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AROMATIC NITRO COMPOUNDS

hydroxide resulted in the formation of potassium picrate,

to the scheme:

203

presumably according

(20a)

At a low temperature the reaction occurred without complete hydrolysis of the

ether group, and the ethyl ether of picric acid was formed:

(20b)

When products of the reaction of higher alcoholates with trinitroanisole were

hydrolysed, ethers of higher alcohols were formed. According to the authors,

this could be a convenient method of preparing higher ethers of picric acid.

The kinetics and mechanism of Meisenheimer’s reaction has been studied by

Caldin and Ainscough [43] who utilized the reactions of addition of sodium etho-

xylate to trinitroanisole, trinitrobenzene and trinitrotoluene. By using temperatures
in the range from-70°C to -100°C they were able to reduce the reaction rate

to a measurable value. On treating the addition product with acetic acid at tem-

peratures ranging from -50°C to -80°C they obtained the starting product.

Thus, the reaction was proved to be reversible, as for example in the case of tri-

nitroanisole (TNA) :

TNA + OC 2 H 5 - <-> [TNA,OC 2 H 5 - ] <->[TNA-.OC 2 H 5 ] (21)

Addition product (II)

The authors consider that the addition product may exist as a complex, in which
a transfer of charge has taken place, while the structure of the true addition product

is III.