1058 MARSH: THE ACTION OF SULPHURIC ACID ON FENOHONE. CVI.-The Action of SLclpl~w'ic Acid 03% Ere~~,clio'~ze, By JAMES E. MARSH. IF fenchone is warmed with strong sulphuric acid, sulphur dioxide is given off and acetoxylene [Ale : Me : Ac = 1 : 2 : 41 is formed. This compound has been obtained synthetically by Claus by the action of acetyl chloride on ortliosylene in presence of aluminium chloride (J p. Chem., 1890, [ii], 41, 396). Armstrong and Kipping (Trans., 1893, 63, '75) obtained the same compound by the action of sulphuric acid on camphor ; they found that camphor is not readily acted on by sulphuric acid at a tempernture below looo, that, it was most ad- vantageous to heat, the mixture to lZO", that acetoxylene is not the only product of the reaction, and that it was not practicable to separate the compound in a pure state by fractional distillation; they effected its separation by preparing the crystalline phenylhydr- ttzone from it and decomposing this by hydrolysis.When .fenchone was warmed with five times its volume of strong sulphuric acid, the action began at a temperatnre below 50" with evolution of sulphur dioxide. The evolution of gas mas rapid at SO", and at 100' was complete in ft few minutes. I used 'small quantities of not more than 10 C.C. of fenchone in one operation. It appeared prefersble to keep the temperature at about SOo, and there was little or no charring. After cooling, the solution was poured into water and distilled in steam. The distillate mas shaken out with ether and the ethereal solution distilled under reduced pressure.After the ether and water had come off without condensing, the residue distilled almost entirely at 131" under 20 mm. pressure; it amounted t o about 70 per cent. of the fenchone taken. If me take into consideration the loss arising from the number of operations which the fenchone had undergone, and that only 10 grams were used, the yield of acetoxylene probably approximates to that required by theory. It was redistilled and the fraction boiling a t 131" under 20 mm. pressure was nnalysed. It gave C = 80.6 ; H = 8.3. The acetoxylene so obtained was a nearly colourless oil smelling somewhat of cinnamon. Its specific gravity mas Found to be 0.9968 at 2Ooj4". When treated with hydroxylamine hydrochloride and caustic potash in alcoholic solution, it gave a good yield of the oxime which crystallised from methylic alcohol, forming colourless crystals melting at 86-87'.Claus gives the melting point at 88-89", Armstrong and Ripping at 84.5-85.5O. To further establish its identity and constitution, cz small quantity CloH120 requires C = 81 '0 ; H = 8.1 per cent.MARSH: THE ACTION OF SULPHURIC ACID ON FENCHONE. 1059 was oxidised by warming gently with a slight excess of bromine dissolved in 4 per cent. caustic soda solution, until bromine was scarcely liberated by addition of acid. On filtering from the crystals of carbon tetrabromide, and on addition of dilute sulphuric acid, a thick precipitate m:is thrown down which, after crystallising from dilnte alcohol, melted at 163’. On analysis the product gave c1 = 71.6 ; H = 6.7.The silver salt was prepared and, on analysis, gave C,H,,O, requires C = $2.0 ; H = 6.6 per cent. Ag = 41 .S. C!,H,Me?* COOAg requires A g = 44 -0 per cent. The acid thus obtained by oxidation of acetoxylene is paraxylic acid [CH, : CII, : COOH = 1 : 2 : 41. It seeins reasonable to suppose that the almost quantitative con- version of fenchone into acetoxylene ought to have a n important bearing on the constitution of fenchone. I have attempted in a paper on “The Constitution of Camphor ” ( I m n s . Oqjbrd Ughiv. Jzm. Xci. Club N.S., 1898,110) to show how the formation of ncetoxylene from camphor, established by Armstrong and Kipping, niay be explained; I here only wish to point out that fenchone is probably still more nearly related in constitution t o acetoxyleiie than is camphor, judging from the ease with which this compound is obtained from fenchone com- pared with the dificulty of i t s production from camphor.The following formula for fenciioiie mas put forward last year by Wallach (Annnlen, lSDS, 300, 320) and by Gardner and Cockburn (Trans., 1898, 73, 70s) independently : CH,* F]H-CH*CH, UH,* CH-U0 I F(CH,), I The coincidence of two separate lines of re.;earch leading to the same conclusion might be regarded as affording a t least n presumption in favour of the formula. But the coincidence is less remarkable seeing that the formula is constructed on the model of Bredt’s camphor formula. Further, neither Wallach nor Gardner and Cockburn ex- press themselves as satisfied with the formula, and bring forward objections to i t which seem to me not less convincing than their argu- ments in its favour.To these objections I think ought to be added the formation from fenchone of ncetoxylene which i t seems impossible to reconcile with the formula proposed. I have from time to time ventured to criticise some of the formulze proposed for members of the terpene group, partly on the ground t h a t they do not account for the derivatives of benzene which are obtained from them by comparatively simple reactions. Nor does it seem to1060 HARCOURT : ON METHODS FOR ESTIMATING me obvious why it should be regarded a sounder principle to base the constitution of closed chain compounds, such as the terpenes, on the products obtained by breaking down their cyclic structure, than on those products in which a ring remains. At present there seems to be an inclination either to disregard the latter entirely, or in certain cases to make a selection of those benzene derivatives which may be accounted for, It is not unreasonable to require that any constitution assigned to a member of the terpene group must account for both the aromatic and the fatty derivatives obtained from it, I wish to thank Mr. Gardner and Mr. Cockburn for kindly giving me the samples of fenchone with wliich these experiments were made. UNIVERSITY hIusEm, OSPOKD.