344 VII. ACIDS, AMIDES, ALDEHYDES AND HYDROCARBONS 



]/ . w-Alkylbenzenes : The metabolism ""M the compounds having n- 

 alkyl side-chains longer than ethyl is identical with that of the correspond- 

 ing aliphatic acids having a phenyl group in the w-carbon. The com- 

 pounds with an odd-numbered aliphatic side-chain, n-propylbenzene 

 (CeHs • CH2 • CH2 • CHs), '''-'' 6-amylbenzene {CU, • CHo • CH, • CH2 • CH2 • 

 CH3),2io are oxidized to benzoic acid and excreted as hippuric acid. On 

 the other hand, the aromatic compounds with an even-numbered aliphatic 

 side-chain (n-butylbenzene (C6H5-CH2-CH2-CH2-CH3)) are oxidized to 

 phenylacetic acid, to be excreted as phenaceturic acid. In the case of n- 

 alkyl derivatives having three or more carbons in the side-chain, the oxida- 

 tion of the side-chain proceeds by /3-oxidation, exactly as occurs when the 

 aliphatic substituent is an acid. (See pages 292-296.) 



c'. Iso-Alkylbenzenes : In contradistinction to the n-alkylbenzenes, 

 the iso-compounds are not oxidized to the aromatic acids, but to phenols. 

 Nencki and Giacosa^^** observed an increased amount of ethereal sulfate in 

 the urine following the administration of these iso-compounds, while no 

 other aromatic acids were present. The products studied included iso- 

 propylbenzene (cumene), CgHb-CH: (CHs)^, the isobutylbenzenes, di- 

 methylbenzylmethane (CeHj -0112 -011(0113)2), and methylethylphenyl- 

 methane (C6H5-CH(CH3) •CH2-CH3). 



In the case of p-cymene (p-isopropyltoluene), which has both a methyl 

 and an isopropyl group attached to the benzene ring, the methyl group is 

 oxidized to a carboxyl while the isopropyl residue is unchanged; this re- 

 sults in the formation of cumic acid, which is excreted after the feeding of p- 

 cymene to sheep, man, or clogs. ^^^•-^-■-■^*'-" 



CH(CH3)2 CH(CH3)2 



CH3 COOH 



/j-Cymene Cumic acid 



The Metabolism of p-C^ymene (p-Isopropyltoluene) in Sheep and Dogs 



(d) Halogenated Aromatic Hydrocarbons. Although the halogenated 

 aromatic compounds are not to be considered as physiologic, their metabo- 

 lism is of importance because of the reactions they evoked in the animal 

 organism. Two pathways of metabolism are possible for the halogenated 

 hydrocarbons, either oxidation to a phenol, which is excreted in conjuga- 



"« J. M. Harvey, M. White, and T. G. H. Jones, Univ. Queensland, Dept. Chem., Coll. 

 Papers, 1, No. 23, 1-10 (1942). 



"^ E. Ziegler, Naunyn-Schmiedeberg' s Arch, exptl. Pathol. PharmakoL, 1, 05-72 (1873). 



