STUDIES IN TEE CAMPHANE SERIES. PART XXXI. 1327

CXL1.-Studies in the Camphane Series. Part X X X I . Condensation of Camphor quinone with Nitromethane, Ethyl Cyanoacetate, and Phenyl- acet onitrile.

By MARTIN ONSLOW FORS'TER and JOHN CHARLES WITHEM. THE facility with which camphorquinone undergoes condensation with typical substituted ammonia derivativ-, such as hydroxyl- amine, hydrazine, semicarbazide, phenylhydrazine, and aniline, suggested the possibility that the other great class of changes to which carboaylic substances are prone, namely, condensation with suitable derivatives of methane, might be brought about between camphorquinone and, for example, nitromethane, ethyl cyano- acetate, phenylacetonitrile, acetophenone, and dinitrotoluene. The products would be derivatives of methylenecamphor, a class com- prising hydroxymethylenecamphor, benzylidenecamphor, camphor- oxalic acid, and enolic benzoylcamphor, presenting features, stereo- chemical and otherwise, which render more complete study of the group desirable.

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1328 FORSTER AND WITHERS :

I n a restricted degree the above anticipation has been realieed. Camphorquinone undergoes condensation with nitromethane very readily, and the resulting nitromethylenecamphor is accompanied, under certain conditions, by the intermediate nitromethylhydroxy- camphor ; nitromethylenecamphor is not mutarotatory in organic media, but the solution in aqueous sodium hydroxide, although colourless when cold, rapidly yields camphorquinone if heated :

On mixing camphorquinone with ethyl cyanoacetate in alcohol containing a small proportion of sodium ethoxide, the liquid becomes warm, and soon deposits brilliant, sulphur-yellow crystals.

C: C(CN)*CO,* C,H, Ethyl camphorylidenecyanoacetate, C H < I Y as

l4 co the substance may be called, is converted by ammonia into the amlde, but with exces of alcoholic alkali is transformed into a dark brown, tarry material, accompanied by liberation of ammonia ; only when a single molecular proportion of sodium ethoxide is employed does hydrolysis lead to camphorylidenecyanoacetic acid, and the

C:C(CO,H), corresponding camphorylidenemalonic acid, C,H14<&, 9

can be obtained by heating the substituted cyanoacetic acid with hydrobromic acid in a sealed tube.

A Eeries of derivatives parallel with those from cyanoacetic ester has been produced also by using phenylacetonitrile; the initial condensation proceeds even more readily with this substance, the

C:C(CN)*C6H5 resulticg phenylcyanomethylenecamphor, CsH14<bo ?

being bright yellow, and having [uID 246O, whence [MI, 6 5 2 O . It is interesting to compare this substance with benzylidenecamphor, of which it is the cyano-derivative, and which has [MI, 1020O; thus, contrary to expectation, the cyano-group, although highly unsatur- ated, fails'to enhance the activity of the molecule into which it enters, and in this respect resembles the hydroxy-group, since enolic benzoylcamphor has [MI, 720O. The behaviour of phenylcyano- methylenccamphor is distinct from that of camphorylidenecyano- acetic acid and its ester towards alkalis, which readily transform it into the amide, whence the acid, camphorylidenephenylacetic acid,

C,H,4<&* C:C(C6H5)*C02H, is obtainable by the action of nitrous

acid.

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STUDIES IN THE CAMPHANE SERIES. PART XXXI. 1329

In reviewing these products it is necessary to point out that the various constitutional formulze given above must not be assumed without definite evidence, because the experimenh of Haworth (Trans., 1909,96, 480; compare also Gardner and Haworth, toc. cit . , 1955, likewise Harding and Haworth, Trans., 1910, 97, 486) have revealed the possibility of an alternative course, according to which the product of condensing camphorquinone with ethyl cyanoacetate, for instance, would $va the constitution :

