. 1917 50 1262) has condensed chloroacetonitrile with resorcinol according to Hoesch’s method and obtained the same substance.The mechanism of the reaction is therefore explained as follolws accord-ing to the above experiment: C,H,(OH) -F CH,Cl.CCl:NE€ 2% C,H,(OH),-C(:NH)*CH,Cl, (1.1 the ketimine (I) yielding the ketone on hydrolysis. Further evidence of the mechanism of the Hoesch reaction is afforded by the fact that certain iV-substituted imino-chlorides for example benzanilideiminochloride CPhCKNPh react on warming with resorcinol yielding the anils of the corresponding hydroxy-ketones. Thus in the case of benzanilideiminochloride the ani 1530 STEPHEN A NEW METHOD FOR THE PREPARATION OF (11) of 2 4-dihydroxybenzophenone is obtained as follows and on hydrolysis yields the ketone : In a similar way 2 4 $’-trihydroxybenzophenone, OH*C6~,-Co-C,H3( OH), (111) was obtained from p-ethylcarbonatobenzanilideiminochloride (Sonn and Muller Ber.1919 52 1927). An attempt to prepare 2 4-dihydroxyphenyl styryl ketone * by condensing cinnamanilideiminochloride with resorcinol was unsuccessful . It may be mentioned that cinnamanilideiminochloride prepared according to Sonn and Muller’s method1 (Zoc. c i t . ) is a solid crystallising from toluene in clusters of needles melting a t 30° and not a red viscous mass as described by these authors although if heated for some time on the water-bath the crystals change into a red mass. The failure to prepare 2 4-dihydroxyphenyl styryl ketone is parallel to that of Fischer and Nouri (Ber. 1917 50 693) who attempted to prepare 2 4 6-trihydroxyphenyl styryl ketone from phloroglucinol and cinnamoaitrile by Hoesch’s method and obtained insteadl 5 7-dihydroxy-4-phenyl-3 4-dihydro~l 2-benzo-pyrone.This anomalous behaviour is due apparently to the unsaturated nature of the nitrile since phloretonitrile (P-p-hydr-oxyphenylpropionitrile) condenses in the usual way with resorcinol or phloroglucinol . In carrying out the condensations of the N-substituted imino-chlorides with resorcinol certain observations have led the author to believe that an imino-ether is the first product of the reaction, which then undergoes isomeric change resulting in a shift of the group *CPh:NPh into the nucleus in the ortho- and para-positions with respect to the hydroxyl groups. Thus in the case of benz-anilideiminochloride the preliminary reaction may be represented This ketone cannot be prepared by condensing resorcinol and cinnamo-nitrile according to Hoesch’s method for reasons which are given later.Bargellini and Marantonio (Atti R. Accad. Lincei 1908 [v] 17 ii 119) state that the same ketone can be prepared by fusing cinnamic acid and resorcinol with anhydrous zinc chloride. This experiment was repeated in order t o obtain a specimen of the ketone for purposes of comparison and the details are so simple that no difficulty would be anticipated. After many attempts had been made the method was abandoned no trace of ketone being obtained, the chief result being the formation of a red-coloured substance the investiga-tion of which was not pursued further and the conclusion was drawn that the statement of the above authors WBS incorrect 2 4-DIHYDROXY- AND 2:4:4'-TRIHYDROXY-BENZOPHENONE.1531 as follows the imino-ether (IV) undergoing subsequent change to yield the anil (11): C,H,(OH) + CPhC1:NPh -HCf C,H,(O€I)*O*CPh:NPh. (IV. 1 The evidence in favour of this isomeric change depends on the observation that the best yield of the anil (11) was obtained by first warming the mixture of the imino-chloride and resorcinol on the water-bath until the evolution of hydrogen chloride ceased and subsequently heating in an oil-bath a t 150°. Several instances of isomeric change of acyl derivatives of phenols involving a migra-tion of the acyl group into the nucleus are also known to take place on heating. The preliminary warming of the above mixture on the water-bath resulted in the formation of an oily product which was found to be easily hydrolysed into benzanilide and resorcinol on boiling for a short time with dilute hydrochloric acid; this would be the behaviour expected of the imino-ether.A similar observation was made in experiments with cinnam-anilideiminochloride and resorcinol and it is probable that the imino-ether (V) is first formed on the water-bath but on heating at a higher temperature in an oil-bath this undergoes internal condensation and not the above isomeric change yielding the anil of 7-hydroxy-4-phenyl-3 4-dihydrocl 2-benzopyrone (VI) : This reaction is thus analogous to the formation of the benzo-pyrone investigated by Fischer and Nouri (Zoc. cit.). The imino-ether (V) was o'btained as an oily product which was easily hydrolysed to cinnamanilide and resorcinol on boiling for a few minutes with dilute hydrochloric acid or by prolonged boiling with water.The formation of the anil (VI) still remains in doubt and is reserved for further investigation. EXP ER I M E N T A L . 2 4Dihydroxy benzophenone (Benzoresorcinol). The benzanilideiminochloride used in this experiment was pre-pared from benzanilide which had been carefully purified. The method adopted was the same as that due to Wallach (AnnuZen, 1877 184 86) and the product was purified by distillation under diminished pressure. Attempts were made to replace the phos-phorus pentachloride as used in Wallach's method by thionyl chloride but without success 1632 STEPHEN A NEW METHOD FOR THE PREPARATION OF Three grams (1 mol.) o'f the imino-chloride were mixed with 2 grams (1 mol.) of resorcinol and then warmed on the water-bath a t 50°; when the evolution of hydrogen chloride had ceased the mixture was transferred to an oil-bath and heated for ten minutes at 1 5 0 O .Longer heating caused much decomposition the product becoming darker in colour. The red-coloured mass was then boiled with water to remove any unchanged resorcinol and the aqueous solution decanted from the viscid red oil. This operation was repeated several times and the oil allowed to remain in the refrigerator overnight. It showed no tendency to crystallise being very readily soluble in most of the usual solvents. After several attempts a small quantity of a bright yellow crystalline compound separated from ethyl acetate which melted and decomposed a t 328-230O.There was unfortunately insufficient for an analysis. H y d ~ o l p i s of the Anilide of 2 4-Dihtydroxybenzophenone. The most successful method of hydrolysis consisted in boiling the oil with about 25 per cent. hydrochloric acid. The oil was first treated with 50 C.C. od hydrochloric acid boiled for fifteen minutes and the yellow solution decanted and filtered from the tarry matter. This operation was repeated several times the accumulated filtrates were boiled with animal charcoal and on filtering a clear solution was obtained from which long needles of 2 4-dihydroxybenzophenone separated. These melted a t 144O, and were identical with a sample of the same substance prepared by condensing benzosnitrile with resorcinol according to the method used by Hoesch who prepared the substance in that way.A more rapid method of hydrolysis but one which leads t o difficulty in the final stage of purification of the product consists in heating the oil with sufficient dilute alcohol to dissolve it and then passing in hydrogen chloride until the solvent is nearly saturated. The mixture was boiled for a whole day under a reflux condenser and then filtered. Some tarry matter passed into the filtrate owing to the alcohol present and this causes difficulty in the purification of the ketone after evaporation of the alcohol but by recrystallising the product several times from hot water and repeated treatment with animal charcoal a pure sample of 2 4-dihydroxybenzophenone was obtained.2 4 4f-Trih~/d.7.ox~/enzophe?zone (111). The start,ing material for the experiment was p-ethylcarbonato-benzoic acid which was prepared according to Fischer an Z?:&DIHYDROXY- AND 2 4 4’-TRIHYDROXY-BENZOPHENONE. 1533 Freudenberg’s method (3nnaZen 1910 372 36) by shaking 30 grams of p-hydroxybenzoic acid with 30 grams of ethyl chloro-formate and 450 C.C. of #-sodium hydroxide. It crystallised from acetone in needles melting a t 156O. The acid chloride was prepared by heating 25 grams of the acid with 24 grams of phosphorus pentachloride. After removing the phosphoryl chloride the acid chloride distilled a t 170°/12 mm. It was then converted into p-ethylcarbonatobenzanilide by dis-solving 20 grams in dry benzene and gradually adding 17 grams (2 mols.) of aniline while shaking.A white solid consisting of a mixture of aniline hydrochloride and p-ethylcarbonatobenzanilide, separated and after allowing to remain overnight the precipitate was collected and triturated with very dilute hydrochloric acid to remove aniline hydrochloride. It was then collected washed with water then with dilute sodium hydrogen carbonate solution to remove any acid present and again with water and then dried. Preparation of the lmino - c hlorid e . Five grams (1 mol.) of p-ethylcarbonatobenzanilide were suspended in dry toluene 3.7 grams (1 mol.) of powdered phos-phorus pentachloride added and the mixture was warmed gently on the water-bath for fifteen minutes when a clear solution was obtained.The phosphoryl chloride and toluene were then distilled off under diminished pressure and the imino-chloride remained as a brown crystalline mass. This was not purified as it easily decomposes in air but it melted a t about 80°. Condensation of R esorcinol with the Imino-chloride. To the imino-chloride in the distillation flask 2.5 grams (1 mol.) of resorcinol were added and the mixture was warmed gently on the steam-bath. A reaction soon started hydrogen chloride being evolved and the mass became darker in colour. After heating for twenty minutes the residue was dissolved in alcohol about 2 C.C. of hydrochloric acid were added and the mixture was boiled for several hours in order to hydrolyse the ethylcarbonato-group and the imino-group. The alcohol was then distilled off under diminished pressure and the residue crystallised from hot water in pale yellow needles melting a t 200O. It gave a purple coloration with ferric chloride in alcoholic solution and was found to be 2 4 4/-trihydroxybenzophenone (Komarowski and Kostanecki, Ber. 1894 27 1999 give the melting point as 200-201°) 1534 HIGGINBOTHAM AND STEPHEN The author desires to express his thanks to Miss L. Higgin-botham and Mr. W. I(. Slater for assistance with certain parts of the experimental work. THE CHEMICAL DEPARTMENT, THE UNIVERSITY, M~CHESTEB. [Received October 14th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701529

