摘要:

FORMATION OF DERIVATIVES OF TETRAHYDRONAPHTHALENE. 87 IX.-The Formation of Derivatives of Tet Yahydro-naphthalene j+om y- Phenyl Fatty Acids. By GEORGE ARMAND ROBERT KON and ARNOLD STEVENSON. THE conditions governing the formation of dicyclic structures of the naphthalene type from benzene derivatives having a side-chain olf not less than four carbon atoms are a t present difficult to determine because we have as yet little knowledge of the effect on the valency directions of carbon atoms caused by their par-ticipation in an aromatic nucleus. That however the conditions are very similar to those which determine the formation of similar monocyclic structures from open-chain carbon derivatives has been clearly shown by experiments which have been carried out on the formation of ring structures through the catalytic action of sodium ethoxide on the relevant dinitrile.Thus it has been shown by Moore and Thorpe (T. 1908 93 176) that the transformation takes place with the greatest ease and by Thorpe (T. 1909 95, 1901) that the change > C X H YH2*CH2'CN $!H2-CH -+ CH,*CH(CN) c H,*C H2*CN can apparently be effected with equal readiness. That' six-membered rings of the two types also exhibit similar beha,viour is to be inferred from the results of a number of experi 88 KON AND STEVENSON THE FORMATION OF DERIVATIVES OF ments oif which the tlransformation represented below may be taken as an example (Atkinson and Thorpe T. 1906 89 1920): /\/\C:NH. CH2 CR, \/\/CH*C02Et Or 1 1 ' \/ /C€€*C02Et CN c NB NH2 Scheme (a).It is therefore remarkable that hitherto no examples appear to have been recorded illustrating the folrmatioin of a six-carbon saturated ring by the elimination of water from a y-phenyl fatty acid through the combination of the hydroxyl group of the carbolxylic complex with a hydrogen atom in the ortho-polsition of the benzene nucleus. The simplest compound which could exhibit this change would be y-phenylbutyric acid (I) but although this GI32 ( 3 3 2 //\/\GH2 + H,O co I I ' \/ P H 2 acid has been made t'he subjectl of exhaustive st'udy by several investigatolrs no record appears to ha,ve been ma.de of any such reaction. The rnat.t,er is an important olne because if a cha,nge of t,his kind cannot be effected it would indicate that there is an essent,ial difference bet<ween the colndit,iolns determining ring form-ation in open-chain compoands and; those of the type under dis-cussion and that the latter are not readily fosmed unless there is the possibility of the production of the true napht'halene nucleus, as illustrated by scheme (a).Tha'tt this is not the case is shown in the present paper wherein is described t,he formatioln of derivatives of fefrahydronaphfhalene frolm two typical derivativw eE y-phenylbutyric acid. It is also shown t,hat a. derivative of y-t.et.rahydroIphenylbutyric acid can be caused ta undergo the same change. It was evident that5 oin theoretical grolunds the derivativw of y-phenylbutyric acid folr use in these experiments should have been formed by hydrolysing the condensation products obtained by colndensing a suitable ketone with ethyl cyanoacetat,e and ammo,nia in accordance witb Guareschi's method but it has been CH,Ph CH,Ph\C,CH(CN) *CO CH,Ph \c/cH2'co2H \co \.N EI Et/ Et/ \CH(CN)*CO/ Et/ \CH,*CO,H (11.) (111.) w.TETRAHYDRONAPHTHALENE FROM T-PHENPL FATTY ACIDS. 89 shown already by Km and Thorpe (T. 1919 115 704) that the acid produced by hydrolysing the colndensation product (111) formed from benzyl ethyl ketone (11) by means of sulphuric acid does not possess the ekpected formula (IV) but has an abnormal structure. Attention was therefolre directed totwards determining the structure of this abnormal prolduct as well as that derived in a similar manner from benzyl methyl ketone and it was soon found that they were actually the tetrahydrojnaphthalene deriv-atives (V) and1 (VI) which had been formed by the elimination of water during the process of hydrolysis.The correctnem of this CH CH2 /\/\cR CH cc ~ I I f\l/\yMe*C H,*CO,H (V- 1 I I ' \/ P H 2 \ / \ P H 2 CO CO,H CHO (VI.) view of the constltution of these acids was shown by the formation of semicarbazones and by the proaduction of phthalic acid on oxidation wibh permanganate. In order to show that the condition of tlhe benzene nucleus did not have any appreciable effect on the formation of the second ring experiments were then carried out with the tetrahydro-ketone (cyclohexenylacetone VII) and in this case also the hydrated naphthalene derivative (IX) is the sole product formed on hydrolysing the imide (VIII) with sulphurio acid.It seems, CH2 /\ CH C CH CH \CH(C N -CO/ \/ \/ CH(CN).CO \NH f €1 R*CH,* CM e/ /"\"I FH E*CH,*COMe (VIII.) C'H CH2 (VII.) CH CH, /\/\ \/\/ $JH2 yMe*CH,*CO,H CK2 C CB, (=*) CH G 90 KON AND STEVENSON THE FORMATION OF DERIVATIVES O F therefore as i f the ease with which a ring closes is influenced by the character of the groups attached to the P-position oC the side-chain. It will be remembered that this point was raised in a recent paper (Day and Thorpe T. 1920 1\17 1465) but it is evident thatl much more experimental evidence will be necessary before any definite proinouncement can be made. An attempt was made to prepare the simplest member of the phenyl series (X) by hydrolysing the condensation produc'i.(Xl) produced from phenylacetaldehyde (XII) and cyanoiacetamide in accordance with the method of Day and Thorpe (Toc. c i t . ) but up to1 the present' WQ have only succeeded in obtaining a small quantity of the compound (XI) because under the usual conditions tho chief product is evidently derived irom the interaction of cyano-CHZ CH2 /'\A c ' q c N ) - co NH, 1 1 C H < ~ ~ ( ~ ~ ) - ~ ~ ()+ K- CH,. CO,H \/\/CHZ \/ C 0 acetamide and phenylacetaldehyde in equimollecular proportions. I t s structure has not as yet been completely elucidated and as it presents several points of interest i t is proposed to investigate it more fully. The behaviour of the acid (V) on regulated oxidation is interest-ing a number of intermediate compounds being formed before phthslic acid is finally produced.It is hoped to make these compounds the subject of a subsequent communication. E X P EK I M E N TAL. ac.-l-.Ueto-3-met hy It etraT~ya?ronnpT~thyl-3-ace t ic A cia? (V, p. 89). It was found that for the hydrolysis of the imide derived by Guareschi's process ( A t t i R. Accad. Sci. Torino 1900-1901 36, 443) from benzyl methyl ketoae Thole and Thorpe's method (T., 1911 99 445) did not give very satisfactory results the best yield being obtained with a large excess of 50 per cent. sulphuric acid (by volume). Twenty grams of iniide were heated under reflux with 400 C.C. s f acid with frequent shaking until solution took place and evolution of gas ceased when the liquid had become dar TETRAHYDRONAPHTHALENE PROM Y-PHENYL FATTY ACIDS.91 red. After diluting with 150 C.C. of water itl was extracted with ether yielding 12-14 grams of crude product (theory 16.3). The crude acid is yellow or brown but fin twice recrystallising from benzene i t is obtained in stellate clusters of colourless prisms melting at 155-156O (Fotund C= 71.35 ; H = 6.53. Ci3HI4O3 requires C=71*5; H=6*5 per c9nt. Silver salt. Found Ag= 32-97. CI3Ri,O,Ag requires Ag=33*2 per cent.). It is a weak acid not effervescing with sodium hydrogen carbonate and after boiling with 10 per cent. sodium hydroxide solution it4 is pre-cipitated by acid unchanged. The silver mercuric lead cupric, chromium aluminium ferric and ferrous salts form readily in the cold from the ammonium salt whilst the barium and calcium salts are solluble both in the1 cold and on boiling.The semicarbazone was prepared by warming an alcoholic sdu-tion of the acid with semicarbazide acetate. On keeping a dense, crystallinel mass formed which on recrystallising fratm alcohol, separated in fine needles melting at 2 2 1 O (Found N=15*44. C,,H,,O,N requires N = 15.3 per cent.). The oxidatioa to phthalic acid with potassium permanganate can be effected bath in acid and alkaline solution. I n the case of the former 4 grams olf tho acid (V) were dissolved in 150 C.C. of sulphuric acid (1 part of acid to 2 parts of water) and a warm, saturated solution olf potassium permanganate was added with heating un ti1 the supernatant' liquid above the precipitate which formed was pink. The excess of perinanganate was destroyed with oxalic acid and the liquid extracted with ether when 1 gram of crude phthalic acid was obtained.After recrystallisation from alcolhol and again from water it melted and decomposed a t 2 0 3 O , and on heating with resorcinol gave fluorescein (Found C= 57.65 ; H=3*83. Calc. C=57.8; IE=3*6 per cent.). The alkaline oxidation was carried out by dissolving the acid in sodium hydroxide sollution hsating on tho steam-bath and adding a warm saturated solution of potassium permanganate until the colour persisted. After destroying the excess of permanganate with sulphurous acid and filtering the liquid was1 extracted with ether the ethereal extract yielding crude phthalic acid which was identified as before. ac . -1 - X e i a- 3 - e t 7 b yl t e t rah ydrona ph thyl-3-ace tic A cid (VI , p.89). I n preparing this acid it is advisable tot use the pure imide as otherwise an oil is fornied which prevents the separation of the acid. Eight grams of imide were heated under reflux with 160 c. 92 RON AND STEVENSON THE FORMATION OF DERIVATIVES OF of sulphuric acid (1 part of acid to 1 part of water by vollume), with frequent shaking until solution took place and evolution of gas ceased. After diluting with water it was extracted with ether the ethereal extract giving on evaporation an oil which solidified in a vacuum yielding 1.4 grams of crude product. On recrystallisation from benzene and light petrolenm itl separated in short' stout prisms which adhered firmly to glass and melted at 7 9 O (Found C = 72.18 ; H = 6.65.Cl4HIGO3 requires C = 72.4 ; H = 6.9 per cent'. Silver salt. Found Ag = 31.91. C,,H1,O3Ag requirw Ag=31-8 per cent.). The metallic salts re$emble those olf its homololgue the barium and calcium salts being solluble both in the cold and on heating whilst the salts of the heavy metals are readily precipitated1 in the cold. The semicarbazone prepared by treating an alcohojlic solution of the acid with semicarbazide acetate was twice recrystallised from alcohol when it separated in needles melting at 2100 (Found: W= 14.73. The oxidation to phthalic acid was carried out in acid solution in the manlier already described (p. 91) and was identified by the resorcinol test. CISH,,O,N requires N= 14.5 per cent.). Condensation of cycloHe x en y lac e t on e with E thy I Cy anoac e tat e : 3 5-Dicyano-2 6-dileeto-4-cyclo?iexenylmethyl-4-methyl~per-s i n e (VIII p.89). The ketone was prepared by Wallach's methold from cyclohexan-one and acetoae (Annalen 1912 394 362) 13-8 grams being con-densed with ethyl cyanoacetate and alcoholic ammosnia by Guareschi's method (Zoc. cit.) giving 12 grams of crude imide. When twice crystallised from alcohol it separated in colourless needles which shrank and darkeneld at 190° and melted and decom-posed a t 202O (Found N = 15.72. C&11,02N3 requires N = 15.5 per cent. ) . l-Reto-3-methyloctnhtydronaphthyl-3-acetic Acid (IX p. 89). It was again found thatl the use oh impure imide gave unsatis-factory results. Concentrated sulphuric acid viollently attacks the, imide in the cold but with an excess of 50 per cent.acid (by volume) the reaction proceeds smoothly. On heating under reflux until evolution of gas ceased and then diluting and extracting with ether an oil was obtained from the ethereal extract which solidified on lea,ving in a vacuum but the yield was rather poor, being only about 25 per cent. of the theoretical. On rscrystallisa TETRAHYDRONAPHTHALENE FROM 7-PHENYL PATTY ACIDS. 93 tim from ether the acid separated in collourless crystals which were however indefinite in form melting a t 90° (Found: C=70.05; H=8*17. Cl3Hl8O3 requires C=70*2; H=8.2 per cent. Titration with N / 10-sodium hydroxide. Found 8.25 C.C. Calc. (monobasic) 8.05 C.C. Silver salt. Found Ag = 32-81. C13H,,03Ag requires Ag = 32.8 per cent.).The metallic salts closely resemble those s f the two acids described above the barium and calcium salts being soluble botsh in the cold and on heating whilst those of the heavy metals form readily in the cold. The semicarbazone was prepared by treating an alcoholic solu-tion 09 the crude acid with semicarbazide acetate. It is very sparingly soluble in hot alcohol and after twice crystallising therefrom formed spherical aggregates of needles melting and decomposing a t 209-210° (Found N = 15-06. C,,H2,0,N, requires N = 15.1 per cent.). The oxidation to phthalic acid was carried obt with potassium permanganate and sulphuric acid in the manner described above, crude acid being employed. Phthalic acid was identified by the resorcind test. Condensatiolz of Pheny lace tald ehyd e with Cyan mce t amide .Cyanoacetamide (8-4 grams) and phenylacetaldehyde (6 grams) welre dissolved in 50 C.C. of water and sufficient alcohol to effect complete solution and 0.5 C.C. of a 50 per cent. aqueous solut4ion of p&assium hydroxide was added. The crystalline precipitate which had folrmed in the course of twenty-four hours was colllected and found to consist of two sub-stances which can be separated by extracting the mixture with boiling alcoshol. The insolluble residue which forms small needles melting a t 245O is the diamide of aaI-dicyano-P-benzylg~utaT~ acid CH,Ph*CH[CH(CN)*CO*NHz]z (Found * C = 62.00 ; H = 5-35; N=20*57. C,,H,,O,N requires C=62.2; H=5.2; N=20-7 per cent'.). The quantity of this substance obtained up to the present is t'oo small for the investigation of its behaviour on hydrolysis. The second substance which separates oa cololing the alcoholic extract crystallises in needles melting a t 2 0 4 O . We have not yet succeeded in obtaining colncordant figures oln analysis but the nitrogen content' (13.8-14.0 per cent.) clearly indicates that the substance is formed by the condensation of cyanoacetamide and phenylacetaldehyde in equimolecular proportions. * We are indebted t o Mr. J. N. E. Day for this analyeis 94 COFFEY THE ACTION OF THE CHLORIDES OE’ We are indebted to Professor J. F. Thorpe for much valuable advice and for the interest he has taken in our work; our thanks are also due to Mr. W. S. G . P. Norris of this College, for kindly preparing wnie of the materials require’d. TIXE IMPERIAL COLLEGE OF SCIENCE AND TEC~NOLOGY, SOUTH KENSINUTON. [Received Dccenzber 171h 192&

ISSN:0368-1645    

DOI:10.1039/CT9211900087

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

94 COFFEY THE ACTION OF THE CHLORIDES OE’ X.-The Action of the Chlorides of Sulphur on Substituted Ethylenes. T h e Action of Propylene on Sulphur &lonochloride and the Synth esiv o j Pp’- DicILIoyodi-n-propyl Sulphide. By SAMUEL COFFEY. GUTHRIE (Quart. Journ. Chem. SOC. 1859 12 116) by the action of ethylene on sulphur dichloride obtained impure @PI-dichlorodi-ethyl sulphide. Later (ibid. 1860 13 134) he obtained the disul-phide by the action of ethylene on sulphur monochloride at looo, but higher chlorinated products and tar were also formed in large quantity. In a recent communication Gibson and Pope (T. 1920, 117 271) have shown that sulphur monochloride and ethylene between the ordinary temperature and 70° give /3/3/-dichlorodiethyl sulphide whereas above 70° the liquid darkens and hydrogen chloride is evolved as in Guthrie’s reaction.Apart from the work mentioned above nothing is known of the reactions involved when sulphur chlorides act on olefines although the action of “ sulphur chloride ” on oils etc. has long been used as a “thermal” test for unsaturation. The aim of these investigations of which this is only a preli-minary communication is to study the action of sulphur chlorides on substituted ethylenes to find the effect of the substituent on the course of the reaction with a view to elucidate the complex changes which doubtless are involved in the thermal test mentioned above. Considering the mono-substituted ethylenes the compounds most likely to be produced are of the types: CHRCl*CH,*S*S-CH,*C€IRCl CH,Cl*CHR*S S - CHR*CH,Cl (1.1 (11.) (CHRCl*CH,),S (111.) (CH,Cl* CHR),S (IV.SULPHUR ON SUBSTITUTED ETHYLENES 95 The course of the reaction will no doubt depend on the temperature and the electrochemical character of the substituent group. In the case of a monoalkyl-ethylene such as propylene for example the electropositive methyl group should cause the second-ary chloride to be produced as the main product as in the case of iodine chloride (Michael J . p r . Ckem. 1892 [ii] 46 345) and theref ore the probable products wiIl be /3B’-dichlorodi-n-propyl disulphide (type I) and @B/-dichlorodi-n-propyl sulphide (type 111). Attempts to prepare these substances by the action of propylene on sulphur monochloride were not very successful but a small quantity of /3/3/-dichlorodi-n-propyl disulphide was obtained from which a barium chloropropa.nes~lphonate was produced on oxida-tion.BP’-Dichlorodi-n-pro~~l sulphide which was not formed in this reaction was prepared from propylene chlorohydrin by Clarke’s modification of V. Meyer’s method (T. 1912 101 1583) for the production of BP/-dichlorodiethyl sulphide : CH,*CH (OH) *CH,Cl+ (C Ht-CH[OH]*CH2)2S + (V.) (CH,*CHCl*CH,),S. (VI.) E X P E R I M E N T A L . Action of Yropylene on Sulphur Monochloride. The sulphur monochloride was repeatedly distilled from sulphur and finally fractionated in a vacuum over charcoal; 2.5 per cent. of sulphur was dissolved in the amber-coloured liquid. The propylene was prepared by the action of phosphoric acid on isopropyl alcohol (Newth T.1901 79 915). The dried propylene was passed into the sulphur monochloride (40 grams) a t a rate of about a litre per hour the absorption vessels being kept a t constant temperature. A t 60° the sulphur monochloride soon became brown and gela-tinous and finally changed into a viscid black product through which the gas would not pass. During the whole time much hydro-gen chloride was evolved. When distilled in a current of steam the product furnished only about 1 gram of volatile oil. In the next experiment the absorption was started a t 40° and the temperature was never allowed to rise above 50°. Ten litres of gas (approximately 20 grams) were passed through three tubes each of which contained 15 grams of sulphur monochloride before all the chloride had become dark brown and semi-solid.The product was extracted with chloroform and then distilled (18-25 mm.) when a small quautity (5 grams) of a red oil ( A ) passed over a t 113-120° 96 COFBEY THE ACTION OF THE CHLORIDES OF The residue was a black tar (more than 25 grams). During the distillation much hydrogen chloride was evolved. The distillate a t first pale yellow gradually became red as it passed over. It was vigorously oxidised by concentrated nitric acid (D 1.4) in the cold but nothing but a little sulphur separated on dilution. Thus the reaction was totally different from that of nitric acid on PB'-dichlorodi-n-propyl sulphide (p. 97). The filtered solution was evaporated until free from nitric acid, when a pale yellow viscous strongly acid liquid was left.This was diluted wfih water boiled with barium carbonate and the filtrate evaporated to incipient crystallisation when a barium salt separated on cooling. 'The barium salt was only sparingly soluble in alcohol but readily s3 in cold water or hot 75 per cent. alcohol from which it crystal-lised in colourless nacreous plates. It contained sulphur and chlorine and on treatment with phosphorus pentachloride gave a very easily hydrolysable sulphonyl chloride (Found in air-dried salt H20 = 5-25 (C3H,03C1S),Ba,l~&0 requires H20 = 5.6 per cent. Found in anhydrous salt Ba = 30-7. (C,H,O&lS),Ba requires Ba = 30.4 per cent.). This was theref ore the barium salt of a chloropropanesulphonic acid and the original substance was in all probability BPI-dichloro-di-n-propyl disulphide.A little barium sulphate was also obtained. BP'-l)ihydroxydi-n-propyl Sdphide (V) . Propplene chlorohydrin was prepared from ally1 chloride by Oppenheim's method (Annalen Suppl. 1868 6 367) for as Smith (Zeitsch. physikal. Chem. 1918 93 59) has shown recently this is the only method which does not give a mixture of a- and j3-chloro-hydrins. Twelve grams of propylene chlorohydrin were gradually added to 37 grams of crystallised sodium sulphide dissolved in an equal weight of water. The mixture became warm and was cooled in water but after a short time the development of heat ceased. The mixture was heated on a water-bath for one and a-half hours; a pale brown oil gradually separated but partly redissolved on cool-ing.The product was then just acidified with hydrochloric acid. The slightly turbid solution was distilled in a vacuum when a yellow oil gradually separated along with sodium chloride. The residue was shaken with alcohol and the extract evaporated in a vacuum until no more distilled. The pB'-clTihydroxydi-n-propyl sul-phi& was left as a non-volatile pale yellow viscous liquid soluble in water or alcohol and heavier than water. The product was no SULPliUR O N SUBSTITUTED ETHYLENES. 97 purified further but used for the preparation of P@’-dichlorodi-n-propyl sulphide. The yield was 80 per cent. of $he theoretical. PB’-DichloroJ.i-n-propy~ Sulphide (VI). The preceding compound (9 grams) was added to Concentrated hydrochloric acid (70 c.c.) when a pale pink turbid solution was produced.This was then heated on a water-bath for one and a-half hours when it gradually became more and more turbid and a heavy dark brown oil gradually separated. It was extracted with chloroform and distilled in a vacuum when a colourless oil, boiling a t 122O/23 mm. passed over. When the temperature quickly rose Lo 126O/23 mm. bhe distillation was stopped. The yield of BP’-dichlorodi-n-propgl sulphide was 7 grams and the residue amounted to less than 1 gram. PPt-Uichlorodi-n-propyl sidphide is a colourless oil boiling a t 122O/23 mm. which does not freeze on cooling to -8O for half an hour. It has properties very similar to its lower homologue “ mus-tard gas,” except that apparently it has no vesicant action (Found, C1= 38.10.C,H,,Cl,S requires C1= 37.90 per cent.). When heated with alcoholic potassium hydroxide solution the chlorine is displaced quantitatively with the production of the dihydroxy-compound. Oxidation of P13f-DichZorodCn-propyl Sulphide. When added to an excess of nitric acid (D 1-4) oxidation took place smoothly and a clear solution was obtained. On leaving for twenty-four hours and diluting a heavy viscid oil separated which from its solubility in concentrated acid and insolubility on dilution appeared to be the sulphoxide (compare Davies T. 1920 117, 299). In the hope t,hat some crystalline compound might be obtained this oil was heated for some time a t 100° with more con-centrated nitric acid. A rather vigorous oxidation took place and on dilution a little oil ssparated; on concentrating the clear solu-tion a solid melting at.10Q-102° crystallised which was in all probability the corresponding sulphone. Another product of the reaction was sulphuric acid showing that under these conditions BPI-dichlorodi-n-propyl sulphide is corn-pletely decomposed. ADDENDUM. Since these results were obtained a paper by Conant Hartshorn, and Richardson ( J . -47nw. Chent. Soc. 1920 42 485) has appearzd, VOL. CXIX. i n which it is shown that t,he production of PB’-dichlorodiethyl sul-phide involves two reactions. An intermediate product, CH,Cl=CH,*SCl has been obtained from ethylene and sulphur dichloride which evolves hydrogen chloride very easily and when warmed with sulphur gives a black tar. In the case of sulphur monochloride a similar product is obtained and unless the sulphur is crystallised from the colloidal solution after the reaction a black tar (CH,Cl*CH,),S, is formed. The results given in this paper are in agreement with those described above and probabIy a similar series of reactions takes place in. the case of propylene to some extent but flD’-dichlorodi-n-propyl sulphide has not yet been detected. The author desires to express his indebtedness to Professor F. 5. THE CHEMICAL DEPARTMENT, Kipping F.R.X. for his interest in and criticisms of this work. UNIVERSITY COLLEGE, NOTTINUHAM. [Received December 9th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900094

