title: Chemical structure and biodegradability of halogenated aromatic compounds. Halogenated muconic acids as intermediates.
abstract: Substituted muconic acids were prepared from the corresponding catechols by pyrocatechase II from Pseudomonas sp. B13. The stabilities of substituted muconic acids were compared under different pH conditions. 3-Substituted cis, cis-muconic acids cycloisomerized readily in slightly acidic solutions, whereas 2-chloro- and 2-fluoro-cis,cis-muconic acids were stable under these conditions and could be isolated as crystalline compounds. They were isomerized to the cis, trans-form in highly acidic solution (pH 1), particularly when heated to 80 degrees C. Cycloisomerization of 2-chloro-cis,cis-muconic acid in 75% (v/v) H2SO4 yields 4-carboxymethyl-2-chloro-but-2-en-4-olide (4-chloro-2,5-dihydro-5-oxo-3H-furan-2-ylacetic acid). THe cis,cis-configuration of 2-chloromuconic acid was certified by 1H n.m.r. spectroscopy and by enzymic cycloisomerization. Although the cis,cis-configuration of 2-fluoromuconic acid was confirmed by corresponding spectroscopic data, it was not cycloisomerized by crude extracts or cycloisomerase II preparations from Pseudomonas sp. B13.
mesh_terms: D001673:Biodegradation, Environmental; D002396:Catechols; D055598:Chemical Phenomena; D002621:Chemistry; D003500:Cyclization; D003998:Dicarboxylic Acids; D004355:Drug Stability; D005231:Fatty Acids, Unsaturated; D006846:Hydrocarbons, Halogenated / Q000378:metabolism; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D013011:Sorbic Acid / Q000031:analogs & derivatives
chemical_list: D002396:Catechols; D003998:Dicarboxylic Acids; D005231:Fatty Acids, Unsaturated; D006846:Hydrocarbons, Halogenated; C005939:muconic acid; D013011:Sorbic Acid