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210 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

It was considered originally to be a tautomer of the picrate. More recently, by

treating aqueous solutions of creatinine picrate of different compositions with alco-

hol, several crystalline compounds have been obtained (Bollinger [67]).

The formula VI was originally suggested for the red tautomer of creatinine

picrate

Because non-basic substances may also produce a similar reaction, it was later

suggested by Anslow and King [66] that the enolate anion of creatinine forms a

coordinate bond with the positively charged nitrogen atom of one of the nitro

groups. The structure of the compound they postulated is VII:

According to the most recent suggestion (Kimura [69]), the product of the reaction

of picric acid with creatinine is not a substitution but an addition product VIII:

With regard to the other coloured compounds formed from m- dinitrobenzene
or sym- trinitrobenzene, it was claimed that the carbanion of active methylene
compounds condenses with the nitro compound in terms of nucleophilic substi-
tution :