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

98 xI.-2 4 6- ~~init.rotolyl.methylnitr.oamine. By OSCAR LISLE BRIDY and WILLIAM HOWIESON GIBSON. TRINITROTOLYLMETHYLNITROAMINE has been described by Blanksma (Rec. trav. chim. 1902 21 327) who prepared it by the nitration of 2 4 6-trinitromethyl-m-toluidine obtained by the action of methylamine on 2 4 6-trinitro-nt-tolyl methyl ether. The prepara-tion of this compound from 2 3 4- and 3 4 6-trinitrotoluenes has now been studied. In 2 3 4- and 3 4 6-trinitrotoluenes one of the nitro-groups is mobile and is readily displaced by treatment with amines. In the case of the latter compound Hepp (Annalen 1882 215 344) showed that it was the 3-nitro-group that was displaced. In the case of 3 4 6-trinitrotoluene it has been shown that the dinitro-toluidine obtained by the action of ammonia is the same as that obtained as the main product in the nitration of aceto-m-toluidide (Cook and Brady T.1920 117 751) and the synthesis of 2:4:6-trinitrotolylmethylnitroamine from 3 4 6-trinitrotoluene confirms the fact that the 3-nitro-group is also the mobile one in this com-pound. These trinitrotoluenes accordingly follow the rule given by Meldola (T. 1908 93 1659) for the mobility of groups in negatively substituted benzene derivatives 2 4 6-TRINITROTOLYLMETIIYLNITROAMINE. 99 When 2 3 4- and 3 4 6-trinitrotoluenes are treated with methyl-amine or dimethylamine the corresponding dinitromethyl-m-tolu-idines and dinitrodimethyl-m-toluidines are formed all of which form 2 4 6-trinitrotolylmethylnitroamine on nitration.In the case of the dinitromethyl-nt-toluidiues the first action of the nitrating acid apparently consists in the formation of a dinitro-nitroamine more energetic nitration resulting in a further nitro-group entering the ring. It has not been found possible to obtain 2 4 6-trinitromethyl-m-toluidine by direct nitration of either 2 4- or 4 6-dinitromethyl-nz-toluidine but it has been prepared by denitration of the nitroamine. In the case of the dinitrodimethyl-m-toluidines the intermediate trinitrodimethyltoluidine has not been obtained; these compounds are not acted on by nitric acid of density 1.4 and are completely nitrated with the elimination of a methyl group by nitric acid of density 1.5 or by a mixture of nitric and sulphuric acids. The reactions are summarisecl on p.100. E X P E R I M E N T A L . 2 3 4- and 3 4 6-Trinitrotoluenes.-T?.e nitration of m-nitro-tcluene is described by Hepp (Zoc. cit.). A mixture of 2 3 4- and 3 4 6-trinitrotoluenes is obtained and Drew ('I?. 1920 117 1615) has shown that about 7 per cent. of 2 :3 6-trinitrotoluene is also produced. Hepp separated the 2 3 4- aud 3 4 6-compounds by crystallisation from carbon disulphide. A more convenient method of preparation and separation than that described by Hepp is as follows. A mixture of 160 C.C. of nitric acid (D 1.42) and 340 C.C. of sul-phuric acid (96 per cent.) is added in small portions a t a time to 225 grams of m-nitrotoluene the temperature being kept in the neighbourhood of 50°. When all the acid has been added the mix-ture is slowly heated to looo on the water-bath and kept at this temperature for thirty minutes with frequent shaking.The mixture is then allowed to cool to 50° and separated. The oil is added slowly to a mixture of 180 C.C. of nitric acid (D 1.5) and 410 C.C. of sulphuric acid (96 per cent.). The mixture is warmed to 70° and kept a t that temperature for thirty minutes with frequent shaking, and then cautiously heated t o looo a t which temperature it is kept for one hour. 'The oil is separated from the acid while still hot run into cold water and washed by tshe injection of steam until free from acid. On cooling and keeping the oil sets to a pasty solid, which is collected and dissolved in boiling alcohol (about 100 C.C. of 95 per cent.spirit for 1 2 grams of the mixture). The solution is cooled to about 50° and seeded with a little pure 3:4:6-trinitro-E 100 I BRADY AND GIBSON : q g z x w I I 0"S 0 2 4 6-TRINITROTOLYLMETHYLNITROAMINE. 101 toluene and shaken vigorously. After two to three minutes a fair quantity of solid will have separated in the form of sandy crystals, which are a t once collected. The filtrate is precipitated with water, and the solid after being freed as much as possible from water by pressing dissolved in boiling glacial acetic acid (about 100 C.C. of acid for 50 grams of solid). The solution is cooled to about 60° a very small quantity of water added and a crystal or so of 2 3 4-trinitrotoluene. When a small quantity of solid has separated this is filtered off rapidly.The filtrate is diluted with water and the solid again crystallised from alcohol and so on. Some little experi-ence is required ,to judge the amount of solid which should be allowed to separate from the alcohol and acetic acid before filtering. The solid separating from alcohol should consist of sandy crystals (if fine needles separate the solution has been cooled too much and must be re-heated) which should melt not lower than 9 7 O and the solid from acetic acid not lower than 104O. With these limits fairly large crops of crystals can be obtained and the process is not unduly prolonged. The crops from alcohol are combined and crystallised from alcohol when 3 4 6-trinitrotoluene is obtained pure. The crops from acetic acid are again crystallised from-acetic acid and then from alcohol when 2 3 4-trinitrotoluene is obtained.In these final crystallisations the solutions may be allowed to become quite cold. In one experiment two portions of 225 grams of m-nitrotoluene were nitratad ; 620 grams of mixed trinitrotoluenes were obtained (84 per cent.).. Three crystallisations from alcohol and three from acetic acid followed by one crystallisation of the combined crops from alcohol and from acetic acid and alcohol respectively yielded 200 grams of pure 3 4 6-trinitrotoluene and 100 grams of pure 2 3 4-trinitrotoluene. 2 ; 4-Binitromethyl-m-toluidine.-Twenty grams of 2 3 4-trinitro-toluene are dissolved in 250 C.C. of hot alcohol and a solution of 7 grams of methylamine hydrochloride in a small quantity of water is added followed by 12 C.C.of ammonium hydroxide (D 0.880) drop by drop. As the ammonia is added the liquid darkens but rapidly turns to a clear orange colour. The mixture is then boiled for a few minutes cooled and water added cautiously until crystallisa-tion begins. The solid is washed with water to remove ammonium chloride and crpstallised from alcohol when 2 4dinitromethyl-m-toluidine separates in long flat orange needles melting a t 81°, readily soluble in hot and sparingly so in cold alcohol (Found, N = 19.7. 4 6-DinitrometI~yl-m-toluicZine.-'T'he preparation is the same as that of the above compound substituting 3 4 6-trinitrotolnene. C,H,O,N requires N = 19.9 per cent.) 102 RRADY AND GIBSON: Soon after the addition of the first drops of ammonia the compound begins to separate and the addition of water during cooling is unnecessary.4 6-Dl'nitromethyl-m- toluidine crystallises from boil-ing alcohol in which it is sparingly soluble in yellow needles melt-ing a t 1 7 3 O (Found N=20.0. C,H,O,N requires N=19.9 per cent.). This compound is possibly the same as that described by Wurster and Riedel (Ber. 1879 12 1800) who obtained it by the nitration of dimethyl-m-toluidine and found its melting point to be 168O. They regarded it however as a dimethyl derivative. 2 4-Dinitrodimetlzyl-m-tollticli?te,-Twenty grams of 2 3 4-tri-nitrotoluene in 250 C.C. of boiling alcohol are treated with 9 grams of dimethylamine hydrochloride and 1% C.C. of ammonium hydr-oxide. The mixture is diluted with two to three times its bulk of water and extracted with ether.Aft,er evaporating the dried ethereal extract 2 4-dinitrodimethyl-m-toluidine remained as an orange uncrystallisable oil. 4 6-Dinitrodimethyl-m-toluidine.-Ten grams of 3 4 6-trinitro-toluene in 100 C.C. of boiling alcohol are treated with 4.5 grams of dimethylamine hydrochloride and 6 C.C. of ammonium hydroxide. 'The mixture is cooled diluted slightly with water and the solid which separates crystallised from alcohol. 4 6-Dinitrodimethyl-m,-toluidine separates in yellow needles melting a t 107O more readily scluble i n organic solvents than the corresponding monomethyl derivative. This compound has been prepared by Wurster and Riedel (loc. c i t . ) by the nitration of dimethyl-m-toluidine in acetic acid solution.2 4 6-Trinitrotolylmethylnitroomine.-For the preparation of this compound 2 4- or 4 6-dinitro-methyl- or dimethyl-m-toluidines may be employed or a mixture of these obtained by the action of cIiide methylamine hydrochloride containing dimethylamine on a mixture of 2 3 4- and 3 4 6-trinitrotoluenes. Forty grams of the compound are added in small quantities a t a time t o 100 C.C. of nitric acid (D 1.5) warmed to 50°. Copious red fumes are evolved. particularly when dimethyl derivatives are present and when all the solid has been added the mixture is heated on the water-bath until the evolution of nitrous fumes ceases. The mixture is then cooled and water added when tri~iitrotolylmethylnitroamine sepa-rates out usually as an oil which solidifies on keeping.The solid is washed thoroughly and crystallised from alcohol to which a few drops of acetic acid have been added or from a mixture of alcohol and benzene. Trinitrotolylmethylnitroamine has a remarkable tendency to separate froin solvents in an oily condition and con-siderable difficulty is generally experienced in crystallising it. When the solid is fused it supercools t o a viscid mass in whic 2 4 6-TRINITROTOLYLMETHYLNITROAMINE. 103 crystallisation is very slow extending over months. Further in the presence of alcohol it is very sensitive to alkalis much more s3 than trinitrophenylmethylnitroamine and when crystallised from alcohol in glass vessels sufficient alkali is introduced to impart a faint violet tinge to the product.The addition of hard water to an alcoholic solution produces a marked colour in the product which crystallises out. 4 6-DinitrotoE~lmethylnitroarnine.-Five grams of 2 4dinitro-methyl-m-toluidine are added to 50 C.C. of nitric acid (D 1.42) warmed to 50°. The mixture is kept a t 50° for five minutes and then filtered while hot through glass-wool 20 C.C. of water are added and the whole is cooled when the nitroamine separates out. 4 6-Dinitrotolylmethyln~troamine crystallises from acetone or water in yellow plates melting and decomposing at 157O (Found, N = 21% C,H,O,N requires N = 21.9 per cent.). This compound on further nitration with fuming nitric acid yields trinitrotolyl-niethylnitroamine. The nitro-group attached t o nitrogen is removed by heating 1 gram with a solution of 0.5 gram of phenol in 20 C.C.of 80 per cent. sulphuric acid on the steam-bath for thirty minutes. The colour of the solution changes through blue to violet and finally brown. After cooIing the mixture is poured into water, the solid which separates washed with ammonia and crystallised from acetone and alcohol with the addition of animal charcoal, when 4 6-dinitromethyl-m-toluidine is obtained and identified by the method of mixed melting points. 2 4-Binitrotoliylrnethylnitroamin e.-This compound is prepared in a similar manner t o the above from 2 4-dinitromethyl-m-tolu-icline and crystallises from alcohol in very pale yellow needles melting a t 1 1 1 O (Found N=21*8. C,H,O,N requires N=21*9 per cent.). On further nitration with fuming nitric acid it also yields 2 4 6-trinitr~tolylmethylnitroamine but when treated with phenol and sulphuric acid 2 4 6-ti-initrornethyl-~n-toluidine is obtained and not 2 4-dinitromethyl-m-toluidine as would be expected.The possibility of this substance being 2 4 6-trinitrotolylmethyl-nitrosoamine was eliminated by the preparation of this compound, which was found t o be qnite distinct. Apparently the nitro-group in 2 4-dinitrotolylmethylnitroainine migrates to the ring so readily in the presence of sulphuric acid owing t o the para-position being free that this reaction takes place in preference t o the nitration of the phenol by the nitroamino-group. 2 4 6-trinitromethyl-m-t oluidine are suspended in 50 C.C. of glacial acetic acid and 30 C.C.of a 20 per cent. solution of nitrogen peroxide in 2 4 6-Trinitrotolylmet?~ylnitrosoamine.-Six grams o 104 2 4 6-TRTNTTROTOLYLMETHYLNITROABTTNE. acetic acid added. The mixture becomes slightly warm and the solid dissolves completely. Water is gradually added with thorough shaking when a buff granular precipitate is formed which is crystallised from alcohol. 2 4 6-T~initrotoZyZn~,.,tlr3/lnitrosoaminc crystallises in pale buff sandy crystals melting a t 120° (Found, N = 24.8. 2 4-Dinitrotolylmeth~lnitrosoamine and 4 6-Dinitrotolylmethyl-nitrosoamine .-These compounds are prepared in a similar manner to the above from 2 4- and 4 6-dinitromethyl-m-toluidine respec-tively. 2 4-Dinitrotolylmethylnitrosoamine crystallises from alcohol in colourless needles melting a t 65O (Found N=23-5.C,H,O,N requires N = 23.3 per cent.). 4 6-Dinitroto7yZmethyZ-nitrosoamine crystallises from alcohol in brilliant yellow needles melting a t 9 4 O (Found N=23*6. C,H,O,N requires N=23-3 per 2 4 6-Trinitromethyl-m-toluidine.-Lt was not found possible to regulate the conditions of nitration of the dinitromethyl-m-tolu-idines so as to obtain this coinpound directly. It may however be prepared from these compounds by nitrating them first to trinitro-tolylmethylnitroamine and removing the nitro-group attached t o the nitrogen atom. Five grams of the nitroamine are added in small portions a t a time to a solution of 4 grams of phenol in 50 C.C. of 80 per cent. sulphuric acid at 50° and the temperature is cautiously raised t o 90°. After heating a t 90° for thirty minutes the product is treated as in the deliitration of 4:6-dinitrotolyl-methylnitroarnine (see above) and the 2 4 6-trinitromethyl-m-toluidine crystallised from a mixture of acetone and alcohol. This compound is identical with that obtained by Blanksma (loc. cit.) by the action of methylamine on 2 4 6-trinitrotolyl methyl ether. The authors wish to express their thanks t o the Director of Artillery for perinission to publish these results. C,H,O,N requires N = 24.6 per cent.). cent .) . RESEARCH DEPARTMENT, ROYAL ARSENAL, WOOLWICH. [Received December 8th 1920

