whole range of organic chemistry more erratic than the condensations of the a-diketones with ketones and ketonic acids; it is hardly possible beforehand what course the reaction will take in any particular to say case. The study of the condensation of benzil with ethylic acetoacetate was begun in 1888 by one of us in conjunction with Dr. Felix Klingemann, who prepared the condensation compound and its ethyl derivative; but, owing to pressure of other work, it was at that time postponed. Chemical Department, University of Aberdeen. - XLIV. Electrolysis of Potassium Allo-ethylic Camphorate. Part II. By JAMES WALKER, Ph.D., D.Sc., and JAMES HENDERSON, B.Sc., University College, Dundee. In our former communication (Trans., 1895, 67, 337), we showed that the chief products of the electrolysis of a concentrated aqueous solution of potassium allo-ethylic camphorate are the ethylic salts of a monobasic acid, C,HO2, and of a dibasic acid, C18H30O4, to which we gave the names of allo-campholytic and allo-camphothetic acids respectively. Besides these ethereal salts, the presence of others was indicated, and an attempt has now been made to isolate some of them. A quantity of potassium allo-ethylic camphorate was prepared, and electrolysed in the manner described in our previous paper, the ethereal product obtained being then subjected to repeated fractional distillation, first under diminished pressure, and, finally, at the pres sure of the atmosphere. In order to ascertain the probable positions of the different ethereal liquids in the fractions boiling below 265° at 760 mm., the sp. gr. and the rotatory power of each fraction of 5° were determined. The density at 16°/4° increased continuously from 0.949 for fraction 200-205°, to 1043 for fraction 260-265°. The rotatory power, on the other hand, exhibited much greater variation, falling from [a]D: +29.8 for 200-205° to a minimum of 147 for 230-235°, thereafter increasing rapidly to 414 at 255-260°, again to diminish in the fractions with higher boiling points. = By far the largest fractions were obtained in the neighbourhood of 200°, the chief product being, as before, the ethylic salt of allo campholytic acid, which boils at 204°. The rotatory power on this occasion, however, fell far short of the specific rotation of the ethylic allo-campholytate formerly prepared. We found (loc. cit., 340) for this substance [x]D D = +39·1, whilst for the fraction 200-205° we have now only [a]D = +29·8. We were at first inclined to attribute this difference to a diminution of the rotatory power caused by the repeated distillation, but on redistilling the ethereal salt several times the rotations remained practically constant. It was, therefore, probable that in this fraction of nearly constant boiling point there were at least two isomeric substances whose boiling points were close together, but whose rotatory powers lay widely apart, one of them being ethylic allo-campholytate with the rotation of at least +39, the other an isomeride with a much smaller positive, or even a negative rotation. It is not surprising that the ethereal salt with negative or small positive rotatory power should be present in the product of the second electrolysis in greater proportion than was the case in the first experiment; for it has been repeatedly shown that very slight variations in the conditions of electrolysis may cause considerable variations in the relative quantities of the products obtained. The specific rotation [a] = +391 given for ethylic allo-campholytate is doubtless somewhat too low, for the isomeric substance was not altogether absent, even in the first electrolysis, although, as will presently appear, the amount of this impurity must have been small; the actual number, therefore, can only be slightly higher than that given. During the distillation of the acid obtained by saponifying the ethylic campholytate with alcoholic potash and acidifying, we had previously been struck by the appearance in the condensed liquid of a dark green coloration, which vanished on heating. No explanation of this was found at the time, but the repetition of the experiment with the second supply of material served to account for the phenomena observed. The fractions boiling below 210°, 54 grams in all, were heated for two hours on the water bath with 30 grams of caustic potash dissolved in alcohol; the alcohol was distilled off, and steam passed through the residue in order to remove any unaltered ethereal salt. Excess of hydrochloric acid was then added to liberate the allo-campholytic acid, and this was extracted from the aqueous liquid with ether, dried, and fractionated at the ordinary pressure. On distillation, practically nothing passed over until the temperature approached 200°, when lively ebullition set in, the thermometer fluctuating unsteadily between 170° and 200°, according to the size of the flame employed. As the amount of liquid distilling over seemed much greater than corresponded to the heat supply, the flame was removed, and it was observed that the ebullition went on for a considerable time spontaneously, the temperature registered by the thermometer remaining fairly constant at 170°. The liquid in the distilling flask did not blacken, and the distillate was of the green colour previously noticed. These results could only be explained by the assumption that decomposition had taken place, a supposition which was confirmed by the fact that the uncondensed gas passing into the receiver was almost pure carbonic anhydride. After a time, the decomposition ceased and the temperature rose rapidly to 230°, by far the greater part of the liquid distilling over at 232-235°. This portion consisted of allo-campholytic acid (b. p. 233-235°). The lower boiling portions were then refractionated, and it was plainly evident that decomposition had occurred, for now the liquid passed over almost completely between 120° and 124°, the slight residue left being of much higher boiling point. On redistillation, the liquid boiled at 120-122°. Hydrocarbon, C.H. The distillate thus obtained was a light neutral oil of pleasant, aromatic odour, and of a feeble yellow colour. On exposure to air its colour deepened to brown, and occasionally, on distillation, a fine green was developed in the condensed liquid. From its boiling point and neutral character, the substance appeared to be a hydrocarbon, probably unsaturated on account of its alterability on exposure to air. As the other product of the decomposition was carbonic anhydride, and as no blackening or other sign of complete destruction of the molecule occurred, the action was probably the splitting up of an isomeride of allo-campholytic acid by heat, according to the equation Elementary analysis supported this conclusion. 