| 摘要 |
PCT No. PCT/EP97/02822 Sec. 371 Date Nov. 12, 1998 Sec. 102(e) Date Nov. 12, 1998 PCT Filed May 30, 1997 PCT Pub. No. WO97/46529 PCT Pub. Date Dec. 11, 1997A process for purifying crude piperidines of the formula I where R1 to R4 are C1-C6-alkyl, or R1 and R2 and/or R3 and R4 together are a CH2-chain of 2 to 5 carbons, which comprises, in a first step, removing high-boiling substances and, if present, water from the crude piperidines by distillation; in a second step, adding from 0.01 to 5% by weight, based on the product of the first step, as a reducing agent; and, in a third step, isolating the piperidines by distillation. |
