Chemistry of the UH-N Fraction

Schnitzer et al. [14] developed a chromatographic procedure that involved separation of the unidentified from the known N, so that they could take an unhindered look at the unidentified N compounds without interference from the known N compounds. Their procedure was as follows  

The soluble hydrolyzates was neutralized and the soluble materials separated on Sephadex G-25 gels  

The highest molecular weight fractions were further separated on Sephadex G-50 gels, and the second highest molecular weight fradions were separated on Sephadex G-15 gels. 

In this manner, several fractions were prepared which contained between 97.5 and 98.6% unidentified N, but only 0.84% amino add N, 0% amino sugar N, and 0.53 % ammonia N. 

In a subsequent study, Schnitzer and Spiteller [15] hydrolyzed each fraction with 2 M H2S04. After neutralization of the soluble materials, the latter were reduced with NaBH4 and then acetylated. The resulting acetates were analyzed by capillary gas chromatography/mass spectrometry, and identified by comparing their mass spectra with those of reference compounds of known structures and with literature data. Eighteen N-heterocyclics were identified. These compounds induded hydroxy-and oxy-indoles, quinolines, isoquinolines, aminobenzofurans, piperidines, pyrro-lines, and pyrrolidines. In addition, a number of benzylamines and nitriles were also identified. It is noteworthy that the N heterocyclics were isolated and identified without the use of pyrolysis. 

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