title: Cyclocondensation of 2,3-butanedione in the presence of amino acids and formation of 4,5-dimethyl-1,2-phenylendiamine.
abstract: The chemical interaction of 2,3-butanedione with amino acids through Strecker reaction has been studied extensively. However, the formation of previously reported 4,5-dimethyl-1,2-benzoquinone from 2,3-butanedione/amino acid model systems has not been investigated in detail. In this study such model systems containing 2,3-butanedione were investigated under pyrolytic conditions using glycine, sodium glycinate and glycine hydrochloride as amino acids able to modulate acid/base catalytic activity of the reaction medium. The analysis of the data indicated that replacing glycine with its corresponding salts promoted significantly the generation of 2,3,6,7-tetramethylquinoxaline relative to tetramethylpyrazine, the indicator compound for the Strecker reaction. The origin of the 2,3,6,7-tetramethylquinoxaline was traced back to the formation of 4,5-dimethyl-1,2-benzoquinone through isotope labelling studies. Furthermore, these studies have also indicated the ability of glycine not only to catalyse the cyclocondensation of butanedione into 4,5-dimethyl-1,2-benzoquinone but also its conversion into 4,5-dimethyl-1,2-phenylenediamine through Strecker-type transformations. The trapping of 2,3-butanedione by this in situ generated 4,5-dimethyl-1,2-phenylenediamine gave rise to the observed 2,3,6,7-tetramethylquinoxaline.
authors.affiliation: McGill University, Department of Food Science and Agricultural Chemistry, 21, 111 Lakeshore, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada.
authors.forename: Paula Vanessa
authors.initials: PV
authors.lastname: Guerra
authors.forename: Varoujan A
authors.initials: VA
authors.lastname: Yaylayan
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D003931:Diacetyl / Q000737:chemistry*; D015416:Maillard Reaction; D015394:Molecular Structure; D010655:Phenylenediamines / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D010655:Phenylenediamines; C011793:4,5-dimethyl-1,2-phenylenediamine; D003931:Diacetyl
keywords: 4,5-Dimethyl-1,2-benzenediamine; 4,5-Dimethyl-1,2-benzoquinone; Aldol cyclocondensation of 2,3-butanedione; Benzene derivatives; Maillard; Strecker