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Reaction of thiobarbituric acid with saturated aldehydes
Author(s) -
Kosugi Hiroko,
Kikugawa Kiyomi
Publication year - 1986
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534048
Subject(s) - chemistry , pigment , hexanal , aldehyde , adduct , organic chemistry , isobutyraldehyde , acetic acid , thiobarbituric acid , heptanal , aldol reaction , catalysis , antioxidant , lipid peroxidation
The reaction of thiobarbituric acid (TBA) with saturated aldehydes, i.e., 1‐butanal, 1‐hexanal and 1‐heptanal, produced a 455‐nm yellow and a 532‐nm red pigment. Formation of the pigments depended on the reaction conditions. The yellow pigment was unstable in the presence of excess amounts of the saturated aldehydes. The red pigment was formed only when the reaction was performed at a TBA/aldehyde ratio of 1∶1 in aqueous acetic acid. Formation of the yellow and red pigments required molecular oxygen. The colorless adducts, intermediates for the yellow and the red pigments, were isolated from the reaction mixtures. Aldol condensation and dehydration of 2 mol of the saturated aldehydes initially gave the α,β‐unsaturated aldehydes, which in turn reacted with TBA to form the colorless adducts, pyranopyrimidine derivatives. The adducts were then converted into the yellow and red pigments under aerobic conditions.