Metabolites of 2,4-dichlorophenoxyacetic acid from bean stems

Publisher Website
Google Scholar
Abstract
Carboxyl labeled 2,4-D was vacuum infiltrated into bean stems and the radioactive metabolites extracted and fractionated after 3 days'' exposure. Radioactivity was found in 10 ether-soluble and 8 ether insoluble compounds. The ether-insoluble compounds were hydrolyzed by HC1 to give 2 ether soluble compounds and some 10 ninhydrin positive ether insoluble, non radioactive compounds. The latter were partly identified by chromato-graphy as [alpha] amino acids. Including the radioactivity released from the ether-insoluble fraction after hydrolysis, the 2 main soluble compounds accounted for some 80% of the total radioactivity. Neither of these compounds was identical with 2,4-D or 6-hydroxy-2,4-dichloro-phenoxyacetic acid. Chemical tests which were design to obtain evidence regarding the functional groups present on these fractions established that the phenoxy ring of 2,4-D was still present (HI cleavage and Br2 reaction), that there were additional phenol groups present in some of the compounds (chloroacetic acid addition) and that there were aliphatic hydroxyl groups present (KMnO4, benzoylation gave more products than chloroacetic acid condensation). No evidence for aliphatic unsaturation was found (catalytic hydrogenation). Since it is not possible to write a structure for a compound having the carbon skeleton of 2,4-D, the carboxyl of 2,4-D and an aliphatic hydroxyl group the possibility of a chain lengthening of the acetic acid side-chain is proposed.