II. CHEMISTRY 



403 



tion .speclrum of 5,G-dimctliyll)CMiziinitlazolc i.s .shown in Fij^. 2. A cliarac- 

 teristic reaction of henzimidazoles with benzoyl chloride in alkaline solution 

 gave (ho cHIkmizovI (lcri\-a(ive (II), which was finally identified by .synthesis. 

 The yield of 5,G-dimethyll)enzimidazole amounted to about 70% of that 



. 1% 



■ I cm. 



220 230 240 250 260 270 280 290 300 

 Wavelength, m// 



Fig. 2. Absorption spectrum of 5,6-(limeth\i-benzimidazole in 95% ethanol. Solid 

 line, in the presence of 0.01. V hydrochloric acid; broken line, in the presence of O.OIA^ 

 sodium hydroxide. 



expected for one molar equivalent supporting the provisional structure 



(III).^" 



CH; 



CH; 



/\/N 



\/\N-^C53-54H77-8lN,20:3PC0 



m 



By an alternative method, the acid hydrolyzate of vitamin B12 was sub- 

 jected to paper strip chromatography.^' Observation of the paper chromato- 

 grams in ultraviolet light revealed the presence of three fluorescent spots, 

 termed components a, /3, and 7. Eluates of these fluorescent areas showed 

 them to have similar ultraviolet absorption spectra. An e.\tensi^'e spectro- 

 scopic comparison with twenty-two different substituted henzimidazoles led 

 to the conclusion that component 7 was 5,G-dimethylbenzimidazole, and 



31 E. R. Holiday and V. Petrow, J. Pharm. Pharmacol. 1, 734 (1949). 