ISSN:0368-1645    

DOI:10.1039/CT9211900098

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

KNAGGS AND VERNON; ORGANIC DERIVATIVES OF TELLURIUM. 106 XIL- Organic Deu.izwtives of Tellurium. Part 111. Crystallographic and Pharmacological Comparison of the a- ccnd P-Lbimethyltelluronium Dihdoids. By ISABEL ELLIE KNAGGS and RICHARD HENRY VERNON. OF the six dimethyltelluro~nium dihaloids the two iodides were the most suitable for crystallographic investigation which was carried out by one of us (I.E.K.) in the Mineralogical Depart-ment under the direction of Mr. A. Hutchinson. a- or (( trans "-Dimetityltelluronium Di-iodide '>Te<Ye. Me This was prepared in the usual manner and t'hhe la,rrge crystals Crystal System.-Monoclinic. Class hdohedral. Axial angle = from chlorsfolrm or benzene were examined. 72O21'. Axial ratio a b c = 0.5578 1 0.4310. No.of measure-Angle measured. ments. A c = (100) (001) 2 w :A' = (201) (loo) 3 B m' = (010) (120) 18 C k' = (001) (201) 6 B m'' = (010) (130) 7 B la = (010):(110) 14 B p = (010):(011) 8 B t = (010) (021) 6 c m = (001) (110) 5 c o = (001) (111) 5 B o = (010) (111) 9 q :n' = (011) (121) 2 n' m = ( i 2 1 ) ( i i o ) 2 A o = (100):(111) 2 q :o' = (911) (111) 2 Ic' m' = (201) (Z20) 21. o :Q = (111) (011) 8 m' n' = (120) (121) 13 n' k' = (121) (201) 13 G :n' = (001) (121) 1 B n' = (010) (i21) 3 n' :o' = (z.21) (ill) 2 m k' = (110) (201) 3 Limits. 72'21' -72'214' 70'2' -70'14' 37'26' -37'34' 32'34' -32'27' 4 3' 10' -4 3'2 4' 61'48' -62'104' 67'17' -67'44' 50'30' -50'46' 74'28' -74'31' 34' 19' -34'22' 73'58~'-74'10~' 40'26' -40'33' 53'29' -53'31' 29'31' -29'52' 44'3' 40°35~'-40047' 44'41' -45'0' 56"29~'-57'14' 78'1' -78'22' 55'18' 52'19' -52'24' 16'33' 45'289'-46'35' Mean served.72'21' 70'9' 37'30' 32'12' 43'16' 62'2' 67'39' 50'37' 74'30' 34'20' 74O5' 40'31' 63'30' 44O3' 29'45' 40'4 1' 78'9' 44'51' ob-57'3' 55'18' 52'22' 16'33' 45'33' Celcu- Differ-lated. ence. 72'2 1' 0' * -* -* - 32'6' 6' 62'1' 1' 67'39' 0' ; p k ' if' 34'21' 1' 7 4' 3' 2' 40'31' 0' 53'27' 3' 43'56' 7' 29'47' 2' 400374' 78'10' P' 44'50' 1' 57'0' 3' 65' 14' 4' 52'16' 6' 16'34' 1' 45'31' 2' E 106 KNAGGS AND VERNON: Habit.-Short prismatic terminated a t either end by a large macrodame Ic and by a variable number of smaller domesi and pyramids (Fig.1). Cleavage .-None observed. Specific Gravity.-Determined by weighing in water D :" 3.335 Topic Axes.-x It/ w = 4.537 8.133 3.506. Optical Characters.-Refractive index high. By immersion metlhold greater than 1-74. On looking through a crystal perpen-dicular to B strong pleochroism was olbserved the colour changing from light red to very dark red. The maximum absorption of light takes place for vibrations parallel to the extinctioln direction, which makes an angle of 4J0 with the vertical axis 2 in the acute axial angle. It was not possible to obtain an optic picture in convergent light owing to the great absorption. (corrected). I Me /3- cr '( cis "-Uin~ethyltelluronium Di-iodide I>Te<Me* This was prepared from the P-base and crystallised from methyl alcohol.The crystals examined were small but well defined. I n reflected light' they had a black metallic lustre. Crystal System-Monoclinic. Class hobhedral. Axial angle = 76O52'. Axial ratio a b c = 0.5465 1 0.4222. Forms 0 bserved. A = {loo} B = {OIO} C = { O O l } m = (IlO} q = {OII}, 0' = (Ti I} n' = (T21). Table of Angles. No. of measure-Angle measured. ments. A c = (100) (001) 7 B m = (010) (110) 18 c q = (001) (011) 9 Q :n' = (011) (121) 5 n' m = ( i 2 1 ) (110) 5 C :n' = (001) (121) 6 B n' = (010) (121) 18 n' :o' = ( i z i ) (i11) 8 A :n' = (loo) (12i) ti Limits. 76'50' -77'31' 22'54' -22'34' 38°23~'-39020' 51'6 ' -51'25' 52'53' -53'59' 53'21' -53'478' 15°55~'-16010' 67'2' -67'1 4' 61048' -6208~ Mean served.77'16' 61'59' 22' 18' 38'55' 51'15' 63'27' ob-53'37' 16'26' 67'74' Caleu-lated. 76'52' 22'21' * 3 9 y 53'31' 16'SY 66'50' * Differ-ence. 24' 3' 134' 4' 6' 174' ---The habitl is characterised by the small development of the prism faces nz(llO} and by tlie large development of the form n'( 1 2 1 }. Faces of the forms C{OOl} o f { T l l } and some small dome faces are also present (Fig. 2) ORGANIC DERIVATIVES OF TELLURIUM. PART III. 107 Had the j3-crystals alone been under coasideration it would ham been natural to regard the faces of the forms {Tal} and ( i l l } as prisms having indices (120) and (110) respectively. In order, however to bring out the relationship which exists between the a- and &crystals it was found necessary to adopt the orientation given above.Cleavage.-None observed. Specific Gravity .-Determined by weighing in water Di4 = 3.305 Tcpic Axes.-x $ to =4*488 8.214 3.468. Optical Characters.-Refractive index high ; as found by the Absorption very high the Observations as t o the pleochroism, (corrected). immersion method greater than 1-74. crystals being nearly opaque. FIG. 1. FIG. 2. 0 a-Di-iodide. p-Di-iodide. therefore could not be made nor could an optic picture be obtained in convergent light. The chief feature of.intersst in this investigation is a comparison between the two crystals (Figs. 1 and 2). Although a t first sight the crystals appear very different this is due entirely to difference of habit.In reality a large number of forms { O O l ) (0111 {110) { O l O } {TZl) are common to1 each substance and the angles in the prominent zones and the axial ratios show striking similarity. This is most marked in the zones [010,110] [010,011] in which the angles are almost identical and the divergence is greatest in the z o m parallel to! the diad axis of symmetry the acute axial angles differing by as much as 48 degrees. The close similarity of form also finds expression in the topic axes, the values of x and w for the P-compound being slightly less and that of 3 slightly greater thsii is {he case for the a-compoand. The difference of habit is mainly due to the large development E* 108 KNAGOS AND VERNON ORGANIC DERIVATIVES OF TELLURIUM.of 74201) in the a-compound and its absence in the P-colmpound, in which m t ( 1 2 1 } plays a prominent part. The similarity of the two forms is sol close1 that they stand to one another much in the same relation as the members of an isomorphous series. The small size olf the crystals their opacity, and high refractive index have precluded a detailed comparison cjd their optical properties nor has it been found possible to prepare mixed crystals containing both compounds. I n marked contrast to the similarity in crystalline structure of the a- and P-iodides is the totally diffelrent physiological behaviour of the a-haloids as compared to the corresponding B ones. m e iodides were notl used €or the pharmacological investigation, as they are insoluble in water but the chloridels and bromides were eminently suitable for this purpose.Dr. W. E. Dixon who is still investigating these substances and will shortly publish a full statement of his results in an appropriate journal has kindly sent the following note: “ Both these organic compounc!s of tellurium when taken into the animal boldy are excreted from the lungs as diiiiethyl telluride, a substance which elxerts little physiological actioa apart from its odoar. ‘(Before this change occurs in the body the a- and p-compounds exert specific actions of an entirely different nature. The former slows and weakens the heart and the bloojd-pressure falls. It also1 stimulates plain muscle particularly that of the uterus and intestine t o increased activity. system is almost negligible. “The P-compound has the most profound stimulant action on the medulla giving rise t o an increase of blood-pressure and increasing the depth and rapidity of respiration. Generally before the bloold-pressure has reached the normal again a second rise occurs; this is due t o the liberation oif adrenalin from the supra-renal glands upon which the &compound exerts a unique and specific effect not comparable with that produced by any other knolwn chemical. Large dosea of the ,&compound such as 60 milli-grams to a cat paralyse the whole nervous system-brain spinal cord and motor nerves.” Its action on the central nervou UNIVERSITY CHEMICAL LABORATORY, CAMBRIDGE. [Rcceivcd December 17th 1930.

ISSN:0368-1645    

DOI:10.1039/CT9211900105

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

THE R6LE O F PROTECTIVE COLLOIDS IN CATALYSIS. 109 XHL-I’he R81e of Protective Colloids in Catalysis. Part I. By THOMAS IREDALE. TEE effect of protective colloids in inhibiting the catalytic decom-position of hydrogen peroxide by colloidal platinum has already been noted by Gr6h (Zeitsch. physikal. Chem. 1914 88 414) who found that they appeared to follow the order of Zsigmondy’s “gold number ” series (Zeitsch. anal. Chem. 1901 40 697; ‘( Colloids and the Ultramicroscope,” 1914 79) in their activity in this respect. It appeared desirable however to extend investigations in this direction as the experimental results obtained by Gr6h were too few to permit of a general statement as to the relative effects of different protective colloids. A number of these colloids have now been examined in this regard and it has been found that in general the stronger a substance is as a protective colloid the greater will be its inhibition of catalytic activity and that a sub-stance like sucrose which is without protective effect is likewise without inhibitive effect.Now in view of the circumstances in which the protective colloids are examined in the two cases-Zsigmondy’s coagulation method and Gr6h’s cat,alytic method-there is nothing altogether surprising in these results. From superficial considerations they might almost be anticipated and the author was inclined t o believe that they might throw considerable light not only on the mechanism of pro-tective action but also on the processes involved in the hydrogen peroxide decomposition Unfortunately owing to war conditions, Gr6h’s paper itself was not available and the author had to be content with abstracts (A.1915 ii 239; Chem. Abstracts 1915 7). From these it does not appear that Gr6h advanced any thorough argument to account for his results but be seems to have en-deavoured to obtain a relation between the gold number of protec-tive colloids and the extent of their inhibitive effect the significance of which seems a t present a little obscure. It is necessary to examine the analogy more thoroughly. In this coiinexion mme recent remarks made by workers in this field are of interest. Bailcroft ( J . Physical Chem. 1917 21 775) considers that a substance like gelatin may increase the degree of dispersity of the catalyst thus exposing a larger surface with increased cata-lytic activity but that this effect may be more than counter-balanced by the presence of the gelatin itself which hinders th 110 IREDALE THE R ~ L E OF adsorption of the hydrogcn j)eroxicie.There is no evidence that protective colloids increase the degree of dispersity of a metal sol already formed and in view of Rusznyak’s work (Zeitsch. physikal. C‘hem. 1913 85 681) on the decreased catalytic activity with imreased dispersity Bancrcft’s argument seems scarcely reason-able. Rideal ( J . Amer. Chem. Soc. 1930 42 749) considers that diffu-sicn is the chief factor concerned in the rate of decomposition of hydrogen peroxide and argues against the idea of a colloidcom-plex formation. If this is the case why should a strong protective colloid inhibit.to a greater extent than a weak one? What part, can diffusion play in the ordinary method of measuring the value of protective colloids as announced by Zsigmondy? The change from red t o blue in the colour of gold sols is assumed to be due to a union of the gold particles after their charges have been neutralised by the adsorption of certain ions. Protective colloids may hinder this change for one or other of two reasons. It may be that after the neutralisatim of their charges the gold particles are prevented from uniting owing to the presence of the protective colloid. On this theory it is difficult to see where the analogy exists in the case of the catalytic process. I f we assume however that the protective cdloid hinders the adsorptioii of the ions that would bring about the coagulation then the analogy is quite complete.The rate of decomposition of hydrogen peroxide is probably determined by a number of factors of which adsorption is undoubtedly one of the chief. Anything which hinders the adsorption of the hydrogen per-oxide by the catalyst will retard t,he velocity of reaction as measured in the usual way and a strong protective colloid which hinders the adsorption of ions better than a weak one may also hinder the adsorption of the hydrogen peroxide more efficiently. It remains to be seen however if the gold number is really expressive of these relations. Zsigmondy (“ Colloids and the Ultramicroscope,” 1914 150) has endeavoured to follow the mechanism of protective action under the ultramicroscope.The assumed union of the gold and gelatin ultra-microns is followed by decreased mobility in the former except a t a certain concentration of gelatin below which there does not seem to be any retardation in the movements of the gold particles. It will be seen later that the inhibitive effect of gelatin is noticeable a t much lower concentrations than the critical one mentioned by Zsigmondy and this inhibition cannot be due therefore to any decreased motility in the particles of the catalyst. As far as the Brownian movement is concerned however the part played by it4 in the catalysis is still somewhat obscure PROTECTIVE COLLOIDS M CATALYSIS. PART I. 111 Bredig (Zeitsch. physikab. Clhem. 1901 37 14) has shown that the adsorption of poisons by the catalyst follows the logarithmic law and it was anticipated that the adsorption of protective col-loids might also obey the same law.From results obtained with gelatin a t very low concentrations it appears that the process is more complicated than a simple calculation can possibly account for owing t o the continual subdivision of the gelatin ultramicrons over a certain range of dilution. T’he results of experiments on the poisoning of protected metals ~ i l i be made available in a later communication. E x P E R I M E N T A L . The hydrogen peroxide used in all these experiments was care-fully purified by distillation under diminished pressure. The col-loidal platinum solutions were prepared by Bredig’s method using a current of 110 volts and 10-12 amperes the temperature of the water being kept below 25O.Solutions made by this method may bc diluted to the extent desired and after allowing the larger par-ticles to settle may be used directly without filtering. They appear, however to be much more sensitive than filtered ones and cannot be used for very exact work where it is desired to follow the course of a reaction with the maximum of accuracy. The velocity constant falls slightly during the reaction instead of rising as is usually the case. The solutions of protective colloids were prepared by simple dis-solution of the materials in water adopting the usual procedure for gelatin and starch. I n the case of gum tragacanth and egg-albu-min which gives extremely turbid solutions a known weight of material was dissolved as much as possible in water and the amount of undissolved matter ascertained after filtration.With a know-ledge of the weight of substance in the filtrate it could then be diluted to the concentration required. T’he concentration of protec-ive colloids when first prepared was 0.04 per cent. and lower concentrations were obtained merely by dilution from this strength. The initial concentration of the hydrogen peroxide in all the experiments was 21.1 / 40. The concentration of the platinum solutions was the same throughout any one series. All the reactions were carried out a t 25O and in every instance the plat,inum solutions on admixture with the protective colloids were allowed to remain for fifteen minutes a t the temperature of the experiment before the addition of the hydrogen peroxide.At different intervals 10 C.C. of the reaction mixture were titrated, after addition to dilute sulphuric acid with standard permanganat 112 IREDALE TI-IE R ~ L E OF (about J / 4 0 ) . It was not i'ound necessary t o apply a correctic to the titrations for organic matter present as the concentration ( thc latter was apparently too small to affect the results. The velocity constant was calculated from the usual formuIa : k = 0.4343 k = - 1 loglo- a t a-x ( t in minutes and a-x in terms of C.C. of potassium permar ganate). The values of k given in the tables are the progressive one obtained durizig any reaction and the mean of these in each cas gives the same result on comparison as the time for 50 per cenl decomposition.The ratio value3 were calculated by taking the velocity constan wit,h unprotected metal as unity. TABLE I. Protective Colloid Preparations Six Days Old. Series. Protective colloid. k. Mean. Rat'io. - I. none ... .. ............... 0.026 0.023 0.023 0-024 1 0.01 yo gelatin ... .. .... 0.0043 0.0043 0.0044 0.0043 0.17 , glue ............ 0.0046 0.0043 0.0041 0.0043 0.17 , egg-albumin . 0,0055 0.0052 0-0050 0-0052 0.23 , gum arabic ... 0.014 0.012 0.012 0.013 0.54 , sucrose ...... 0-027 0.025 0.025 0-025 1 11. none ..................... 0.039 0.038 0.037 0.038 1 0.001% gelatin ... ... 0-0074 0.0082 0.0078 0-0078 0-20 , egg-albumin 0.013 0.012 0.012 0.012 0.32 , gum arabic. 0.032 0.031 0.031 0.031 0.82 , sucrose . ..... 0.038 0-036 0.036 0.037 1 , glue ......... 0.0080 0.0078 0.0077 0.0078 0-20 TABLE 11. Preparations One Day Old. Series. Protective colloid. k. Mean. Ratio. - I. none ..................... 0.057 0.052 0.056 0.055 1 O.Olyo gelatin ......... 0-0058 0-0061 0.0060 0-0059 0 . 2 2 , glue ............ 0-0071 0.0073 0-0071 0.0072 0.13 , egg-albumin. 0.0093 0-0095 0.0094 0-0094 0-17 , gum arabic ... 0-037 0.035 0.034 0.035 0.64 11. none .......... .. ....._. ... 0.025 0.024 0-025 0.025 1 0.001% gelatin ... ... 0.0044 0.0043 0.0045 0.0044 0.18 , glue ............ 0-0055 0.0059 0-0053 0.0056 0-22 , egg-albumin . 0-0068 0.0072 0.0071 0.0070 0.28 , gum arsbic ... 0.020 0.021 0.020 0.020 0.8 PROTECTIVE COLLOIDS IN CATALYSIS. PART I. 113 From these results it is evident that the inhibitive effect is in the order gelatin and glue>egg-a1bumin)gum arabio>sucrose, which does not appear to affect the reaction a t all.Tbis order is also followed in Zsigmondy’s coagulation experi-ments but the author has n o t been able to discover any exact rela-tionship between the gold numbers of these colloids and their inhibitive activity as indicated in the ratio table. Subsequent determinations of the gold number by the usual method (Zsigmondy loc. c i t . ) gave values of 0.006 and 0.008 for the samples of gelatin used and 0.2 for gum arabic so that the author was not working with materials showing any great anomalies in this respect. The gold numbers seem therefore to be only a useful guide to enable one to predict the probable order of inhibitive activity.The protective colloids are themselves without appreciable action on hydrogen peroxide. Eredig (Zeitsch. physilcal. Chem. 1899 31, 342) showed this in the case of gelatin and it has been found that the stability of a hydrogen peroxide solution is not appreciably affected by tha addition of protective colloids of the concentrations indicated irr any of these tables. The extent of the inhibition produced by some of the weaker protective colloids is shown in the following table: TABLE 111. Preparations Two Days Old, Series. Protective colloid. 1. none ......................... 0.01 % gum tragacanth , dextrin ............ , starch ............. , gun arabic ...... 11. none .......................... O * O l ~ o egg-albumin ...... , tragacanth ........111. none ........................ 0.001 % egg-albumin ... , tragacanth ...... IV. none ........................ 0.01 yo sodium oleate ... o*Oo5~0 , Y ? ... o.Ooly0 , 9 7 * * a 0.0025% , ? ? k. 7-0.080 0.083 0-086 0.030 0.029 0.027 0.032 0.031 0.030 0.042 0.042 0.040 0.044 0-044 0.040 0.017 0.018 0-018 0.0036 0.0038 0.0039 0.0078 0.0074 0.0073 0.017 0.018 0.019 0.0057 0.0058 0.0056 0.012 0-013 0-013 0.017 0.018 0.019 0.021 0.023 0.023 0-0130 0.0130 0.0132 0.0127 0.0129 0-0127 0.0150 0.0152 0.0151 Mean. Puatio. 0.083 1 0.025 0.34 0.031 0.37 0.041 0.50 0-043 0.52 0.018 1 0-0038 0.22 0.0075 0.42 0.018 1 0.0057 0.32 0.013 0.72 0.018 -0.023 -0.0130 -0.0128 -0.0151 -From these results it is evident that tragacanth inhibits to a less est,ent’ thau egg-albuniin but is somewhat more effective than dextrin which is inore effective than starch and gum arabic 114 THE RbLE OF PROTECTIVE COLLOIDS IN CATALYSIS.Sodium oleat,e behaves abnormally as it must be completely hydrolysed at these low coiicentrations and the velocity constant will rise owing to the presence of hydroxyl ions. It is interesting t o observe however that on dilution from 0.01 per cent. concentra-tion the protective effect of the soap begins to dominate the situa-tion and the velocity constant therefore falls but rises again on further dilution of the protective colloid. This observation is of great importance as it shows that the protective action of soaps on gold sols is not due to the stabilising effect of the hydroxyl ions alone-the concentration of the latter in a 0.01 per cent.sodium oleate solution could not be greater than N / 3000-but more prob-ably in greater part to the acid-soap residue which is more complex, perhaps than is generally realised. Gelatin appears to be active as an inhibitor a t extremely low concentrations. With a platinum solution of medium concentra-tion (about 1 /30,000 gram-atoms per litre) the following results were obtained : TABLE IV. Series. Protective colloid. k. Mean. I. none ..................... 0.005% gelatin ...... 0.001 % , ...... 0*0001 yo , ...... 0.00005y0 , ...... 0~00001 yo , ...... 0*000005~0 , ...... 0 ~ 0 0 0 0 0 1 ~ , ...... 11. none ..................... 0.001% gelatin ......0.000 1 % , ...... 0.00005% , ...... 0~0000 1 % , ...... 0.000005% , ...... 0*000001% , ...... 0:0148 0-0152 0.0151 0.0154 0.0028 0.0026 0.0026 0.0027 0.0032 0.0032 0.0031 0.0029 0.0045 0.0044 0.0041 0.0040 0.0050 0.0049 0-0050 0.0051 0.0105 0.0108 0.0108 0.0108 0.0137 0.0142 0.0141 0.0139 0.0149 0.014-8 0.0152 0.0154 0.0158 0.0161 0.0167 0.0162 0.0030 0.0032 0-0030 0.0029 0.0043 0.0039 0.0038 0-0038 0.0060 0.0047 0.0045 0.0047 0.0108 0.0110 0.0114 0.0117 0.0123 0-0123 0-0129 0.0133 0.0155 0.0156 0.0159 0.0160 0-0151 0.0027 0.003 I 0-0050 0.0107 0.0140 0.0151 0.0162 0.0030 0.0039 0.0048 0.0112 0.0127 0.0158 0.004.3 Series I and I1 were carried out with different samples of g cla tin.) The most striking fact about these results is the gradual rise of the velocity constant with diminishing gelatin concentrations down to 0*00005 per cent.and the rapid rise on further dilution of the protective colloid. Now Menz (Zeitsch. physikat. Ghem. 1909 66 129) found that the protective action of gelatin increased on dilution but the results were usually dependent on the mode of preparation of the original solution. It seems not improbable however that on diluting a gelatin solution of low concentration the larger gelatin ultra-microns split into smaller ones and these being more strongl YEAST CROPS AND THE FACTORS WHICH DETERMINE THEM. 116 adsorbed by the gold or platinum particles will partly make UP for the decreased concentration of the protective colloid.Hence the velocity constant will only rise very slowly until this subdivision process ceases when further dilution of the protective colloid will now bring about its more rapid elevation. Summary. (i) The inhibitive effect of protective colloids on the catalytic decpmposition of hydrogen peroxide by colloidal platinum has been examined in a number of instances. (ii) It has been found that the stronger a substance is as a pro-tective colloid the greater will be its inhibition of catalytic activity. (iii) I n the case of a strong protective colloid like gelatin the inhibitive effect is noticeable a t very great dilution for example, 0.000005 per cent. or one part in twenty million parts of water. (iv) The inhibition is explained on the ground of selective adsorption resulting in a decreased concentration of hydrogen peroxide a t the platinum surface and a consequent fall in the value of the velocity constant. (v) There is no precise relation between the gold numbers of protective colloids and the extent of their inhibition. (vi) The reaction may be used not only to detect adsorption effects but probably also changes in state of the protective colloid owing to the subdivision of its ultramicrons. I am indebted to the Committee on award of Science Research Scholarships in this State for a scholarship which has enabled me t o carry out this investigation. UNIVERBITY OB SYDNEY. CHEMICAL LABORATORY, [Received September 14th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900109

