GB517692A - Process for the manufacture of ª‰-indole acetic acids - Google Patents

Abstract

517,692. Indole derivatives. I.G. FARBENINDUSTRIE AKT.-GES. Aug. 4, 1938, Nos. 23094 and 23095. Convention dates, Aug. 4, 1937 and July 8, 1938. [Class 2 (iii)] #-Indole acetic acid and its substitution derivatives are prepared by condensing indoles which are unsubstituted in the #-position with formaldehyde and hydrocyanic acid or a salt thereof and saponifying the resulting #-nitrile to the corresponding carboxylic acid. It is also possible to obtain the carboxylic acids in one step. Specified substituents which may be present in the benzene nucleus of the parent indole are alkyl, alkoxy or aryl groups and halogen atoms ; the substituents in the 4- and 5- positions may also form a ring system as in naphthindole. Substituents which may be present in the pyrrole ring in alpha-position are alkyl, aralkyl and aryl groups (which may themselves be substitutedby hydroxyl or ether groups) and halogen atoms. The nitrogen atom may also bear a substituent, such as an alkyl or aryl group. Polymers'of formaldehydemay be used instead of formaldehyde as the reagent. The reaction may be carried out in the presence or absence of solvents, of which are mentioned water, methanol, ethanol, n-butanol and acetone. In the examples, indole, alpha-phenylindole, alphamethylindole and 2:5-dimethylindole, condensed with formaldehyde and potassium cyanide and saponified, yield respectively #-indole acetic acid, alpha-pheynl-#-indole acetic acid, alpha-methyl-#- indole acetic acid and 2:5-dimethyl-3-indole acetic acid. Other specified starting materials are 2:5-diethylindole, N-methylindole, and 6- chlorindole. The products are useful for promoting plant growth. The Specification as open to inspection under Sect. 91 also indicates the use of N-etheylindole, N-phenylindole, alpha-ethylindole, alpha-butylindole, alpha-tolylindole and 6-chlorindole as starting materials. This subject-matter does not appear in the Specification as accepted.