CH,--O===C* CH(CN) C0,Et I Caxe, 1 CH,--CMe-CO

1

I I

Haworth found that when condensation takes place between ethyl cyanoacetate and cy clohexanone or analogous compounds& hydrogen migrates in the ketonic substance, which behaves virtually as an en01 ; thus cyclohexanone yields ethyI a-cyano-A*-cyclohexeneacetate,

whilst benzoin gives rise to Y Y

abdicyano-/3y-diphenyl-AB-butene-u&dicarboxyIic acid,

It seems clear, however, that camphorquinone behaves differently, because when camphorylidenecyanoacetic acid is oxidised with potawium permanganate, camphoric acid is the sole product, whereas the alternative representation demanded by analogy to Haworth's experiments would certainly not lead to that substance, as the ring would probably open a t the point of unsaturation, giving rise to trimethylcyclopentanonecarboxylic acid. Moreover, the derivatives of camphorquinone, i f comparable with the condensation products obtained by Haworth, should contain hydrogen replacable by alkyl groups, and although the peculiar behaviour of ethyl camphoryli- denecyanoacetate towards alkali renders this compound unsuitable for the test, we have ascertained that the corresponding phenyl- cyanomethylenecamphor cannot be alkylated. In this connexion it'may perhaps be pointed out that .while there

is not the slightest remon t o doubt the propriety of Haworth's explanation, hydrogen available for enolisation is by no means essential to the course of such a condensation. Enolisation can scarcely be supposed to occur, for example, in benzaldehyde, although that substance undergoes condensation with ethyl cyano- acetate, and it is equally impossible in benzil, which some experi- ments conducted by Mr. R. T. F. Barnett have shown to yield a compound, C19H1503N, that is, a product of condensation between molecular proportions of the diketone and the ester.

Nevertheless, it has to be admitted thae the ethenoid linking in

CO,H*CH( CN) *CPh :CPhsCH(CN) COBH.

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1330 FORSTER AND WITHERS :

these new derivatives of camphorquinone presents curious features ; for instance, addition of bromine or hydrogen bromide dom not take place, and although the presence of the nucleus, *CO*CX:CX,, suggests analogy to pulegone, which yields acetone and methylcyclo- hexanone when heated with formic acid, protracted action of the last-named substance on ethyl camphorylidenecyanoacetate does not produce a trace of camphor. Furthermore, camphorquinone has not been recovered by the action of either- pttassium ferricyanide or mercuric acetate, although the latter agent gives rise to the diketone when acting on enolic benzoylcamphor (Trans., 1903, 83, 103). Moreover, it has not been possible to draw any conclusion from the behaviour of the condensation products towards hydrogen peroxide.

When the difficulty of hydrolysing the cyano-group in ethyl camphorylidenecyanoacetate was first encountered, the action of hydrogen peroxide was studied, this agent having been found applicable in some cases of transforming nitriles into amides. It has this effect on the substance under discussion, there being added, simultaneously with water, one molecular proportion of oxygen. The action is pursued in alkaline solution, and the resulting amide- ester, Cl,H2106N, is accompanied by the monobasic amide-acid, @13H1706N, both these substances being hydrolysed to the dibasic acid, Cl3HI6O7. The problem of their constitution, however, has remained unsolved, as they are extremely resistant towards chemical agents. The most likely course for the action to follow suggests the addition of oxygen to the double linking and simultaneous conversion of the camphor nucleus into a derivative of camphoric anhydride, because hydrogen peroxide rapidly transforms camphor- quinone into that substance, and also, as we have recently found, converts phenyliminocamphor into camphoranilic acid :

The amide-ester from ethyl camphorylidenecyanoacetate would accordingly be represented as having the constitution :

0 C a C ( CO*NH2)*C0,*C2H, ,

co CSH14,, /\O

but the recent work of Prileschmff (J. Buss. Phys. Chem. SOC., 1913, 43, 609) suggests that such an oxide should be readily hydrated, yielding the glycol or its products of further hydrolysis ; alkalis, however, do not bring about the alteration expected, and we are obliged t o leave this part of the work in abeyance,

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STUDIES IN THE CAMPHANE SERIES. PART XXXI. 1331

I n conclusion, it may be stated that condensation has not been effected between camphorquinone and acetonitrile, acetophenone, ethyl phenylacetate, 1 : 2 : 4-dinitrotoluene, ethyl acetoacetate, or the monoxime of diacetyl.