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

YEAST CROPS AND THE FACTORS WHICH DETERMINE THEM. 116 XIV.-Yeast Crops and the Factors which Determine them. BY ARTHUR SLATOR. MANY investigations have been carried out to determine the factors which influence the amount of yeast produced by growth in a suitable medium and much of the important earlier work on the subject is published in these Transactions. It has been shown i 116 SLATOR YEAST CROPS AND THE recent years that the growth of micro-organisms under simple conditions follows the exponential law of increase and equations expressing growth and fermentation have been worked out and experimentally verified. In this communication an attempt has been made t o express yeast crops in terms of generation-times and fermentative activity of the yeast and t o use such equations to test some of the generally accepted views on the subject.The reproduction of yeast in a medium such as malt wort takes place in definite phases. A period of quiescence (lag phase in growth) is iollowed by unrestricted growth (logarithmic phase in growth), which continues until retarding influences such as lack of necessary food or the production of toxins come into play. Growth finally ceases when these retarding influences become sufficiently great. Under the usual conditions of yeast growth and alcoholic fermenta-tion several factors play a part in limiting growth but a simple case where one factor only determines the total growth will be first discussed. Conditions can be so arranged that the sugar in the medium can be made this limiting factor.All other foods must be in large excess and substances toxic to growth must not be allowed to accumulate. The crop then admits of calculation in the following manner. It has been shown (Slator Bio-Chem. J. 1913 7 198) that during the logarithmic period of growth the ratio of the increase in the number of cells n to the amount of sugar s fermented is a where K is the constant of n constant and that this ratio - = -s F ' growth and F is the fermentative activity of the yeast. During later stages in growth K and F may not remain constant but at any given time they have definite values and the small increments in the yeast and sugar fermented are determined by the equation d n E We have therefore n= - ds + constant. Yeast crops (from a K small seeding) are therefore determined by the way this ratio E / F varies with different concentrations of sugar.A graphical method of calculation of such crops is shown in Fig. 1. The values of K and F are obtained experimentally and plotted against the cor-responding concentration of sugar. The K / F curve is then con-structed. The crop obtained during the complete fermentation of '' a" grams of sugar is represented by the area oabc. A curve can now be constructed showing yeast crops with various init'ial concentrations of sugar FACTORS WHICH DETERMINE THEM. 117 This theoretical curve should coincide with the experimental one as long as the sugar is the limiting factor determining the final crop. I n the case described in the experimental part of this paper the ratio E / F is almost constant and the crop is approxi-mately propmtional to the initial concentration of the sugar.This method of calculat,ing yeast crops is of general application, and a similar diagram can be constructed when other limiting factors are predominant. The other factors discussed in this paper are those relating t o the seeding oxygen carbon dioxide and tem-perature. Only a brief reference is made to the important influence which nitrogenous food can exert on yeast crops. FIG. 1. r- 1 Concentration of sugar. The influence of the amount of seeding admits of simp1 calcula-tion if no change in the limiting factor takes place owing to change in the amount' of seeding. The ratio R I P is independent of the number of yeast cells the growth under definite conditions should therefore be a constant.The yeast crop is the sum of the seeding and the growth the latter being constant. That this relationship holds good was first shown by A. L. Stern (T. 1901 79 943; J. Z m t . Brewing 1902 8 690). A. J. Brown had previously drawn the conclusion that the final yeast crop is almost independent of the amount of the seeding and deduced the idea of a non-multi-plying limit to yeast growth (T. 1892 61 369). 13. T. Brown considers the cell increase of most importance (Ann. Botany 1914 118 SLATOR YEAST CROPS AND THE 28 197). There would probably be general acceptance of the idea of a constant cell increase under constant conditions if it were not for the fact that large seedings of yeast refuse t o bud or show only a small increase (A.J. Brown Zoc. cit.). A satisfactory explanation of this abnormality is given here. It was found that, if actively growing yeast cells are used for seeding the normal increase takes place even though the seeding is very large. Quiescent yeast cells pass through a lag phase before active growth occurs and if retarding influences accumulate quickly the yeast never passes out of its quiescent state. Abnormally low crops are sometimes observed if very small seedings are used. Many investi-gators have noticed this effect (compare Lampitt Bio-Chem. J., 1919 13 461). If actively growing yeast is used for seeding this abnormality partly disappears and the effect is probably connected with the lag phase in growth. Much of the interest in yeast growth centres round the favour-able influence which atmospheric oxygen has on the growth of the organism.Although i t is more than 40 years since Pasteur’s work on the subject appeared there is still much diversity of opinion as to the method by which air acts. A. J. Brown (T. 1905 87, 1395) drew the conclusion that the development of yeast in malt wort is determined by the oxygen initially dissolved in the wort. H. T. Brown (Ann. Botany 1914 28 197) considers that the growth can be attributed t o oxygen absorbed by the yeast used for seeding. It is possible however that these experimental results can be interpreted in other ways. Carbon dioxide retards yeast growth t o a rnu-ch greater extent than is recognised in these experi-ments. Moreover yeast growth takes place under anaerobic con-ditions although the cells have lost all their ‘‘ oxygen charge ” (see table IX).Euler and Lindner (“Chemie der Hefe,” Leipzig, 1915) summarise the work of Pasteur Chudiakow Buchner and Rapp Delbruck and others on the subject. They recognise the retarding influence of carbon dioxide on growth and conclude that oxygen accelerates the growth of the yeast cells. One of the argu-ments against this view is the fact that growth in its simplest form is not accelerated by air or oxygen. Unrestricted growth is appre-ciably retarded by oxygen (see table V). I n a short summary of the factors which influence growth ( J . Soc. Chem. Ind. 1919, 38 391 R) the view (previously discussed by other authors) is taken that malt wort contains a substance which easily gives up its oxygen to the yeast and that this substance accounts for growth under anaerobic conditions.Attempts were made to verify this assumption by estimating yeast crops uiider conditions that the unknown substance would become the limiting factor determinin FACTORS WHICH DETERMINE THEM. 119 the crop. The experiments were unsuccessful and this explana-tion appears to be incorrect. The matter has been reconsidered in the light of these experiments and the following interpretation is advanced. It is considered that there are two different modes* of growth of yeast each involving a different set of chemical reactions. The initial stages of growth in malt wort illustrate the one mode of growth. Oxygen either free or combined or absorbed by the yeast plays no part in the process.Free oxygen slightly retards this growth. The energy necessary for growth is obtained from the fermentation of the sugar. Carbon dioxide retards the growth and if air is passed through the fermenting wort yeast growth is increased owing to the displacement of carbon dioxide. Growth in lactose yeast water illustrates the other mode of growth. This growth is unaccompanied by alcoholic fermentation but zymase is present in the cells. Free oxygen is here essential t o growth and if absent hardly any growth occurs. The necessary energy is obtained through some oxidation reaction carried out by the yeast. Carbon dioxide in large amounts also retards this growth. The factors determining which mode of growth takes place when both are possible have not yet been completely in-vestigated.The available nitrogenous food is probably of import-ance for whilst yeast growth in wort is not influenced by air a t the beginning of the reaction yeast growth in a medium prepared from half-fermented wort is favourably influenced by air (Slator, Bio-Chem. J. 1918 12 254). Whilst the influence of large amounts of air on yeast growth admits of explanation on these lines the influence of small amounts is less easy to understand. A wort saturated with air produces a larger yeast crop than one which contains no air. The increase is out of all proportion to what would be expected from the amount of air availab1e.f A number of experiments were carried out t o obtain further information on the subject.It was found that if fermentation and yeast growth occur under conditions that supersaturation of the wort with carbon dioxide takes place the effect is readily verified. If however care is taken to control the concentration of the carbon dioxide the * Pasteur considered yeast to be an organism endowed with two modes of life and the theory advanced here agrees in some respects with that of Pasteur. The aerobic growth in Iactose yeast water was investigated by Pmteur and the view that this growt,h depends on air has been confirmed. The very slight growth under anaerobic conditions is probably due t o a trace of fermentable sugar. According to H. T. Brown’s figures 1 C.C. of oxygen dissolved in wort causes the growth of GOOOX lo8 yeast cells. Experiments in sealed tubes showed less than lOOx lo6 cell increase for each C.C.of oxygen 120 SLATOR YEAST CROPS AND THE effect disappears. The conclusion is drawn that the idfluence of dissolved air is only indirect and doubts are cast on the usually accepted explanation of the matter namely that the effect is due to the favouring influence of the dissolved oxygen. It is possible that supersaturation by carbon dioxide is lessened by the presence of dissolved air and that larger yeast crops are a conse-quence of this influence. The work of Findlay and King (T. 1913, 103 1170) on the rate of evolution of gases from supersaturated solutions is of much interest in this connexion. Many of the arguments advanced in this publication depend on the assumption that carbon dioxide retards yeast growth.That the gas has this effect was considered to be the case by Delbruck (1886) and Foth (1887). (For a summary of the work see Del-briick and Hayduck Die Garungsfuhrung,” 1911 Berlin.) The correctness of these conclusions is accepted in this paper but it is considered that the effect is more far-reaching than either these investigators or others have realised. A. J. Brown (T. 1905 87, 1406) concluded that carbon d;ioxide had no such effect and that the retarding influence attributed to the gas was due to exclusion of oxygen. The experiments however are not conclusive for no precautions are taken to remove the carbon dioxide formed during fermentation. Measurements of rates of growth in wort and in wort saturated with carbon dioxide show a very marked retarding influence of the gas.Some measurements of yeast crops grown under conditions that carbon dioxide becomes the limiting factor confirm these results in an interesting manner (see table IV). The influence of temperature on yeast crops is small (compare Stern, J . Inst. Brewing 1902 8 694). Both R and F have tempera-ture-coefficients not greatly different from each other. I f there-fore the sugar is the factor controlling growth the crops which depend on the ratio K / F will be almost independent of tempera-ture (see table XI). This has been experimentally verified. A publication by Carlson (Biochem. Zeitsch. 1913 57 513) is of much interest. Measurements of yeast growths and yeast crops in wort are made. The wort is kept continually stirred and the amount of yeast in suspension estimated by centrifuging a method adopted here.I f allowance is made for the fact that Carlson’a wort is saturated with carbon dioxide the conclusions regarding rates of growth are in general agreement with those given here and in previous papers. His method of treating yeast crops is less easy t o follow for no precaution is taken t o make a single factor the limiting one which determines the crop; moreover it is unlikely that the relationship between concentration of food supply and growth is as simple as is assumed FACTORS WHICH DETERMINE THEM. 121 The question whether any food accessory substance (vitamin) is necessary to yeast growth has been considered in so far as it affects the experiments described here. No evidence of the necessity of such a substance was forthcoming for heating the wort to a high temperature and filtering through Fuller’s earth caused no decrease in the value of the wort as a medium for growing yeast.E x P E R I M E N. T A L. Methods of Estimating Concentrations of Yeast. Two methods were employed in this investigation to estimate the amount of yeast suspended in a liquid. When the amount was greater than a few million per C.C. it was estimated by centrifuging and measuring the quantity of deposit. The straight 5 cm. graduated capilliary tube used for blood analysis is not sensitive enough to estimate any but large amounts of yeast. If however, tubes with a bulb a t the end are used the volume is increased and smaller concentrations can be conveniently estimated.Three tubes were used which had capacities given in table I. TABLE I. Equivalent of 1 scale 1 ............ 0.011 C.C. 44.5 x lo6 cells per C.C. 2 ............ 0.064 , 7.65 x lo6 , 9 , 3 ............ 0.447 , 1.11 x 106 , ¶, Tube. Volume. division. A suspension of yeast containing 216 x 106 cells per C.C. by count-ing under the microscope gave by centrifuging in tube 2 a deposit showing 27-7 27.6 27.5 scale divisions (0.5 mm. in length) on diluting t o twice the volume the deposit was 14-1 14.2 13.9 and on diluting again t o twice the volume the readings were 7.0 7.4, 7.1. One scale division on tube 2 is therefore equivalent to 216 x 106//28.2 = 7.65 x 106 cells per C.C. The other tubes were similarly calibrated and checked one against the other.As tube 1 is a straight capilliary tube the yeast when it has settled down t o a constant volume has a consis-tency of 4450 million per C.C. This corresponds approximately with the consistency of pressed barm. Yeast cells vary in size but the figures given in table I have been used throughout the paper to convert scale divisions into cells per C.C. Carlson used a method of this kind the deposit from about 15 C.C. being determined. Paine (Proc. Roy. SOC. 1911 [B] 84 289) also employed straight capillary tubes for estimating the volume of yeast cells suspended in a liquid. The averages are 27.6 8 x 28.2 $ x 28-8 122 SLATOR YEAST CROPS AND THE When the number of yeast cells is below a few million per c.c., yeast counts under the microscope were made t o determine the concentration.The usual hzmacytometer was employed but the average number of cells appearing per field was estimated and the concentration obtained by dividing this average by the volume cf liquid appearing in the field of the microscope. Methods of Growing the Yeast. The medium used in most of these experiments was lightly hopped malt wort. Yeast grows readily in this medium and large crops are produced. To eliminate the influence of carbon dioxide small quantities of wort were placed in large test-tubes to which had been sealed a piece of glass tubing. The tube is then exhausted or filled with any desiredl gas sealed up and rotated in a thermo-stat. Mosf; of the carbon dioxide passes from the liquid into the space above. I n some experiments accumulation of carbon dioxide is required.The fermentations were then carried out in straight tubes in which the liquid is sealed. High pressures of gas are obtained in this way. The yeast used in most cases was a Burton yeast (8. cereuisiae). I n some experiments a pure culture of actively growing yeast was used and in others quiescent yensf, (pressed barm) . The ZnfFuence of Seeding on the Crop. Tests were first made to determine whether large seedings of yeast would grow. T"he results which are summarised in table I1 (p. 123) show what conditions must be fulfilled for growth to take place. I f actively growing yeast cells are used for seeding normal growth takes place even though the seeding is very large (370 x 106 cells per c.c.). Large seedings of quiescent yeast cells show only a small growth (Expt.h). When the carbon dioxide cannot escape, moderately large seedings show no growth a t all (Expt. i). Under conditions of continual agitation larger crops were obtained and the cell increase was found to be approximately con-stant although the seeding varied greatly. I n the following experiments about 3 O.C. of wort (D 1.050) were placed in a tube of capacity about 100 c.c. the tube being afterwards exhausted and sealed. The time of growth was three days a t ZOO Expt. a ......... b ......... c ......... d ......... e ......... f ......... g ......... h ......... i . . . * . . . Temp. 25" 25 25 25 25 25 25 25 15 Wort D 1.050. Time. 2 days 2 Y Y s) 7 ) 3 hours 1 day 3 hours TABLE 11.Yeast concentrations fcnit = 7.65 x Yeast. Vessel. Agitation. actively large tubes occasional growing exhausted shaking 9 9 flask 7 ? Y ? 9 9 ?9 quiescent Y7 Y Y ? ? 9 9 Y Y ? Y ? ? Y Y 9f sealed tube 11 almost ful 124 SLATOR YEAST CROPS AND THE TABLE 111. Yeast concentrations u n i t = 7-65 x lo6 cells per C.C. Expt. Seeding. a ......... 37-1 27-8 18.6 13.9 9.3 4.6 b ......... 19.3 13.6 3.4 Crop. 56.0 48.6 37.9 30.6 25.9 25.1 37.8 29.7 20.4 Cell increase. 18.9 20.8 Average. 18.8 = 143 x lo6 cells per C.C. 16.6 20.5 ::: ] 17-2 = 132 x 106 cells per C.C. 17.0 T h e Influence of Carbon Dioxide o n the Crop. A wort (D 1.050) was seeded with yeast. A tube was filled almost completely exhausted to remove dissolved air and then sealed.Into a large tube was introduced a small quantity of the seeded wort and this tube was exhausted and sealed. Both were rotated slowly a t ZOO. The yeast increase in the first case amounted to 30x lo6 cells per c.c. and in the second to 140x 106 cells per C.C. This great difference is attributed to the carbon dioxide which remains in solution in the first case and is removed in the second. If simultaneously an ordinary fermentation open t o the atmosphere is carried out the cell increase amounts to about 80 x lo6 cells per C.C. This is a typical result obtained from a large number of experiments of this kind. It was considered probable that carbon dioxide could be made the limiting factor which deter-mines the growth.The matter was tested by varying the ex-hausted space above the wort and determining the influence such variations had on the crop. I f vul and v2 are the volumes of liquid and space respectively then the concentration of carbon dioxide in the liquid when a given amount of gas is forniecl is proportional t o a= 'd where s is coefficient of absorption of the gas in Vl the liquid. A consideration of Fig. 1 shows that the cell increase should be proportional to a if the carbon dioxide is the limiting factor. This was found t o be the case as table IV (p. 125) shows. I f the tube is full (a=l) cell increase is 2.9 =22 x 1 0 6 cells per C.C. In Expt. g where the space above is great proportionality no longer exists. When more dilute worts were used similar results were obtained but as the space increased the deviation from pro-portionality occurred earlier.Experiments in which the space above was not exhausted but filled with air showed that the ai FACTORS WHICH DETERMINE THEM. 125 TABLE IV. 25O; tzcbes rotated three days; s=0*70. W o r t D 1.101. Small seeding of yeast; exhausted tubes; temp.= Expt. Q)1 a ......... 23.3 b ......... 23.0 c ......... 14.5 d ......... 11-8 e ......... 10.3 f ......... 12.3 g ......... 7.4 V2' 1.2 1.3 4.8 4.0 8-3 11-7 17.2 Crop (unit=7.65 x lo6 1.08 3.0 2.8 1.08 3.0 2.8 1.46 4-1 2.8 1-48 4.5 3.1 2.13 6.1 2.9 2.33 6.5 2.8 4-26 9.9 2-3 Average (excluding g) ... 2.9 a. cells per c.c.). Crop/a. -increased the crop.increased growth averaging 15 x 106 cells. One C.C. of air (+ C.C. oxygen) caused an The Influence of A & and Oxygen o n Growth and Crop. Small seedings of yeast in wort were allbwed to grow one t o two days a t 20° in tubes which were continually rotated. Some of the tubes were exhausted some filled with air oxygen and carbon dioxide. The constants of growth were calculated in the usual way, and the results are summarised in table V. TABLE V. Wort D 1-047. Wort D 1.040. - - 0-434K. G.T. 0.434K. G.T. Exhausted ........................ 0.110 2-7 hours. 0.109 2.7 hours. Air ................................. 0.107 2.8 , 0.092 3.3 ,, 60 per cent. oxygen + 40 per cent. nitrogen ............... 0.096 3-1 , - -100 per cent. oxygen ......... 0.085 3.5 , - -100 per cent.carbon dioxide 0.079 3.8 , 0.073 4-1 horn. The influence of air on the whole range of growth was then investigated large tubes being used to eliminate the influence of carbon dioxide. The curves in Fig. 2 show the retarding influence of air during the early stages of growth and the favouring effect during the latter stages. The final yeast crop is greater under aerobic conditions. In tables VI and VII are summarised some experiments on yeast growth in worts saturated with air. Wort (D 1.040) was introduced into a pressure flask and seeded with yeast. All dis-solved air was rapidly removed by exhausting the flask. Fifty c . ~ . of the seeded wort were then introduced into a large test-tube. 126 SLATOR YEAST CROPS AND THE parallel experiment was made with wort saturated with air.Although in the first case the wort is exposed to the atmosphere and traces of air become dissolved the amount dissolved in the second case is much great'er and the effect on growth is very noticeable. FIG. 2. 140 120 0 Time of growth in hours. Anaerobic growth X . Aerobic growth 0. InJEuence of CO eliminated. TABLE VI. Il'emp. about 1 5 O . Unit =7*65 x 106 cells per C.C. Cell increase Time of Ekhsusted Aerated Yeast. Seeding. growth. wort. wort. Ratio. Quiescent ......... 1-4 18 hours. 1.7 2-5 100 148 9 9 1.4 24 , 1.5 3.4 100 227 9 7 ......... 3.0 48 ) 5.0 7.3 100 146 ......... 3.0 18 .. 2.8 4.0 100 143 Actively growing 0.2 48 , 2.3 5.5 100 239 9 ) 0.1 48 , 2.0 4.0 100 200 .........Y FACTORS WHICH DETERMINE THEM. 127 The experiment was repeated but the wort both free from air and saburated with air was placed in bottles. The bottles were filled completely with the liquid and stoppered to prevent escape of gas. I n this case no such differences were observed. TABLE VII. Temp. about 1 5 O . Unit=7*65 x 106 cells per C.C. Cell increase ____h___? Time of Exhausted Aerated Yeast. Seeding. growth. wort. wort. Ratio. Quiescent ......... 1.0 18 hours. 1.8 1.8 100 100 9 9 ......... 1.0 1s , 1.1 1.1 100 100 9 0.2 40 , 2.5 2.8 100 111 9 0.2 48 , 2.6 2.8 100 108 Activelygrowing 1.5 18 , 2-8 3.0 100 107 A number of experiments were then made in which yeastl growth took place under anaerobic conditions and under conditions that a limited quantity of air was present.The tubes were rotated in a thermostat. Usually these small quantities of air had little or no influence on the yeast growth. In Expt. e when large quantities of air are present an appreciable retardation in growth is noticed. TABLE VIII. Temp. 20°. Unit=7'65 x 106 cells per C.C. Expt. Yeast. a Quiescent b 7, C Y, d Y, e 9 , f Actively growing. VOl. liquid vol. air. 5 1 1 l 1 l 5 150 5 150 1 l Time of Seeding. growth. 0-2 48 hours. 5.2 2 ,, 5.2 6 ,, 2.9 2.9 46' : 1.7 8 ,, Cell increase m Anaerobic aerobic. Ratio. 4.7 4.8 100 102 1.4 1.3 100 93 5.7 5.1 100 90 1.1 1.0 100 90 2.3 1.6 100 70 5.7 6.4 100 113 All these experiments show that small quantities of air have little influence so long as the concentration of the carbon dioxide is con-trolled.The results are in accordance with the idea that dissolved air aids yeast growth owing to the effect it has in lessening the supersaturation of the wort with carbon dioxide. The early stages of growth of quiescent yeast do not require air (table VIII, Expts. a 6 c d). The following experiments were carried out to test H. T. Brown's suggestion that oxygen absorbed by the seeding yeast determines the subsequent growth. Yeast was grown in a small quantity of wort in an exhausted tube A . This yeast wa 128 SLATOR YEAST CROPS AND THE used to seed fresh wort in another tube the process being carried out under strictly anaerobic conditions in the manner shown in Fig. 3. The T-piece C is exhausted and the wort in B is boiled to free it from air.The point 1) is then broken off some of the TABLE' IX. Time of growth Expt. Density of wort. and temp. 1 ......... 1.040 2 days at 25" 2 1.052 7 7 20 3 1.063 7 7 20 k.... 1.063 7 7 20 4 1.040 9 9 20 4a. 1.040 7 7 20 ......... ......... ..... ......... ........ Crop (unit=7.65 x lo6 cells per c . c . ) . 8-0 10.0 15.1 15.0 11.4 11.2 liquid from A passes into B which is then sealed a t E . The results which are given in the above table show that good crops were obtained in tube B in spite of all absence of air. In Expts. 3a and 4a the seeded wort was allowed to come in contact with the air for some hours and the tube then exhausted. This contact with the air had however no influence on the subse-quent crop.There seems therefore no necessity for FIG. 3. oxygen to- be a t the disposal of the yeast used for seeding. The Influence of Concentrations of Sugar. Some difficulty was experienced in obtaining a suitable medium to show th2 effect of sugar on yeast crops when this constituent of the medium is made the limiting factor. 730 medium finally chosen was the residue of a fermenked wort (D 1.080). This wort was fermented with yeast and the alcohol disitilled off. The process was repeated in order to free the medium entirely from fermentable sugar. To the final residue (D 1.017) was added small amounts of glucose, and this proved a good medium for wild yeast growth although unsuitable for the growth of S. cerevisiae.The following table summarises measurements of K F and crops with different concentrations of sugar the organism used being a wild yeast of the S. ellipsoideus type FACTORS WHICH DETERMINE THEM. 129 TABLE X. R = constant of growth in hours-1. F=grams of sugar fermented per hour per yeast Temp. = 20°. cell. K / F = yeast cells produced per gram fermented. Grams of glucose per 100 C.C. G.T. K . P. K IF. 1.50 2 - 86 hours. 0.242 57 x 10-l2 4200 x lo6 1.00 2-84 , 0.244 57 4300 0.50 2-84 , 0.244 56 4400 0.20 2.82 , 0.246 53 4600 sverage ... 4400 x lo6 According to table X when 1 gram of sugar is fermented, 4400 x 106 cells should be produced. Some rather indefinite cor-FIG. 4. Grams of glucose per 100 C.C. rection has to be made for the amount of sugar used in building up the yeast.This correction would reduce the figure to approxi-mately 3700 x 106. The curve Fig. 4 shows proportionality be-tween crop and initial glucose concentration up to about 1 per cent. of sugar. The slope of the curve corresponsds with VOL. CXIX. 130 SLATOR YEAST CROPS AND THX 3 9 0 0 ~ 1 0 ~ cells per gram a figure in fair agreement with that calculated from K and F . Influence on Temperature. The following table summarises measurements of K and F of The ratio K I P is approxi- yeast (8. cereuisiae) in wort ( D 1.040). mately independent of temperature. TABLE XI. Temp. G.T. K. P. K IF. loo 11.6 hours. 0-060 12.5 x 4800 x 106 15 6.4 Y Y 0.108 24.5 4400 20 2.95 , 0-235 47.0 5000 25 1.77 , 0.392 75-0 5200 Average ...4900 x 106 4900x 106 cells are therefore produced when 1 gram of sugar is fermented. Assuming that this amount of yeast uses up 0.2 gram of sugar for its growth 1.2 grams of sugar produce 4900x lo6 yeast cells (about 1.2 grams of pressed yeast). This represents the maximum possible crop. I n table XI1 is given the actual crops obtained a t 1 5 O and 2 5 O under conditions that the sugar is the limiting factor (a and b ) , anfd under conditions that the carbon dioxide is the limiting factor ( c and d). The medium in ( a ) and ( b ) is a mixture of 50 C.C. fermented wort residue and 5 C.C. of wort (D 1*040) and the experi-ment is carried out in large exhausted tubes. I n ( c ) and ( d ) wort (D l * l O l ) is used in long tubes half-filled in (c) and two-thirds filled in ( d ) .The cell increase was almost the same a t 1 5 O and 2 5 O . They were exhausted and sealed. TABLE XII. Unit =7*65 x 106 cells per C.C. 15" 25" (actively Cell Tim'e of Cell TimS of Seeding growing). increase. growth. increase. growth. a ...... 4.8 2.3 2 days 2.3 1 day b 0-7 2.2 2 9 9 2.5 1 1 7 c 1.8 7.1 2 9 ) 7.1 1 Y d 0.5 3.4 3 1 7 3.8 2 Y 7 ...... ...... ...... Growth of Yeast in Malt W o r t . As a result of these experiments it is suggested that the generally accepted views on yeast growth should be considerably modified FACTORS WHICH DETERMINE THEM. 131 The influence of carbon dioxide is greater than has been realised, and great variations in the crop are obtained by altering the con-centration of the carbon dioxide in the wort.Air (oxygen) has much less influence than is usually attributed to it. It plays no part in the initial budtding of the yeast (the lag phase in growth) and has no direct accelerating influence during the first stages of growth. Later stages are favourable influenced by air; the aerobic vegetative growth here comes into consideration. Air dis-solved in wort favours yeast growth. This is considered to be due to a decrease in the supersaturation of the wort with carbon dioxide and not to the yeast cell requiring free oxygen for its development. Note o n Spore Formation of Yeast Cells. Little is known of the chemical reactions which accompany the formation of spores in yeast cells but the belief is very generally held that oxygen plays an essential part in the process. This belief seems justified but it was found that traces of air are suffi-cient to induce sporulation. The experiments were carried out in the following manner. Young and vigorous yeast cells of a wild yeast which readily forme'd spores were mixed with slightly acidi-fied water (0.2 per cent. phosphoric acid neutralised with potassium hydroxide to give a Y value 5-6) so that the solution was just turbid. Some of the liquid was placed in sterile conical flasks and some in tubes which were then carefully exhausted. In two days a t 2 3 O abundant spore formation took place in the flasks whilst no spores were formed under anaerobic conditions. I n some cases a small quantity of air was allowed t o enter the exhausted tube. One cm. pressure of air in the tube was found to cause the produc-tion of spores. It is sometimes stated that tlhe growth of yeast spores requires air. This proved incorrect for spores were found to develop readily in wort free from air. BURTON-ON -TRENT. [Received December 9th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900115