出版商:RSC    

年代:1920

数据来源: RSC

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1534 HIGGINBOTHAM AND STEPHEN CLX1X.-Studies zn the Coumaranone Series. Pal$ I. The Preparation of 4- 5- and 6-Methgl-coumaran-%ones and some Derivatives of o- m-, and p- Tolyloxyacetic Acids. By LUCY HIGGINBOTHAM and HENRY STEPHEN. STOERMER and Bartsch (Ber. 1900 33 3181) were the first to prepare the above three methylcoumaranones by condensing the corresponding p - m- and o-tolyloxyacetic acids by means of phosphoric oxide. The reaction which takes place in the formation, for example of 4-methylco;umaran-Z-one (I) from p-tolyloxyacetio acid may be represented as follows: 0 (1- ) Poor yields of the coumaranones were obtained by the above method and the compounds isolated and certain derivatives of them were impure as subsequent investigation has shown. The preparation of 4-methylcoumaranone (I) was carried out success-fully by Auwers and Muller (Ber.1908 41 4233) and Fries and Finck (ibid. p. 4271) almost simultaneously and the latter authors also describe the preparation of 5-methylcoumaranone.* The method in both cases depends on the withdrawal of the elements of hydrogen haloid from o-halogen-o-hydroxyacetophenones but, owing to the 'difficulty in obtaining the required acetophenones the method is not suitable for more general application. The present investigation provides a method for the preparation of all three coumaranones and is in principle analogous to the method given by Shermer and Bartsch indicated above but with * Auwers (Ber. 1916,49 809) has recentIy prepared 6-methylcoumaran-2-one by a similar method STUDIES IN THE COUMARANONE SERIES.PART I. 1535 the difference that the coumaranones are derived from the acid chlorides of the three tolyloxyacetic acids. Methods for the pre-paration of these acids have been known for some time but modifi-cations of them are described in the present paper which give improved yields and shorten the time required for reaction. The conversion of the acids into the acid chlorides was found to take place more readily using thionyl chloride rather than phosphorus pentachloride. Michael (Amer. Chem. J. 1889 9 216) has shown that phenoxyacetic acid on treatment with phosphorus penta-chloride yields the acid chloride but a t the same time a con-siderable amount of a mixture of o- and p-chlorophenoxyacetyl chlorides is formed.Using thionyl chloride almost quantitative yields of the three tolyloxyacetyl chlorides are obtained. Phenoxy-acetyl chloride is also readily prepared in this way. Stoermer and Atenstadt (Ber. 1902 35 3569) have shown that when phenoxyacetyl chloride is dissolved in benzene and treated with aluminium chloride two products result from bhe reaction, namely coumaran-2-one (m. p. 101O) and w-phenoxyacetophenone (m. p. 72O). These were separated according to the above authors, by distillation in a current of steam coumaran-2-one being volatile and o-phenoxyacetophenone being isolated from the residue after distillation. This procedure is not however in agreement with the statement of Mohlau (Ber. 1882 15 2497> who prepared w-phenoxyacetophenone (m. p. 72O) from w-bromoacetophenone and phenol in alkaline solution and describes the ketone as being volatile in steam.It is thus difficult to understand how Stoermer and Atenstadt could have isolated the ketone in the manner described. A repetition of their experiment has been made and, whilst no ketone was isodated a small amount of coumaran-2-0110 was obtained (m. p 101O). The latter substance was also isolated from the reaction which took place when a solution of phenoxyacetyl chloride in carbon disulphide was treated with aluminium chloride. In both cases much residue was left after distillation with steam. The above reaction was then applied to the three tolyloxyacetyl chlorides mentioned above and in the first series of experiments the reaction was carried out using an excess of benzene as solvent.None of the three w -tolyloxyacetophenones which might have been formed in the usual way by the condensation of the tolyloxyacetyl chlorides with benzene was obtained the only crystalline products isolated from the reactions being the 4- 5- and 6-methylcoiumaran-ones. The same compounds were formed by treating solutions of the acid chlorides in carbon disulphide with aluminium chloride. The yields of coumaranones obtained by either method of pro-cedure are approximately the same usually about 35 to 40 pe 1536 HIGGINBOTHAM AND STEPHEN : cent. of the theoretical and although not quite so good as those obtained by Auwers and Miiller and by Fries and Finck (Zoc. cit.), the method offers several advantages over that given by these investigators .For purposes of comparison attempts have been made to pre-pare the three o-tolyloxyacetophenones according to the method described by Kunckell (Her. 1897 30 577) who claims to have prepared o -m-to1 yloxyacet op henone by treating o - bromoacet o-phenone and nt-cresol dissolved in alcohol with sodium hydroxide, and in a similar way w-p-tolyloxyacetophenone was prepared from o-bromoacetophenone and p-cresol. Both experiments were repeated with a slight modification using o-chloroacetophenone instead of the corresponding bromo-compound and from each experiment two substances were obtained both of which contained chlorine and melted at' 118O and 1 4 8 O respectively. These com-pounds were isolated under different conditions the former being obtained by warming a mixture of w-chloroacetophenone with either m- or p-cresol in the presence of alcoholic sodium hydroxide on the water-bath for an hour.After filtering off the sodium chloride formed during the reaction from the alcoholic solution, which no longer possessed the pungent odour of the chloro-ketone, although the odour of cresol was evident fine needles were deposited which melted as above after recrystallisation from methyl alcohol. The compound of higher melting point was formed when the heat-ing of the alcoholic solution of the mixture was continued for several hours. After similar treatment the above-mentioned com-pound melting a t 1 4 8 O and crystallising from methyl alcohol in small prkrns was obtained. Subsequent investigation has shown that both substanem could be obtained in several ways; thus on treating an alcoholic solution of o-chloroacetophenone with the dry sodium compounds s f phenol 0- m- and p-cresolls and &naphthol, respectively each experiment gave one or other of the above chloro-compounds according to the duration of the reaction.The action of these sodium compounds and also thaC of sodium hydroxide on o-chlo'roacetophenone is the same as that of ammonia and sodium ethoxide on the same substance as was investigated by Staedel and Riigheimer (Ber. 1876 9 1769) and by Paal and Stern (Ber. 1899 32 531) respectively and both investigations have shewn that two chloro-compounds are formed namely the so-called u- and P-chlorodiphenacyla melting a t 1 1 7 O and 1 5 4 O respectively.Widman and Almstrom (AnnaZen 1913 400 86) have investigated the constitutions of both compounds and shown that a-chlorodiphenacyl is cis-2-chloro-3 4-oxido-3 5-diphenyltetra-hydrofuran (11) (m. p. 117-118O) and that the &compound i STUDIES IN THE COUXARAHONE SEEXES. PART I. 1537 t'he corresponding trans-isomeride (111) (m. p. 149O and not 154O, as given above). c1 O*CHPh*CH I,O*OHPh*CH / " I (3' / I I \-&h.O i3 ' L-CPh*" Gl (11.1 (111.) It is thus difficult to understand how various investigators in the past have succeeded in preparing a-alkylated or o-arylated acetophenones by the action of sodium compounds of alcohols or phenols on o-halogenacetophenones . An investigation of this problem is being carried out by one of us. The preparation of other derivatives of 0- m- and p-tolyloxy-acetic acids is described below.EXPERIMENTAL. 0- m- and p-Tolyloxyacetic Acids. The preparation of these acids by treating a mixture of chloro-acetic acid and the corresponding cresol with an aqueous solution of sodium hydroxide has been known for some time the ortho-acid having been first prepared by OglialorocTodarol and Cannone (Gazzetta 1889 18 511) and the meta- and para-acids by OglialorocTodaro and Forts (Gazzetta 1891 20 508) and Gabriel (Ber. 1882 14 923). Details of a modified method for t8he preparation of the three acids by the same reaction are given in D.R.-P. 79514 and 85490. Numerous experiments carried out according to the details given in the above investigations have shown that the yields of the acids nelver exceed 60 per cent.of the theoreltical loss of chloroacetic acid by hydrolysis probably taking place. The present investigation has shown that the effect of hydro'lysis can be mini-mised by adding ths cresol dissolved in alkali hydroxide to the chloroacetic acid. I n the particular case of the meta-acid the sodium hydroxide was replaced by an equivalent amount of potassium hydroxide which gave an increased yield of the product; in other respects the process was the same. Ninety-six grams (I mol.) of chloroacetic acid were heaked in an oil-bath a t 110-120° and a solution of 108 grams (1 mol.) of the cresol and 100 grams (2.5 mols.) of sodium hydroxide in 400 C.C. of water was slowly added with frequent shaking. The addition of the solution was complete in two hours when the product after being cooled to about 40° was acidified with approximately 2N-sulphuric acid.The tolyloxyacetic acid was collected drained, VOL. c3xVI.I. 3 1538 HICIQINBOTHAM AND STEPHEN: and finally washed with 20 C.C. of light petroleum to remove traces of adhering cresol. The weight of crude acid was 140 grams and a further 10 grams were extracted with ether from the filtrate the combined yield being 90 per cent. of the theoretical. The acid obtained in this way is pure enough for most purposes without further treatment. The temperature stated above a t which the acidification was carried out is of importance since the meta-acid undergoes decom-position to some extent by mineral acid' a t higher temperatures.On the other hand the sodium salt of the para-acid is only moderately soluble in water a t 40° and the free acid was best obtained by warming the solution to 70° when the sodium salt dissolved and slowly adding 2N-sulphuric acid at the same temperature until acid. The acids may be purified by crystallisation from dilute alcohol, and are then obtained in thin glistening plates the melting points of which are 151-152O 102O and 1 3 5 O for the ortho- meta- and para-acids respectively agreeing with those given in the literature. The acids are decomposed into the respective cresol and glymllic acid on distillation in a current of steam or by boiling with dilute mineral acids the meta-acid more readily than the para- the ortho-acid being the most resistant to such treatment.Preparation of the Ammonium Salts of the above Acids. In connexion with the preparation of the nitriles of the tolyl-oxyacetic acids the ammonium salts were obtained most readily in the following way. Twenty-five grams of the acid were dissolved in 100 C.C. of dry ether and the solution was saturated with dry ammonia a t the ordinary temperature. The anhydrous ammonium salt separated from the ethereal solution as a. fine crystalline powder. The ammonium salts of the 0- m- and p-acids decompose at 126O 18S0 and 1 7 7 O respectively. 