EXPERIMENTAL. C: CH= NO, co Nitromethylenecamphor, C,H,,< I

A suspension of sodioni tromethane was prepared by mixing 8 grams of nitromethane with 100 C.C. of alcohol in which 3.6 grams of sodium had been dissolved; 16 grams of camphorquinone in 50 C.C. of hot alcohol were then added, when the major part of the sodium derivative disappeared. The liquid was set aside, and quickly changed to a pasty mass of bulky, indefinitely crystalline material, which, after twelve hours, was filtered, drained on earthen- ware, dissolved in water, and immediately acidified with dilute sulphuric acid. An oil separated, rapidly becoming crystalline, the product weighing 15 grams. Repeated extraction with 200 C.C. of hot petroleum (b. p. 60--80°) gave spherical nodules of minute, silky needles, the snow-white product obtained on recrystallisation melting a t 77O:

0.1573 gave 0.3628 CO, and 0*1024 H,O. C= 62-90; H=7*28. 0.2627 ,, 15.4 C.C. N2 a t 25O and 763'6 mm. N=6.61.

C,,H,,03N requires (3 = 63-12 ; H = 7.23 ; N = 6.70 per cent. The substance is freely soluble in cold- benzene, chloroform, or

methyl alcohol, and also in sodium carbonate, from which camphor- quinone is rapidly precipitated ; the alcoholic solution is indifferent towards ferric chloride, which develops an intense red coloration with an aqueous solution of the sodium derivative. The latter yields with copper acetate a bulky, grass-green precipitate, insoluble in alcohol or acetone, and becoming black when suspended in boiling water. The sodium derivative, even when freshly prepared from nitromethylenecamphor and sodium ethoxide, is highly unstable towards excess of alkali, quickly becoming yellow and depositing crystals of camphorquinone within a few minutes; it is not surpris- ing, therefore, that an aqueous solution decolorises potassium per- manganate instantly, yielding camphorquinone. A solution contain- ing 0.2446 gram of nitromethylenecamphor in chloroform, diluted to 25 c.c., gave a, 2O35' in a 3-dcm. tube, whence [a], 88'0°, remain- ing constant during twelve days; 0.2490 gram in 25 C.C. of alcohol, containing 0.12 gram of sodium per 100 c.c., gave aD 4OO' in a 3-dcm. tube, whence [ulD 133*8O, falling to 117.1O within twenty-seven hours, and becoming had ive after the lapse of three weeks. A

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1332 FORSTER AND WITHERS :

solution containing 0.2468 gram in 10 per cent. aqueous sodium hydroxide was colourless when freshly prepared, and gave a, 305’ in a. 3-dcm. tube, whence [aJD 104.1O; the liquid gradually became yellow, gave [a], 47.3O after six weeks and 36’6O after seven months.

Kitromethylenecamphor does not decolorise bromine in chloro- forni, being deposited unchanged on evaporation ; if, however, the sodium derivative is suspended in dry chloroform, the colour of the halogen is immediately discharged, and bromopicrin is formed along with a crystalline substance melting a t 124O, dissolving in alkali, and yielding camphorquinone when the liquid is heated. After remaining in contact with fuming hydrobromic acid during six weeks, nitromethylenecamphor was found to be unaltered ; no change occurs, moreover, when the substance is heated with aniline on the water-bath, or dissolved in 30 per cent. acetic acid containing the base, in spite of the fact that under similar conditions hydroxy- methylenocamphor yields a condensation product (Bishop, Claisen, and Sinclair, Annaten, 1894, 281, 331; compare also Pope and Read, Trans., 1909, 95, 171).

(OH) *CH,* NO, aa-Nit To me thyzi+ydroxycamphor, c,H,,<F co On one occasion i t was noticed that the nitromethylenecamphor

was accompanied by a substance considerably less readily soluble in petroleum, and it was subsequently found that a slight modifica- tion in the conditions led to a preponderating quantity of this material.

