GB1032257A - Synthesis of heterocyclic compounds - Google Patents

Abstract

Diazabicyclo-(2,2,2) octane or C-substituted derivatives thereof are made by a process which comprises contacting a feed stock with a metal phosphate at a temperature from 250-550 DEG C. to form a reaction product comprising said compounds, said feed stock being an alkanolamine containing one to three hydroxyalkyl groups, an N-(hydroxyalkyl) polyalkylene polyamine or a substituted piperazine, each of the alkyl or alkylene groups in any of the foregoing starting materials being of the formula -CHR-CHR-, said substituted piperazine having the formula <FORM:1032257/C2/1> R in said formula being hydrogen, methyl; X being OH oz NH2; and Y being H or -CH2CH2X. Especially suitable metal phosphates include aluminium, calcium or iron, and it is preferred to feed 1 to 15 moles of ammonia per mol of feed stock to the reaction. Named starting materials include monoethanolamine, monopropanolamine, monobutanolamine, diethanolamine, triethanolamine, N-aminoethylpiperazine, N - hydroxyethylpiperazine, and mixtures thereof and hydroxypropyldiethylene triamine. An extensive list of metal phosphate catalysts which have been used include those of boron, lithium, zinc, nickel, chromium, copper and cobalt. The examples which include a comparative example outside the scope of the invention wherein the use of a silica alumina catalyst is contrasted, describe the cyclization of N-aminoethylpiperazine over aluminium phosphate, zinc phosphate, nickel, chromium, copper and cobalt phosphates, the reaction of triethanolamine over aluminium phosphate, diglycolamine over aluminium phosphate, hydroxypropyldiethylenetriamine over aluminium phosphate and isopropanolamine over aluminium phosphate. The last reaction yields 2,5-dimethylpiperazine, and trimethyltriethylenediamine isomers. The assays of the products were carried out by gas chromatography. The invention includes 2-methyl-1,4-diazabicyclo-(2,2,2) octane.