0- m- and p-Tolyloxyacetyl Chlorides C9H,0,C1. Twenty grams (1 mol.) of the acid previously dried by fusion were finely powdered and placed in a small flask fitted with a reflux apparatus on a water-bath a t 60°; 18' grams (1-5 mols.) of thionyl chloride were added slowly and the reaction was moderated if necessary, by removal of the flask from the water-bath.The reaction was complete at the end of fifteen minutes and a. pale yellow liquid remained ; longer heating caused the product to darken in colour, These acid chlorides have hitherto not been described STUDIES IN THE COUMARANONE SERJES. PART I. 1539 resulting in a poor yield of the acid chloride. The excess of thionyl chloride was removed by distillation on the water-bath a t 30° under about 15 mm. pressure and the residue finally distilled a t 10 mm. Twenty grams of each acid chloride were obtained as colourless liquids the yields being about 90 per cent. of the theoretical and in ail three cases the products were obtained solid.B. p.110 mm. 35. p. m- ...... 126 19.3 o-Tolyloxyacetyl chloride ....... 120" 29-30' P- 9 9 39 ...... 124 17.9 They are al! soluble in carbon disulphide benzene or ether and are decomposed by water yielding the respective acids. 9 9 9 9 01- m- and p-Tolylozyacetarnides C,H,,O,N. (1) Twenty grams of the ammonium salt of o-tolyloxyacetic acid were heated under 10 mm. pressure in a distillation flask in an oil-bath a t 135O water passed over and the reaction was com-plete when the solid in the flask had liquefied the amide formed being then a t a temperature above its melting point. In the cases of the ammonium salts ob the meta- and para-acids, the temperature of the oil-bath was maintained a t 190-200° in consequence of the higher decomposition points.The liquid residue solidified on cooling and the product crystallised from alcohol. (2) On warming the acid chlorides with an excess of ammonium carbonate on the water-bath for half an hour and removing the ammonium chloride formed by triturating the solid mass with cold water and filtering the amides were obtained pure after crystal-lisation from alcohol and identical with those prepared by the first method. The three compounds were purified for analysis by recrystal-lisation from benzene being obtained in stout rhombic prisms and the purity of each substance was tested by boiling a known weight with aqueous sodium hydroxide and collecting the ammonia liberated in standard acid. The results were in close agreement with the theoretical values.M. p. M. p. o-Tolyloxyacetamide.. .......... 127" 128' 713- 9 9 ............ 118 111-112 P- 7 3 ............ 119 126 The figures in the second column are those given by Forte (Gazzetta 1893 22 ii 526). The amides are sparingly soluble in cdd methyl and ethyl alcohols or benzene but dissolve readily on warming and are slowly hydrolysed by boiling with water. 3 ~ 1540 HIMINBOTHAM AND STEPHEN : The yields of the amides obtained by both met,hods are about 90 per cent. of the theoretical. o- m- and p-Tolyloxyacetonitriles C,H,ON. The meta- and para-compounds were obtained by Stoermer and Schmidt (Ber. 1899 30 1705) from the oximes of the correspond-ing tolyloxyacetaldehydes the former being a yellow liquid (b. p. 254O) and the latter crystallising in needles (m.p . 40O). The ortho-compound has not hitherto been described. The three sub-stances are more readily prepared by treating the .amides with phosphoric oxide. Ten grams of the amide were intimately mixed with 10 grams of phosphoric oxide in a distillation flask and the mixture was warmed in an oil-bath a t 1 2 0 O . When the reaction had begun, the sidetube of the receiver attached to the flask was connected to the pump and a yellow oil distilled a t 130°/10 mm. After fifteen minutes the temperature of the oil-bath was raised to 150° and the distillation was complete after a further ten minutes. Six grams of nitrile were obtained in this way. B. p./lO mm. M. p. o-Tolyloxyacetonitrile.. ........... 133" yellow oil. m- 7 9 141 Y 9 P- ...............136 38-39' ............... 7 9 The nitriles are easily hydrolysed on boiling with aqueous sodium hydroxide yielding the corresponding acid and are soluble in the usual organic solvents. o- m- aitd p-Tolyloxyace tanilides C15H150,N. Them anilides may be readily prepared by the following method. Ten grams (1 md.) of the acid chloride were dissolved in 100 C.C. of dry benzene in a flask fitted with a reflux apparatus and 10 grams (2 mols.) of freshly distilled aniline slowly added with vigolrous shaking. After cooling the solid which had separated was filtered and the benzene solutioa containing some aniline was evaporated and the residue added to the main bulk. The whole was then triturated with dilute hydrolchloric acid to remove aniline hydrochloride and finally treated with cold dilute sodium carbonate solution to remolve traces of acid.Tho substance was then crystallised from ethyl alcohol in which the ortho-compound was the most and the para-compound the least soluble the meta-compound being moderately soluble. They are readily hydrolysed on boiling with dilute hydrochloric acid STUDIES IN TRE COUMARBNONE SERIES. PART I. 1541 M. p. o-Tolyloxyacetanilide (cubes) .................. 108.5" m- 9 9 (needles) 96 7 9 ( , ) .................. 109 .................. 23-These values are in closta agreement8 with those given by Forte (ibid.). 4-Methylcoamaran-2-one (I). Ten grams (1 mol.) of p-tolyloxyacetyl chloride were dissolved in 15 grams (3 mols.) of dry benzene and 8 grams of finely powdered aluminium chloride slowly added with vigorous shaking, the mixture being cooled in ice.The reaction proceeded slowly, and the solution became dark red but if the temperature was allowed to rise the mixture rapidly turned into a dark-coloured, tarry mass and the yield of cumaranone was considerably diminished in consequence of decomposition. The red solution, after remaining in the cold for two holurs was poured on polwdered ice mixed with hydrochloric acid and the oll suspended in the water submitted to distillatio'n in a current of steam for several hojurs until the distillate no longer showed a reducing action with Fehling's solution and the characteristic odour of the coumaranone was imperceptible. The upper layer of benzene containing some coumaranone in solution was separated from the aqueous layer, and the latter was extracted with ether several times to remove coumaranone dissolved in the water.The combined benzene and ethereal extracts were dried over anhydrous sodium sulph ate the solvents removed on the water-bath and on cooling the residue solidified to a mass of fine needles. The substance crystallised from ethyl alcohol in white needles melting a t 5 1 O . The yield was 3 grams. The semicarbazone (yellow needles from alcohol) melted a t 228O (heated slowly) and the oxime a t 143-144O (Stoermer and Bartsch, Zoc. cit. give 1 8 1 O and 144O respectively). The p-nitrophenylhydrazone was obtained by adding a solution of p-nitrophenylhydrazine in dilute acetic acid to an aqueous solution of the coumaranone.The hydrazone soon separated as a red crystalline powder and after crystallisation from dilute acetic acid it melted and decomposed a t 230-232O (Found N=14*4. C,,H,,O,N requires N = 14.85 per cent.). 6 -Methylcoumaran-2-cne was prepared in a manner similar to that described above from m-tolyloxyacetyl chloride and was obtained in needles melting a t 8 5 O . The semicarbazone and mime melted a t 208O and 1 5 6 O respectively. For the latter Fries and Finck (Zoc. cit.) give 1 6 5 O probably a misprint. The p-nitro 1542 COPISAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET. phenylhydrazone crystallises from dilute acetic acid in red needles melting and decomposing a t 214-216O. 6 -Bet hylco umaran-2- one prepared f rom o-tolyloxy acetyl chloride, crystallised in needles melting a t 8 8 O . The semicarbazone and oxime melted a t 2 2 7 O and 148O respectively and the p-nitroplzenyl-hydrazone (red needles) a t 195O with decomposition. The above coumaranones give purple colorations with ferric chloride they reduce Fehling’s solution on warming and give an immediate precipitate of silver with Tollens’ reagent. On treat-ment with concentrated sulphuric acid they dissolve with the production of an intense red colour and subsequent formation of tarry matter. On remaining in the air for some time the crystals of the cournaranones become coated with a bright red-coloured substance probably an oxidation product. They have a characteristic odour resembling that of hyacinth. The authors desire to thank Professor 1,apworl;h for facilities placed at their disposal in connexion with this investigation and also Dr. W. \V. Adamssn for analysing several of the substancM described above. CHEMICAL DEPARTMENT, THE UNIVERSITY, MANCIIESTER. [Received October 14th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701534