Four grams of camphorquinone and 2 grams of nitromethane were added to 25 C.C. of absolute alcohol, i n which 0.1 gram of sodium had been dissolved. As there did not appear to be any change during twelve hours, a further quantity of sodium ethoxide prepared from 25 C.C. of alcohol and 0.8 gram of sodium was added, when the liquid set to a paste of crystals within one hour. After filtration the product was dissolved in water and immediately acidified with dilute sulphuric acid, which precipitated a solid instead of an oil; the melting point was constant a t 104O when the substance had been recrystallised three times from boiling petroleum :

0-1534 gave 0.3284 CO, and 0.1008 H,O. 0.284’7 ,, 16-0 C.C. N, at 21° and 745 mm. N=6*29.

The hydroxy-compound requires about twice aa much hot petroleum as nitromethylenecamphor to dissolve it (60 C.C. to 1 gram), and separates therefrom in long, silky needles. A solution containing 0-2600 gram in chloroform, made up to 25 c.c., gave

C= 58.39 ; H = 7.35.

C,,E,,O,N requires C = 58-11 ; H= 7.55 ; N = 6-17 per cent.

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STUDIES IN TEE CAMPHANE SERIES, PART XXXI. 1333

a, 3O19' in a 2-dcm. tube, whence [aID 159*5O. It dissolves slowly in sodium carbonate, which becomes bright yellow when warmed, from separation of camphorquinone. The nitro-compound is freely soluble in all organic media excepting petroleum.

Ethyl Camphtorylidenecyanoacetate (Ethyl MethTtylenecamphor- cyanocarb-oxylate), C,H,,< C:C(CN)*CO,-C,H,. I

co Fifty grams of ethyl cyanoacetate, followed by 70 g r a m of

camphorquinone (1 mol.), were added to 300 C.C. of absolute alcohol in which 0.5 gram of sodium had been dissolved; although not completely soluble a t first, the quinone gradually passed into solution, accompanied by a noticeable rise of temperature and a slight darkening in colour. This faded, however, and separation of sulphur-yellow crystals began within one hour. Including a further deposit from the diluted mother liquor, the yield amounted t o 93 grams, and as 5 grams of unused camphorquinone was recQvered by still further dilution, represented 90 per cent. of the theoretical quantity. Recrystallisation from hot alcohol gave flat, lustrous, sulphur-yellow prisms, melting a t 970 :

0-1536 gave 0.3878 C02 and 0.1022 H,O. C= 68.86; H= 7.48. 0.3188 ,, 15.0 c.c.'N2 a t 22O and 776 mm. N=5*47.

C,,H,,03N requires C = 68-92 ; H= 7.33 ; N= 5.36 per cent.

The substance is freely soluble in cold organic media, excepting petroleum, which dissolves it readily when warm, depositing long, yellow, striated needles, growing together into six-sided plata. A solution containing 0.2527 gram, made up to 25 C.C. with chloroform, ga.ve a, 6O6' in a 3-dcm. tube, whence [a]D 201'2O; concentrated nitric acid dissolves the compound freely, the pale yellow solution remaining unaltered during many days, when water precipi tah the original material. Moreover, a solution in anhydrous formic acid was boiled continuously during seven days without producing any effect beyond hydrolysis of about 5 per cent.

Action of Sulphuric Acid.-Ten grams of the finely powdered substance were dissolved in 50 gram8 of concentrated sulphuric acid, and after an interval of six hours poured on 125 grams of ice. The filtered liquid having been heated on0 hour on the steam-bath, a considerable proportion of dark brown t a r separated, from which the clear liquid was decanted as soon as cold; from this there separated 4.5 grams of indefinite crystals, deposited by boiling water in snow-white needles melting at 179O, and evolving gas a t about 210O:

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1334 FORSTER AND WITHERS :

0.1544 gave 0.3766 CO, and 0.0852 H20. C-66.52; H=6*18. C13H,,O4 requires C= 66.63 ; H = 6-03 per cent.