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

132 TIZARD AND ROEREE T'HE \'OLUMETRlC' ESTIMATION OF XV.--The Volunzetric Estimutioit of Mixtures of Acids and of Bases and of Yolybasic Acids or Bases. By HENRY THOMAS TIZARD and ALFRED RE~GINALD BOEREE. THE conditions which control the accuracy of titration of mixtures of acids or bases have hitherto been too much obscured by some-what coinplicatecl mathematical expressions to allow of their ready application to particular cases. The object of the present paper is to point out and illustrate certain relations which are applicable in all but very exceptional circumstances. The estimation of bi- and ter-valent acids or bases in solution is a special case of the estimation of mixtures of acids or bases. If an aqueous solution contains one equivalent of a weak acid HA,, and x equivalents of a weak acid HA, the dissociation constants of which are R and R respectively (R being >K2) the concen-tration of hydrions in the solution after the addition of one equivalent of a strong base BOH can be calculated in the following way : Suppose the solut,ion is sufficiently dilut'e for the assumption to be made that for all practical purposes the dissociation of any salt present is complete.Then there is present in 'Tr litres of solution one equivalent of the ion B; y equivalents of All say, andv therefore 1 -y equivalents of A12 C being negligible. Hence since E$lCHA a z c € I and we have R,C,, = C x C 3 1 -y Y V l V K L =C,X or I n the special case when x =r 1 we have . . . aiid CI i s independent of dilut8ioii wilhiii wide liniits.Hence i i i order to titrate a dibasic acid or a mixture of acids in cguivalen MIXTURES OF ACIDS AND OF BASES ETC. 133 proportions to the half -way point an indicator must be chosen which changes over a t concentration of hydrions giveii by equa-tion (2). Now the accuracy of the titration is affected not only by the choice of the indicator but also by the effect on the acidity of the solution of small changes in the amount of alkali added near the " equivalent " point. To calculate this suppose (1 + z ) equi-valents of BOH are added to a solution containing one equivalent, each of HA and HA,. Then if y equivalents of A' are preseut, i n the solution there are (1 + z - y ) of AI2 andl therefore, This condition is already well known. or and (3) .. . I n order to get a sharp end-point it is necessary that a small excess or deficit of alkali should produce a large change in the concentration of hydrions. Inspection of the expression on the right-hand side of equation (3) shows that the nearer y is to unity the smaller will be the value of the expression for small values of z . Trial shows that if CH is to be equal to &+l/.LC,K, when z = O * O l or in other words if the concentration of hydrions at the equivalent point is t o be halvedl by adding as 1 per cent. excess of alkali then y = 0.997 approximately. Substituting this in (4) we see that K,/K in this oase must be of the order of 104. The larger the ratio of Kl to K2 the sharper is the end-point and all necessary information can be obtained by giving K1//.LC2 certain arbitrary values then calculating y from equa-tion (4) for different values of z and finally substituting these figures in equation (3) thus obtaining the corresponding value h The following tables give calculations for various values of X / K and for various additions of alkali.It is assumed for the sake of clearness that 20 C.C. of a solution containing equi-valent quantities of the two acids are titrated by an equivalent solution of a strong basc 134 TIZARD ANT BOEREE 1 TTTE VOLUMETRIC! ESTIMATION OF C.C. of base added. 8.0 9.0 9.5 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.5 11.0 12.0 1 0 2 . 3.0 1.8 1-4 1.2 1.1 1.05 1.0 0.95 0.9 0.83 0.71 0.56 0.33 103. 8.0 4.0 2.1 1.6 1-4 1-2 1-0 0.83 0.7 1 0.63 0.48 0.25 0.12 104.26.0 11.0 5.5 3-6 2.5 1.6 1.0 0.63 0.4 0.28 0-18' 0-09 0.04 106. 80.0 35.0 17.0 10.0 6.8 3.5 1.0 0.29 0.16 0.10 0.06 0.028 0.012 It is clear from these figures that when Ri/Ei2, 106. 250.0 110.0 56.0 32.0 20.0 10.0 1.0 0- 1 0.05 0-03 1 0.018 0.009 0.004 is very large, lo6 say a small excess or deficit of alkali near the equivalent point makes a very large difference to the hydrion concentration; a 1 per cent. error alters the concentration by a factor of 10. Hence not only will the end-point be very sharp but i t is not necessary to be too particular about the choice of an indicator, so long as the end-point of the indicator is somewhere between 1 0 J V and l/lOd=.I f Ki/K2=10z a 1 per cent. excess or deficit of alkali alters the hydrion concentration only by 5 per cent. ; it requires more than a 10 per cent. excess or deficit before the hydrion concentration is altered by a factor of 2. It is hardly possible even with the best indicators to be certain of titrating by eye to within a factor of 2 unless elaborate precautions are taken so that if Xi/I~a=102, titration will be uncertain and inaccurate even if an indicator is chosen which changes over very nearly at the correct hydrion concentration given by C,= JKlK2. The theoretioal half-way point is supposed to correspond with an addition of 10 C.C. -~ These conditions are illustrated in the figure. rl JKIKz b H is plotted of the alkaline solution.The logarithm of ~ against the amount of alkali added and the flatness of the curves near the equivalent point gives a measure of the accuracy obtain-able. A factor of 2 in the hydrion concentration corresponds with a difference of 0.3 in the logarithm that is 3 units on the scale of absciss. Using this criterion it is clear that even if K,/K is as great as 104 an accuracy of 1 per cent. can only be obtained if an indicator is chosen which changes over as near as possibl MIXTURES OF ACIDS AND OF BASES ETC. 135 to the true equivalent point; although if such an indicator is not available the curves can be used to correct approximately the results obtained by the use of the best available indicator. I n general consideration of the figures of table I shows that an accuracy of 1 per cent.in the titration of a dibasic acid in the half-way point by ordinary methods cannot be trusted unless the ratio K,/K is a t least equal to 104. This condition can be obtained directly and more accurately from equations (3) and (4). I f the concentration of hydrions a t the equivalent point is halved by a 1 per cent. excess of alkali it has already been shown - 2 - 1 0 that y=0*997. we get Substituting y=0.997 and z =0*01 in equation (4), Similarly if the same alteration in CR is caused by an excess of alkali of 0.1 per cent.; or one part in a thousand then we must have The same relations hold1 good of course for the estimation o 136 TIZARD AND BOEREE THE VOLUMETRIC mixtures of bases except that a t the equivalent we have CoH=dKK,Kti’ .. . and .*. where lir is the dissociation constant of water, dissociation constants of the bases. ESTIMATION OF (half-way) point, . . . . (7) (8) . . . . and K, K the Before giving the results of ezperinients made to check these conclusions it will be useful to generalise these conditions and t o apply the general conditions t o other special cases of interest. The special case we have already discussed is that where z=1. Now when x is not unity that is when the acids are mixed in any proportions it is still true to say that for accurate titration of the strongest acid in solution y must be very nearly equal to I , when an equivalent amount of alkali has been added. Hence from equation (1) we get C, or in the case of bases COH at the equivalent point= .. . . . . . q?iczz2 (9) and by exactly the same methods as given above we find that the condition of titration to 1 per cent. is that . . . . 3- shall be a t least=2*5x 104 -->2*5 Kl x lo6 (10) (11) XKZ and the condition for titration to 0.1 per cent. is that . . . . . . . xK2 These general conditions can be applied in nearly every case; i t is only when solutions are so concentrated that the ‘(neutral salt *’ effect comes in that they are likely t o fail. The titration of a single acid or base in the presence of water is simply a special case where the second dissociation constant H is equal to K x V , where V is the dilution and K the so-called dissociation constant of water.At 18O K,=0*6 x 10-14 so that if V=20 K x V is approximately 10-13. The choice of an indicator in solutions of approximately this strength is therefore given by and the condition of titration to 1 per cent. is approximately . . . . . C,=,/KlxlO-13 (12) . . . . ~ ~ = ~ ~ 5 x 1 0 4 0 r ~ ~ = 2 ~ ~ x 1 0 9 (13) The absence of a suitable indicator may upset this condition; it is only when H is much larger that considerable latitude in the choice of an indicator is possible MIXTURES OF ACIDS AND OF EASES ETC. 137 The following experiments illustrate the theory given above : (1) ( a ) The dissociation constant of ainmonia is about 1.8 x 10-5. Hence the concentration of hydroxyl ions in the solution when equivalent quantities of N / 10-ammonia and N / 10-hydrochloric acid are mixed is cOH= j i - s 10-5 10-13 = 1 .3 x 10- 9 approximately Methyl-red changes over a t this concentration and this indicator is known to be very good for the estimation of ammonia. Further, 1.8 x 10-5 since (see equation 13) -I - = 1.8 x lo8 that is is much 10 l3 greater that lo4 a considerable latitude in the choice of an indicator is permissible. For example both methyl-orange (C = about 10-4) and cresol-red (C==about 5 x 10-8) are reasonably good indicators for ammonia although not so accurate as methyl-red. An approximately N / 10-solution of ammonia titrated by N / 10-hydrochloric acid gave the following results : Indicator 25 C.C. of methyl-red. ammonia taken. Acid added. Colour of indicator. 24.0 C.C. yellow 24-65 $ 9 a .7 orange 24.8 pink Indicator 25 C.C. of cresol-red. ammonia taken. Acid added. Colour of indicator. 22.5 C.C. pink 24-1 244.8 25-0 very yellow EYgiYkk The correct end-point is very nearly 24.7; titration when using cresol-red is much less certain. ( b ) Now consider the conditions if it is required to estimate ammonia in presence of an approximately equivalent quantity of aniline. Aniline is a very weak base with a dissociation constant of about 3.5 x 10-10. Hence the conoentration of hydroxyl ions in the solution when an amount of acid equivalent to the ainmonia present is added (the half-way point) is -CoH= J1-8 x 10-5 x 3.5 x 10-10 (see equation 7) = 8 x 10-8 01' Further since the ratio ~ = ~ ~ ~ ~ ~ o = x 10-4 it is necessary to be particular over the choice of an indicator in order to get a result within 1 per cent.Methyl-red will therefor6 bo F 138 TIZARD AND BOEREE THE VOLUMETRIC ESTIMATION OF quite unsuitable whereas cresol-red may be expected to give a good result. Twenty-five c.c of the same solution of ammonia were mixed with 25 C.C. of an approximately N/lO-solution of aniline and titrated against N / 10-hydrochloric acid. Indicator methyl-red. C.C. of acid added. Colour of indicator. 24.1 greenish-yellow 26.8 faint change 28.3 yellowish-orange 29.6 pinkish-orange 33.0 pink Note the indefiniteness and inaccuracy of the end-point which should have occurred a t 24.7 (see above). Indicator cresol-red. C.C. of acid added. Colour of indicator. 24.0 orange-pink 24-3 still slightly pink 24-56 orange N.6 dull yellow 24.7 quite yellow Note the sharp end-point correct to within 1 per cent.This is a very good example of the substantial accuracy of the condi-tions given by theory; it is interesting to note the striking effect caused by the presence of so weak a base as aniline in a solution of ammonia. (2) Consider next the estimation of mixtures of bases of about the same strength as ammonia and P-picoline. Take first the estimation of such a base as picoline alone in aqueous solution, approximately NjlO. Since the dissociation constant is 1 x 10-8, we have Hence i t should be possible to estimate j3-picoline to within 1 per cent. but only by choosing the indicator with care. When an equivalent amount of hydrochloric acid is added The best indicator to use is therefore methyl-orange (orange to pink) ; methyl-red will be quite unsuitable MIXTURES OF ACIDS AND OF BASES ETC.139 Titration of an Approximately N/ 10Solution of 13-Picoline by Hydrochloric Acid. Colour of indicator. C.C. of acid aclcled. Methyllorange. Methyl-red. 15-0 yell ow yellowish-orange 18.0 Y 9 pinkish -orange 19.0 1 Y pink 22.5 Y Y 23.0 23.4 pink -orange - -The end-point given by methyl-orange namely 23.0 c.c. is prob-ably within 1 per cent. of the correct value; that given by methyl-red is hopelessly inaccurate. I n the case of a mixture of equivalent amounts of ammonia and P-picoline the concentration of hydroxyl ions a t the half-way point is Go,= di.8 x 10-6 x 10-8 =about 4 x 10-7, or Phenolphthalein (about 10-8) should therefore indicate a fairly correct half-way point but i t can only be very approximate since which is considerably less than 2.5 x 10-4.A mixture of 25 C.C. each of the standard ammonia solutions and of the above fl-picoline solution gave the following results when titrated against N / 10-hydrochloric acid : Colour of indicator. C.C. of acid added. Phenolphthalein. 20.8 pale pink 21.8 trace pink 22.0 c ol our1 ess The correct half-way point is 24.7 [see example ( l ) ] . the solution, The titration was then completed by adding methyl-orange to Colour of indicator C.C. of acid added. (methyl-orange). 45.0 yellow 46.3 yellowish- orange 47.5 orange 48.0 pinkish- orange The correct end-point should have been 24.7 + 23.0 = 47.7 which agrees as well as could be expected with that found.F* 140 TIZARD AND ROEREE THE VOLUME'rXilC ESTIMATION OF (3) Similar experiments were lilade with mixtures of pheiicll and acetic acid. The dissociation constant of phenol is given as 1.3 x 10-10; it is therefore too weak an acid to be estimated volu-metrically for is in uch smaller than 2.5 x 104. its estimation alone is therefore given by .K for acetic acid is 1.8 x 1 0 - 5 ; t'he correct indicator for c,= J1.s 1 0 - 5 ~ 1.0 x 10-13 = 1-3 x 10-9 approximately. Phenolphthalein (10-8) is quite satisfactory since the ratio If it is required to estimate the acetic 1.8 x 10-6 '10-13 is very large. acid present in a mixture of this with phenol in approximately equivalent proportion an indicator must be used which changes over a t CH= d1.s 10-5 1.3 x 10-10 = 6x10-8 Hence cresol-red should indicate the half -way point whereas DhenolDhthalein will give too high results for the ratio is too low t o allow Twenty-five C.C.t o be iieutralised phenolphthalein. of any latitude in the choice of an indicator. of approximately N / 10-acetic acid were found by 25-15 C.C. of M/lO-sodium hydroxide using The end-point was very sharp and this result is probably accurate t o 0.1 per cent. The results obtained by titrating a mixture of 25 .c.c. of the same acetic acid solution and 25 C.C. of N/lO-phenol against N/lO-sodium hydroxide were as follows : Colour of indicator. A-C.C. of alkali added. Cresol-red. Phenolphthalein.25.3 pinkish- orange 9 9 25-5 pink 1 9 25.8 dark piiik trace pink 25.0 yellow colo1lrless The results are in good agreement with theory; an equally good, if not slightly better half-way point was obtained by using azolitmin as an indicator (lo-7.1) ; this suggests that the dissocia-tion constant of phenol given in the literature is slight,ly too low. (5) Some other examples may now be given in less detail. Monochloroacetic acid ( K = 1.55 x 10-3) cannot be estimated accurately in the Iireseiice of acetic acid (1.S x 10-6) since the rati MIXTURES OF ACIDS AND OF BASES ETC. 141 of the constants is too small. The total acid present can of course, be accurately estimated by using phenolphthalein. The nearest indicator for the “half-way” point would be that changing over at I______- CH= &‘55 x 10-3 x 1-8 x 10-5=1’7 x An attempt made to estimate the monochloroacetic acid in a mixture with an exactly equivalent quantity of acetic acid gave a result with methyl-orange corresponding with 13.5 +0*5 C.C.of standard alkali whereas the total acid present was neutralised by 25.75 C.C. of alkali. On the other hand trichloroacetic acid (3 x 10-l) can be approximately estimated in the presence of acetic acid since the ratio is only slightly less than 2.5 x 104. 3 x 10-1 mm5 luhe best indicator to use is methyl-violet. Trial gave 12.8k0.2 C.C. for the half-way point and 25.70 C.C. for the end-point (phenolphthalein). The first and second steps of the “ neutralisation” of phosphoric acid can as is well known be detected accurately by the use of suitable indicators.This agrees well with theory for R = 1 x 10-2, R,=2 x 10-7 K,=4 x 10-13 and the ratios Kl - and - K9 are large. K9 K, The best indicator to use for the first step is-that changing over a t .\/a x 10-4.35 that is methyl-orange (orange to yellow) ; similarly phenolphthalein is suitable for the second stage. The third dissociation is too weak for a final “end-point ” to be obtained. These facts are of course well known and are only quotedl to show how they agree with the conditions given above. cannot be titrated to a half-way point but maleic acid ( X I = 1.3 x 10-2 R,=3.0 x 10-7, ratio=4 x 104) can methyl-orange being a suitable indicator. As the second dissociation constants of these acids are fairly high, accurate final “end-points” can be obtained in both cases by the use of phenol- or thymol-phthalein so that titration to the half-way point is unnecessary when the solution contains no other acid ; but if another weak acid for example of the order of 10-7 is present in each solution the succinic acid cannot be separately estimated but the maleic acid can by titrating to the half-way point with methyl-orange.This has also been confirmed by experiment. Finally attention may be drawn to a point of some importance. Solutions of acid salts are often recommended1 as “ hydrion regulators.” It should not be overlooked that if the salt is that ____~ -Succinic acid (IT = 6.5 x 10-5 K = 3 142 COX THE INFLUENCE OF THE SOLVENT ON THE of a di- or tri-basic acid the dissociation constants of which are very different a small excess of base or acid in the solution will have a large effect. This is dearly shown by the figure on p. 135. For example if a solution of disodium hydrogen phosphate is chosen as the regulator an excess of one part in a thousand of sodium hydroxide or of phosphoric acid will alter the hydrion concentration nearly by a factor of 2 since On the other hand a similar excess in the case of sodium hydrogen succinate will have a negligible effect since the ratio of the two dissociation constants of this acid is small. As stated in a previous paper (Tizard and Whiston T. 1920 117 151) i t is considered that the best and most convenient way of preparing solutions of known hydrioii content between C,,=lO-3 and CH=lO-ll is by mixing solutions of ammonia and acetic acid the relative strengths of which can be estimated with great accuracy. ORIEL COLLEGE OXFORD. [Received December 7 t h 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900132

