中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | (4-Methylenecyclohexylmethyl)bromide | 76825-09-7 | C8H13Br | 189.095 |
4-亚甲基环己基甲醇 | 4-methylene-1-cyclohexanemethanol | 1004-24-6 | C8H14O | 126.199 |
Bromination of methylene groups exocyclic to cyclohexyl systems can afford, besides the expected trans-dibromo products, considerable quantities of a tribromide. For example, simple bromination of 4-t-butyl-1-methylidene-cyclohexane affords c. 20% yield of (r-1, t-2, c-4)-1,2-dibromo-1-bromomethyl-4-t-butylcyclohexane.
Bromination of methylene groups exocyclic to cyclohexyl systems normally affords two isomeric products; the axial 1-bromo equatorial 1-bromomethyl compound and the axial 1-bromomethyl equatorial 1-bromo derivative. Free energy differences between these two isomers, and the conformations adopted by the axial 1-bromomethyl group, have been explored by n.m.r. spectroscopy, by X-ray crystallography and by MM3 calculations. Evidence is presented to show that the ax-bromomethyl group exists primarily as those rotamers which site the bromine atom synclinal to the vicinal bromine. The A value for a bromomethyl group in this system is then similar to that of an unsubstituted methyl group.