2.5- Dimethyl-2-hexyl cation

Dimethyl-2-hexyl cation and 1,4-dimethyl-1-cyclohexyl cation 257... 

Doom, 1969 Saunders and Stofko, 1973). The barrier for 1,4-hydride shift in 2,5-dimethyl-2-hexyl cation [12] is some 12-13 kcal mol" (Saunders and Stofko, 1973) which is even higher than for [11]. Going to 1,5-shifts in 2,6-dimethyl-2-heptyl cation [13] either the barrier is drastically decreased to... 

In ion [12], the 2,5-dimethyl-2-hexyl cation, Brouwer and van Doom (1969) observed no band broadening in the H-nmr spectrum due to 1,4-hydride shifts up to —50°C. However 1,4-hydrogen shifts do occur in [12] as demonstrated by Saunders and Stofko (1973) using spin-transfer saturation (12). The... 

The 3,4-dimethyl-3-hexyl cation [66] was investigated by Olah and Donovan (1977) using C-nmr spectroscopy. Excellent correlation between experimen-... 

C AH° = — 26 cal mol per D] on the other shows that the dimethyl-bicyclo[2.1.1]hexyl cation falls in the intermediate range. The decreasing size of the CDj-isotope effect on (85)-(87) indicates a decreasing demand for C—H hyperconjugative stabilisation due to increasing a-stabilisation in... 

A y-isotope effect in 3,4-dimethyl-3-hexyl cation. The isotope effects observed in cations [116], [104] and [140]-[144] are differential P- y-effects, i.e. / observed = A differential y- vj 5-equilibrium isotope effect... 

Trialkyl-4-vinylbenzyl phosphonium chloride/ acrylamide copolymers. This type of crosslinked trialkyl-4-vinylbenzyl phosphonium chloride (TRVB)/acrylamide (AAm) copolymers were prepared by copolymeiization of TRVB, AAm, and MBAAm (crosslinking monomer) in dimethyl sulfoxide. Three TRVBs with different alkyl chain lengths (butyl, hexyl, and octyl) in phosphonium groups were used. They are abbreviated as TBVB, THVB, and TOVB, respectively. The copolymers obtained have phosphonium groups. Therefore, they are crosslinked cationic polymers. 

For 2,3- and 1,2-dimethylnorbomyl ions the values of A5 are 287 and 274 ppm, respectively, lower than for classical 1,2-dimethylcyclopentyl and 1,2-dimethylcyclo-hexyl ions ( 350 ppm) being in a rapid degenerate equilibrium. These facts agree with the stmcture earlier ascribed by Olah to the l,2-dimethyl-2-norbomyl ion — a structure of partially c-delocalized, rapidly equilibrated ions (Wagner-Meerwein rearrangement) The same applies to Saunders s data on the 1,2-dimethylnor-bornyl cation in which one CHj is replaced by CDj (see below)... 

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