3-Cyano-pyridine prepn. - by reacting 3-formyl 5,6-dihydro 2H-pyran with ammonia and air in the presence of a catalyst

摘要

3-Cyanopyridine (I) is prepd. by conducting a mixt. of 3-formyl-5,6-dihydro-2H pyran (II) ammonia and air in the gas phase at 250-450 degrees C (pref. 300-400 degrees C) over an ammonoxiden. catalyst. Allows direct prodn. of (I) from (II), ammonia and air. Suitable ammonoxidation catalysts include the oxides and mixed oxides of V, Mo, P, Fe, Co, Bi, Ti, Cr, U B etc. a V2O5/Al2O3 catalyst is pref. The catalyst can be in a fixed or fluid bed. The molar ratio of NH3 to (II) is 2-40:1 pref. 10-20:1. The amount of oxygen is 1-20 (pref. ca 3-10) mol per mol (II). The gas mixt is pref. diluted with e.g. nitrogen or steam as an inert diluent. The contact time of the gas mixt. with the catalyst bed is pref. 0.1-30 (pref. 0.5-5) seconds.