Cyclopentanones monoalkylated in the 2-position and of the general formula I ##STR1## where R.sup.1 is a branched or straight-chain aliphatic group of 2 to 12 carbon atoms and R.sup.2 to R.sup.7 may be identical or different and are each hydrogen or alkyl of 1 to 5 carbon atoms, are prepared by a process in which a cyclopentanone of the general formula II ##STR2## or a corresponding cyclopentenone, is reacted with an aldehyde of the general formula III ##STR3## at from 80.degree. to 280.degree. C. in the presence of hydrogen in an autoclave, over a catalyst which contains, as active components, on the one hand an oxide or a phosphate of magnesium, aluminum, titanium or zinc or of one of the rare earth metals, and on the other hand a noble metal of group VIII of the periodic table, preferably palladium. The 2-alkylcyclopentanones obtainable according to the invention in a simple single-stage reaction with virtually complete conversion and high selectivity are important as intermediates and in particular as scents.
通式I的
环戊酮单烷基化产物,其中R1是2至12个碳原子的支链或直链脂肪基,R2至R7可能相同也可能不同,均为1至5个碳原子的氢或烷基,通过以下方法制备:在自动
化学反应釜中,在
氢气存在下,在80℃至280℃的条件下,将通式II的
环戊酮或相应的
环戊烯酮与通式III的醛反应,反应催化剂包含以下活性组分:一种
镁、铝、
钛或
锌或稀土
金属的氧化物或
磷酸盐,以及一种VIII族贵
金属,优选的是
钯。根据本发明,通过简单的单步反应,可以获得几乎完全转化和高选择性的2-烷基
环戊酮,这些化合物是重要的中间体,特别是作为
香料。