In this connection reference may be made to the large number of synthetic organic products which have been introduced into medicine during the past few years. The investigation of the constitution of the alkaloids has served to show in many cases to what particular molecular grouping the physiological action of the drug is mainly due, and this has led to the production of substances containing these groups, but not necessarily existing as natural products. Among these may be mentioned antipyrin, a derivative of the pyrazol group, discovered by Knorr in 1883, and of which upwards of 17,000 kilos, of the approximate value of £35,000, were produced in 1899. This substance is a phenyl-dimethyl-pyrazolone.
Acetanilide C6H5NH.COCH3, an aniline derivative, was discovered by Gerhardt in 1853. Phenacetin is a derivative of para-aminophenol:
An extraordinary number of synthetical soporifics have been introduced at various times during recent years—e.g., chloral hydrate, veronal, sulphonal, trional and tetronal, etc. The three last-named substances are closely related, as the following formulæ indicate:
Sulphonal.
Trional.
Tetronal.
Sulphonal is prepared by the oxidation of a substance obtained by the combination of acetone and ethylmercaptan. Veronal is an ethyl compound of barbituric acid, obtained by the condensation of urea and diethyl malonyl chloride: