| 摘要 |
<p>Saturated aliphatic carboxylic acids are substituted by X, where X is halogen, hydroxy or hydroxy esterified with mineral acid, by elimination of HX, catalysed by non-basic salts of metals with inorganic acids. More specifically, the starting acid is a derivation of a trialkylacetic acid, and especially with X as a beta-constituent, and particularly beta-hydroxy-, beta-bromo-, or beta-chloropivalic acid. Preferably the catalyst is a halide of Li, Na, Ca, Mn, Ni or Co, more particularly LiCl and/or CoCl2 or a Lewis acid such as ZnCl2; on a porous or granular silica or alumina support. For reaction in the gaseous phase, diluent vapours of toluene or nitrobenzene can be used; and in the liquid phase, a high-boiling solvent such as sulpholane. Operating temperatures are preferably between 200 and 400 degrees C, pressures between 20 and 50 mm Hg.</p> |
