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56 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

(7)

V

The addition of a nitric acid molecule to the double bond was first studied

by Kekulé [11], who obtained an oily, explosive product on treating ethylene with

concentrated nitric acid. Wieland [9,10] and Anschütz [12] believed the reaction

to proceed principally according to the eqns. (8) and (9).

In support of this theory Wieland [10] reported the results of his investigations,

carried out in co-operation with Sakellarios, where two products (VI) and (VII)

were obtained in the reaction of ethylene with nitric acid:

(8)

(9)

In both reactions products were formed which resulted from addition (in the

first stage of the reaction) of a nitric acid molecule to the double bond.

Wieland’s theory was criticized. Michael and Carlson [2] called in question

Wieland’s view and proposed a different mechanism:

(10)

since they found that at temperatures below 0°C concentrated nitric acid adds

to olefines, such as isobutylene, trimethylethylene, to yield the nitric esters of the

corresponding alcohols. Other objections to the Wieland theory were also put

forward by Topchiyev [13]:

(1) The cyclohexadiene derivative (V), formed by addition of a nitric acid

molecule, is very unstable and it is difficult to speak about a definite direction of

the decomposition reaction of the compound V.

(2) Against the theory of the similarity of the processes of attaching HNO 3

and Br 2 to the double bond is the fact that molecules are attached with different

rate. Bromine is attached only with great difficulty (without a catalyst). On the

contrary, nitration is very easy to carry out.