0.0543 gave 0.1726 CO2 and 0·0628 H2O. C = 867; H = 12.8. CH requires C 873; H = 127. 14 The unsaturated nature of the hydrocarbon was rendered evident by its action on alkaline permanganate and on bromine, both of which it at once decolorised. The ethereal product of electrolysis, boiling at 200-210°, thus contains the ethylic salts of two acids, one of which, allo-campholytic acid, may be distilled unchanged; whereas the other isomeric acid. breaks up at about 200° into the hydrocarbon, CH, and carbonic anhydride. Very little of the latter acid was present in the product of our first electrolysis, for the hydrocarbon derived from it existed. in such small quantity that it was not detected in the distillation, although it imparted its colour (or rather that of its oxidation products) to the distillate. 14 References to hydrocarbons of the formula C.H1, are frequent in the literature of camphoric acid and its derivatives. The following table gives the origin, boiling point, and density of the hydrocarbons obtained by various investigators. 149 It would appear from these results that there are (apart from stereoisomeric considerations) two hydrocarbons, C.H1, derivable from camphoric acid, one boiling at about 120°, the other at about 108°. Both may be obtained from camphoric acid or its salts directly, but when the source is an acid derived from camphoric acid, then only one of the hydrocarbons is generated. Thus camphanic acid and aminolauronic acid yield the hydrocarbon boiling at 120°, whilst sulphocamphylic acid and isocampholytic acid yield the other isomeride. This corresponds to the genetic relations of the different substances. There are genetically connected with each other two series of camphoric acid derivatives. To one series belong campholytic acid, sulphocamphylic acid, iso-campholytic acid; to the other allo-campholytic acid, aminolauronic acid, lauronolic acid, camphanic acid, and the campholactones. The hydrocarbon boiling at 108° is derivable from the compounds of the first series; the hydrocarbon boiling at 120° from the compounds of the second. *The nomenclature of the isomeric acids, CH13 COOH, is at present somewhat confused. Four isomerides are known: (1) campholytic acid cis-trans-campholytic acid (Noyes); (2) isocampholytic acid isolauronolic acid (Koenigs); (3) allocampholytic acid (4) lauronolic acid. VOL. LXIX. = = cis-campholytic acid (Noyes) = 3 E Now, the difference between the two series is that the compounds of the first retain one of the two carboxyl groups of camphoric acid, whilst the compounds of the second retain the other carboxyl group of the original substance. It is true that camphanic acid retains both, but on heating it loses one with formation of lauronolic acid, so that it may be ranked along with that compound. By the electrolysis of sodium ortho-ethyl camphorate, campholytic and isocampholytic acids are produced; by the electrolysis of sodium alloethyl camphorate, we obtain allo-campholytic acid and the isomeric acid which decomposes with formation of CH4. As the latter acid must also have its carboxyl group in the allo-position, the hydrocarbon derived from it should correspond to the second series of hydrocarbon derivatives, that is, be identical with that obtained from camphanic acid. This conclusion is borne out in the first place by the boiling-point of our hydrocarbon which is 120-122°, no indication of a substance of lower boiling point being observed. The hydrocarbon obtained from camphanic acid according to the equation has been recently thoroughly investigated by Aschan (loc. cit.), who has given to it the name laurolene. The quantity of substance at our disposal was unfortunately too small to enable us to effect an accurate numerical comparison of its physical properties with those of laurolene, but the general resemblance leaves little doubt as to their identity. The density of our hydrocarbon at 16°/4° was found to be 0.798; that of laurolene at 18°/4° is given by Aschan as 0·802°. The hydrocarbon obtained by us was optically active, rotating the plane of polarisation to the left. Aschan gives [a];=-230 as the specific rotatory power of laurolene. We had not sufficient material to determine the rotatory power of our substance in the pure state, but we found that in 25 per cent. ethereal solution (by volume), its specific rotatory power was [a] = -29.2. The chemical properties of the two substances are exactly alike. Besides those already mentioned, depending on the unsaturated nature of the compound, we may refer to the behaviour of the hydrocarbon towards nitric acid. Wreden, who originally prepared the substance of boiling-point 120°, states that, when gently warmed with a mixture of nitric and sulphuric acids, it is partially converted into trinitrometaxylene. Aschan on the other hand found that laurolene was violently acted on by strong nitric acid alone, and also by a mixture of nitric and sulphuric acids, but by cooling with ice, he succeeded in moderating the action, and on subsequent careful warming found that the hydrocarbon disappeared. The whole product, however, was then soluble in water, with the exception of a "scarcely |