For a long time, the nature of the acyl in N-acylglucosamines was considered to be nonessential to the course of the Morgan-Elson reaction (1). Later (2), it was noted that, when being reacted, 2-acylamino derivatives of hexoses (acyl, formyl, glycine, propionyl, butyroyl, benzoyl, and p-toluene sulfonyl) give different amounts of color in comparison with 2-acetyl derivatives.
In this communication, we report the results of a quantitative study of this influence for a series of 2-acylamino,derivatives of glucose synthesized and characterized earlier (3,4).
The molar extinction coefficient l s85 of the chromophores obtained under the conditions of the known Reissig modification
(5) was taken as an estimate of comparison for the color reaction of various N-acylglucosamines; for N-acetylglucosamine, l s85 was equal to 17.4 f 0.5 * lo3 and was taken tentatively as 100%.
The absorption spectra of chromophores in all the compounds were identical in the range of 300-700 nm and had two maxima at 530 and 585 nm. eSS5 was determined for five concentrations (0.02-0.1 PmoVml), at which the compounds studied were fully soluble in water.
The results obtained are shown in Table 1. Contrary to earlier observations (2), as is apparent from Table 1, the amount of color for glucosamines acylated by the residues of fatty acids C3-C8 on the amino group proved to be the same as the amount of color forming with N-acetylglucosamine.
Substitution of acetyl for benzoyl also does not affect color formation.