The results of a study of the kinetics and mechanism of the reaction of 4, 4, 4- trinitrobutyronitrile and 4, 4-dinitro-4-halobutyronitriles with base have shown that the isolated products are derived from an extremely reactive 1, l-dinitro-or 1-halo-1-nitroethylene intermediate. The a-fluorine effect has been utilized as a transition state probe to show that the mechanism by which the olefin intermediate forms is a nonreversible, second-order ...