Adducts from Other Substituted Trinitrobenzenes

Adducts from Other Substituted Trinitrobenzenes 1. Picric acid 

Because of its high acidity picric acid exists in dilute sodium hydroxide solution as the picrate ion (Aroax, 3600 A). As the concentration of sodium hydroxide is increased, this absorption is gradually replaced by a more intense band (Araax, 3900 A) which has been attributed by Abe (1960) to 33. Gold and Rochester (1964f) found that the extent of conversion of the picrate ion to complex depends on a high power of base concentration, suggesting that the interaction probably involves more than one hydroxide ion. Evidence that this is the case and that the structure of the complex is in fact 34 has recently been obtained from 

NMR measurements (Crampton and Ghariani, 1968). The resonance due to ring protons which occurs at — 8-8 p.p.m. in the picrate ion is shifted strongly upheld to — 6-1 p.p.m. in concentrated sodium hydroxide solution, indicating a covalency change at both C3 and C5. 

Adducts from meta-Dinitrobenzenes 1. With allcoxides 

Chemical shifts measured downfield from tetramethylsilane. 

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