出版商:RSC    

年代:1920

数据来源: RSC

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1542 COPISAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET. CLXX- Carbcrxole- blue and Carbaxole-violet. By MAURICE COPISAROW. CARBAZOLE-BLUE was first obtained by Suida (Ber. 1879 12 1403) by fusing carbazole with olxalic acid. He regarded it as the internal anhydride of 2-aminodiphenyl-2’-carboxylic acid whilst Bamberger and Muller (Ber. 1887 20 1903) recognised that its properties pointed to a dye of the triphenylmethane class and assigned to it the formula (C,,H,N),C*OH although’neither Suida’s nor Bamberger and Miiller’s analytical figures agreed with either of these two formulz. The author hgs now found that carbazole-blue like the triphenyl-methane dyes furnishes a carbinol of the above formula which gives variously coloured salts with acids of which the formate is identical with the colouring matter in question.The corresponding tricarbazylmethane has also been prepared by reducing carbazole-blue. When 9-ethylcarbazole is similarl COPISAROW CARBAZOLE-BLUE AND CAl3BAZOLE-VIOLET. 1543 fused with oxalic acid a corresponding violet colouring matter is obtained which it is proposed to name carbazole-violet and the carbinol and parent hydrocarbon of this have been prepared. From analogy to the triphenylmethane dyes and from the fact that phthalyl chloride and phthalidm are intermediate products in the formation of tetraphenylmethaneo-carboxylic acids (Copisarow, T. 1917 111 l o ) just as keto-chlorides are intermediate in the formation of the triphenylmethane dyes from carbon tetrachloride (Fierz and Koechlin Helv. Chim.Acta 1918 1 218) and further, that the attachment of the central carbon atom in the phthalide of 9-ethylcarbazole is a t the %position in each of the carbazole nuclei (Copisarow and Weizmann T. 1915 107 878) it may reasonably be assumed that in the tricarbazylmethane cohuring matters the methane carbon atom is linked to each carbazole nucleus a t the p-position with respect to the nitrogen atom. The constitutional formuh of carbazole-blue and carbazole-violet are therefore represented by formula I and I1 respectively.* 0,C.H 0,C.H NH IkH NEt NEt The chZoride of tri-3-carbazylcarbinol (111) is obtained by con-densing carbazole with chlor opicr in and that of tri-9-ethy 1 tri- 3 -carbazylcarbinol (IV) by condensing 9-ethylcarbazole with carbon tetrachloride.An important property of both carbazole-blue and carbazole-violet is the ease with which they are sulphonated. This indicates that the presence of a phenylene group like that of the benzyl and phenyl groiips makes possible the production of soluble dyes of the triphenylmethane series. In connexion with the mechanism of formation of carbazole-blue, N-oxalylcarbazole cannot be regarded as an intermediate compound in the synthesis of carbazole-blue and obviously not in the case of carbazole-violet (Copisarow T. 1918 113 816). Carbazole con-denses in this case not with oxalic acid itself but with its decom-* ( C,,H,NR),C:C,aH,NR'OH is regarded a8 the base whilst the carbinol, (C,,H,NR),C'OH may be taken as the pseudo-base I544 COPISBROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET.position products formic acid and carboa monoxide. This synthesis of carbazole-blue and carbazole-violet may thus be regarded as a combination of the “ aldehyde” and “phosgene ” processes of formation of members of the triphenylmethane series. The formation of carbazole-blue and carbazole-violet throws interesting light on the manner of decomposition of oxalic acid, definitely indicating formic acid’ as an intermediate product. The direct decomposition of oxalic acid without means of retain-ing the intermediate products results in the formation of carbon monoxide carbon dioxide and water (Calcagni Gazxetta 1920, 50 i 245). EXPERIMENTAL. Carbazole- blue (I). Carbazole-blue was prepared according to Suida’s method (Zoc. cit.) but the yield did not exceed 5 per cent.of the theor6tical. The employment of anhydrous oixalic acid zinc chloride aluminium chloride or modifying the conditions of heating gave no better results. NO carbazoleblue was formed on condensing carbazole with carbon tetrachloride in the presence of aluminium chloride. The isolation and purification of the carbazole-blue was carried out in the following manner. The greenish-blue product of fusion of carbazole with oxalic acid was extracted with hot water until free from oxalic acid. The residue was dried finely powdered and exhaustively extracted with benzene in a Soxhlet apparatus. The blue product remaining as a residue insoluble in benzene was then extracted with alcohol in which it is fairly soluble the blue alcoholic solution being allowed to evaporate slowly.In this manner carbazoleblue was obtained as a deep blue, granular powder exhibiting a metallic lustre on trituration or in thin layers. It charred without melting a t above 300O. Alcoholic or aqueous extracts of carbazole-blue gave no precipitate with silver nitrate or calcium chloride. The benzene extract was found to contain in addition to unchanged carbazolle a little tri-3-carbazyl-methane as indicated by oxidation which gave the salt of the carbind. Fission‘ of Carbazole-blue. Bamberger and Muller (Zoc. c i t . ) notticed an d o u r of carbazole on deehructive distillation of carbazole-blue alone or with zinc dust. The fact that no carbazole was actually isolated and that destruc-tive distillation is apt to lead not only to fission but also reduc COPHAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET.1545 tion (Copisarow P. 1914 38 111) made it necessary to investigate the matter further. Pure carbazole-blue was mixed with five times its weight of powdered potassium hydroxide and the fused mixture kept at 240-250° for half an hour. The product was extracted with hots water filtered washed with dilute hydrochloric acid and dried. The dried residue was extracted with benzene the extract being decolorised with animal charcoal and allowed to evaporate gradu-ally. The small grey crystals obtained in this way were recrystal-lised from alcohol separating in white pearly scales melting at 238O and were identified as carbazole. Tri-3-car baz ylcarbinol, N H NH (111.) The method adopted for the synthesis of the carbinol was that employed by Baeyer and Villiger (Ber.1904 37 2873) for the preparation of the carbinol of rosaniline-blue. Carbasoleblue was dissoflved in pyridine with the addition of a lit'tle benzoic acid and water gradually added until the solution became slightly turbid. The liquid was allowed to remain until its brown colour had prac-tically disappeared then poured into dilute sodium hydroxide and the mixture extracted with ether. The ethereal solution wits washed several times with water dried over sodium sulphate the ether evaporated and the residue crystallised twice from toluene. In this manner the carbinol was obtained in small white prismatic crystals melting at 117-118O. F o r analysis the substance was dried at 1 0 5 O in a current of hydrogen (Found C=83*1; H=4.64; N=7*9.C,,H,ON, requires C=84*22; H=4*78; N=7-97 per cent.). On adding organic o r mineral acids to the carbinol or its solu-tion coloured salts are instantly formed. The colour of the salts varies with the acid the range of coloura being between violet and purple the acetate being bluish-violet the oxalate greenish-blue, the sulphate blue and the nitrate reddish-blue to purple. 3 L 1546 COPISAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET. Carbazoleblue was dissolved in pyridine with the addition of a litt'le benzoic acid. To the boiling solution a saturated solution of hydrogen chloride in pyridine was gradually added with stirring. The cooled mixture was poured into dilute hydrochloric acid, filtered washed with dilute hydrochloric acid and water pressed, and dried.The fine blue granular product was purifled by means of alcohol in a manner identical to that adopted1 in the case of carbazole-blue (Found C = 80.46 ; H =4*3 ; C1= 6.4. C,H,N3Cl requires C=81*36; H=4*44; C1=6-5 per cent.). This compound decomposes without melting on heating above 300O. It is practically insoluble in water or benzene and fairly soluble in alcohol glacial acetic acid or pyridine. The Formate (I). This was prepared by treating tri-3-carbazylcarbinol dissolved in pyridine with an excess of concentrated formic acid. The mixture was poured into dilute formic acid filtered washed with dilute formic acid and water pressed and dried. The blue, granular powder was purified by crystallisation from alcohol (Found C = 81.84 ; H = 4.5 ; N = 7.48.C,H,,O,N requires C=82-1; H=4-54; N=7*56 per cent.). The analytical data and general characteristics of this substance are identical with those of carbazole-blue as indicated by Suida (loc. cit.) and Bamberger and Miiller (Zoc. cit.). Tri-3-car bazylmethane (C12H,N),CH. The reduction of carbazole-blue was carried out as described by Bamberger and Miiller (Zoc. c i t . ) . The product crystallised from ether in small white rhombic needles melting a t 217-218O. For analysis the substance was dried a t 120° in a current of hydrogen (Found C = 85.62 ; H = 4.7 ; N = 8.2. C,,H,N3 requires C = 86.85 ; H=4.93; N=8.22 per cent.). Tri-3-carbazylmethane gave the corresponding coloured salts of the carbinol on oxidation with potassium permanganate in acid solution or with chloranil in the presence of acetic acid.The Chloride and Tri-3-car bazylmethane. These t.wo substances were also prepared in the following manner. A suspension of carbazole in an excess of chloropicrin was heate COPISAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET. 1547 under an air condenser in an oil-bath for six hours the tempera-ture being gradually raised from 1 2 5 O to 1 4 5 O . The reaction is sluggish and incomplete about 90 per cent. of the carbazole remain-ing unchanged. The gases evolved during the reaction contain nitrogen carbonyl chloride hydrogen chloride etc. The mixture was treated with dilute hydrochloric acid and distilled in a current of steam. The residue was collected washed with water dried, and then extracted with benzene in a Soxhlet apparatus.The residue a blue granular powder was crystallised from alcohol and was found to consist of the chloride of tri-3-carbazylcarbinol. The benzene extract freed from solvent was crystallised from ethyl alcohol the solution being decolorised with animal charcoal. The white crystalline product contained in addition to unchanged carbazolle some other substance which owing to its small amount, could not be isolated. When this white product' was oxidised with potassium permanganate in the presence of hydrochloric acid a blue product was obtained which on extraction with benzene was found to consist of carbazole and a blue powder identified as the chloride. This clearly indicated that the white substance accom-panying the unchanged' carbazole was tri-3-carbazylmethane which is formed as a by-product during the condensation.It is to be noted that whilst the products of condensation of carbazole with chloropicrin are identical in composition and general propertj es with the chloride of tri-3-carbazylcarbinol and tri-3-carbazylmethane the colouring matter appears to be somewhat duller and redder. This is probably due to the presence of traces of the chloride of benzhydrol R,CH*OH formedl during the condensation and oxidation. Car bazole- viole t (11). 9-Ethylcarbazole was fused with ten times its weight of crystal-lised oxalic acid as in tlie case of carbazoleblue. The product was thoroughly extracted with hot water the residue dried and extracted with benzene in a Soxhlet apparatus.The residue, purified by crystallisation from alcohol was a fine violet powder exhibiting a metallic lustre on trituration or in thin layers. This product which it is proposed to term " carbazoleviolet," closely resembles carbazole-blue in its general properties. It is practically insoluble in water ~ 1 ' benzene and fairly soluble in alcohol or glacial acetic acid. Concentrated' sulphuric acid sulphonates the substance in the cold the mixture giving when poured in water, a bluish-violet solution. On heating it chars without melting (Found C=81.78; H=5*4; N=6.4. C,,H,,O,N requires 3 L+ 2648 COPISAROW CARBAZOLE-BLUE AND CBBAZOLE-VIOLET. C=82*59; H=5*83; N=6.57 per cent.). As in the cam of carbazole-blue a small amount osf the reduction product was found in the benzene extract along with unchanged 9-ethylcarbazole.Tri-9-ethyltri-3-carbazylnzethaneJ (CI4Hl2N)&H. This is obtained by reducing carbazole-violet as in the case of carbazde-blue ; it crystallises from ether and benzene in white, short needles melting atl 186-187O. For analysis the substance was dried a t 120° in a current of hydrogen (Found C =85*84 ; H=5*9; N=6.98. C43H3,N3 requires C=86*68; H=6*26; N=7*05 per cent.), On oxidation as in the case of tri-3-carbazylmethaneJ the colour is regenerated with the formation of the salts of the carbinol. The Chloride (C,,H,,N),C:C,,H,2NC1. To a mixture of 55 grams (2 mols.) of 9-ethylcarbazole and 24 grams (1 mol.) of carbon tetrachloride in 400 C.C. 04 carbon disulphide 40 grams of finely powdered aluminium chloride were gradually added in the course of an hour and the reaction was completed by heating the mixture on a water-bath for eight hours.The solvent was then distilled G f f the residue treated with ice and a little hydrochloric acid and the mixture distilled in a current of steam. The residue was collected dried and extracted thoroughly with benzene. The portion insoluble in benzene was a violet powder of a delicate shade showing a coppery lustre in thin layers or on grinding. In its general characteristics this substance differs but! little from carbazole-blue or carbazole-violet. For analysis it was purified by recrystallisilng from alcohol (Found : C = 81-12 ; R = 5.6 ; C1= 5-56. C",,H,N3Cl requires C = 81.93 ; H=5*76; C1=5-64 per cent.).The yield of the chloride was 87 per cent. of the theoretical, calculated on the basis of the 9-ethylcarbazole employed. Reduc-tion in the manner adopted in the case of carbazole-blue and carbazole-violet furnished t8ri-9-ethyltri-3-carbazy1methane (m. p. 1 8 7 O ) in a much purer state than when obtained by reducing carbazole-violet. The condensation of 9-ethylcarbszole with chloroform in the presence of aluminium chloride in a manner similar to that employed in the condensation with carbon tetrachloride gave as main product tri-9-ethyltri-3-carbazylmethane. No substance of the diphsnylmethane type could be isolated. The presence of some by-product probably of the R,:CR type was however indicate COPISAROW CARBAZOLE-BLUE AND CARBAZOLE-VIOLET.1549 by the shades of the coloured products of oxidation. Oxidation of the twice recrystallised tri-9-ethyltri-3-carbazylmsthane gave in the presence of hydrochloric acid a violet substance the shade of which closely resembles that of carbazole-violet and the product of the condensation of 9-ethylcarbazole with carbon tetrachloride. Oxidation of the crude product gave on the contrary a deep greenish-blue substance apparently due to the presence of the chloride of a benzhydrol. Tri-9- e t hyltri- 3 -car baz y 1 car biriol, NEt NEt The method (IV. 1 adopted for the preparation of t,his carbinol from t,he chloride was identical with that employed in the case of tri-3-carbazylcarbinol. After crystallisation from ether and then benzene tri-9-ethyltri-3-carbazylcarbinol was obtained in small, white needles melting a t 92-93O.For analysis the substance was kept for three days under diminished pressure over paraffin and then in a current of hydrogen a t 8 5 O (Found C=8'3.8; H=6-0; N = 6.84. C,,H,,ON requires C = 84.41 ; H = 6.1 ; N = 6.87 per cent.). The general behaviour of the carbinol towards solvents and acids is similar to that exhibited by tri-3-carbazylcarbinol. The Formate (11). The folrmate was prepared by shaking a solution of tri-9-ethyl-tri-3-carbazylcarbind in benzene with an excess of formic acid. The finer violet powder which separated was collected and dried. The analysis and general properties of this substance indicated it to be ident.ica1 with carbazole-violet.Conversion of Car bazole-uiolet i n t o Carbazole-blue. Tri-9-ethyltri-3-carbazylmethane was heated with four t,imee its weight of hydriodic acid (b. p. 126-127O) and a little aluminiu 1550 MILLS AND HAMER THE CYANINE DYES. PaRT III. amalgam the temperature of the mixture being gradually raised to 130° in the course of two hours. When all the ethyl iodide was expelled (accelerated by a current of air) the residue was washed with dilute sodium carbonate and water. The dried residue was extracted with toluene from the decohised solution of which small white crystals melting at 21 7O separated and were identified as tri-3-carbazylmethane. On oxidation in the presence of acid the coloured salts of the carbinol were obtained. The author wishes to express his thanks to Drs. C. Weizmann and H. Stephen for the interest taken in this investigation and to acknowledge with thanks a grant from the Research Fund of the Chemical Society covering part of the expenses. CHEMICAL DEPARTMENT, T ~ E UNIVERSITY, RTANCHESTER. [Received November lst 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701542