We are not able to indicate the structure of this product. The empirical formula is that of camphorylidenemalonic anhydride, but it is an acid, and if it were a bimolecular acid anhydride, the molecular weight would be 486, corresponding with the formula C,H,O,; the substance is not readily soluble in benzene, and a small proportion separated before the freezing point of the solvent was reached, but an estimation of molecular weight under these conditions gave 280. As this value is not greatly in excess of 234, required by the formula C1,H140,, and as premature crystallisation tends to decrease the depression and thus raise the observed molecular weight, it follows that the substance is almost certainly unimolecular.

Twenty grams of ethyl camphorylidenecyanoacetate were added to 150 C.C. of absolute alcohol in which 2 grams of sodium had been dissolved, when a pale brown coloration began to develop, intensify- ing as the crystals slowly dissolved. After fourteen days the deep brown liquid, which had not liberated ammonia, was evaporated t o dryness and the residue dissolved in water, 'which formed a clear solution with a small proportion, becoming turbid on dilution; the liquid was therefore boiled qith charcoal, filtered, cooled, acidified with dilute sulphuric acid, and extracted with ether. The latter deposited crystals on evaporation, and after the residue had remained six days in the desiccator, it was treated with a small quantity of benzene, in which it formed a clear solution, changing almost immediately into a crystalline paste; the product was there- fore drained and recrystallised twice from hot benzene, which deposited lustrous, sulphur-yellow needles, melting a t 141-143O :

C = 67.10 ; H = 6.70. 0.1642 gave 0.4040 CO, and 0.0983 H,O. 0-2597 ,, 13.6 C.C. N, a t 22" and 767 mm. N=6*01.

A solution containing 0.2630 gram in chloroform, made up to 25 c.c., gave aD4042' in a 3-dcm. tube, whence [aID 223'4O. The acid is moderately soluble in hot water, from which it separates as an oil on cooling; organic media dissolve it freely excepting petroleum, in which it is insoluble, even on boiling.

The ammonium salt is very readily soluble in water, crystallising in minute, pale yellow needles, and decomposing a t 195O. The silver salt is sparingly soluble, crystallising in long, slender needles, which

C1,H,,O,N requires C== 66.91 ; H = 6.49 ; N = 6-01 per cent.

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STUDIES IN THE CAMPHANE SERIES. PART XXXI. 1335

are moderately stable towards light. The lead salt is much less readily soluble, separating as a pasty mass of minute, very pale yellow needles. An aqueous solution of the ammonium salt gave a white precipitate with soluble salts of mercury, zinc, and tin, whilst f emic chloride developed a buff precipitate; the salts of copper, cobalt, and barium are not precipitated.

The methyl ester, prepared from the aqueous sodium salt and methyl sulphate, crystallised from hot petroleum in lustrous, golden- yellow needles, melting at 81O:

0-2337 gave 11.6 C.C. N, a t 21° and 765’4 mm. N=5*71. Cl4H1,O3N requires N = 5-67 per cent.

The amide, prepared from the ethyl ester in alcohol by the action of ammonia, crystallises from hot water in slightly yellow leaflets melting at 104O: 0.0974 gave 10.4 C.C. N2 at 21° and 755.4 mm. N=12.12.

Cl3H1,O2N, requires N = 12.07 per cent. Oxidation with Potassium Permanganate.-One gram of cam-

phorylidpecyanoacetic acid dissolved in 10 C.C. of sodium, carbonate was treated with ice-cold potassium permanganate until the super- natant liquid was pink, when the equivalent of slightly more than four atoms of oxygen had been used. Proceeding subsequently as usual in such cases, a specimen of camphoric acid melting at 185O was obtained.

C:C( CO,H )z Cam ph ol”y lidenema I onic A cid, C, H,

In order to convert cyanomethylenecamphor into camphorylidene- acetic acid, Bishop, Claisen, and Sinclair (Zoc. cit . , 389) found it necessary t o heat the nitrile in a sealed tube with glacial acetic and hydrochloric acids. Camphorylidenecyanoacetic acid is even more stable, and was recovered unchanged after being subjected to this treatment; by the use of hydrobromic acid, however, hydrolysis has been effected.

