Cocaine

Cocaine, C17H21NO4, an alkaloid occurring to the extent of about 1% in the leaves of Erythroxylon coca (see above). It is associated with many other alkaloids: cinnamyl cocaine, C19H23NO4; α-truxilline, (C19H23NO4)2; β-truxilline, (C19H23NO4)2; benzoylecgonine, C16H19NO2; tropa-cocaine, C15H19NO2; hygrine, C8H15NO; cuscohygrine, C13H24NO2. These substances, which may be collectively termed “cocaines,” are all derivatives of ecgonine (q.v.). Cocaine is benzoylmethyl ecgonine. It crystallizes from alcohol in prisms, which are sparingly soluble in water. Its solution has a bitter taste, alkaline reaction, and is laevorotatory. Its use as a local anaesthetic (see Anaesthesia) makes it the most valuable of the coca alkaloids, and it is much used in ophthalmic practice. Applied to the conjunctiva it causes anaesthesia, dilatation of the pupil, diminution of the intraocular tension, and some interference with accommodation. The conversion of the mixture obtained by extracting coca-leaves into cocaine is effected by saponifying the esters into ecgonine and the respective acids, and then benzoylating and methylating the ecgonine. Homologues of cocaine—ethylbenzoylecgonine, &c.—have been prepared; they closely resemble natural cocaine. Cinnamyl cocaine is cinnamylmethylecgonine, i.e. cocaine in which the benzoyl group is replaced by the cinnamyl group. α- and β-truxillines, named from their isolation from a coca of Truxillo (Peru), are two isomeric alkaloids which hydrolyse to ecgonine, methyl alcohol, and two isomeric acids, the truxillic acids, C18H16O4. The alkaloids are therefore methyl truxillylecgonines. The truxillic acids have been studied by K. Liebermann and his students (Ber., vols. 21-27, and 31), and are diphenyl tetramethylene dicarboxylic acids.