出版商:RSC    

年代:1921

数据来源: RSC

摘要:

142 COX THE INFLUENCE OF THE SOLVENT ON THE XVI.-The 1n.v.ence of the Solvent on the Temperattire-coeficient of certain Reactions. A Test (f tI2e Radiation Hypothesis. By HENRY EDWARD Cox. IN a former paper (T. 1920 117 493) the velocity of three analo-gous reactions-sodium naphthoxide and the alkyl iodides-in fifteen alcohols was discussed and a relation was shown between the constitution of the solvents and the effect on the velocity. The present paper deals with the temperature-coefficients of the reaction in different solvents of bromoacetophenone with aniline and of sodium naphthoxide with ethyl iodide. The point of view adopted is that the reactions take place by the formation of intermediate coinpounds or solvent-solute complexes, the velocity being dependent on the constitution of the complex and hence on the constitution of the solvent.Much experimental evidence could be adduced in support of this and the remark of Patterson and Montgonierie (T. 1912 101 26) that solvents fre-quently affect different reactions in the same order is capable of interpretation on this line. Further it may be supposed that th TEMPERATURE-COEFFICIENT OF CERTAIN REACTIONS. 143 reaction-whether or not the solvent takes part in it-is brought about by the infra-red radiation present in the system as proposed by Lewis in his papers on catalysis. A study of the temperature-coefficients in different solvents affords a crucial test whereby the radiation theory as developed by Lewis may be examined and the results obtained in this investigation generally support the theory subject to certain restrictions on account of the special characters of the solvent.It is now generally recognised that reaction velocity depends not on kinetic energy but on the internal energy of the molecules oon-cerned; they react when their energy exceeds a certain critical value. The well-known equation of Arrhenius which agrees with the experimental data more nearly than any other of the many equa-tions which have been proposed for the influence of temperature, involves the idea of a critical value for the energy of the molecule, although it was suggested i]hat kinetic energy is principally con-cerned. Arrhenius applies van’t Hoff’s isochore to direct reactions by assuming an equilibrium between active and passive molecules so that in the well-known equation.logk’l=A kt2 stant which denotes half the heat required to transform 1 gram-molecule from the passive to the active state. Lamble and Lewis (T. 1914 105 2330) deduce from this equa-tion that when a positive catalyst is present in large quantity a diminution of the temperature-coefficient should follow. They state Chat (assuming the identity in nature of temperature and catalytic effects) when much catalyst is present the transformation from pas-sive t o active molecules should have taken place and therefore tem-perature should have a less additional effect in accelerating the reaction. Arrhenius supposes however that the number of active molecules is so small that the concentration of the inactive molecules is for purposes of calculation equal to the concentration of the sub-stance; so whilst Lamble and Lewis’s statement may be correct in extreme cases it cannot apply to reactions where the velocity is accel-erated only a relatively small number of times by the catalyst.In their experiments on the hydrolysis of methyl acetate the accelera-tion by the added catalyst is only about forty times a t constant temperature and no regularity of effect on the temperature-coeffi-cient is observed which confirms the opinion that no diminution is required on the Arrhenius view. On the radiation theory such diminution is a necessary mathematical consequence so that if a sufficient change of velocity can be examined experimentally herein lies a test of this application of the quantum theory.The fundamental equation for the influence of temperature o 144 cox THE INFLUENCE OF THE SOLVENT ON THE the radiation theory is that of Marcelin and of Rice (C’ompt. rend., 1914 158 116 407; and Rep. Brit. Assoc. 1915 397) namely, - - ~ -E/RT2 where R is the gas constant and E is the critical increment of internal energy which the molecule must receive before i t can react. This equation leads to an integrated equation of the same form as that of Arrhenius; hence it is equally in accord with the experimental results. It has the merit also that E represents a definite physico-chemical property of the substances and which can be measured. Lewis (T. 1916 109 796) by suggesting that the increase in internal energy E’ which the molecule must receive before reacting is communicated t o it by the infra-red radiation present in the system and absorbed in quanta of a definite frequency correlates the velocity of reaction effect of temperature and added catalyst or solvent.Applying Planck’s radiation formula t o the Marcelin-Rice equation Lewis draws the necessary conclusion that ‘‘ any agency which increases the reaction velocity (positive catalysis) diminishes the temperature-coefficient of the constant ; any agency which diminishes the velocity (negative catalysis) increases the value of the coefficient.” Skrabal (Adonatsh. 1916 37 495) from an entirely different line of argument arrives at a more general conclusion that the relations between reaction velocity temperature effects influence of the sol-vent added catalyst and photocheniical action are all essentially the same; accordingly change in the reaction velocity effected by any one of these factors diminishes as the magnitude of the velocity-constant rises.A special case of this generalisation is clearly that the temperature-coefficient will be inversely as the velocity in the presence of any given solvent or catalyst. Experimental evidence either for or against these conclusions is up to the present rather scanty. Since the examples quoted by Lewis a few more results have been published by Dhar (T. 1917, 101 707) who has obtained results from the investigation of cer-tain reactions sensitive to light in which there is a gradual diminu-tion of the temperature-coefficient as the velocity rises due to the increased concentration of the catalyst in aqueous solution.These experiments differ from those contemplated by the radiation hypo-thesis (ordinary thermal reactions) in being truly photochemical. Apart from the question of the possible relations between the physical properties or chemical constitution of a solvent and its effect on the reaction velocity it has been suggested that it may for purposes of temperature-coefficients be considered purely from the point of view of a catalyst; the experiments here described were d . log k -d TEMYERATURE-COEFFICIENT OF CERTAIN REACTIONS. 145 designed specially to test this application of the quantum theory in so far as it leads to a relation between velocity and temperature-coefficients. Two reactions have been measured in a range of sol-vents so selected as to obtain as wide a difference as possible in the velocities at one temperature and the value of the temperature-coeffi-cient in each solvent has been found.I f Lewis’s deductions are correct there must be an inverse proportionality between velocity and temperature-coefficients. One of the reactions measured is between molecules only and is measured in a series of dissimilar solvents; the other is a dual reac-tion beiween ions and molecules jointly and has been measured in a series of related solvents. The object of this is to test the radiation hypothesis under widely differing conditions and to find in what respect its conclusions require modification on account of the special effects of a solvent such as ionisation and the formation of definite complexes or intermediate compounds which is indicated by the experimental results of so many papers to be found in the litera-ture and is supported by the conclusion deduced in the former paper that solvent action is in part a constitutive property of the solvent.The results will be discussed after the experimental data have been summarised. E x P E R I M E N T A L . The Velocity of the Reaction of w-Bromoacetophenone with Aniline. This reaction is a simple addition no further change taking place i n non-aqueous solut>ion; this is shown by the analysis of the pro-duct. The bromoacetophenone was prepared by Rather and Reid’s method ( J . -4mer. Chern. Soc. 1919 41 75) and recrystallised several times from hot alcohol.The aniline was redistilled and frac-tionated immediately before use (b. p. 183‘5-184O). The requisite quantities were dissolved separately so as to make the resulting solution N / 2 with respect to each substance; a quantity of the solution was placed in each of six small tubes placed in the thermo-stat and the time counted from the moment of removing the first tube after allowing time for the tubes to atta.in the temperature of the bath. In methyl and ethyl alcohols in which the reaction is very fast the mixture was made in a small flask in the thermostat and a fraction withdrawn a t intervals by a specially calibrated pipette. The reaction was followed by pouring the contents of the tube into cold water containing 5 C.C. of N/lO-silver nitrate and some ferric sulphate acidified with nitric acid; the excess of silver nitrate was then titrated wit,h N/lO-thiocyanate.This gives 146 cox THE INFLUENCE OF THE SOLVENT ON THE measure of the concentration of the product containing the ionised halogen. The temperatures for this reaction were 27*8O 37*8O and 47*8O registered on a standard thermometer. Time is reckoned in minutes and the value of the velocity-constant obtained from the usual bimolecular equation; the results are calculated in terms of gxam-molecules per litre. From the examples given below it will be seen that the results are concordant over the range of concentration investigated and in certain of the solvents in which after a time the salt produced begins t o crystallise out there appears no change in the velocity-constant .Duplicate experiments were made in several solvents and the agreement is satisfactory. The solvents used for this reaction were benzene chloroform, nitrobenzene acetone and methyl ethyl +butyl and benzyl alco-hols. These solvents were in each case carefully dehydrated and redistilled or fractionated the same batch of solvent being used for each temperature so that no variation in the temperature-coefficient could be due to a variation in the purity of the solvent. A few examples of the experimental data are as follows: T~BLE I. Solvent Chloroform. Tern pera tur e 2 7 * 8O. 1.646 C.C. titrations. t. KCNS/10. AgNO,/10. k. 0" 4.92 4.92 -68 4.65 4.92 0.000997 174 4-30 4.92 0.000937 263 3.99 4.92 0.000966 328 3.78 4.92 0.000981 Mean .... . . . . . 0.000970 Temperature 47*8*. 1.646 C.C. titrations. t. KCNS/10. AgNO,/10. k. 65 4.20 4.92 0.00295 149 3.38 4-92 0.00309 270 2-66 4-92 0.00281 335 2.10 4.92 0.00311 Mean ......... 0.00299 - c)" 4-92 4.92 Solvent Methyl A41cohol. Temperature 27-8O. 1,646 c.c titrations. t. KCNS/lO. AgNO,/10. k. 0" 9-63 9.83 -6 8.80 9.83 0-0404 11 8.34 9.83 0.0367 17 7-68 9-83 0.0400 21 7.42 9-83 0.0384 Mean ......... 0.0389 Temperature 47.8O. 1.646 C.C. titrations. t. KCNS/10. AgNO,/lO. k. 0" - 4-92 2 3-78 4.92 0-161 4 3-13 4-92 0-139 5 2.86 4.92 0.134 6 2-51 4.92 0.138 Mean ......... 0.143 TEMPERATUSE-COEFFICIENT OF CERTAIN REACTIONS. 147 TABLE I.-continued. Solvent Nitrobenzene. 1 Solvent Acetone. Temperature 37*8O.1 Temperature 37.8O. 1.646 C.C. titrations. t. KCNS/10. AgNOS/lO. k. 0" 4.92 4.92 -15 4.14 4.92 0.014.0 25 3.73 4-92 0.0136 42 3-06 4.92 0.0139 51 2-80 4-92 0.0136 &lean ......... 0.0135 1.646 C.C. titrations. 1. KCNS/lO. AgNO 110. k. - 4-92 - 0" 11 3-89 4.92 0-0260 16 3.43 4.92 0.0277 24 2-97 4-92 0.0260 28 2.61 4.92 0.0279 I Mean ......... 0.0269 !J%e results of these and other experiments are summarised in table TI. TABLE 11. Temperature. Solvent. Ethyl ether ............... Benzene ..................... Chloroform ............... Nit robenzene ............... Acetone ..................... Benzyl alcohol ............ n-Butyl , ............ Ethyl , ............ Methyl , ............ 2'7.8". 0.000607 0.000644 0.000970 0.00617 0.0139 0.0208 0.0267 0.0290 0.0389 37.8".0.000985 0.00186 0-0135 0-0269 0.0440 0.0550 0-0626 0.0748 I 47.8". 0.001 50 0.00299 0.0262 0.00440 0.0924 0-1 16 0.124 0.143 -The velocity in methyl alcohol which is the most rapid is about seventy times that of the slowest of the series a t the one tempera-ture and the other solvents examined give a good range of varia-tion for the velocity-constant so that if the temperature-coefficient is proportional to the velocity a distinct difference in its value is reasonably to be expected. Before proceeding to this point it is necessary to find whether the integrated equation of Arrhenius or of the radiation theory is in agreement with the experimental results.This may be coiiveniently tested graphically for it is clear that if the logarithm of the velocity is plotted against the reciprocal of t,he absolute temperature the results should lie upon a straight line if the equation is applicable. The slope of the line will indicats approximately the temperature-coefficient. The figure shows that these results are represented by the equation in question within the limits of experimental error. Tempernt ur e-co e ficients. The most usual form of expressing temperature-coefficients is by the ratio-kt+l" the value of which for reactions a t ordinary tem-k 148 cox THE INFLUENCE OF THE SOLVENT ON THE peratures is generally from 1.5 to 3.5 for thermal reactions very large or very small values being usually associated with photochemi-cal effects.It is however clear from the form of the equation d log k / d t = E J R P that the ratio for ten degrees varies inversely with the temperature so that it is essential in comparing the tem-perature-coefficients for the reaction in all solvents that the same range of temperature be considered in all cases. The values of the w -Bromoacetophenone and aniline. 1 x 106 Absolute temperature. .__-above ratio over the range 27.8O to 47.8O are shown in table 111; it will be noted that the ratio k87.80/k2i.y4 is slightly higher than the ratio k47.So/k37.80 as is required by the theory. The effect of temperature on the velocity is however better expressed in terms of the ra.diation theory by E which represents the extra amount of energy in calories per grain-molecde which is required t o enable the reaction to proceed.This constant is incie TEMPERATURE-COEFFICIENT OF CERTAIN REACTIONS. 149 TABLE 111. k m Solvent k2’1.80 Benzene ........................ 1.53 Chloroform .. . . ..... . . ... ... . 1-92 Nitrobenzene . . . . . . . . . . . . . . . . . . 2.19 Acetone ........................ 1.93 Benzyl alcohol . . . . . . . . . . . . . . . 2.12 n-But$ . . . . . . . . . . . . . . . 2 * OG Ethyl . . . . . . . . . . . . . . . 2.16 Methyl , ..........._... 1.93 , ,, k c k.3,.80 1.52 1.61 1.87 1-64 2.10 2.10 1-98 1.91 k47.80 k27.80‘ 2-33 3-09 4.08 3.16 4.44 4.33 4-28 3.69 pendent of temperature and may therefore be used for the com-parison of differentp reactions over different ranges of temperature.The mean values of E for this reaction are shown in table IV; R the gas constant is taken as 1.985 calories. TABLE IT. Solvent.. w. Benzene . . . . . . . . . . . . . . . . . . . . . . . . 8088 Chloroform . . . . . . . . . . . . . . . . . 10760 Nitrobenzene . . . . . . . . . . . . . . . . . . 13470 Acetone . .. . . . . . . . . . . . . . . . . . . . . . 11080 Renzyl dcohol . . . . . . . . . . . . . . . 14290 14060 13910 Methyl ,. ............... 12440 n-BLItyl , . .. . . . . . . . . . . . Ethyl ,) . . . . . . . . . . ... . k s 7 4 0.000985 0.00186 0.01 35 0.0269 0-0440 0.0550 0.0626 0.0748 The value of the temperature-coefficient for this reaction is smaller tha.n is frequently the case; especially is this so in solvent benzene.This suggests the possibility that the reaction is sensitive to light or is photochemical; all the reactions in these papers were conducted in the dark in a covered thermostat. Experiments in benzene showed that there is no difference in the velocity of this reaction in the dark or in strong sunlight. The Reaction bet w e e n Sodium fi-Naphthoxide and Ethyl Iodide. This reaction and the influence of the solvent upon it has been investigated in some detail by the author (T. 1918 113 666 821; 1920 117 493). It differs essentially from the reaction of bromo-acetophenone with auiline in that it is a dual reaction between ions and molecules of the base (in different proportions in the different solvents) and the molecules of alkyl iodide.It has been shown, too that there exists some relation between the chemical constitu-tion of the solvent and its effect on the velocity. The details o 150 cox THE INFLUENCE OF TTIE SOLVENT ON THE the preparation of the solvents and reactants and the method of measurement is the same as has been described in the last paper. The temperatures a t which the velocity has been measured are 40*0° 5 0 ' 5 O and 68.2O. The solvents used are nine alcohols, namely methyl ethyl n- and iso-propyl 12- and iso-hutyl iso- and tert.-arnyl and benzyl alcohols; the range of variation of the velocity at any one temperature is about fifteen t o one so that a small but; distinct change in the value of the temperature-coefficient is reasonably t o be expected.Although there are indications that i n some of the associating solvents the reaction is very fast com-pared with that in the alcohols it is not possible to measure the velocity under comparable conditions because of the relative insolu-bility of the sodium salt in them. It has been shown also that the initial concentration has a very large effect on the velocity; this change due to initial concentration is not found in the reaction of bromoacetophenone and a study of the literature suggests that such effect is an indica,tion of the dual nature of the reaction in which it is obserked. A small point here t o be noted is that while in the reaction of bromoacetophenone with aniline the precipitation of the salt has n3 effect on the velocity in the reaction of sodium naphthoxide the precipitation of the ether formed has a very marked effect in accel-erating the reaction; ccnsequently one is limited t o solvents in which the products are completely soluble to nearly normal concentration.The experimental results are exemplified and surnmarised in tables V and VI. TABLE V. Solvent isoAmyl Icohol. Temperature 68'2O. #-Ethyl iodide. rV-Sodium naphthoxide. 1-00 C.C. titrated with t. Q - x. k. 0 21-36 -3 19.75 0.0316 6 15-30 0.0325 9 17.20 0.03 14 12 16-00 0.0326: 15 15.15 0.0320 Mean ......... 0.0320 N / 2 5 -HC1. Sotvent n-Butyl Alcohol. Temperature 6 8 * 2 O. iV-Ethyl iodide. N-Sodium naphthoxide. 0.498 C.C. titrated with: t. a - x. k. 0 10-70 3 9.20 0.0632 5 8-45 0.0819 7 7.75 0.0632 9 7-15 0.0642 11 6.70 0.0631 Mean .........0-0631 N / 25-H C1. TEMPERATURE-COEFFICIENT OF CERTAIN REACTIONS . 15 1 Sohent . Ethyl rtlcohol ............ i PoPropyl .............. Methyl .............. n-Propyl .............. . %.BUtyl .............. im B tit. yl .............. Benzyl .............. iso Amyl .............. tcrt . -Amy1 .............. TABLE V I . k40.00. 0.007 9 0 0-00646 0-00460 0.00442 0.00404 0-00399 0.00273 0.00223 0.000533 k50.50' 0.0212 0.0177 0.0130 0.0127 0.0 107 0.0113 0-0078 1 0.00649 0.001 55 kz** ... 0.125 0.101 0.0875 0.0868 0.063 1 0.0525 0.0456 0-0320 0.00987 On plotting the values of log Tc against the reciprocal of the absolute temperature it is again found that the experimental results are accurately represented by the integrated equation of Arrhenius or of the radiation theory .The mean values of E. the real tem-Ferature.coefficient. may. therefore. be calculated with the results set out in table VII. in which the solvents are placed in the order of decreasing velocity . TABLE V I I . Solvent. . Ethyl alcohol ............... isoPropyl ................. n-Propyl ................. i8oButyl ................. Benzyl ................ iso Amyl ................. tert .. Amyl ................. Methyl ................. rt-Butyl ................. E . 19840 19990 21010 21300 19650 19650 20650 20240 21190 k40'00' 0.00790 0.00646 0*00460 0.00442 0-00404 0.00399 0-00273 0.00223 0.000533 For the purpose of comparison of the temperature-coefficients of this reaction with those of the addition of bromoacetophenone to aniline.the values of the ratio kt,., / k t for 37-8O and 4 7 ' 8 O are set out in table VIII. and it will be observed that they are consider-ably higher in all the solvents than those of the aniline reaction. the velocity of which is much higher a t the same temperature in those solvents which are common to the two sets of experiments . TABLE VIII . Solvent . Ethyl alcohol ............... isoPropy1 ................. Methyl ................. n-Propyl ................. n-Butyl ................. i3oRut. y 1 ................. Benzyl ................. iso Amyl ................. tert . -Amy1 .................k47'R*/JCQ7'80' 2-73 2.75 2-89 2.93 2.70 2.70 2.84 2.78 2.92 k47.80' 0.0188 0-0156 0.0109 0-0105 0.00957 0~0100 0.00664 0.00563 0.00 12 152 cox THE INFLUENCE OF THE SOLVENT ON THE On the radiation hypothesis some importance attaches to the refractive index of the solvents and its temperature-coefficient strictly the value of n for the infra-red wave-lengths is concerned, but it has been shown that f o r many liquids the refractive index for the infra-red region is close to that for the visible portions of the spectrum (compare for example the results of Seegert Diss., Berlin 1908 who finds the refractive index for many liquids in the infra-red and whose results are not much different from those given for the &line).* It is therefore sufficient for the present purpose to refer to the temperature-coefficient for the refractive index for the sodium line; the error so introduced will be small.The values of n and its temperature-coefficient for all the solvents are set out in the following table. These have been determined by the author in most cases; reference is given to those taken from the literature (Landolt-Bornstein). T ~ L E IX. Solvent. nD at 20”. dnldt. Methyl alcohol ............ 1-3290 0.00040 Ethyl alcohol ............... 1.3617 0.00040 n-Propyl , ............... 1.3849 0.0003 1 isoPropy1 ............... 1.3795 0.00030 n-Butyl , ............... 1.3992 0.00026 iso Amy1 ............... 1.4053 0.00026 tert. -Amy1 , ............... 1.4042 0.00030 Benzyl , ...............1.5402 0.00037 Acetone ........................ 1.3687 0.00039 Benzene * ..................... 1.5014 0.00065 Nitrobenzene ............... 1.5421 0.00033 Chloroform ti .................. 1.4462 0*00059 isoButyl ............... 1.3937 0*00046 Jahn Ann. Phrys. Chem. 1591 [iii] 43 301. Ketteler ibid. 1858 [iii] 33 508. Weegmmn Zeitsch. pliysiknl. ChPm. 1858 2 337. Lewis T. 1916 109 796. Lorenz Ann. Phys. Chem. 1880 [iii] 11 70. There is no apparent connexion between the value of n and its temperature-coefficient. By using Einstein’s law of the photochemical equivalent which Lewis shows to be applicable on the radiation theory the wave-lengths and frequencies of the infra-red radiation absorbed can be calculated. Taking Avogadro’s number as 6.85 x 1023 and Planck’s constant as 6.55 x1O-27 the wave-lengths (in microns) and the frequencies (21) for the bromoacetophenone reaction are as follows : is not accessible in this country.* These data are taken from IAandolt-B6rnstein’s tables. Seegert’s pape TEMP~RATURE-UOEFBICLE" OF UEICTAJN REACTIONS. 163 TABLE X. Solvent. Benzene ........................ Chloroform .................. N trobenzene .................. Acetone ........................ Henzyl alcohol ............... n-Butyl y y ............... Methyl ) ............... Ethyl , ............... Frequency v. 7.57 x 1013 9.85 x 10'3 1-04 x 1014 1.26 x J0'4 1.34 x lo1& 1.31 x 1014 1-30 x 10l4 1.16 x 1014 it'ave - leiig th ( p ) . 3.96 3.04 2.38 2.89 2.24 2.29 2.30 2.58 These are of course mean values as it is not supposed that only one frequency is concerned.F o r the reaction of sodium naphth-oxide with et,liyl iodide trhe values of u and p are near together and lia between u = 1.84 x 10'4 p= 1.63 and u = 1.98 x 1014 ,U = 1.51 respectively. DiscussioiL of the Results. It is quite evident that if the application of the radiation theory to the problem of the r81e of the solvent in chemical kinetics is to be accepted other factors must be considered which may exert a very considerable modifying influence on the true E value as distinct from that observed for there is no obvious relation between the observed velocities and their temperature-coefficients. Some of these factors and the question of the legitimacy of comparing reactions in different solvents and of treating the solvenf as an added catalyst will now be briefly considered.The Influerice of the Refractive Index of the Solvent. The equations for the velocity of reaction on the radiation theory are deduced by multiplying the ordinary concentration terms by the radiation density which is supplied by the solvent or added catalyst. This is given by Planck's equation, in which expression h is the universal constant u is the absorbable frequency n the refractive index for the wave-length concerned, c the absolute velocity of light and Ic the gas constant. The ex-pression shows that the requisite energy supply is proportional to the cube of the refractive index so that variation of the latter with temperature may be important in modifying the value of E .i t has been shown that the value of the temperature-coefficient of' the refractive indices of these solvents varies froiii dn / d t =0*0002 154 COX THE IWPLUENCE QF THE SOLVENT ON THE to 0.00065 so that the effect of this on the observed E value may bo calculated. Instead of writing dnldt the temperature-coefficient of the refractive index may be expressed by writing nt=no- bt and when P Lewis (Zoc. cit.) deduces the equation b no is written St,arting from follows : this equation. the effect of b can be calculated as - 3/39 d log 16 - E - -dt for by Einstein's law E = Nhv. Integrating this expression between the limits T and TI, The effect of this correction is illustrated by calculating the corrected valne for E' for the first reaction in solvent benzene for in this liquid fl has the greatest value and so the correction will be greatest.The corrected value for h' works out to 8330 using the approximate value for no. This correction is not negligibly small when E is conipared with the mean uncorrected value 8088 given in table IV; its magnitude is comparable in value with the possible experimental errors and will not alter the general relationship between velxi ty and temperature-coefficients. I n the second reaction in the alcohols the correction for the tern-perature-coefficients of the refractive indices will be smaller than the value calculated out. for benzene because p is smaller and the E value to be corrected is larger. The Effect of Dissociation of the Solute.This cannot be treated in a precise manner. The fundamental relationship of the radiation theory is deduced from an equation of the form (for a unimolecular reaction) d x / d t = A. ( a - z) x G x U, where C is the concentration of the added cata-lyst or solvent and U is the radiation density which for simplicity is considered as of a single frequency v. In a bimolecular reaction there vill be energy absorbed in quanta by each of the reactants so that two radiation density terms are concerned. I f however the reaction is a dual one and the reactants are ionised in solution both the ions and the molecules are concerned and there will be energy absorbed in quanta by the ions and the molecules. There will the TEMPERATUEE-COEFFICIENT OF CERTAIN REACTIONS.155 bs three or four (if both reactants are ionised) characteristic frequencies. It has been shown in a previous paper that the reaction of sodium naphthoxide concerns ions and molecules of the base and molecules of the alkyl iodide ; three frequencies are therefore concerned. The work of Acree and others makes it clear that the ions are about five times as reactive as the molecules in these bases. The relation between these factors is expressed by the equation (com-pare Robertson and Acree Amer. Chem. J. 1913 49 474)) So that to correct the values of E obtained for the reactions it is necessary to know the extent of ionisation of the reacting sub-stances in a variety of solveiits; also by means of velocity measure-ments a t different concentrations to find the values of ki and k,, then t o incorporate these into the equations of the radiation theory.‘Such data are not available a t present but in the author’s view this is the explanation of the observed facts in the reaction of sodium naphthoxide that the teniperature-coefficients are not in the inverse order of the velocities. This is borne out by a con-sideration of the probable extent of ionisation as evidenced by the dielectric constants of the solvents. and iso-propyl their dielectric constants are similar and in them it may be supposed that the extent of dissociation is also similar; their other properties also are only slightly varied. In these solvents the temperature-coefficients are inversely as the velocities. Considering the first four alcohols methyl ethyl n-TABLE XI.Dielectric Solvent. constant. h7.8- E. Ethyl alcohol ............... 26 0.0188 19840 isoPropy1 , ............... 26 0.0156 19990 Methyl , ............... 33 0.0109 21010 n-Propyl , ............... 23 0.0105 21300 n- and iso-Butyl alcohols have the same dielectric constants and in them both the velocity and E are practically the same. With the increasing length of the carbon chain in the higher alcohols the dissociating power connected with the hydroxyl group un-.doubtedly becomes less so that these members of the series cannot be compared with the lower members from the point of view of probable ionisation. Also it mag be noted that isoamyl and benzyl alcohols have simi 156 COX THX INFLUENCE 04’ ‘l’HJ3 SOLVBBT ON THE lar dielectric constants (lG) and here again the observed tempera-ture-coefficient is inversely as the velocity.A simi!ar deduction is possible in the reaction of bromoaceto-phenone (which is not ionised in organic solvents) for whilst there is no apparent relation between the velocity and temperature-coeffi-cisnt in the whole range of solvents when similar solvents are compared such relation appears. It is even possible to compare scilvents which are not comparable for the other reaction because in this reaction differences of ionisation do not arise. On comparing the alcoholic solvents used €or the bromoacetophenone reaction the relation is quite evident. TABLE XII. Solvent,. liq,.Bo. 15’. Benzyl alcohol ............... 0.0924 14290 ta-Butyl ...............0.116 14060 E thy1 ............... 0.124 13910 Methyl ............... 0.143 12440 I s the Solvent to be Treated as a Catalyst? The results of this investigation as a whole indicate clearly that the deductions of the radiation theory are supported by the facts when similar solvents are considered and when t h e state of the solute in the solvents is strictly comparable. I n dissimilar liquids the relations of temperature-coefficients and velocity are quite dis-cordant. This shows that the influence of a solvent is more than that of a simple catalyst; it actually participates in the reaction. It is on this account that the effect of a solvent is partly constitu-tive for if it be supposed that the solvent forms a definite com-pound or complex with the solute by means of residual affinity (in the sense used by Baly “ Spectroscopy,” 1918 edn.486) it is clear that the velocity will depend upon the constitution of the solvent-solute complex and this in turn will depend on the constitution of the solvent and of the solute. The fact that velocities in different solvents are a t all comparable will be due to the ‘dominating influ-ence of the solute on the constitution of the complex. The internal energy of the complex will be specific so also will be its critical increment; hence in general there will be no proportionality in dissimilar solvents between the velocity and the temperature-coefficient. When however solvents are ohemically similar and the conditions above referred to respecting the extent of dissoci-ation are fulfilled then the solvent may be considered purely as a catalyst for the purposes of calculation on the radiation theory TEMPERATURE-COEFFICIENT OF CERTAIN REACTIONS.1 57 and the critical increment of internal energy will be less as the velocity increases. In additicn to the experimental data recorded in this paper the above conclusions are supported by the results of von Halban (Zeitsch. physikal. Chem. 1909 67 129) for different solvents. These results show no relation between the velocity and tempera-ture-coefficients over the whole series of solvents which are very diverse in kind; but when similar solvents are selected from the list the values of E are inversely as the velocity (von Halban cal-culates the il of the Arrhenius equation which is of course pro-pcrtional to the E of the radiation theory).The figures are shown in table XIII and refer to the rate of decomposition of triethyl-sulphine bromide. TABLE XIII. Solvent. k70-Benzyl alcohol ............... 0.00010 n-Propyl , ............... 0.00018 isoAmyl , ............... 0.00045 A . 7450 7380 7260 Summary. The influence of eight chemically dissimilar solvents upon the temperaturecoefficients of the reaction of bromoacetophenone with aniline and of nine chemically similar solvents upon the reaction of sodium P-naphthoxide with ethyl iodide has been measured. The equation of Arrhenius for the effect of temperature does not require any relation between the velocity and temperature-coeffi-cient but the mathematical development of the radiation theory by Lewis and others requires that the temperature-coefficient of the reaction in the several solvents shall be inversely proportional t o the velocity in that solvent, These experiments have been designed to test this deduction of the radiation theory and to throw some light on the r61e of the solvent in chemical kinetics by showing to what extent the solvent may be considered as a simple catalyst; and to what extent it has a constitutive effect dependent upon the chemical constitution of the solvenbsolute complex.Temperature-coefficients of tho refractive indexes of the solvents for the B-line have been measured and the effect of this on the temperaturecoefficient of the velocity is considered ; the effect of dissociation of the solute in the case of the reaction of sodium naphthoxide is also discussed. It is found that the temperature-coefficient is inversely as the velocity in similar solvents for the reaction of bromoacetophenone, G 158 COX THE INFLUENCE OF THE SOLVENT ETC. and for the reaction of sodium naphthoxide in those solvents in which the extent of ionisation is similar; but that the relationship does not hold for dissimilar solvents so that these cannot be regarded as simple catalysts and the radiation theory does not apply in such cases. The radiation theory is therefore supported by these results when allowance is made for the special effects of solvents. The view is taken that reactions proceed by the formation of intermediate solvent-solute complexes solvent action being a constitutive pro-perty by reason of the effect of the solvent on the constitution of the complex. Tzle author again wishes to record his thanks to Mr. G. Rudd Thompson for providing all facilities for this work. 69 DOCK STHEET, NEWPORT MON. [Received November 20th 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900142