Two grams of the acid were dissolved in 12 grams of glacial acetic acid, and heated with 8 grams of hydrobromic acid (D 1-49) in a sealed tube during four hours a t 140-180°. No pressure was noticeable on opening the tube, but the contents had become slightly brown, and crystals of ammonium bromide had been deposited. The liquid was poured into water and extracted with ether, from which the solid residue (0.5 gram), after recrystallisa- tion from hot yater, separated in straw-coloured needles, melting with vigorous intumescence at 206O :

0-1123 gave 0.2550 CO, and 0-0637 H,O. C= 61.93 ; H = 6.25. CI3H,O, requires C = 61.87 ; H = 6-40 per cent.

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1336 FORSTER AND WITHERS :

Contrary to expectation, we could not convert this compound into Claisen’s camphorylideneacetic acid.

d ction of Hydrogen Peroxide o n Ethyl Camphorylidene- cyanoacetate.

Twenty-five grams of the ester were dissolved in 150 C.C. of hot alcohol, which was then cooled rapidly and treated with 225 C.C. of hydrogen peroxide (“20 vok.”) in quantities of 40-50 c.c., the alkalinity of the liquid being maintained by adding a few drops of sodium hydroxide from time to time. The crystals quickly dis- sclved, and when the colour had faded with the last portion of hydrogen peroxide, colourless crystals began t o separate ; 200 C.C.

of water were then added, and the cooled liquid filtered after two hours. Fifteen grams of snow-white material were obtained, crystal- lising from hot alcohol in lustrous prisms melting and evolving gas a t 209O:

0*1400 gave 0’2964 CO, and 0.0876 H,O. C= 57-74 ; H = 7-00. 0.3155 ,, 12.3 C.C. N, a t 22O and 776 mm. N=4*53.

The substance is soluble in boiling water, and requires about 10 C.C. of boiling alcohol per gram to dissolve it. A 1 per cent. solution in chloroform appeared inactive when viewed through a 3-dcm. tube.

In association with this amide-ester there is produced an equal proportion of the corresponding amideacid. On evaporating to small bulk the filtrate from the first-named substance, allowing it to remain twenty-four hours, adding a ismall quantity of water, and filtering from 1 gram of the amide-ester, dilute sulphuric acid gave a white, crystalline precipitate weighing 12 grams; the substance melted and evolved gas a t 138O, then solidified, and fused finally a t about 203O. Recrystallisation from hot water or from absolute alcohol gave lustrous, transparent, six-sided plates, melting a t 205O, when the acid turns brown and liberates gas:

Cl,Ha06N requires C=57.88; H=6*75; N=4*50 per cent.

0-1300 gave 0,2497 CO, and 0.0775 H,O. 0.2301 ,, 9.4 C.C. N, a t 21*5O and 747.4 mm. N=4.58.

Cl8Hl0O7N requires C=51*83; E= 6.31 ; N=4*65 per cent. Titration with N / 10-sodium hydroxide showed the substance to

‘be monobasic, assuming the molecular weight 301; hence it appears to have the composition C,811,70,N + H,O, a small proportion of the crystallisation water having been removed in the desiccator, since the formula Cl8El7O8N requires C-55.1, H=6*0, and N=4*9 per cent.

The same substance has been obtained by the action of hydrogen

C= 52.39 ; H = 6.67.

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STUDIES IN THE CAMPHANE SERIES. PART XXXI. 1337

peroxide on camphorylidenecyanoacetic acid, and also by the incomplete hydrolysis of .the amideester, complete hydrolysis leading to the dibasic acid. A solution of the amide-acid in alcohol, made up to 25 C.C. containing 0'2536 gram, gave a, 0°22/ in a 3dcm. tube, whence [aID 12.6".

The Dihasic Acid, C13Hl,0,.--Fourteen grams of the amide-ester were covered with 20 grams of 20 pOr cent. aqueous sodium hydroxide, when a clear solution was formed, and ammonia liberated from the hot liquid. After sixteen hours on the water-bath ammonia was no longer noticeable, and the acidified solution having been extracted eight times with ether, about 10 grams of crystalline residue were obtained on evaporating the latter. On being twice recrystallised from the minimum quantity of boiling water, colour- less, transparent prisms were deposited, melting with vigorous intumescence a t 231", when the substance became dark brown :

0.1286 gave 0.2572 CO, and 0.0679 H,O. C =54.55 ; H = 5.91.

