74 PEDLER ON THE ISOMERIC FORMS OF VALEKIC ACID. X.-On the horneric forms of Lhleric Acid. By ALEXAWDER Esq. PEDLER INthe concluding pages of Frankland and Duppa's memoir on Synthetical researches on Ethers," the authors state that ordinary valeric acid rotates a ray of polarized light to the right ; whilst W urt 2; had previously asserted that ordinary valeric acid is without any action upon a polarized ray. To reconcile these discrepant observations F ran kl an d and Duppa suggested that active amylic alcohol yields an active valeric acid when oxidized and inactive amylic alcohol an inactive acid and that the sample of arnylic alcohol from which Wurtz's valeric acid had been prepared was the inactive variety. To test the validity of this suggestion the two amylic alcohols were first separated by Past eur's process and then individually oxidized with a mixture of dipotassic dichromate and sulphnric acid in the usual manner.Equal weights of concentrated sulphuric acid and amylic alcohol were mixed together the amylic alcohol being added very gradually ; the mixture was then allowed to stand for 24 hours and neutralized with baric carbonate so as to form baric sulphamylate. The baric sulphamylate obtained from the active amylic alcohol is as stated by Pasteur about .two and a half times as soluble as that obtained from the inactive amylic alcohol ; the mixed sulphamylates were consequently separated by fractional crys- tallisntion which was continued until the two salts were obtained in a state of purity.Care must be taken to keep the solut<ioiis alkaline by baric hydrate or the sulphamylates will decompose when heated. This process is long and tedious as numerous crystallisations have to be made before the perfect separation of the sulph- amylates is effected. The two amylic alcohols were obtained by decomposing the baric sulphamylates with sodic carbonate and again decom- posing the sodic sulphamylates by ebullition with excess of f Chem. SOC.Journ. vol. xx p. 102. PEDLER ON THE ISOMERIC FORMS OF VALERIG ACID. 75 sulphuric acid. The amylic alcohols thus obtained were purified by drying and rectification ; they then exhibited the following characters :-The amylic alcohol obtained from the less soluble sulph- amylate was found to boil at 129"C.and to have a penet'rating and oppressive odour which produces coughing and a burning taste. In the polai-iscope when tested with a yellow sodium flame it was found to be perfectly incapable of rotating the ray of polarized light. The alcohol obtained from the soluble sulphamylate had a boiling point of 128" C. and an odour resembling that of the inactive alcohol but more fruity; it was however equally irritating and had a burning taste. It was found to rotate a yellow ray of polarized light 17' to the left in a tube 50 cen-timetres long. For the conversion of these alcohols into valeric acid a hot oxidizing mixture was used made by dissolving two parts of dipotassic dicliromate in moderately hot water and then adding three parts of concentrated sulphuric acid.The alcohol was added through a funnel tube slowly the vessel containing the mixture being also connected with a condenser. The inactive alcohol when oxidized was converted into valeric acid and amylic valerate which latter was decomposed by sodic hydrate and the resulting amylic alcohol again oxidized. There was no effervescence when the alcohol was added to the hot oxidizing mixture. The act'ive amylic alcohol when added to the nearly boiling oxidizing mixture was found to effervesce strongly from the evolution of carbonic anhydride. On allowing the oxidizing mixture to cool and then adding more of the alcohol scarcely any effervescence was observed. It was allowed to stand for some hours and then distilled and the distillate was found to contain valeric acid and amylic valerate which latter was again decomposed and oxidized as before.The two valeric acids were freed from the accompanying water which had distilled over with them by neutralizing with pure sodic carbonate evaporating to dryness and decomposing with sulphuric acid. When dried and distilled they had the following characters The valeric acid obtained fiom the inactive variety of amylic alcohol boiled at 1'75" C. and had the characteristic persistent 76 PEDLER ON THE ISOiMERIC FORMS OF VALERIC ACID. * odour and taste of ordinary valeric acid. It was found when tested in the polariscope not to possess the slightest action on the polarized ray.It is highly probable that this acid is identical with the isopropacetic acid prm @( CMe,H)H IL COHO Or {COHO. L obtained by Frankland and Dnppa and described in their memoir before mentioned. The boiling points of inactive valeric acid and of isopropacetic acid are identical. The valeric acid from the rotating amylic alcohol boiled at about 170' C. and had t,he same disagreeable odour and taste as the inactive acid. When tested with the ray of polarized light it gave a right-handed rotation of 43 degree8 in a tube 50 centimetres long. The above observations with the polariscope were most kindly takeii by Dr. Frankland to whom my most cordial thanks are due. In order to ascertain the products of the graduated oxidation of the two amylic alcohols some experiments were made by digesting them in sealed tubes at 100" C.with ordinary chromic acid oxidizing mixture. When the rotating alcohol was thus treated it evolved abun-dance of carbonic anhydride and produced a large amount of acetic acid ; while the inactive alcohol which when similarly digested gave a mere trace of carbonic anhydride seemed to produce scarcely anything but valeric acid. The above experiments therefore indicate either that the non-rotating valeric acid of W u r t z had been made as suggested by Frankland and Duppa from a non-rotating sample of arnylic alcohol; or that the acid made fiom the mixed alcohols had been allowed to remain in contact with the hot oxidizing mixture sufficiently long to destroy the whole of the less stable rotating acid. In a future paper I hope to be able to give a more detailed description of the oxidation products of the two alcohols together with a comparison of the properties of the salts obtained .from the two acids.