SORABJI ON SOME NEW PARAFFINS. 37 By KHAN BAHADUR BOMANJI SORABJI, Ph.D., C.E., &c. AT present, comparatively little is known of the higher members of the paraffin series; the difficulty of separating them froiu one another rendering it impossible t o isolate them from their natural sources, such as petroleum, ozokerit, &c, The solid paraffin obtained from such sources can be partly separated into its constihents by means of fractional crystallisation, but the fractions thus prepared ere still far from being homogeneous and pure compounds. In order to study these higher paraffins, therefore, it is necessary t o prepare them synthetically. Several syntheses of this kind hare35 SORABJI ON SOME NEW PARAFFINS. lately been made by Krafft (Abstr., 1882, 1271 and l272), but many gaps in the series of paraffins still remain, and the present communica- ticn gives the results of an endeavour to prepare some of the missing members of the series.The method which appeared most likely to yield satisfactory results was that of Wiirtz, which consists in treating the iodide of an alcohol radicle with sodium, according to the equation- But in these reactions more or less of the paraffin containing the same number of carbon-afoms as the alcohol radical is almost always produced, according to the equation- 2CwH2,1+J + Na2 = 2NaI + ClrHzn + CnH2% + 2 . As my especial aim was the preparation of dicetyl, CS2HG6, and the paraffin cetane, C,,H,,, which would probably be produced as a bye- product, had not been prepared from cetyl iodide, it appeared of interest first to make and examine this body so as to minimise, as far as possible, the after difficulty of the purification of the dicetyl.I. Cetane from C'etyl Iodide. This paraffin was obtained from the iodide by the reduction of the latter by concentrated hydriodic acid in the presence of phosphorus, and also by the digestion of the iodide with zinc and hydrochloric aci d , Cetyl iodide was mixed with four times its weight of pure alcohol, and introduced into a flask containing a considerable quantity of granulated zinc, the flask being connected with a i-eflux condenser. Fuming hydrochloric acid was then slowly added, causing a t once a precipitation of a heavy oil (cetyl iodide). After four or five days' digestion, the oil rose to the top of the liquid, but as it still contained much iodine it was resubjected to the same treatment for a, week.Water was then added, and the oil which separated was washed repeatedly with concentrated sulphuric acid containing nitric acid, with water, with caustic soda, and with water until it no longer con- tained a trace of iodine. It was then dried over solid potash and distilled. Cetane, thus obtained, boils constantly at 278', and when cooled, solidifies to a crystalline mass which melts a t 18-20'. A combustion yielded the results- Calculated. rL-- 7 Found. CI6 . . . . . . 192 84.96 per cent. 84.76 €Id4 . . . . . . . 34 15.04 ,, 15 29SORABJI ON SOME NEW PARAFFINS. 39 Two vapour-densities made with V. and C. Meyer's apparatus yielded 7.9 and 7.85 respectively, theory requiring 7.84.Zincke's dioctyl (An~zalen, 152, 16) from primary octyl iodide melted a t 21", and the same body obtained from mercury octyl by Eichler (Bey., 12, I882) had a melting point of 14". Cetane resembled Zincke's dioctyl in all other respects, and its low melting point, as well as that of Eichler's compound, is probably due to the presence of a trace of im- purity. Cetane is miscible in all proportions with alcobol and ether: and as cetene is also very soluble in these reagents, the purification of dicetyl from these bye-products did not seem to offer any difficulty. 11. Dicetyl f r o m CetyZ Iodide. Cetyl iodide dissolved in six times its weight of ether was intro- duced into a flask connected with a reflux condenser. Finely cut sodium was then added, and the whole allowed to stand for some time a t the ordinary temperahre.Action set in rapidly, the metal became coated with sodium iodide, and iridescent flakes were deposited in the liquid. The reaction was completed by heating the mixture for 10 hours on the water-bath. On cooling, no trace of cetyl iodide could be detected, but the whole liquid became filled with beautiful glistening scales. In order to remove excess of sodium, alcohol was added, and after the evolution of hydrogen had ceased, the precipitated sodium iodide was dissolved by the addition of water. The whole was then thrown on a filter and the residual crystalline mass dried, and extracted with boiling absolute alcohol, in which it is almost insoluble. Dicetyl is also nearly insoluble in ether, but dissolves readily in boiling glacial acetic acid, crystallising out again almost entirely on cooling. When recrystallised twice from acetic acid, it melts at 70" and distils undecomposed, but at a temperature lying far above t'he range of the mercury thermometer.On cooling, the distillate solidifies to beautiful pearly scales. Dicetyl is neither dissolved nor blackened when treated with concentrated sul- phuric acid at 150". Combustions yielded the following results :- 11. 