Arginine dinitronaphtholsulfonate

One hundred grams (0.21 mole) of finely powdered arginine dinitronaphtholsulfonate is added, all at once, to 230 cc. of cold 2 N sodium hydroxide the salt dissolves readily on agitation. There is then added without delay (Note 13) 35 g. (0.33... 

According to the literature,2 pure arginine dinitronaphtholsulfonate melts at 258-260° with decomposition. Presence of moisture lowers the melting point considerably. If the mother liquor be allowed to stand for several days at 0-5°, some sodium dinitronaphtholsulfonate may crystallize out. 

Vigreux column, 12, 86 Arginine dinitronaphtholsulfonate, 12, S d-Arginine hydrochloride, 12, 4, 6 Arsonoacetic acid, 10, 108 Arylarsonic acid, preparation, 15, 59 Arylsulfur chlorides, preparation, 15, 45... 

Arginine dinitronaphtholsulfonate, 12,5 d-ARGININE HYDROCHLORIDE, 12, 4 Arsanilic acid, 16, 85... 

The over-all loss involved in the various steps may be estimated from the following experiment 5.0 g. of arginine nitrate was converted through the dinitronaphtholsulfonate into benzylidenearginine and then back into aiginine nitrate, when 4.2 g. was recovered. 

Arginine has been precipitated (a) in the form of its silver derivative at pH io 1 (b) as its dinitronaphtholsulfonate which is then decomposed by means of 33 per cent sulfuric acid,2 by the combined action of hot dilute sulfuric acid and butyl alcohol,3 by cold concentrated hydrochloric add followed by aniline,4 or by barium hydroxide.5 Arginine has likewise been precipitated... 

In the present directions, Method i is essentially that developed by Bergmann and Zervas 6 Method 2 forms a combination of methods (b and c) and thus at once affords a product of high purity, while avoiding the mechanical difficulties involved in the complete removal of the dinitronaphtholsulfonic acid from its arginine salt. 

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