| 摘要 |
<p>Reduction of 4-oxo piperidines to 4-hydroxy piperidines comprises hydrogenation in a tert. aliphatic phosphate ester at 20-140 degrees C under H2 pressure of 1-100 bar, in presence of Ni, Ru, Rh, Os, Ir or Al metal as catalyst. Suitable esters contain 2-18C branched or linear alkyl gps. or 5-8C cycloalyl gps. The 2,2,6,6-tetra-substd. 4-hydroxy piperidines and their dervis. e.g. esters are useful stabilisers for plastics, e.g. polyolefines. Pure prod. needing no recrystallisation are obtained in good yields. The catalyst consumption is reduced and the process presents minimum hazards, since no self-igniting system is used.</p> |