0.1470 ,, ,, 0.4592 ,, 0.1956 ,, I. 0.1655 gram subs. gave 0.5138 gram COzand 0.2197 gram H,O. These yield t'he numbers- Calculated. Pound. rA-- 7 w - - - - - I C32 = 384 = 85.33 85.18 85.19 H 6 6 = 66 = 14.67 14.84 14.7840 SORABJI ON SOME NEW PARAFFINS. Vapour-densities conducted by means of V.and C . Meyer's ap- paratus gave tlhe numbers:- I. 0*2:354 gram substance gave 12.56 C.C. air a t 18" and 743.9 mm. 11. 0.2332 gram substance gave 13.10 C.C. air a t 23" and 746.1 mm. 111. 0.0929 gram substance gave 5.20 C.C. a i r a t 23" and 746.1 mm. pressure. pressure. pressure. The results when calculated out give- Found. v-- 7 Calculated. I. 11. 111. C32H66.. . . . . 15.5 16.1 15.64 15.70 The mother-liquors from the crude dicetyl yielded, on evaporation, a very slighh crystalline residue, which proved to be almost entirely dicetyl. It is thus clear that hardly any bye-products are formed in this reaction. 111. Ethyl-cetyl from E t h y l and Cetyl Iodides. This compound was obtained by allowing sodium, cut in thin flakes, to act on a mixture of ethyl and cetyl iodides dissolved in ether.The reaction was slower than when cetyl iodide alone was used. A good deal of dicetyl was formed, but( the ethoric liquid contained a second body, which, on evaporat'ion of the ether, remained as a colourless oil. After purification with sulphuric acid, &c., as before, this oil was dried with solid potash a8nd distilled, when it passed over a t 312-313", and the distillate solidified when cooled with ice. This substance was undoubtedly ethyl-cetyl, but the quantity obtained was too small for a combustion or vapour-density determination. It is also doubtful whether it was quite pure, so that the above boiling point must only be looked upon as approximate. IV. Dihepty l fiom Heptyl Iodide. Although heptyl alcohol can be prepared without great difficulty from oenanthaldehyde, and the iodide is very easily obtainable from the alcohol, on attempt appears yet to have been made to synthesise the normal paraffin of the formula, ClaHw from this iodide.It was thought that the synthesis of normal diheptyl might prove of some interest. The heptyl alcohol employed was prepared from oenanthaldeh yde in part by Cross's method (Chenz. Xoc. J., 1877, 32, 124), as modifiedSORABJI ON SOME NEW PARAFFINS. 41 by Jourdan (AnnaZen, 200, l02), in part by Krafft's method for the reduction of aldehydes of high molecular weight (Abstr., 1883, 1075). According t o the tirst-named process, a solution of the aldehyde in glacial acetic acid is reduced by means of sodium-amalgam ; accord- ing to the second, a similar solution is employed, but zinc-dust takes the place ol sodium-amalgam.A better yield of alcohol and a smaller admixture of bye-products was obtained by the first than by the second process. The heptyl alcohol boiled at 175*5", and gave satis- factory numbers on analysis. It was converted into the iodide by saturating i t with gaseous hydriodic acid (Moslinger, AnnaZen, 185, 55). The conversion of the iodide into the paraffin was effected in a manner precisely similar to that employed in the case of dicetyl. The reaction was completed a t the ordinary temperature in about three days. Diheptyl, prepared in this way, is a colourless mobile oil having a slight odour. It boils without decomposition at 245" under 750 mm. pressure. When cooled by means of ice, it solidified to a lamellar. crystalline mass, which began to melt again at Go, and was completely liquid at 10.5". The pure iodide boiled at 201". Analpis yielded the following results :- 0-1880 gram substance gave 0.5831 gram CO, and 0.2616 gram H20. Calculated. r--L-- 7 Found. Cia.. . . . . . 168 84.80 per cent. 84.58 H30 .... .. 30 15.20 ,, 15.47 Vapour-density determinations gave the numbers- I. 0.0602 gram substance gave 7.40 cm. air at 21" and 747.2 mm. 11. 0.0429 gram substance gave 5.35 cm. air at 23" and 746.1 mm. pressure. pressure. These numbers when calculated out give 7.06 and 7.04 respectively, whilst theory requires for the formula CIdHso, 6.82. In conclusion, I have to express my thanks to Professor Johannes Wislicenus, at whose suggestion and in whose laboratory this work was carried out, both for the interest he has taken in my work, and for the valuable advice he has given me during its progress.