出版商:RSC    

年代:1920

数据来源: RSC

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1550 MILLS AND HAMER THE CYANINE DYES. PaRT III. CLXX1.-The Ciyanine Dyes. Part III. The Con-stitutzon of Pinacyanol. By WILLIAM HOBSON MILLS and FRANCES MARY EAMER. ONE of the most valuable of the photographic sensitisers in common use is a substance patented in 1905 by the Farbwerke vorm. Meister Lucius & Bruning (Brit. Pat. 16227 of 1905; D.R.-P. 172118) and sold under the name of pinacyanol. The action of alkali on a hot alcoholic solution of a mixture of a quinoline and a quinaldine alkyl haloid brings about as is well known the development of an intense reddish-purple colour on account of the formation of an isocyanine. I f however form-aldehyde as well as alkali is added to the solution the colour produced is a beautiful deep blue and the substance to which this is due is a dye of the type of pinacyanol.Corresponding with the difference in colour these blue dyes sensitise much further into the red than the isocyanines. A large number of compounds of this class have been prepared and examined in this laboratory and the name carbocyanine has been proposed for them to provide a basis for their systematic nomenclature (Pope and Mills Phot. J., 1920 60 253). I n view of the practical importance of these dyes and of the interest attaching to the relationship between photo-semitisin MILLS AND HAMER THE CYANINE DYES. PART III. 1551 activity and struct,ure a definite knowledge of their constitution is much to be desired. Two structural formulae have previously been put forward but neither of them can be regarded as free from objection.0. Fischer ( J . p r . Chem. 1918 [ii] 98 204) has proposed formula I and Wise Adam Stewart and Lund ( J . Ind. Eng. Chem. 1919 11 460) suggest the constitution 11. /\ R I (1.1 (11.1 Fischer’s formula appears not to represent the composition of the dyes correctly. It contains one atom of carbon less than is indicated by our analytical results. It is also improbable that compounds of this structare would possess the intense colour of the car bocyanines. The formula suggeted by the American investigators represents the carbocyanines as dimethyl derivatives of the true cyanines. This does not accord with their photo-sensitising action nor does it agree with their behaviour on oxidation. The formula which our experiments have led us to regard as the most probable repre-sentation of the structure of the carbocyanines is 111.It is based I (111.) on the following facts and considerations. (1) The carbocyanines are quaternary ammonium salts evidently containing tlwo atoms of nitrogen and one equivalent of acid radicle in the molecule. A series of careful halogen determinations made on the dye obtained by treating quinaldine ethiodide with form-aldehyde and sodium hydroxide (1 1’-diethylcarbmyanine iodide), and on the corresponding bromide showed that the molecular weight of the iodide was 479 f 1. Two molecules of quinaldine ethiodide are clearly concerned in the production of one molecule of the dye but since it contains carbon hydrogen nitrogen and iodine only the maximum mole-cular weight it could possess if derived from two molecules o 1652 MILLS AND HAMER THE CYANME DYES.PART III. quinaldine ethiodide with the loss of hydrogen iodide would be 470. The observed molecular weight therefore shows that con-tsary to the view of 0. Fischer (Zoc. cit.) it must contain the residue of one molecule of formaldehydel. Bimple condensation with one molecule of f orinaldehyde would result in the addition of 12 units t o the molecular weight. The observed increase of about 10 units indicates that in addition to the elimination of hydrogen iodide and water hydrogen (probably 2 atoms) has been remo'ved by some process of oxidation. The probable reaction for the formation of the dye is therefore 2C,oH9N,C2H5X + CH20 = C,,H&,X + H,O + HI + 2 8 , and the formula C,,H,,N,X thus indicated is in excellent agree-ment with the analytical results.(2) Whilst the isocyanines are formed by condensation of one molecule of a quinoline alkyl iodide with one of a quinaldine alkyl iodide two molecules of a quinaldine alkyl iodide are necessary for the formation of a carbocyanine; a quino'line alkyl iodide i f present takes no1 direct part in the condensation. This fact was discolvered by 0. Fischer (Zoc. cit.) and also strongly suspected by the American investigators. It was similarly discovered in t'his laboratory through observing that' the compolund produced by the action of alkali and formaldehyde on a mixture of the ethiodides of quinoline and quinaldine was identical with that obtained from quinaldine ethiodide alone.The yield is however very much better in the former case and this suggested that possibly the additional amount of carbocyanine might be formed from one molecule of quinoline alkyl iodide two molecules of formaldehyde and one of quinaldine alkyl iodide. The action of alkali and formaldehyde on a mixture of p-tdu-quinaldine ethiodide and quinoline ethiodide was therefore investigated. The amount of sensitisw produced was about the same as from the corresponding mixture of quinaldine ethiodide and quinoline ethiodide and itl was found1 to be a homogeneous substance since, by extractioln with successive quantities of methyl alcohol it was divided into six fractions identical in properties and analysis showed that these consisted of the 1 1'-diethyl-6 6/-dimethylcarbo-cyanine iodide described by Pope and Mills (Zoc.cit.). The whole of the carbocyanine formed thus contained two p-toluquinaldine residues and the quinoline ethiodide did not contribute to the carbon skeleton of any portion of the dye produced. The behaviour of many other substituted quinaldine alkyl ioldides in the carbocyanine condensation has been examined in this labora-tory with similar results (Pope and Mills Zoc. cit.); thus fo MILLS AND HAMER TRE CYANINE DYES. PART 111. 1663 example from bromoquinaldine ethiodide and quinoline ethisdide, a dibrcmocarbocyanine iodide is formed. It therefore appears that the alkyl iodides of the quinoline bases can only take part in the carbocyanine condensation prosvided they contain a 2-methyl group and in this condensation two molecules of such an alkyl iodide and one of formaldehyde are concerned.(3) When a solution of diethylcarbocyanine bromide in dilute nitric acid is heated the dye is rapidly oxidised and the liquid, after becoming almost immediately bright orange-red is gradually decolorised the colour practically disappearing after about an hour's boiling. From the residue left after the nitric acid has been evaporated which consists of a mixture of highly soluble substances FL crystalline quaternary nitrate can be isolated. The composition of this nitrate together with its properties and the fact that it gives 1-ethyl-2-quinolone on oxidation with potassium ferricyanide shows it to be quinaldinic acid ethyl nitrate ( A ) . It is clearly derived from one of the quinaldine residues present in the pinacyanol molecule and the yield of analytically pure material isolated varied in four experiments from 89 to 93 per cent.of the theoretical. The production of this compound shows that piaacyanol cclntaihs the grouping IV. ( A * ) (IV. 1 (V.) Moreover that it is formed so smoothly and easily further indicates that this residue is united to the rest of the molecule by an ethylenic linking and thus that pinacyand cohtains the grouping V. The other main oxidation product or products are exceedingly soluble and have not yet been identified. The residue left after the removal of the quinaldinic acid) et,hyl nitrate was therefme further oxidised with alkaline ferricyahide ahd was found to give rise to 1 -ethyl-2-quinolone.* The weight of distilled colourless, crystalline product was 60 per cent.of the weight of ethylquinolone theoretically obtainable from one quinaldine residue in the pina-cyan01 originally taken. It1 was not quite pure (m. p. 50-54O with incipient softening a t 40° ; pure 1-ethyl-2-quinolone melts a t 53-55*5O) but analytically pure ethylquinolone was easily isolated from it and it was evident that far more quinolone had been pro-duced than could possibly have been derived from the 11 p0r cent. * The production of ethylquinolone by the oxidation of pinmyanol bg potassium feicyanide was observed by 0. Fischer (Zoc. cit.) 1554 MILLS AND HAMER THE CYANINE DYES. PART 111. of the first quinaldine residue unaccounted for as quinaldinic acid ethyl nitrate.It must therefore have been formed mainly from the second quinaldine residue present in pinacyanol. That this second quinaldine residue should be split off on oxidation as l-ethyl-2-quinolone shows that the quinoline nucleus contained in it must be attached to the rest of the molecule through the 2-position. More precise conclusions can scarcely be drawn from this fact for oxidation with alkaline ferricyanide is not fitted to decide more delicate points of constitution ; for example Decker and Remfry (Ber. 1905 38 2773) have shown that quinaldine alkyl iodides are converted by this reagent into the corresponding quinolones. The action of potassium permanganate on pinacyanol acetate in aqueous acetone solution a t Oo was therefore studied (compare Mills and Wishart# this vol.p. 579). The permanganate was added gradually and the end of the reaction was sharply marked by the persistence of the permanganate colour after a quantity corresponding with 4.8 atoms of oxygen to one molecule of pina-cyanol had been added. Oxidation under these conditions brought about the fission of the pinacyanol molecule with the production of 1 -ethyl-2-quinolone. The quantity of pure substance isolated' amounted to 79 per cent. of that theoretically obtainable from one quinaldine residue. The other product was exceedingly soluble and showed the behaviour of a quaternary salt. When boiled with dilute nitric acid it gave quinaldinic acid ethyl nitrate but the oxidation did not proceed smoothly and the quantity of the nitrate isolated was only 25 per cent.of the theoretical yield from half the pinacyanol molecule. These observations especially when con-sidered in relationship to the action of potassium permanganate on dimethylisocyanine acetate (Mills and Wishart Zoc. c i t . ) , indicate that whilst oxidation with dilute nitric acid splits off from the pinacyanol molecule the quinaldine residue which contains the quinquevalent nitrogen at0.m (forming quinaldinic acid ethyl nitrate) potassium permanganate splits off as ethylquinolone that containing the tervalent nitrogen atom. It thus appears that. the second quinaldine residue is present in pinacyanol in the form (4) It has thus been shown that (i) the carbocyanine condensa-tion takes place between two molecules of quinaldine alkyl iodide and one of formaldehyde and that (ii) the two quinaldine residues are both attached t c ~ the rest of the molecule through the carbo MILLS AND HAMER !THE CYANINE DYES.PART III. 1555 atoms of their 2-methyl groups. the condensation must therefore be The main reaction concerned in PI. 1 This is analogous to several well-known reactions in which one molecule of formaldehyde condenses with two molecules of a com-pound containing EL group of similar reactivity to the %methyl group in quinaldine ethiodide (compare Kiioevenagel Ber. 1894, 27 2345). In the alkaline reaction mixture the hypothetical intermediate product VI would lose hydrogen iodide forming the substance (VII. 1 (VIII.) VII for the existence of reactions of this type is well established (compare Decker Ber.1905 38 2493). VII is however not a possible formula for a substance as intensely coloured as pinacyanol. From analogy to other basic dyes the saturated and the unsaturated nitrogen atoms in this compound must be connected by a chain of conjugated unsaturated1 linkings. There are reasons which make the presence of an ethylenic linking between the carbon atoms 9 and 10 exceedingly probable and therefore we assign to pinacyanol the formula VIII. These reasons are first that in the closely related isocyanine con-densation a similar oxidation involving the removal of two hydrogen atoms occurs,* and secondly as has already been pointed out that the great readiness with which pinacyanol can be oxidised * The two hydrogen atoms by which formula VII differs from VIII would be unusually reactive on account of their respective positions relative to unsaturated linkings and would therefore be readily removable.That the carbocyanine condensation involves a process of oxidation would also explain why a larger yield of sensitiser can be obtained from a given quantity of quinaldine ethiodide when the Condensation is carried out in presence of quinoline ethiodide ; the latter probably gives rise to substances which serve to take up this hydrogen 1656 BEILLS AND HAMER THE CYANINE DYES. PART III. tol quinaldinio acid ethyl nitrate is scarcdy to be accounted for unlem an ethylenic linking is present in this position. There is a somewhat remarkable reaction of pinacyanol which is probably dependent on the presence of this unsaturated three-carbon chain uniting the t’wo quinoline residues.If a solution of the nitrate of the dye in dilute nitric acid is carefully warmed to 60° the orangered colour to which reference has already been made suddenly appears and on cooling t,he solution a bright red compound crystallises. This is a quaternary nitrate and analysis indicates that it is formed by the entrance eibher by substitution or addition of two nitro-groups into t’he pinacyanol molecule. Since on oxidation it gives like pinacyanol itself quinaldinic acid ethyl nitrate and 1 -ethyl-2-quinolone both nitro-groups must be attached to the 3-carboln chain connecting the two quinoline residues unless as is less pro’bable one of them is in the 2’-position. This reaction which does not take place in the presence of carb-amide accordingly recalls the action of nitrogen peroxide on quinoline-yellow (Eibner and Lange Arznaken 1901 315 342), and the stability olf this pinacyanol derivative in comparison with Eibner and Lange’s additive compound would indicate that it is a substitution derivative.