Polyhalogenated derivatives

The accidents that are described below deal with chlorinated, brominated, iodised and mixed polyhalogen derivatives the polyfluoridated derivations are much more stable. 

There is also the haloform reaction (effect of a haloform on a ketone in a basic medium), already described with halogen derivatives on p.272 (the danger is more related to the interaction of the polyhalogen derivative with the base, according to the author). A large number of accidents involved the ketone as much as butanone. The accident below illustrates the danger of this reaction ... 

With polyhalogen derivatives the amount of the potassium hydroxide must be equivalent to the number of halogens to be replaced by hydrogen. 

Uses Intermediate for prod, of vinylcyclohexene dioxide comonomer in polymerization of other monomers in halogenation to polyhalogenated derivs. used as flame retardants prod, of insecticides with ethylene chlorohydrin organic synthesis Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, Fluka http //www.sigma-aldrich.com, Sigma... 

Bromochloro-5,5-dimethyl hydantoin halogenation, polyhalogenated derivs. 

Although N-halogenated pyrazoles are known, they are quite unstable compounds, increasing in stability from chloro to iodo. They may be implicated in the formation of polyhalogenated derivatives (76MI2). There are many examples of competition between nuclear and side-chain halogenation, particularly when radical species can form (90CHE301). 

The three types of compounds reported in Table 6 are more strained than those in Table 3. This factor, as well as others, such as the differences in reactivity and in experimental conditions, the steric and electronic factors, are all much more favorable for a semibenzilic rather than for a cyclopropanone mechanism. For derivative 67 of the cubane series, Eaton and Cole proposed such a mechanism. For the bicyclo[2.2.1]heptane derivatives, with the exception of 76, no a or a hydrogens are available, so that the semibenzilic mechanism is the only one possible (quasi-Favorskii). However, in the latter compounds, the aa -dihalogenated or the polyhalogenated derivatives can undergo ring opening. We will now discuss the influence of the steric and electronic factors on this secondary reaction. 

Very many volatile halogenated and polyhalogenated derivatives, little condensed in carbons halogenoketones and halogenated lactones with short chain (butenones, heptanones, octenones and nonenones). 

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