338 VII. ACIDS, AMIDES, ALDEHYDES AND HYDROCARBONS 



H 

 C 



HC COOH 



HC COOH 



-> CO, + H2O 



C 



H 

 Ben- Gate- Muconic 



zene Phenol chol acid 



The Postulated Course of the Oxidation of Benzene in the Animal Body'™-"* 



The course of the oxidation of muconic acid to CO2 and H2O is not 

 entirely clear. It is believed that muconic acid is oxidized by /3-oxidation, 

 inasmuch as Hensel and Riesser^^i observed that this acid (presumably 

 the trans-trans isomer, since this was the only one known in 1913) was con- 

 verted to acetone when perfused through the surviving liver. According 

 to Raizon and Yamamoto,^^^ /mws-/mns-muconic acid gives rise to acetone 

 bodies when perfused through dog liver, while the cis-cis form does not. 

 No other products resulting from the oxidation of muconic acid have been 

 demonstrated. Mori^' observed that the administration of trans-trans- 

 muconic acid did not increase the output of oxalic acid in rabbits. More- 

 over, Parke and Williams^^* were unable to demonstrate C^^-labeling in 

 acetic or fumaric acids after C^Mabeled benzene had been fed; no radio- 

 activity was observed in succinic, oxalic, adipic, or mesotartaric acids iso- 

 lated from the urine under these conditions. 



According to Kuhn et al.,--^ small amounts (0.1-0.2%) of trans-trans- 

 muconic acid also originate after the feeding of sorbic acid, CH3 • CH : CH • 

 CH:CH-COOH, to rabbits. Muconic acid hkewise originates following 

 the administration of ethyl sorbate (0.5%), but not after that of the 

 methyl ester; sorbamide, CH3 • CH : CH • CH : CH • CONH2, gives a 32% 

 yield of the trans-trans acid, while the methyl amide, CH3 • CH : CH • CH : 

 CH-C0NH(CH3), and the anilide of sorbic acid, CH3-CH:CH-CH:CH- 

 CONH-C2H2, give rise to 44% and 36%, respectively, of muconic acid. 

 The presence of the amide group decreases the loss of sorbic acid by /3- 

 oxidation. A similar decrease in the oxidation of sorbic acid obtains in 

 the /3-methyl derivative, which can be converted to the corresponding 

 muconic acid compound to the extent of 62%. 



221 M. Hensel and O. Riesser, Z. physiol. Chem., 88, 38-43 (1913). 



222 T. Raizon and I. Yamamoto, Osaka Igakkai, Zasshi {J. Osaka Med. Assoc), 39, 

 525-526 (1940); Chem. Abst., 36, 5559 (1942); Japan. J. Med. Sci., II, Biochem., 4, No. 

 4,105-106(1941). 



223 R. Kuhn, F. Kohler, and L. Kohler, Z. physiol. Chem., 247, 197-219 (1937). 