(5) According to this view of the constitution of the carbo-cyanines they stand in an interesting relationship to the cyanines. The cyanihes can be regarded as consisting of a l-alkylquinolenyl radicle united through the methenyl group :CEO to a univalent residue of an alkylquinoliniurn salt. Since the union can take place from a 2- to ai 2’-positioln a 4- to a 4’-position or from a 2- to a 4/-position there are three types of cyanines : (111.) The dyes of type I1 are the true cyanines those of type I11 are Dyes of type I are at present unknown in t h e the isacyanines MILLS AND HAMER THE CYANINE DYES.PART JII. 1557 quinoline seriw but the cornpounds obtained by Hofmann (Ber., 1887 20 2262) by the action of ammonia on a mixture of the alkyl iodides of benzothiazole and 1 -methylbenzothiazole are so closely analogomus to the isocyanines in the method by which they are formed and in their properties that Lhey undoubtedly possess the constitution C B < ~ ~ > C :CH* C<$>C,H , /\ R I and thus are repraentatives of this class. According to the constitution now assigned to the carbocyanines, they are cyanines of class I in which the carbon chain connecting the two quinoline nuclei has been lengthened by the introduction of the group =CH:CH*.The great resemblance between the carbo-cyanine and the cyanine dyes thus finds a simple explanation and the dseper collour of the carbocyanines compared with the reddish-purple of the cyanines of the benzothiazole series is associated with the lengthening of the chain of conjugated unsaturated linkings which connects the two nitrogen atoms. Corresponding with the three types of cyanines the following three classes of carbocyanines should be capable of existence: (II’.) /-\ (111’. ) Thus in addition to the dyes of the type of pinacyanol (I/) it should be possible to prepare compounds of the formulae 11’ and III’ which would probably prove to be dyes possessing polwerful photo-sensitising properties similar to those shown by the rest of this group of compounds.EXPERIMENTAL. Composition of I 1’-Diethylcarbocyanine Salts. 1 I’-Dieth2glcarbocyanine iodide prepared as described by Pope and Mills (Eoc. it.)^ by the action of formaldehyde and alkali o 1558 MILLS ANDZHAMER THE CYANINE DYES. PART III. a mixture of quinaldine ethiodide and quinoline ethiodide after having been crystallised five times from methyl alcohol and dried to constant weight a t 145°/20-30 mm. was found on analysis by tjhe Carius method to coatain I=26*60 per cent. The iodide pre-pared from quinaldine ethiodide alone was found in two1 analyses to contain I=26*61 and 26.68 per cent. The iodide pre-pared from quinaldine ethiodide and quinoline methiodide gave I=26.53 and 26.54 per cent.The mean of these values which are probably slightly too high on account of occlusion of silver nitrate by the silver iodide is 26*59* (C,H,N,I requires 1=26.43; Fischer’s formula C,H,N,I requires I = 27.23 per cent.). 1 1’-Diethylcarbocyanine bromide after drying to constant weight a t 140°/20-30 mm. was found to contain Br=18.49 and 18-53 per cent. in two experiments carried out by Mr. J. E. G . Harris. These analyses to which on account of the accuracy of the Carius method for the estimation of bromine we attach especial importance give it molecular weight of 432 for the bromide (corre-sponding with a molecular weight of 479 for the iodide) (C,H,N,Br requires Br = 18.45 ; Fischer’s formula C24HBN2Br requires Br= 19.06 per cent.). Combustion of the dried bromide gave results in excellent agree-ment with the formula C,H2,N,Br (Found C,= 69-18 ; H = 5.83 ; N=6.55.Calc. C=69*26; H=5*82; N=6.47 per cent.). Oxidation of 1 1 1-Diethylcarbocyanine Bromide with Nitric Acid. 1 1’-Diethylcarbocyanine bromide (2 grams) was boiled under reflux with il. mixture of nitric acid (D 1-42; 40 c.c.) and water (40 c.c.). Nitrous fumes were evolved and the liquid rapidly became orangered but the colour gradually disappeared and, after about one hour’s boiling the liquid became co1ourless.t The liquid was then evaporated first on the water-bath and finally over sulphuric acid’ under 2 mm. pressure. The residue was treated with water and a sinall quantity (about 0.1 gram) of undissolved material was removed by extraction with chloroform.The aqueous layer was again evaporated on the water-bath and finally in a highly exhausted desiccator over sulphuric acid. The residue gradually solidified and by trituration with a little acetone an almost colourless crystalline solid was readily isolated. After * These analyses were carried out by one of us and Mr. F. H. Jeffery. t During this operation a small quantity of a heavy volatile oil with a pungent odour resembling that of chloropicrin appeared in the condenser. The amounts obtained were insufficient to enable the substance to be identified but it contained nitrogen and bromine and waa possibly bromo-nitromethane MILLS AND HAMER THE CYANINE DYES. PART III. 1559 recrystallisation from absolute alcohol it melted and decomposed a t logo.The following observations show that this compound is quin-aldinic acid ethyl nitrate : (i) It is a nitrate. An estimation of the NO radicle by ‘ I nitron ” gave NO,=23.6. C,,H,,O,N*NO requires NO,= 23.5 per cent. (Found N = 10.8. C,,H,,0,N2 requires N = 10.6 per cent .). (ii) Although a quaternary ethyl nitrate (as shown by its con-version into ethylquinolone on oxidation and its behaviour with excess of alkali) it was strongly acid and could be sharply titrated with alkali and phenolphthalein and therefore contained a carboxyl group (Found C0,H = 17.05. C,,H,,O,N,*CO,H requires CO,H = 17.04 per cent.). (iii) Its conversion by alkaline f erricyanide into ethyl-2-quinol-one shows that the carboxyl group was in the 2-position. An aqueous solution of the nitrate (0.5 gram) was slowly dropped into a solution of potassium ferricyanide (6 grams) in 5 per cent.sodium hydroxide (60 c.c.) maintained at 0-5O. The resulting liquid was extracted with ether and the residue left on evaporation of the ether after drying with potassium hydroxide was pure 1 -ethyl-2-quinolone. I t s melting point 53-55*5O was identical with that of a specimen of ethylquinolone prepared for comparison by oxidising quinoline ethiodide and a mixture of the two specimens melted a t the same temperature. The weight of quinolone obtained was 0.27 gram or 82 per cent. of the theoretical amount. The material from which the quinaldinic acid ethyl nitrate had been separated by means of acetone was then examined. It was left after evaporation of the acetone as a clean brown oil which was excessively soluble in water alcohol or acetone.It was investigated in various ways such as by crystallisation of the platinichloride without much further information being gained. It was therefore oxidised with alkaline potassium f erricyanide. The material obtained from 2 grams of diethylcarbcwyanine bromide by oxidation with dilute nitric acid and subsequent removal of the quinaldinic acid ethyl nitrate was dissolved in water a small quantity of insoluble matter being removed by filtration and the liquid was dropped into a solution of potassium ferricyanide (8 grams) in 5 per cent. sodium hydroxide solution a t 0-5O. The quinolone produced was extracted with ether and dried with potassium hydroxide.The material from three such experiments was united and dis-tilled under 2 mm. pressure from an oil-bath a t 155-168O. The distillate was a colourless oil which solidified to crystals meltin 1660 MILLS AND HAMER THE CYANINE DYES. PART III. a t 50-54O with previous softening a t 40°. It was therefore not quite pure and was recrystallised from light petroleum. It then melted a t 50-54-5O and was shown by its general characters and analysis to be 1-ethyl-2-quinolone (Found N = 8.3 Calc. N = 8'1 per cent.). The quantities obtained in these experiments were as follows. By the oxidation of 6 grams of 1 l'-diethylcarbocyanine bromide, C,,H~N,Br,CH,OH 3.03 grams of quinaldinic acid ethyl nitrate were obtained. This melted at 107-108° and' was pure (Found: C02H = 17.2 ; NO,= 23.6.Calc. C02H = 17-04 ; NO,= 23.5 per cent.). This weightl is 89 per cent. of that theoretically obtainable. The weight of crude 1 -ethyl-2-quinolone obtained was 1.64 grams. The weight of redistilled material was 1-35 grams which is 60 per cent. of the weight of quinolone theoretically obtainable from one quinaldine nucleus in the pinacyanol taken. The weight of recrystallised material from which the sample for analysis was taken was 0.76 gram. Oxidation of 1 l 1-Diet~tylcarbocyanine Acetate with Potassium Permunganate. To prepare the acetate a solution of 1 1 1-diethylcarbocyanine bromide (4 grams) in boiling rectified spirit (450 c.c.) was treated with it hot saturated aqueous so'lution of silver acetate (1.44 grams). The residue olbtained after evaporating the filtrate from the pre-cipitated silver bromide was dissolved in a mixture of acetone (450 c.c.) and water (450 c.c.).Into this sollution which was mechanically stirred and kept a t 0-5O 140 C.C. of a solution of potassium permanganate containing 3.16 grams per litre were slowly dropped an snd-pointl having been reached when 137 C.C. had been added. The red filtrate which was neutral to litmus, was extracted with ether after evaporating the acetone under diminished pressure. The broiwn ethereal extract .was shaken with very dilute hydrochloric acid which extracted some tarry matter (0-18 gram) leaving an almost colourless solution. This was dried with potassium hydroxide and1 then evaposated ; the residue (1.26 grams) which soon crystallised melt'ed a t 45-50°.When distilled under diminished prelssure this gave a colourless distillate of pure 1 -ethyl-2-quinolone (melting point 52-55O ; melting point of a mixture with pure 1 -ethyl-2-quinolone 52-55') (Found C=76*1; H=6*7. Calc. C=76*3; H=6*4 per cent.). The weight of the dist'illate was 1.18 grams which is 79 per cent. oQ the theoretical yield. The aqueous solution left after extraction of the ethylquinolon was acidified with hydrochloric acid evaporated and the residue then treated with absolute alcohol to separate the organic matter from potassium chloride. The brown material left after evaporation of the alcohol was boiled for thirty hours with 140 C.C. of dilute nitric acid (D 1*2), and the solution was then examined in the same way as that obtained by oxidising diethylcarbocyanine bromide with nitric acid.The weight of quinaldinic acid ethyl nitrate obtained was 0.61 gram or 27 per cent. of the theoretical amount and further oxidation of the residual material with alkaline f erricyanide gave 0.46 gram of ethylquinolone equivalent to 31 per cent. of the theoretical yield from the original diethylcarbocyanine acetate. The Red Salts obtained by the Action of Nitric Acid on 1 1 f-Diethylcarbocyanine Salts. 1 1'-Diethylcarbocyanine brolmide (1 gram) was dissolved in dilute nitric acid by warming to 40° with a mixture of 4 C.C. of nitric acid (D 1*42) previously boiled to expel oxides of nitrogen, and water (16 c.c.). The bromine was then exactly precipitated with silver nitrate and the blue or green filtrate containing the nitrate of the dye was warmed to 60-65O when the liquid suddenly turned orange and red crystals began to separate.The liquid was cooled to Oo and the crystals were collected. By boil-ing the filtrate a short time and coaling to Oo a further yield was obtained and the process of boiling the filtrate and cooling was repeated as long as fresh quantities of crystals separated; 13 grams of 1 1'-diethylcarbocyanine bromide thus treated gave 7.36 grams of the red crystals. The yield is less if larger quantities of carboc eyanine than 1 gram are taken. The reaction is dependent on the production of oxides of nitrogen. If commercial nitric acid not previously boiled is employed the colour change takes place considerably below 60°.On the other hand if carhamide is added the mixture can be boiled without the formation of the red salt. This red salt is a quaternary nitrate. To obtain EL compound which could be more accurately analysed it was converted' into the correspolnding bromide by dissolving in boiling water and adding the solution to an equal volume of a hot concentrated solution of potassium bromide. The red bromide began to) crystallise from the hot solu-tion and separated practically completely on cooling. This treat-ment with potassium bromide was then repeated three times and the product was finally recrystallised from hot water 1562 MILLS AND HAMER THE CYANINE DYES. PtLRT III. For analysis it was dried a t 50°/20-30 mm. The dried material melted and decomposed a t 201-202O (Found C =56.76, 56.65 ; H =4.80 4-58 ; N = 10.52 10.73 ; Br = 15.37 15.37 15.16.CZ5Hz3O4N4Br requires C = 57.4 ; H = 4.42 ; N = 10.7 ; Br = 15.27 per cent. Loss on drying 6-92 7.75. C25H,304N,Br,2H,0 requires H20 = 6.9 per cent.), Oxidation of the Red Nitrate.-One gram was boiled with a mixture of 10 C.C. of nitric acid (D 1-42) and water (10 c.c.). Oxides of nitrogen were evolved the colour slowly faded and, after boiling under reflux for six hours a pale yellow liquid was obtained. This liquid was treated in the same way as the similar solution obtained by oxidising diethylcarbocyanine bromide with dilute nitric acid (p. 155S) and the same products namely, quinaldinic acid ethyl nitrate and l-ethyl-2-quinolone were similarly isolated. From 4 grams of the red nitrate correspond-ing with 3-95 grams of anhydrous substance were obtained 1.51 grams of quinaldinic acid ethyl nitrate (73 per cent. of the theoretical quantity) and 0.84 gram of ethylquinolone melting a t 52-53" (62 per cent. of the theoretical quantity). Colrresponding experiments were carried out with the bromide. This salt was much more rapidly attacked by the dilute nitric acid, the bromine present evidently assisting the oxidation and the volatile heavy oil to which reference has already been made (p. 1558) appeared in the condenser otherwise the products of oxidation were the same. Quinaldinic acid ethyl nitrate and 1-ethyl-2-quinolone were obtained in quantities corresponding with 93 per cent. and 60 per cent. respectively of the theoretical amounts. One of us (F.M.H.) is indebted to the Department of Scientific and Industrial Research for a grant for which she desires to express her thanks. UNIVERSITY CHEMICAL LABORATORY, CAMBRIDGE. [Received October %Oth 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701550

