OF the various types of isomeric change, that which involves a change of position of one hydrogen atom only, as in a simple desmotropic change, would, for various reasons, appear to be the most simple, and probably the most easy to investigate.We do not intend to review the many important contributions already made to this subject, in particular since such a course would involve, for the most part, a repetition of much with which Lowry has somemhat recently dealt in his suggestive paper on mutarotation and
IN continuation of researches on the tautomerism of P-ketonic esters, the study of an optically active ester of acetoacetic acid was undertaken, as little is yet known as to the mode in which interconversion of the enolic and ketonic Forms of ethyl acetoacetate is brought about, for although it is already well established that bases in small quantities are effective in establishing equilibrium, tke effect of acids has not been properly investigated. After a number of attempts had been made to obtain the menthyl ester from menthyl acetate by the action of metallic sodium-a method which was found to afford the desired compound only in small quantity-the action of menthol on the ethyl ester in presence of hydrogen chloride was tried. A preliminary experiment indicated that alcohol was evolved in Considerable amount before the hydrogen chloride was introduced, and we afterwards prepared some quantity of menthyl acetoacetate by the action of heat on a mixture of menthol and ethyl acetoacetate, a method which afforded excellent results. Shortly afterwards, we found that Cohn had obtained the compound by this process (Mornatsh., 1900, 21, 200), but as he shortly afterwards notified that he had abandoned the work (Bar., 1900, 33, 734), with his concurrence we proceeded with the investigation. The ease with which the ester is prepared renders it possible to produce large quantities of it in a short time, and we propose to employ the compound as the starting point in the preparation of a number of other active compounds which may possess interest from various standpoints.
IN the course of an investigation on the chemistry and pharmacology of the jaborandi alkaloids by one of us and Professor C. R. Marshall, it was shown (Trans., 1900, 77, 481) that, when caustic alkali is added to an aqueous solution of pilocarpilie or ,isopilocarpine, the specific rotatory power is diminished and that the minimum value is obtained when a molecular proportion of alkali has been added. The fact has also been observed (Marshall, J. P?~ysioZ., 1904, 31, 153) that a n aqueous solution of pilocarpine to which a molecular amount of caustic alkali has been added does not possess the characteristic physiological action of pilocarpine. Furthermore, it has been found that the specific rotatory power of pilocarpine in aqueous solution dropped from 100.5O to '77.5" simply on standing for three weeks; it has also been shown (Albertoni, Arch. exp. Pat?&. Pharrn., 1879, 11, 415 ; Marshall, Zoc. cit., 144) that, when instilled into the eye, aqueous solutions of the base are less active than solutions of a salt of similar strength. The explanation of these facts would appear t o be that, under the above conditions, the lactone ring opens and the corresponding hydroxy-acid
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