出版商:RSC    

年代:1921

数据来源: RSC

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FARGHER ARYLAZOGLYOXALINECARBOXYLIC ACIDS. 159 tion one of the carboxylic acid groups being displaced by the arylazo-group. The same product namely 4-p-bromobenzeneazo-2-phenylglyozaline-5-carboxyl.ic acid is obtaingd when the mono-carboxylic acid is substituted for the dicarboxylic acid in the reaction. Similar results are obtained with 2-methylglyoxaline-4 5-dicarb-oxylic acid although in this case the reaction appears to proceed rather more slowly. It had been anticipated that as the possibilities of benzidine formation had been very largely excluded the reduction of these compounds with cold stannous chloride solution would lead to the corresponding amino-acids and that although subsequent trans-formation into the glyoxalone might be anticipated in the oase of the 2-methyl derivative unless indeed the presence of the adjacent carboxylic grouping proved inhibitive in that of the 2-phenyl derivative stability might reasonably be anticipated as it had already been ascertained that the reduction of 4-p-bromobenzene-azo-2-phenylglyoxaline led to a substance which almost certainly possessed the constitution 5 -amino-4-( 2/-amino-5’-bromophenyl)-2-phenylglyoxaline.The reaction follows a somewhat novel and unexpected course the second carb-oxylio grouping being eliminated during the process of benzidine formation the acids yielding the same products as the correspond-ing non-carboxylated glyoxalines. I n view of these results it appeared to be of interest to examine the reduction of 2-p-bromo benze~neazoglyoxaline-4 5-dicarboxylic acid under similar conditions.The tendency towards benzidine formation is here sufficiently less pronounced to permit of the isolation as main product of 2-p- brornobenzenehydrazoglyoxaline-4 5-dicarboxylic acid. It has already been shown that glyoxalinedicarboxylic aoid and its %methyl homologue are not acted on by a warm mixture of nitric and sulphuric acids (T. 11319 115 217). 2-Phenylgly-oxaline-4 5-dicarboxylic acid reacts under these conditions but as the composition of the product indicated that substitution had taken place only in the benzene nucleus its further examination has been omitted. This has however proved not to be the case. E x P E R I Y E. N T A L. 4-p-Bromo benzeneazo-2-phenylglyoxaline-5-car boxylic A cid. A .solution of 6.8 grams of p-bromoaniline in 130 C.C.of 10 per cent. hydrochloric acid was diazotised with 2.88 grams of sodium 6 160 PARGHER ARYLAZOGLYOXALINECJARBOXYLIC ACIDS. nitrite and added to an ice-cold1 solution of 9'23 grams of 2-phenyl-glyoxaline-4 5dicarboxylic acid in 400 C.C. of water containing 67.2 grams of sodiym carbonate crystals when gradual separation of a deep orange preoipitate took place. After five hours this was collected. It consisted of the sodium salt of 4-p-bromo bertzene-azo-2-phenylglyoxaline-5-car boxylic acid admixed with that of the unchanged acid. Separation was readily effected by crystallisation from water containing a little sodium carbonate the former dis-solving very sparingly in cold water. The corresponding acid was readily obtained on acidification and was further purified by crystallisation from aloohol.4-p- Bromo benz eneazo-2 -phenylgEyoxaline-5-car boxylic acid is in-soluble in water and only very sparingly so in alcohol from which i t separates in glistening red needles which darken on heating above 160° and effervesce and decompose a t 210° (corr.). It dis-solves in sulphuric acid with the production of an eosin-red color-ation (Found C= 51.6 ; H = 3.3 ; N = 14-8. C,6H,,0,N,Br requires C=51*6; H=3.0; N=15*1 per cent.). The sodium salt separates from water as a felted mass of orange needles containing 3H20 (Found loss a t 60° in a vacuum =12*0. C16Hl,0,N,BrNa,3H20 requires B20 =11*8 per cent. In dried material Na =5*6. C,,H,,O,N,BrNa requires Na = 5.8 per cent.).The same product was obtained1 when 2-phenylglyoxaline-4-carb-oxylic acid was substituted for the dicarboxylic acid. Reduction.-Four grams of the acid were triturated with 25 C.C. of concentrated hydrochloric acid and gradually treated with 14 O.C. of stannous chloride solution,* the trituration being con-tinued until the completion of the experiment. Evolution of carbon dioxide quickly became evident. The insoluble stanni-chloride was collected freed from tin by means of hydrogen sulphide and the resulting solution evaporated to low bulk under diminished pressure when separation of a crystalline hydrochloride took place. This was purified by recrystallisation from water con-taining a little hydrochloric acid and formed colourless needles melting a t 255O (corr.).This was fully identified by analysis (Found C ~ 4 5 . 1 ; H=4*0; N=13.6. Calo. C=44*8; H,=3*8; N = 13.8 per cent.) by the preparation of the triacetyl derivative (Found N=12*2. Calc. N=12-3 per cent.) and by its reactions (T. 1919 115 257) as 5-amino-4-(2/-amino-5'-bromophenyl)-2-phenylglyoxaline (T. 1920 1\17 671). In an attempt to characterise and compare the two products more completely it was found that sodium acetate yielded a grey precipi-tate which redissolved on adding a little acetic acid and warming, * Prepared as described in the earlier communications F'ARGHER ARYLAZOGLYOXALINECARBOXYLIC ACIDS. 161 and separated in clusters of minute needles melting a t 1 6 1 O (corr.). This proved to be the monoacetate of the base (Found C'=52*1; H =4*8 ; N = 14.1.C,,Hl3N,Br,C2R,O2 requires C = 52.4 ; H =4*4 ; N = 14-4 per cent.). Ammonium oxalate yielded a grey precipitate, which darkened rapidly on warming the solution. Addition of excess of sulphuric acid to the concentrated solution of the hydro-chloride caused on stirring the separation of a sparingly soluble sulphate which crystallised in minute flattened prisms. Ammoniacal silver nitrate was reduced in the cold. After separation of the above hydrochloride no further orystal-line material was obtained as the solution decomposedl rapidly on exposure. The residue after removal of tin from the soluble stanni-chlorides amounted to only 0.5 gram and consisted mainly of ammonium chloride although a little p-bromoaniline (0.07 gram) was isolated and identified by means of the acetyl derivative.Reduction with sodium hyposulphite in alkaline solution gave p-bromoaniline in a yield amounting to 52 per cent. of the theoretical but no other pure substance was isolated. The form-ation of small quantities of a blue dye similar t o that obtained by the reduction of nitroglyoxaline was observed. 4-pBromo b enxeneaz o-2-methylglyoxaline-5 -car boxylic A cid, This substance was prepared in a similar manner to the 2-phenyl homologue. Starting with 7.52 grams of 2-methylglyoxaline-4 5-dicarboxylic aoid the precipitate which formed was collected ( A ) and the filtrate acidified with hydrochloric acid when 2 grams of pale orange crystals were obtained. These dissolved somewhat sparingly in alcohol and separated in glistening orange needles.The precipitate ( A ) was suspended in water and acidified with hydrochloric acid when it gave 7 grams of an orange powder con-sisting of a mixture of the azo-compound and the unchanged acid. Separation was effected by extraction with and crystallisation from alcohol in which the original acid is practically insoluble, when 5.4 grams of 2-methylglyoxalinedicarboxylic acid were recovered unchanged. I n a later experiment the reaction was allowed to proceed for several hours but although the yield of the product was larger it was much darker in oolour and more dificult to purify. The ultimate filtrates from the recrystallisation from alcohol yielded a small proportion of a product approximating in composition to 4 5-bis-pbromobenzeneazo-2-methylglyoxaline but owing t o the ease with which resinification took place it was not obtained pure 4-p-Bromobenzeneazo-2-methylglyoxaline-5-c~r boxylic acid separ-ates from alcohol in which i t is somewhat sparingly soluble in orange needles containing 4R20.It is very sparingly soluble in water and dissolves in concentrated sulphuric aoid with the pro-duction of an orange-red coloration. On heating i t darkens rapidly above 160° (Found loss a t 60° in a vacuum=3.2. $H,O requires 2.8 per cent. I n dried material C=43.0; H=3.2; N= 17.8 ; Br = 25.4. C,,H,O,N,Br requires C = 42.7 ; I3 = 2.9 ; N = 18- 1 ; Br = 25.8'5 per cent .). Reduction.-On reduction as described in the previous case the evolution of carbon dioxide was again noticed. The insoluble stannichlorides which accounted for almost the whole of the start-ing material yielded 2-me thy1 -4 - ( 2 '-amino-5 '-bromo phen yl) -5 -glyoxalone hydroohloride which melted a t 2 7 2 O (corr .) the mix-ture with the reduction product of 4-p-bromobenzeneazo-2-methyl-glyoxaline melting a t 272O in the same bath (Found C=39*2; H = 3.9 ; N = 13.7.C,,H,,ON,Br,HCl requires C = 39.4 ; H = 3.85 ; N=13*8 per cent.). The identity was further confirmed by isolation of the base and picrate and by comparison of the reactions of the bases from the two sources both of which gave the reactions previously described (T. 1920 117 677). 2-p-Bromobenzenenzo~lyoxal~ne-4 5-dicar boxylic A cid. This was prepared in the manner already described. The pre-cipitate which formed fairly rapidly was collected after three hours.The filtrate on acidification gave a further quantity of the azo-compound admixed with the unchanged acid. The pre-cipitate was boiled with water containing a little sodium carbonate, leaving a dark brown residue insoluble in sodium carbonate or sodium hydroxide.* The extract on acidification gave an orange-red precipitate which after boiling with alcohol and drying, darkened above 200° and melted and effervesced a t 250° (corr.). It dissolved but sparingly in alcohol and separated in bunches of minute red needles which melted a t the same temperature and contained lC,H,O (Found in air-dried material C = 40.9 ; H = 3.7 ; N = 14.6; Br = 21.3; loss a t looo in a vacuum = 11.5. C,,H,O,N,Br,C,H,O requires C = 40.5 ; H = 3.4 ; N = 14.55 ; Br = 20.75 ; C2H,0 = 12.0 per cent.I n dried material C = 39.3 ; H=2*4. Reduction.-The reduction was carried out as in the previous instances. The decolorised solution from 4 grams of the azo-deriv-C,,TI,O,N,Br requires CL=38.95; H=2.1 per cent.). * This is possibly 2 4 5-tris-p-bromobenzeneazoglyoxaline ative on dilution with water gave a precipitate amounting to 3 grams This dissolved sparingly in water dilute acids and the usual organic solvents but rather more readily in 50 per cent. acetic acid from which it separated in clusters of minute needles. On heating these darkened rapidly above 190° and effervesced a t 203O (corr.) (Found loss a t looo in a vacuum = 2.9. C,,H,O,N,Br,~H,O requires H,O = 2.6 per cent. I n dried material C=39-1 39-0; H=3-1 3.0; N=16*2 16.3; Br=23*8.CIIH,O,N,Br requires C'= 38.7 ; H= 2.7 ; N = 16.4 ; Br = 23.4 per cent .). In aqueous solution the following characteristic reactions were observed with warm dilute hydrogen peroxide development of a reddish-brown coloration ; with warm ferric chloride a turbid, orange solution ; with warm dilute nitric acid a bright yellow coloration whilst silver nitrate and Fehling's solution were reduced on warming. The oomposition and properties therefore indicate that the sub-stance is 2-p-bromobenzenehydrazoglyoxaline-4 5-dicar boxylic acid. The solution remaining after precipitation of the above sub-stance was freed from tin and evaporated to dryness leaving 0.7 gram of residue. From this by suitable means 0.35 gram of p-bromoaniline was isolated and identified whilst the residual solution then developed a strong odour of ammonia on warming with alkali.Nitration of 2-Phenylglpoxaline-4 5-dicarboxylic A cid. A solution of 2 grams of the acid in a mixture of 4 C.C. of nitric acid (D 1.4) and 4 c.c.of sulphuric acid was heated for eight hours on the water-bath then oooled poured on ice and the precipitated product crystallised from 120 parts of boiling water. It separates in small needles very sparingly soluble in cold water or the usual organic solvents but readily so in alkalis with the production of a red coloration. On heating the substance effervesces a t 266O (corr.) (Found C = 47.9 ; I3 = 2.6 ; N = 15.3. Cl,H70,N requires ( 2 ~ 4 7 . 7 ; H=2*5; N=15*2 per cent.).The composition of the product therefore indicates that nitration has taken place only in the benzene nucleus and that, as in the case of glyoxalinedicarboxylic acid and its 2-methyl homo-logue there is no tendency for displacement of the carboxylic by the nitro-group. I n view of the predominating negative character of the glyoxalinedicarboxylic acid substituent the substance is in all probability 2-rn-nitrophenylglyoxaline-4 5-dicarboxylic acid. The corresponding amino-acid was obtained by reduction wit 164 NTERENSTETN THE CONSTJTUTTON OF CATECHTN. PART TTI. sodium hyposulphite in alkaline solution. It dissolves readily in dilute mineral acids but very sparingly in the usual organic solvents 50 per cent. acetic acid or hot water from which i t separates in powdery crystals containing 2H,O. After treatment with nitrous acid i t develops a deep red coloration on addi-tion to sodium P-naphthoxide (Found loss a t 1100= 12.4. C,,H,04N,,2H,0 requires H,O = 12.7 per cent. I n dried material : N = 16.2. C,1H,04N requires N = 16.2 per cent .). WELLCOME CHEMICAL RESEARCH LABORATORIES. [Receiucd January 14th 1921.

