Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
作者:Jun-ichi Tateiwa、Ei Hayama、Takahiro Nishimura、Sakae Uemura
DOI:10.1039/a701744h
日期:——
The alkylation of aromatic compounds with aldehydes and ketones in
the presence of a variety of metal cation-exchanged montmorillonites
(Mn+-mont;
Mn+ = Zr4+,
Al3+, Fe3+, Zn2+, H+,
Na+) has been investigated. Al3+- and
Zr4+-Monts are revealed to be effective as catalysts, while
no reaction takes place with Na+-mont.
Al3+-Mont-catalysed alkylation of phenol with several
aldehydes produces mainly or almost solely the corresponding
gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that
with several ketones affords selectively the corresponding alkylphenols
in moderate to good yields. The alkylation always occurs at the carbonyl
carbon without any skeletal rearrangement and the kind of products
depends much on the steric hindrance of an electrophilic intermediary
carbocation. The alkylation of anisole, veratrole and p-cresol
proceeds well, while that of toluene, benzene, chlorobenzene and
nitrobenzene scarcely occurs.
在各种金属阳离子交换的蒙脱石(Mn+-mont;Mn+ = Zr4+、Al3+、Fe3+、Zn2+、H+、Na+)存在下,研究了芳香化合物与醛和酮的烷基化反应。发现Al3+和Zr4+蒙脱石是有效的催化剂,而Na+蒙脱石则不发生反应。由Al3+蒙脱石催化的苯酚与几种醛的烷基化反应主要或几乎只生成了相应的双(羟苯基)烷烃(双酚),产率良好;而与几种酮的烷基化反应则选择性地生成了相应的烷基苯酚,产率适中至良好。烷基化总是发生在羰基碳上,没有骨架重排,产物的类型很大程度上取决于亲电中间体的碳正离子的空间位阻。茴香醚、邻苯二甲醚和对甲酚的烷基化反应良好进行,而甲苯、苯、氯苯和硝基苯的烷基化反应几乎不发生。