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Color development in C 18 unsaturated hydroxyamides
Author(s) -
Schneider W. J.,
Gast L. E.
Publication year - 1976
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02633301
Subject(s) - chemistry , colored , linseed oil , copper , polyunsaturated fatty acid , metal , sodium borohydride , potassium , organic chemistry , fatty acid , catalysis , materials science , composite material
Dark colors both of hydroxyamides produced from unsaturated fatty acids and of alkanolamine compounds in general might possibly limit their industrial applications. While metal salts have long been recognized as probably involved in the problem, little appears in the literature concerning the nature of these colored compounds. When we prepared linseed and soy N,N ‐bis(2‐hydroxyethy)amides as intermediates for protective coatings, we discovered that metals‐iron and copper in particular‐formed highly colored products with these unsaturated hydroxyamides. On standing at room temperature, these intermediates became deep reddish brown (18 on the Gardner scale) if only 1 ppm of cooper was present. Because purified starting materials (i.e., alkanolamines, methyl esters, or oils) do not color or darken in the presence of copper and air, several structural features and conditions must be present if color is to develop. While either chelating agents or antioxidants are somewhat effective over a short time, color formation has been successfully retarded during long‐term storage of polyunsaturated N,N ‐bis(2‐hydroxyethyl)amides by adding 1% potassium borohydride.