On titration with N/lO-sodium hydroxide, the acid was found to be dibasic, assuming the molecular weight 284. A solution contain- ing 0.2536 gram in alcohol, made up to 25 c.c., gave a, -0O45' in a 3-dcm. tube, whence [a], -24'6O. Continued heating with con- centrated aqueous alkali or boiling pyridine left the substance unchanged, whilst hot alcoholic alkali gave rise to an indefinite, resinous material.

C,H,,O, requires C = 54-90 ; H = 5' 68 per cent.

C:C(CN)-C,H,. co Pheqlcyanome thy1 enecamphor, C,H,,< I

Fifteen grams of phenylacetonitrile were added to 100 C.C. of absolute alcohol in which 3 grams of sodium had been dissolved; 20 grams of camphorquinone were stirred into the liquid, rapidly forming a clear solution, from which crystals began to separate within half-an-hour. The first crop weighed more than 20 grams, requiring about 400 C.C. of boiling alcohol for recrystallisation, when sulphur-yellow prisms were obtained melting a t 167O :

0.1448 gave 0.4335 C02 and 0.0966 SO. C = 81-65 ; E= 7-47. 0-2781 ,, 12.8 C.C. K2 at 19O and 754 mm. N=5-26.

C,,H,,ON requires C=81*46; H=7*22; N=5*28 per cent. A solution containing 0.2608 gram in chloroform, made up to

25 c.c., gave Q, 7O42' in a 3-dcm. tube, whence [aID 246O. Continued heating with methyl iodide in presence of sodium methoxide (1 mol.) left the substance unaltered; hence there i~ not a replaceable atom of hydrogen associated with the carbon which carries the cyano- group.

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1338 FORSTER AND WITHERS :

A ction of Alcohol~c Alkali.-Five grams of phenylcyanomethylene camphor were heated with 50 C.C. of alcohol and 10 C.C. of 20 per cent. sodium hydroxide solution under reflux, when the suspended crystals gradually disappeared and the yellow colour faded. On pouring the mixture into water after two hours, 5.6 grams of a white solid separated, and ww recrystallised from diluted alcohol, which deposited transparent plates melting a t 97O; the fused material became solid again forthwith, melting finally at 156O, and an unheated specimen which had been left in a desiccator melted first at 158O:

0.1553 gave 0.4354 CO, and 0-1079 &O. C = 76.47 ; H =7*77. 0.2316 ,, 10.1 C.C. N, a t 22O and 756.7 mm. N=4-93.

Cl8H2,O,N requires C = 76-27 ; €I= 7.48 ; N = 4.95 per cent. The amide dissolves in concentrated sulphuric acid, but is pre-

cipitated therefrom unchanged ; it is also indifferent towards hydrogen peroxide in the cold or on warming. The substance is freely soluble in chloroform, alcohol, or benzene, but disgolves only sparingly in hot petroleum, crystallising in minute, silky needles on cooling; a solution containing 0.2609 gram in chloroform, made up to 25 c.c., gave a, 5O52' in a 2-dcm. tube, whence [uIn 281'1O.

Action of Concentrated Sulphum'c A cid-Five grams of finely powdered phenylcyanomethylenecamphor were added to 25 grams of concentrated sulphuric acid, and after an interval of six hours poured on ice. The filtered liquid was heated on the water-bath until turbid, allowed to cool, and decanted from a honey-like mass; this was kneaded with a small quantity of cold water, which changed it. into a milky fluid, slowly depositing a colourless solid. After extraction with sodium carbonate, which removed but little acid material, the rwidue was dissolved in a small quantity of hot alcohol, precipitated with water, and recrystallised fro-m boiling alcohol, which deposited lustrous, transparent prisms, melting a t 204O:

0.1593 gave 0.4437 CO, and 0.1029 H20. C=75*96; H=7-23. Cl8€I&Os requires C= 76.01 ; H = 7-10 per cent.

