Chemical structure and biodegradability of halogenated aromatic compounds. Halogenated muconic acids as intermediates

Publisher Website
Google Scholar
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.degree. C. Cycloisomerization of 2-chloro-cis,cis-muconic acid in 75% (vol/vol) 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 NMR 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.