viii, a, i Gibbs and Pratt: Hydroxyl and Carboxyl 47 



BENZYL ALCOHOL, BENZYL ACETATE, BENZYL METHYL ETHER, 

 BENZYL CHLORIDE, AND METHYL BENZOATE. FIG. 5 



The absorption spectra of benzyl alcohol and benzyl ethyl ether 

 have been studied by Baly and Collie, 23 and since it did not seem 

 probable that the absorption band at 1/A=3600 was correctly 

 ascribed to this type of compounds by these authors and also 

 for the reasons given above, we have included a study of benzyl 

 alcohol and 4 closely related compounds in this investigation. 

 Benzyl alcohol, acetate, methyl ether, and chloride were dissolved 

 in pure ethyl ether and shaken repeatedly with dilute aqueous 

 alkali, and then with water until neutral. The ether layer was 

 dried with anhydrous copper sulphate, the ether evaporated, and 

 the residue fractioned several times under reduced pressure. 

 This procedure was found necessary to obtain pure compounds. 

 The substances thus prepared show only one absorption band 

 which lies in the benzene region of the spectrum and heads at 

 1/A=3850 in each case. The persistence of this band decreases 

 in these compounds in the order in which they are mentioned 

 from the maximum shown by benzyl alcohol. From log. 3.0 to 

 4.8, and 1/A=3600 to 3850, the curves of the first three com- 

 pounds are identical while that of benzyl chloride apparently 

 shows slightly greater general absorption. The divergence in 

 the curve of the latter may be due to traces of impurities. No 

 indication of an absorption band in this region of the spectrum 

 is shown by any of these compounds. There is no doubt that 

 their true absorption spectra bear little resemblance to the 

 descriptions of Baly and Collie. Absorption bands outside of 

 the benzene region of the spectrum are not to be expected in 

 compounds of this type. 



The absorption curve of methyl benzoate is very similar to 

 those of the benzyl derivatives, but appears at greater dilution, 

 and the absorption band heads nearer the visible region of the 

 spectrum; namely at 1/A=3700. The absorption spectrum of 

 the free acid has been described by Hartley and Huntington, 24 

 and it shows no noteworthy differences from that of methyl 

 benzoate. 25 



^Journ. Chem. Soc. London (1905), 87, 1343. 



2i hoc. cit. 



" Baly and Collie (loc. cit.) state: "The spectrum of benzoic acid has 

 been observed by Hartley and Huntington, and only shows general ab- 

 sorption rather strongly. This is only to be expected from the presence 

 of the ketonic oxygen in the /3-position," a statement which does not 

 seem to be strictly in accord with the facts. 



