Geometrical Influences on Rate of Ionization

Although the loss of beta hydrogens should decrease the stability of a carbonium ion or its related transition states, if enough of the beta 

One possible explanation for the effect of increased branching is the relief of B strain when the bonds connecting the central carbon atom to the substituent groups spread out on passing to a less tetrahedral and more nearly planar arrangement.224 

Some doubt is thrown on B strain as the sole explanation of the branching effect by the observation that the tri-te -butylboron-ammonia complex is actually less dissociated than the trimethylboron-ammonia complex.227 Since the products of the ionization of these highly branched compounds contain large amounts of rearranged material, another effect may be operating. As will be discussed in the next section, many ionization reactions produce directly an ion of structure different from that of the covalent parent compound. The transition state presumably resembles the new ion or a non-classical 

Relative rate constants of the chlorides prepared from the carbinol 

The numerous straightforward examples of internal displacement reactions leading to isolable cyclic products will not be discussed here, but only, for the most part, those ionization reactions in which a cyclic intermediate or transition state is deduced from the rearranged structure of the product. A well-known example is mustard gas and other alkyl chlorides with sulfur on the /3-carbon atom. Although mustard gas is a primary and saturated alkyl chloride, its behavior is like that of a typical tertiary alkyl chloride. It reacts so fast by a first order ionization that the rate of the usual second order displacement reaction of primary alkyl halides is not measureable. Only the ultimate product, not the rate, is determined by the added reagent.228 Since the effect of the sulfur is too large to be explicable in terms of a carbon sulfur dipole or similar explanation, a cyclic sulfonium ion has been proposed as an 

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