ISSN:0368-1645    

DOI:10.1039/CT9211900158

出版商:RSC    

年代:1921

数据来源: RSC

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164 NTERENSTETN THE CONSTJTUTTON OF CATECHTN. PART TTI. XVIII.-The Constitution of Catechin. Part I I I . Synthesis of Acacatechin. By MAXIMILIAN NIERENSTEIN. IN the previous communications (T. 1920 117 971 1151) a provisional formula was suggested for catechin (I). A t the same time it was shown that catechin* tetramethyl ether yields on reduction with metallic sodium and alcohol and subsequent methyl-ation (compare Kostanecki and Lampe Ber. 1909 40 720), 3 4 21 4' 6~-pentamethoxy-au-diphenylpropane (11) which sub-stance may be oxidised to 3 4 2/ 4/ 6l-pentamethoxydiphenyl-aoetic acid (111). It was also shown that the acyl chloride of this acid (111) is converted by the action of diazomethane (compare Clibbens and Nierenstein T. 1915 107 1491) into 3 4 21 4/ 6'-pentamethoxydiphenylmethyl chloromethyl ketone (VI) from which 3 4 21 41 6/-pentamethoxy-au-diphenylpropane (11) is obtained on reduction with metallic sodium and alcohol.The present communication describes the synthesis of 2 4 6 31 4~-pentahydroxy-3-phenylchroman (I). This was carried out according to the following scheme 3 4 21 4' 61-pentameth-oxydiphenylmethyl chloromethyl ketone (VI) was converted into 4 6 31 4~-tetramethoxy-3-phenylchroman-2-one (V) which was reduced; to 2-hydroxy-4 6 31 4~-tetrarnethoxy-3-phenylchroman * The catechin used was obtained from Merck at Darmstadt in 1911 and 1920. After purification both preparations melted at 175-177" which is the melting point given by A. G. Perkin and Yoshitake (T. 1902 81 1183 1173) for catechin from gambier NIERENSTEIN THE CONSTITUTION OF CATECHIN.PART III. 165 (I+). pentahydroxy-3-phenylchroman (I). The latter product yielded on demethylation 2 4 6 3' 4l-0 0 0 MeO/\/><yH MeO/\/\' F€X2 MeO/\OMe Me0 CH t- Me0 CH -+- MeO/ I ICH-CO*CH,CI \./ I I t !!\,CH*OH \/\p / I \. I \ )OBIe '\I L O M e O O M e OMe OMe (IV. 1 (V.1 WI.) 2 4 6 31 4/-pentahydroxy-3-phenylchron1an (I) yields the original 2-hydroxy-4 6 3' 41-tetramethoxy-3-phenyl-chroman (IV). Both the latter product (IV) and 4 6 3/ 4I-tetra-methoxy-3-phenylchroman-2-one (V) give on reduction with metallic sodium and alcohol and subsequent methylation, 3 4 21 41 61-pentamethoxy-aa-diphenylpropane (11) which is in every respect identical with Kostanecki and Larnpe's (Zoc.cit .) methylated reduction product from Merck's catechin. 2 4 6 31 4/-Pentahydroxy-3-phenylchroman (I) is in every respect identical with acacatechin which occurs in Acacia catechu (A. G. Perkin and Yoshitake T. 1902 81 1169; Perkin T., 1905 87 398). The identity of these two substances is evident from the following comparative summary of melting points and from the fact that there is no depression in the melting points of the respective synthetic products when mixed with acacatechin and its penta-acetyl and pentabenzoyl derivatives kindly sent by Professor A. G. Perkin. 2 4 6 3 l 41-Yentahydroxy-3-phenylchroman sinters a t 140°, resolidifies a t about 180° on slowly raising the temperature and melts and decomposes a t 204-205O.OMe On methylation, Q 166 NIERENSTEIN THE COXSTITUTION OE' CATECHIN. PART 111. Acacatechin sinters a t about 1 40° resolidifies on slowly raising the temperature and melts and decomposes a t 204-205O (Perkin and Yoshitake loc. c i t . p. 1169). 2 4 6 3/ 41-Penta-acetoxy-3-phenylchroman sinters a t about 130° and melts and decomposes at 158-16O0. Penta-acetylacacatechin melts a t 158-159O (Perkin loc. c i t ., 2 4 6 3' 4/-Pentabenzoyl-3-phenylchroman melts at 181-183O. Pentabeiizoylacacatechin melts at 181-183O (Perkin and 2-Hydroxy-4 6 3/ 4/-tetramethoxy-3-phenylchroman melts at Acacatechin tetramethyl ether melts a t 152-154O (Perkin Zoc. cit. p. 400). 2-Acetoxy-4 6 31 4/-tetramethoxy-3-phenylchroman melts a t 136-137O.Monoacetylacacatechin tetrainethyl ether melts a t 135-13'7O (Perkin loc. c i t . p. 400). When fused with alkali 2 4 6 3' 4/-pentahydroxy-3-phenyl-chroman (I) gives phloroglucinol and protocatechuic acid. It has, however not been possible t o identify acetic acid which is also formed when acacatechin is fused (Perkin and Yoshitake Zoc. c i t . , p. 1170). This is probably due to the small amount of material (2.3 grams) which was used. p. 399). Yoshitake Zoc. cit. p. 1171). 152-153'. E X P E R I M E N T A L . 4 6 31 4~-Tetran~etl~ozy-3-phe.nylckro?nut~-2-o~~e (V). This substance may be prepared according t o either of the following methods : ( a ) A suspension of 5 grams of 3 4 2/ 4' 6/-peiitamethoxydi-phenylmethyl chloromethyl ketone (VI) in 50 C.C.of water is vigorously heated for thirty-two hours with 20 grams of sodium hydrogen carbonate. The cold solution is filtered and acidified with dilute hydrochloric acid when a bulky white precipitate is formed. The o-hydsoxy-3 4 21 41 6~-pentamethozy-aa-diphen.y1-MeO/)OMe ( (YH* CO c H,* OH Me0 ,,!, ()OM* OMe (VII. NIERENSTEIN THE CONSTITIJTION O F CATECHIN. PART 111. 167 propane-&one (VII) thus formed crystallises from dilute alcohol in small prismatic needles which melt and decompose at 121-122O. It is soluble in the usual organic solvents with the exception of light petroleum. The yield is 71 per cent. of the theoretical (Found * C= 63.8 ; H = 6.3. C,,H,,O requires C=63.8; H=6*4 per cent.). o-Hydroxy-3 4 2' 41 6'-pentainethoxy-aa-diphenylpropane-/3-one (VII) is converted into 4 6 3l 41-tetramethoxy-3-phenyl-chroman-2-one (V) by dissolving 5 grams in 50 C.C.of acetic anhydride and heating for eight hours on a water-bath with 25 C.C. of a solution of 4-32 grams (1 mol.) of acetyl chloride in 100 C.C. of acetic anhydride. After reducing the volume to about 50 c.c., water is added and the precipitate collected and warmed with a dilute solution of sodium hydroxide. The solid remaining is filtered off and freed from alkali. It crystallises from absolute alcohol in small pointed needles melting a t 146-147O. The pro-duct is soluble in the usual organic solvents. The yield is 51 per cent. of the theoretical (Found f- C =66.1; H=5.7. C,,H,,O, requires C = 66.3 ; H = 5.8 per cent.).( b ) To a solution of 5 grams of 3 4 2' 4' 6l-pentamethoxy-diphenylmethyl chloroinethyl ketone (VI) in 75 C.C. of dry benzene is added 0.1 t o 0.3 gram of aluminium chloride and the solution heated on a water-bath for twelve to sixteen hours. The solid left on evaporation of the benzene is purified by dissolving in 50 C.C. of 80 per cent. alcohol filtering and adding 300 C.C. of water to the filtrate. The precipit,ate thus obtained crystallises from absolute alcohol in small pointed needles which melt at 146-147O. The melting point of a mixture with the substance prepared accord-ing to the previous method shows no depression. The average yield of six preparations is 86 per cent. of the theoretical (Found 4 : C=66*2; H=5.6. Calc. C=66*3; H=5-8 per cent.).When condensed with phenylhydrazine in acetic acid solution, the phenylhydrazone C,,H,,O,:N,HPh is obtained. It crystallises from acetic acid in yellow needles which melt and decompose a t 236-239O (Found N = 6.5. C,,H,,O,N requires N = 6.4 per cent.). On reduction with metallic sodium and alcohol and subsequent methylation with diazomethane 2 grams of 4 6 31 4'-tetrameth-oxy-3-phenylchroman-2-one (V) gave 1-7 grams of 3 4 21 4/ 6'-pentamethoxy-aa-diphenylpropane (11) which melted at 83-84O. This melting point was not depressed when the substance was mixed with (1) the same substance obtained from catechin tetramethyl ether and (2) the synthetically prepared product (Zoc. cit. p. 1153). ''- Dried at loo" 168 NIERENSTEIN THE CONSTITUTION OE' CATECHIN.PART III. 2-Hydroxy-4 6 31 4/-tetrametkoxy-3-phenylchro~nan (IV). Three grams of 4 6 3' 4/-tetramethoxy-3-phenylchroman (V) dried a t looo are dissolved in 75 C.C. of acetic anhydride and heated in a boiling-water bath for five hours with 20 grams of zinc dust dried a t looo. The filtered solution is diluted with water and the precipitate collected after twenty-f our hours. The crude product is dissolved in 70 C.C. of alcohol and heated for several hours with 20 C.C. of a 20 per cent. solution of sulphuric acid. The product is again precipitated with water and treated in the cold with a 10 per cent. solution of sodium hydroxide when nearly all the solid dissolves. The filtered alkaline solution is acidified with dilute sulphuric acid and the precipitate crystallised from alcohol with the aid of animal charcoal.The average yield of five prepar-ations is 62 per cent. of the theoretical. This substance melts a t 152-153O which is the melting point (152-154°) given for acacatechin tetramethyl ether (Found * C = 65.8 ; H = 6.6. Calc. : C=65.9; H=6-4 per cent.). It differs however in one respect from Perkin's acacatechin tetramethyl ether in that it does not give the indigo-blue coloration with acetic and nitric acids observed by him for his product ( l o c . c i t . p. 400). Since this difference might be due t o the formation of an isomeric tetramethyl ether during direct methylation of acacatechin 2 grams of 2 4 6 31 4l-pentahydroxy-3-phenylchroman (I) were methylated with methyl sulphate according to Perkin's method.The tetramethyl ether obtained in this way melted a t 152-15307 and gave Perkin's indigo-blue coloration. Several mixed melting points of these two tetra-methyl ethers gave somewhat doubtful depressions of 1.5-Z0 but i t was found that both yielded on acetylation identical mono-acetyl derivatives (m. p. 136-137O) which showed not the slightest depression when their mixed melting point was taken (Found t : C=64.7; H=6*4. Calc. C=65.0; H=6*2 per cent.). It is 'difficult to see why the two tetramethyl ethers should show this difference unless Perkin's colour reaction is due t o a trace of another substance. Ferric chloride produces a violet coloration if added to a suspension of either 2-hydroxy-4 6 3' 4/-tetramethoxy-3-phenyl-chroman (IV) or 4 6 3' 4~-tetramethoxy-3-phenylchroman-2-one (V) in concentrated sulphuric acid.This is due to the 3-phenyl-chroman nucleus (compare Greenwood and Nierenstein T. 1920, 117 1594) and not to the coumaran nucleus as assumed by Kostanecki and Lampe (Ber. 1906 39 4007). On reduction with . * Dried at 110". t Dried at 100" NIERENSTEIN THE CONSTITUTION OF CATECHIN. PART 111. 169 metallic sodium ansd alcohol and subsequent methylation with diazomethane 3 grams of 2-hydroxy-4 6 3/ 4'-tetramethoxy-3-phenylchroman (IV) gave 1.9 grams of 3 4 21 4' 6'-pentameth-oxy-act-diphenylpropane (II) which melted a t 83-84O. This melting point was not depressed by admixture with other prepar-ations of this substance. 2 4 6 3' 4~-Pentahydroxy-3-phenylchroman (I), Four grams of 2-hydroxy-4 6 3' 4/-tetramethoxy-3-phenyl-chroman (IV) dissolved in 70 C.C.of glacial acetic acid are heated a t 130° in a sealed tube for six hours with 4 grams of acetyl chloride.* After opening the tube the content is a t first heated for several &ours with 50 C.C. of a 10 per cent. solution of sulphuric acid hydrogen being passed through continuously. The solution is then concentrated to about 10 C.C. in an atmosphere of hydrogen, diluted with 170 C.C. of water neutralised with solid barium carbonate filtered and extracted several times with ethyl acetate. The residue left on evaporation of the ethyl acetate dried over anhydrous sodium sulphate is purified according t o Perkin and Yoshitake's method (Zoc. c i t . p. 1163) by crystallising i t at first from 25 per cent.alcohol and subsequently dissolving in boiling ethyl acetate and benzene from which mixture it separates with the aid of animal charcoal in wart-like clusters consisting of small, pointed needles. The average yield of four preparations is 78' per cent. of the theoretical. 2 4 6 31 4'-Pentahydroxy-3-phenylchroman (I) is in every respect identical with acacatechin (Found j- C= 61.9. 62.0 ; H =4*9 6.0. Calc. C= 62.1 ; H=4-8 per cent.). It crystallises, like acacatechin from distilled water with 3H,O (Found + H,O = 15.8. Calc. H,O= 15.7 per cent.) and gives all the colour reac-tions of catechin including the phloroglucinol test with pine-wood and hydrochloric aci'd (compare Perkin and Yoshitake loc. c i t ., p.1172 ; Perkin loc. cit. p. 405). Both the penta-acetyl derivative (Found $ C = 60.1 ; H = 5.2. Calc. C = 60.0 ; H =4.8.per cent.) and the pentabenzoyl derivative (Found T C=73.9; H=4*6. Calc. C=74.1; H=4*2 per cent.) were prepared according to Perkin's method (Zoc. cit. p. 399) and * All attempts to demethylate both 2-hydroxy-4 6 3' 4'-tetramethoxy-3-phenylchroman (IV) and catechin tetramethyl ether (m. p. 144-146") from Merck's catechin with hydriodic acid have resulted in the production of amorphous substances. Acetyl chloride also gave good results in the caw of catechin tetramethyl ether. Thus 5 grams of this substanoe gave 3.8 grams of catechin which melted correctly at 175-177". t Dried at 160". $ Dried at 100" 1.70 FTNDLAY AND THOMAS TNFLUENCE OF COLLOIDS Perkin and Yoshitake’s method (Zoc. cifi. p. 1171) respectively. They proved in every respect identical with the corresponding derivatives of acacatechin. The author’s thanks are due to Professor A. G. Perkin for the specimens of acacatechin penta-acetylacacatechin and penta-benzoylacacatechin used in this investigation. He also thanks the Colston Society of the University of Bristol for a grant which has covered the expenses of this research. BIOCHEnf ICAL LAB ORATORY, CHEMICAL DEPARTMENT, UNIVERSITY OF BRTSTOL. [Received Dmmbcr 3014 1920.

ISSN:0368-1645    

DOI:10.1039/CT9211900164

出版商:RSC    

年代:1921

数据来源: RSC