Thus the substance is isomeric with camphorylidenephenylacetic acid, and i t probably arises from the opening of the camphor ring, followed by anhydride formation between the resulting group and that produced from hydrolysing the nitrile :

carboxyl

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STUDIES IN THE CAMPHANE SERIES. PART XXXI. 1339

Camphor y lid em e p hen9 la c e tic A cid,

The foregoing amide was found to resist the further action of alkali, for after heating with alcoholic sodium hydroxide during three days the major portion was recovered on diluting w'ith water ; on acidifying the mother liquor, however, a small amount of floccu- lent, yellow matter separated, and proved to be the expected carboxylic acid.

This is more readily obtained by the action of nitrous acid on the amide. A solution of 1 gram in 10 C.C. of concentrated sulphuric acid was diluted with 10 C.C. of water, cooled in ice, and treated with 0.5 gram of sodium nitrite in a small quantity of water; a solid wm a t once precipitated, and to complete the action the mixture was heated on the steam-bath, then diluted with water, and filtered. The product crystallised from diluted alcohol in faintly straw-coloured needles melting at 186O; it is scarcely charred a t 250°, and in this respect recalls camphorylideneacetic acid, which may even be distilled without undergoing change (Bishop, Claisen, and Sinclair, Zoc. cit.) :

0.1562 gave 0.4354 CO, and 0.0983 H20. C=76*02; H=7*04. C,,H,O, requires C = 76.01 ; H= 7.10 per cent.

The acid dissolves freely in cold benzene, ethyl acetate, methyl alcohol, or glacial acetic acid, but is insoluble in boiling petroleum; a solution containing 0.2518 gram in chloroform, made up to 25 c.c., gave a,, 4O42' in a 2-dcm. tube, whence [a], 233'3O.

Action of Hydrogen Peroxide ofi Phenylcyanomet~~lenecamphor.

Phenylcyanomethylenecamphor (2.65 grams) dissolved in hot alcohol (30 c.c.) was treated with hydrogen peroxide (30 C.C. of " 20 vols.") and 20 per cent. sodium hydroxide (4 c.c.) added in four or five portions during the course of fifteen minutes. The colour faded somewhat, and the liquid, which remained clear, was poured on ice and acidified with dilute hydrochloric acid ; the white precipitate was recrystallised from diluted alcohol, forming well-defined, rhombic prisms melting a t 153O:

0.1588 gave 0.4051 GO, and 0.1133 H,O. C= 69-59 ; H = 7.80. 0.2613 ,, 9.6 C.C. N, at 21° and 746.5 mm. N=4.12.

C,,H&O,N + C2H,0 requires C= 69.52 ; H = 7-88 ; H = 4.06 per cent. Whilst cold acetone, chloroform, or ethyl acetate dissolve the

substance freely, it is less readily soluble in benzene or methyl alcohol, crystallising from the former in lustrous, transparent, rectangular prisms ; it is insoluble in boiling petroleum.

VOL. CI. 4 U

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1340 FORSTER AND SPlNNER :

Action of Concentrated Sdphuric Acid.-The solution in concen- trated sulphuric acid was ruby-coloured, and yielded a bright yellow solid when poured on ice; repeated crystallisation from diluted alcohol gave bright yellow prisms melting a t 161O: 0.0986 gave 0.2776 COz and 0'0624 E20. @= 76'78; H = 7-08. 0.1386 ,, 6.3 C.C. N2 a t 22O and 752 mm. N=5*11.

C,8H,,0,N requires C=-'i6.82; E= 6-81 j N=4*98 per cent. Hence it appears that thp substance has been converted into an

internal anhydride, which might possibly arise in the following manner :

0 0

\/ N

It is freely soluble in organic media, excepting petroleum, which dissolves it when heated, and deposits slender, ailky needles on cooling. Boiling water does not dissolve it, but it is readily soluble in warm alkali, forming a yellow solution, which rapidly becomes colourless and yields a yellow precipitate when acidified.

ROYAL COLLEGE OF SCIENCE, LONDON, SOUTH KENSINGTON, S. W.

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