Aromatic aldehyde prepn. by simple selective gas phase hydrogenation

摘要

Prepn. of aromatic aldehydes of formula (I) comprises gas phase reaction of aromatic carboxylic acids or esters of formula (II) with H2 at 200-450 deg C and 0.1-20 bar in the presence of a catalyst (III), in which the catalytically active compsn. contains 80-99.9 wt.% ZrO2 and 0.1-20 wt.% lanthanide(s); R<1>-R<5>=H, 1-6C alkyl, 3-8C cycloalkyl, aryl, OH, 1-4C alkoxy, phenoxy, 7-12C alkylphenyl, 7-12C phenylalkyl, NH2, NHMe, NMe2 or halo; and R<2>-R<4> may also = CHO or COOR<6>; R<6>=H, 1-6C alkyl, 3-8C cycloalkyl, aryl, 7-12C alkylphenyl or 7-12C phenylalkyl; R<6>=as R<1>; or R<6>+R<1> = a -CH2- bridge.