出版商:RSC    

年代:1920

数据来源: RSC

摘要:

COAGULATION OF GOLD HYDROSOLS BY ELECTROLYTES. 1563 CLXXI1.-The Coagulation of Gold Hydrosols by Electrolytes. The Change in Colour Influence of Temperature and Reproducibility of the Hydrosol. By J~ANENDRA NATH MUKHERJEE and BASIL CONSTANTINE PAPACONSTANTINOU. IN view of the results obtained by one of us (this vol. p. 350) with arsenious sulphide it was thought desirable to investigate the influence of temperature on the precipitation of gold sols. In the course of this work it was found necessary to examine the reproducibility of the sols prepared by Zsigmondy’s nucleus method. A spectrophotometric study of the changes in colour on coagulation has been made and this has been utilised to measure the rate of precipitation. Preparation of the Hydrosol. All the sols were prepared by Zsigmondy’s nucleus method.The specific conductivity of the water obtained from a pure tin condenser varied from 2 x 10-6 to 3 x 10-6 mhos. a t 15O. The nucleus solution was prepared as follows: To 100 C.C. of pure water in a resistance-glass beaker were added 2 C.C. of a solution of chloroauric acid containing 6 grams of the acid in a litre followed by 6 C.C. of a N/18-solution of pure potassium carbonate. Five C.C. of a saturated solution of phos-phorus in ether were diluted to 100 C.C. with pure ether and the solution was added to the gold solution gradually-a few drops a t a time. After each addition the solution was stirred and this was continued until a deep chocolate colour was produced. It was then heated and a ‘‘ red ” sol resulted.To prepare the hydrosol proper 2 C.C. of the chloroauric acid solution were added to 100 C.C. of water followed by 6 C.C. of the potassium carbonate solution. The mixture was then heated to boiling and 4 C.C. of the nucleus sol were added followed by 4-5 C.C. of a 0.03 per cent. solution of formaldehyde. The ruby-red sol which was formed was boiled for a minute. The hydrosols obtained in this way have all the properties of the best solutions prepared by Zsigmondy. In the cardioid ultra-microscope the hydrosols show mostly green particles with a few brown ones. The sols contain 0-067 gram of gold per litre 1564 MUKHERJEE AND PAPACONBTANTINOU THE COAGULiATION The Colour Changes in a Gold Hydrosol o n t h e Addition of c m Electro Zyt e. Zsigmondy (AnnaZe?b 1898 301 46) studied the colour changes qualitatively only.I n the numerous subsequent researches on the optical properties of gold sols the change in the absorption on coagulation has n o t been examined. The changes in colour were observed with a Konig-Martens spectrophotometer. The changes in the colour from red to blue on the addition of an electrolyte are mainly a result of a change in the abmrption-coefficient of red and violet rays. The change is greatest in the red region. There is a limiting value of the absorption-coefficient corresponding with the blue colour of the sol and these limiting values are independent of the nature o€ the electrolytes used. The coefficients were calculated from the quation 1 tan2a K = XJ2.306 = - loglo ~ d tan% ao* (Hildebrand Zeitsch.Elektrochern. 1908 14 349). I n studying the precipitation equal volumes of sol and1 electro-lyte were mixed. The coefficients for the pure sol refer to that for the sol diluted with an equal volume of pure water. The electrolytes used were potassium chloride sodium chloride barium chloride potassium nitrate strontium nitrate and potassium sulphate. The results are given in Fig. 1 and are the mean of observa-tions with different samples of sols and different electrolytes. The wave-lengths are correct within +1 ,up. It is interesting to note that in the region near 523 pp there is scarcely any change in the a bsorp tion-coefficien t . It will be seen later that the results obtained for the absorption of light by the hydrosols prepared under exactly similar conditions, differ a little among themselves except in this region which is close to the spectral region where the absorption is a t a maximum (near 5 0 6 ~ ~ ) (compare Ehrenhaft Ann.Physik 1903 [iv]) 11, 489). Assuming the particles in a gold sol to be spherical and that there am many particles to a wave-length of light Garnett (Phil. Trans. 1904 [ A ] 203 385; 1906 [ A ] 205 237) deduces that the maximum of absorption should be for light of wave-lengt<h 533 ,up. Mie (Ann. Physik 1908 [iv], 25 377) also deduces from his theory that the maximum * a,=the angle for water or electrolyte solution alone OF WLD 3YDR01SOLS BY ELECTROLYTES. 1665 of the pure (corrected) absorption lies in the region 525 to 5 5 0 p p . He further shows that for spherical particles the region of maxi-mum of absorption does not vary with the size of the particles, although the value of the absorption-coefficient depends on the size.According to these theories the colour of a gold sol by trans-Wave-lengths i n p p . I. Hydrosol diluted with water. I I I . Nucleus sol dilute with water. 11. , mixed with electrolyte. IV. HydroaoZ mixed with electrolyte. initted light is the result of two properties of the goldl particles or aggregates : (1) Minute spherical gold particles have a fairly well-defined maximum of absorption in the green. Reflection in the ordinary sense is very weak in this case and the colour is due to the absorp-tion of the green light which is the colour of the light scattered most strongly by these particles.(2) With increasing aggregation as the size becomes comparabl 1566 MDI(HERJEE AND PAPACONST~!CINOU THB OOAQULATION to the wave-length of light there is increasing reflection. When the size becomes sufficiently large the optical discontinuity of the medium becomes manifest as a turbidity. As is to be expected from the properties of metallic gold red and yellow rays are mostly reflected and the transmitted light becomes correspondingly weaker in the red and yellow. The observed constancy of the absorption-coefficient therefore indicates two possibilities namely (1) The reflection of green light is relatively small for gold (47-3 per cent. for fjOOpp). The minute particles in a gold sol scatter green light almost completely, and the part played by reflection is negligible.The formation of clusters therefore may be taken not to affect$ the absorption. (2) It is possible that the change in scattering is counterbalanced by that due to reflection with the progress of aggregation. Garnett remarks that “when the particles are not sufficiently thickly distributed to satisfy the condition of there being many particles to a wave-length of light . . . the absorption that we have in-vestigated is therefore not present ” ( P h i l . Trans. 1904 [ A ] 203, 402). Indeed it is found that on coagulation the intensity of the blue light (5OOpp) diminishes for the sol. This is in accordance with the theories mentioned as neither of them leads to the expectation of a constant absorption on aggregation. The theoretical aspect is further complicated by the fact that the shape of the aggregate has to be considered.However the observed constancy is striking as it coincides with the region of maximum absorption deduced by Garnett and Mie from the properties of. metallic gold. It is possible that the scattering of green light is a characteristic property of the gold atom and is independent of cluster formation. T h e Measurement of t h e R a t e of Coagulation with t h e Spec trop h o t onae t er . The change in absorption on coagulation is great in the red region and it has been utaised to measure the rate of precipitation at the ordinary temperature. The reciprocal of the time required to reach the limit of absorption is a measure of the rate of coagula-tion. As a characteristic change in the sol itself is utilised this method has an advantage over others dependent on an arbitrarily selected stage of change.For the fine sols used in this work the direct method of determining the rate of decrease in the number of particles is not possible with ordinary ultramicroscopes (Zsigmondy %eitsch. physikal. Cltem. 1918 92 600). This simple spectrophotometric method can be used with a suit OF BOLD HYDROSOLS BY ELECTROLYTES. 1567 able ultramicroscope with economy of labour and time. The number of particles corresponding with the absorption-coefficient values can be determined by the ultramicroscope and their mutual relationship can be utilised to substitute the spectrophotometer for the tedious ultramicroscopic work. This is possible for the whole range of changes in colour from red to blue but is not applicable when the limit of absorption has been reached.The influence df the concentration of an electrolyte has been followed with the spectrophotometer for potassium chloride, potassium sulphate potassium nitrate and barium chloride. The mean results of three observations are given in tables 1-111. The absorption-coefficients are for light of wavelength 683 ,up. The observations shomw that for low concentrations of an electrolyte the " limiting " values of absorption are not reached and coagula-tion practically stops a t a certain stage. TABLE I. Electrolyte Potassium Chloride. Time in minutes after mixing equal volumes of electrolyte. and sol. 0.5 1 1.5 2 3 5 9 13 15 -Absorption-coefficients for various concentrations.N/24. N/26. N/28. 0.0453 0.0453 0.0453 0-3732 0-2867 0.1683 0.438 0.3630 0.2257 0.4497 0.4046 - 0.438 0.2777 - 0.4497 0.3431 0.3836 - 0.4263 0.438 - 0-4497 r 7 -- -__ - --TABLE 11. Potassium Nitrate . Time. 0.5 1 1.5 2 3 4 5 8 10 16 -F N/24. 0.0453 0-3336 0.4263 0.4497 Concentration. N/26. 0.0453 0.2866 0.3271 0.3629 0.4156 0.438 0.4497 J. --7 N/30, 0.0453 0.269 0.3143 0.3336 0.3732 0.394 0.4263 0.438 0.4497 - 1568 MUKBEWEE AND PAPAUOWSTANTINOU THE COAGULATION Time. -1 2 4 5 7 8 9 11 13 16 TABLE 111. Barium Chloride. Concentration. p-0-85237/900. 0-852N/lOOO.0-0453 0.0453 0.2257 -0.2867 -0.3529 -0.3836 0-3051 0.438 0.3431 0.4497 -0.4497 0.3836 - 0.4263 - 0.4497 - -0*852N/1100. 