Muconic acid

Mucic acid [526-99-8] Mucoadhesives Muconic acid [505-70-4] Mucopolysaccharidoses Mucor circinelloides Mucor spp. 

Conversion of Cyclic to Acyclic Structures. Upon oxidation, the aromatic rings of lignin may be converted direcdy to acycHc stmctures, eg, muconic acid derivatives, or indirectly by oxidative splitting of o-quinoid rings. Further oxidation creates carboxyUc acid fragments attached to the lignin network. 

Neither the mechanism by which benzene damages bone marrow nor its role in the leukemia process are well understood. It is generally beheved that the toxic factor(s) is a metaboHte of benzene (107). Benzene is oxidized in the fiver to phenol [108-95-2] as the primary metabolite with hydroquinone [123-31-9] catechol [120-80-9] muconic acid [505-70-4] and 1,2,4-trihydroxybenzene [533-73-3] as significant secondary metabolites (108). Although the identity of the actual toxic metabolite or combination of metabolites responsible for the hematological abnormalities is not known, evidence suggests that benzene oxide, hydroquinone, benzoquinone, or muconic acid derivatives are possibly the ultimate carcinogenic species (96,103,107—112). 

Norite, is heated to boiling by introduction of steam, filtered through a Norite filter pad by suction, and cooled in an ice-salt bath. The muconic acid is precipitated by the addition of a large excess (1500 ml.) (sp. gr. 1.18) of concentrated hydrochloric acid to the cold solution. The acid is added in a thin stream to the well-stirred solution. After 2 hours the muconic acid is filtered, washed first with two 400-ml. portions of cold water and then with 200 ml. of methyl alcohol, and dried at 85°. The yield of nearly colorless product melting at 296-298°, with decomposition, amounts to 165-195 g. (37-43%). 

Muconic acid has been obtained in a variety of ways. The procedures that seem most important from a preparative point of view are by treatment of ethyl o ,5-dibromoadipate with alcoholic potassium hydroxide, by condensation of glyoxal (as the sodium bisulfite addition product) with malonic acid, by heating ethyl l-acetoxy-l,4-dihydromuconate (obtained by condensing ethyl oxalate and ethyl crotonate, acetylating, and reducing),and by oxidation of phenol with peracetic acid. ... 

Certain monomers crystallize in a conformation such that they can be zipped together without changing the symmetry of the crystal lattice. In the crystalline state, the arrangement of monomers is strictly determined by crystal packing. Polymerization is usually initialed by irradiation with UV, X- or y-rays and is assumed to proceed by a radical mechanism. For example, muconic acid esters (25, 27, 29) and ammonium salts (26,28, 30) can be stcrcospccifically polymerized in the crystalline state to high conversion.224-227228 This form of... 

Hydroxylation and dioxygenation are not, however, mntnally exclusive, because the toluene dioxygenase from Pseudomonasputida FI hydroxylates both phenol and 2,5-dichloro-phenol with the introduction of only one atom of oxygen (Spain et al. 1989). Snbsequent degradation by dioxygenation follows established pathways in which chloride is eliminated from muconic acids after ring fission. 

Schmidt E, G Remberg, H-J Knackmuss (1980) Chemical structure and biodegradability of halogenated aromatic compounds. Halogenated muconic acids as intermediates. Biochem J 192 331-337. 

At longer reaction times, the formation of an acidic product, probably cfs,cfs-muconic acid, and a copper containing precipitate were observed. This latter could be a polynuclear product of quinone and semiquinone fragments (37,38). In agreement with this stoichiometry, about 50% of 02 was regenerated by adding a small amount of catalase to the reaction mixture at relatively short reaction times. 

The differences between the iridium and rhodium systems were interpreted by considering that Int 1 may open an oxygenation path via intramolecular rearrangement. In this case, the scission of a M-0 bond between the semi-quinone and metal center would be followed by intra-diol insertion of an oxygen and ultimately by the formation of muconic acid and water. The results indicate partial preference of the rhodium complex toward the oxygenation path. 

Fig. 9.72Structures of MCPA(4-chloro-2-methylphenoxyacetic acid (I)), its metabolites 4-chloro-o-cresol (II), 5-chloro-3-methyl catechol (III), 4-chloro-2-methyl muconic acid (IV), reagent pentafluorobenzyl bromide (V), and the derivatives VI-VIII from l-lll Source Reproduced with permission from the American Chemical Society [155]... 

One further compound should be mentioned in this connexion, namely, p-fluorophenylacetic acid (XXII), which has the carbon skeleton of the highly toxic 5-fluoropentanecarboxylic acid (XXIII). It seemed unlikely that (XXII) could be broken down in vivo to fluoroacetic acid, and as expected it was non-toxic. It should be mentioned, however, that aromatic compounds are capable of certain types of oxidative breakdown in the animal body. Jaffe,1 for example, isolated small quantities of muconic acid from the urine of dogs and rabbits which had received considerable quantities of benzene. 

Its dicarboxylic acid, muconic acid, yields the /iy-unsaturated dihydromuconic acid on reduction ... 

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