ZEOLITE CATALYZED INTRAMOLECULAR CYCLIZATION OF 5-AMINO-1-PENTANOL TO PIPERIDINE BASES

5-amino-1-pentanol (5-AP) undergoes facile intramolecular cyclocondensation to piperidine and to methyl or ethyl piperidines in the presence of methanol or ethanol over zeolite catalysts like ZSM-5 (Si/Al = 30, 129, 280), HM and HY. 2-Aminopyran (2-AP) is also observed as a major product in the conversion of 5-AP to piperidine on the ZSM-5 (280) and HY. Piperidine and N-methylpiperidine are predominantly formed over HY zeolite with near total conversion (98%) of 5-AP in the 5-AP alkylation with methanol. 2-Methyl piperidine is also formed as a side product in this reaction over all the zeolites studied. Methanol conversion does not show any trend. The HY catalyst is also studied for its ethylation activity of 5-AP with ethanol to synthesize ethyl piperidine bases. The effects of temperature and W/F factor on the conversion of 5-AP and ethanol and also on the yields of ethylpiperidines is presented. The possible schemes for the cyclocondensation of 5-AP and alkylation with methanol and ethanol are discussed. No dehydrogenated products (pyridine, picolines and ethylpyridines) are observed in these condensation reactions.