0.0453 0-1603 0.2007 0.2687 0.3051 0.3237 0.3336 0.3529 0.363 0.363 0.3732 These experiments were carried out within a short interval and with the same sol. There is scarcely any difference between the coagulating effects of the three potassium salts. Smoluchowski (Zeitsch. physikal. Chem. 1917 92 129) has deduced the follow-ing equation for the rate of decrease in the total number of particles : L where n is the total number of particles in unit volume just after mixing the sol with the electrolyte (zero time) nt is the number a t time t (second) and' T is characteristic of the rate of coagulation. Zsigmondy finds that when the minimum coagulation-time has been reached two particles on coming in contact as a result of their Brownian movement are held together by forces of cohesion.The work of Westgren and Reitstotter (Zeitsch. physilcal. Chem., 1918 92 750) lends support to this as all these authors find that the radius of the effective sphere of attraction (as defined by Smoluchowski) is nearly equal to twice the radius of the particles. Under these conditions, where q =the viscosity of the solution. R =the gas constant. No =the Avogadro number. 0 =the absolute temperature. E = the fraction of mutual collisions between the particles which result in a stable union OF GOTJD HYDROSOLS BY ELECTROLYTES. 1569 For a constant value of y z t = n ’ i t is evident that C .t =constant . . . . . . (3) (4) . . . . . . . . . k t The reciprocal of the times for a definite change is thus directly proportional to the fraction of collisions which result in coalescence, and hence measures the rate of coagulation. The data obtained on the influence of concentration will be discussed on another occasion. The equations given above will be discussed later when dealing with the influence of temperature. or E = -The It?fluence of Tenzpernture. The great variation in the colour of a ruby-red gold sol makes i t suit-able to use a definite shade of violet-red or bluish-violet for comparison. Standards for comparison were made by arresting the colour-change a t a selected stage with gelatin and with care, perfectly reproducible standards can be prepared.The times necessary for the sol to change t o the colour of the standard are given below. TABLE IV. The method used by one of us (loc. c i f . ) was adopted. Electrolyte 0.85 3N 1000-Bnriv m Chloride. Violet. Blue. I. [I. 1. 11. & Sol. A ...... 6 min. 6 min. 29 min. 29 min. Sol. B ...... 2 min. 2 min. 25 see. 10 min. 45 sec. 10 min. 30 sec. The results are the meall of six observations taken separately by each of us. Sol B was obtained by boiling sol A for a few minutes and then cooling. It will be seen that the boiling produces a change in the sol. The concentration of the electrolyte used for producing the change in the colour should be such as will bring about a slo8w rate of precipitation. About 2 C.C. of a 2 per cent.gelatin solution (liquid) were added to 10 C.C. of the sol-electrolyte mixture. The same standards remain satisfactory for ten t o twelve days. Wide test-tubes were used to secure a suitable depth of colour. As is well known ruby-red gold sols are extremely sensitive to impuri-ties. Reproducible results can only be obtained if the vessels are cleaned with sufficient care. The glass vessels were washed with conductivity water after the usual cleaning with hot chromic acid and distilled water. The test-tubes were washed with boiling dis-VOL. CXVTI. 3 1570 MUKH.ERJEE AND PAPACONSTANTINOU THE COAGULATION tilled water (after chromic acid had been used) then with con-ductivity water and finally by passing steam derived from conductivity water. They were then dried in a steam-oven.There is a noticeable difference between cleaning with distilled water and conductivity water. Table V illustrates the reproducibi1it)y of the results. TABLE V. N / 1000-StroiLtium Nitrate. Ohservations. 1. 2. 3. 4. 5. 0. A A A /7 A A Times. Min. Sec. Min. See. Min. Xec. Min. Sec. Min. Sec. Min. Sec. Violet ... 1 10 1 6 1 11 1 13 1 0 1 12 Blue ... 5 46 5 48 5 30 5 30 3 30 6 0 In each case three to five readings were taken. With all these precautions a t times discordant results were obtained which were probably due to the occasional presence of particles of dust. The agreement between the different observations and the appearance of the characteristic blue colour is the surest indication of the absence of impurities.With long intervals it is difficult to avoid dust. A slow change ih colour is also much less easily perceptible to the eye. For these reasons it was found suitable to use con-centrations of electrolytes which change the colour to blue within an hour. As different standards were used they are indicated as Vl V2 etc. for violet standards and in a similar manner for blue standards. TABLE VI. Temperatures. A Stan- / \ Elm tr 01 y te . dards. 15". 30". 50". N/3O-potassirun chloride V Sol. C. 5 min. 10 min. 8 min. 30 sec. N!30- , sulphats y Sol. D. 30 see. 10 see. LO sec. "30- 9 9 9 , 42 sec. 18 see. 12 sec. TABLE VII Electrolyte Barium Chloride. ,Sol E, Temperatures. Concentra- Stan- 4 - tion. dards. 15". 30". 40". 50". 0-852N/1000 V 7 min. 6 min.4 min. 50 sec. 4 min. 20 sec. 0-852N/1000 B 34 , 83 y - 13 min. 30 see. 0*852N/1200 V 23 , 13 , 12 min. 30sec. 6 min. 15 see. 0'852N/1200 B 124 , 74 , 62 min. OF GOLD HYDROSOLS BY ELECTROLYTES. TABLE VIII. Electroly f e Strontium :Titrate. Sol F, Temperature. 1671 Concentration. Standards. 16". 30". 50". "1000 ..................... V 1 min. 10 sec. 20 sec. 8 sec. N/1000 ..................... B 8 min. 15 see. 1 min. 40 sec. 45 see. With barium chloride and strontium nitrate there is a distinct increase in the rate of coagulation with rise of temperature. Potassium chloride has been examined a t different concentrations. Temperature has a relatively small effect in the case of the potassium salts. With potassium chloride both an increase and a decrease in the coagulation times have been observed with rise of temperature.This behaviour is similar to that observed by one of us in the case of arsenious sulphide sols and aluminium sulphate. The effect of temperature is also dependent on the concentration of the electrolyte. Westgren (Arlciv. Kern. Min. Geol. 1918 7 No. 6) has found that in the case of coarse gold sols sodium chloride and hydro-chloric acid show an increase in the rate of precipitation with rise in temperature. With sodium hydroxide he found no change in the rate with rise of temperature. From equations (1) and (2) if n and rd have the same values we have . . . . . . ( 5 ) '+ = it a constant 17 where From equation (5) the variation in t can be calculated. remains constant we have If E .. . . . . . . . (6) - - '0 - constant rl 17 that is the times are proportional to the values of - a t different 0 temperatures. At 1 5 O 30° 400 and 50° 12 has the values 3.96 x 10-6 3.3 x 1 0 - 5 2.1 x 10-5 and 1.7 x 10-5 respectively. The results with hydrosols of gold and arsenious sulphide show that E varies with temperature and that the variation is deter-mined by the nature of the electrolyte. For any given concen-tration of an electrolyte E measures its coagulating power. On the adsorption theory the coagulating power of an ion is deter-mined by its adsorbability. In order to explain the results on the e 3 M 1572 MUKHERJEE AND PAPACONSTANTINOW THE COAGULATION adsorption 1 Iieory itl iiiusC be assuiiied as pointed out previously, that the adsoi-hhilil y of ail ioii depends 011 I hc 1 eiiJl)erat ure (t h i h vol.p. 350). The Reproducibility of the Hydrosols prepared by the X u c l e us Method. I n the course of this investigation it was noticed that these sols even when prepared under identical conditions do not give FIG. 2. 7 00 600 500 Wave-lengths pp. I. Upper limit of ubsorption. 11. Lower limit of absorption. the same coagulation times. According to Zsigmoncly the sols are reproducible if the quality of the water is unchanged. We find that the various samples of gold sols (prepared in an identical manner) show small but percepiible differences in coagulation times although they have constant gold numbers. This is due to the fact that the gold numbers are independent of the slight differences in the quality of the sols OF GOLD HYDROSOLS BY ELECTROLYTES.1573 Some twelve samples were prepared under the same conditions, and the absorption and the coagulation times were compared. The latter are extremely sensitive to any change in the sol. The limits of variation in the absorption-coefficients will be evident from Fig. 2. It will be observed that the variation is least in the region 520 to 540pp. A sol on keeping undergoes somewhat irregular changes which may in part be due to particles of dust getting in accidentally, and in part to the fungus that grows in these sols. For this reason it is necessary to vary one factor only a t a time and com-pare its effects. Table IX illustxates the variations the same “ violet” and ‘‘ blue ” standards being used.The times given are the mean of’three to five observations. The last column gives the time that has passed since the preparation of the sol. The sols were kept in resistance-glass vessels. Sol I is an “old” prepar-ation kept for two months. It was boiled twice during this interval to prevent organic growths. TABLE IX. Electrolyte O*S52N/ 1200-Barium Chloride. Sol. G . - S t rtndrtrds. Min. Sec. Violet ..................... 3 15 , ..................... 2 30 ....................... 1 4 ....................... 2 0 , ..................... 2 45 Blue ........................ 7 0 , ........................ 5 45 , ........................ 4 40 .......................... 9 0 ......................... 9 0 Sol H. Min. Sec. 3 35 s o 6 15 6 62 4 10 6 30 1s 0 19 0 22 30 14 0 7-Sol I. Min. see-11 0 12 30 12 30 12 30 22 0 30 0 30 30 33 0 --On the other hand reproducible results were obtained in some instances. At the suggestion of Professor Donnan the gold number of a number of soaps has been determined. The sols give a constant gold number for the same soap solution. We desire t o express our thanks to Professor F. G . Donnan, F.R.S. for his kind interest in this work and also to Dr. J. C. Ghosh. CITEMICAL LABORATORY, UNTVETWTS COLLEGE LONDON. [Received October 12th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9201701563

出版商:RSC    

年代:1920

数据来源: RSC