Studies on the Blue Pigments Produced from Genipin and Methylamine. I. Structures of the Brownish-Red Pigments, Intermediates Leading to the Blue Pigments.

Abstract

During the course of studies on the blue pigment formation by the reaction of genipin with methylamine, nine red to brownish-red intermediary pigments were obtained under conditions excluding oxygen. They were identified as monomer, dimer, trimer and tetramer of 2-methyl-4-carbomethoxy-2-pyrindine derivatives on the basis of spectroscopic evidence.