Abstract: A method for continuously crystallizing a solid component by continuously feeding a solution of the solid component in water or an organic solvent to a centrifugal film evaporator equipped with a scraper blade, which comprises feeding the solution from the top of the evaporator which comprises a heating section in the upper stream and a cooling section in the lower stream, forming a film of the solution on the wall of the evaporator, passing the film of the solution down into the heating section in order to evaporate the solvent, discharging the evaporated solvent from an upper outlet by feeding an inert gas or aspirating the solvent vapor in order to prevent the passage of evaporated solvent into the cooling section and contacting the cooling section of the evaporator with the concentrated solution whereby a crystallized solid or a slurry of solid particles is formed.This is a continuation, of application Ser. No. 443,519, filed Feb. 19, 1974 now abandoned.

Abstract: Nitrogen-containing heterocyclic compounds are prepared by cyclization of a compound having the formula: ##EQU1## or ##EQU2## wherein X represents a hydrogen atom or --CH.sub.2 CHR-Y; R represents a hydrogen atom or methyl atom; Y represents an --OH group or --NH.sub.2 group; and n represents the integers 0 or 1 - 4; with a zeolite catalyst having the formulaa(M.sub.2/n O). (Al.sub.2 O.sub.3) . m(SiO.sub.2)wherein M represents a cation selected from alkali metals, alkaline earth metals, zinc group elements, hydrogen and ammonium cations; n represents the valence of the cation; a is 1.0 .+-. 0.5 and m is 2 - 12.