GB849541A — Preparation of unsaturated cyclic urea derivatives

USPTO Abstract

Cyclic ureas of the formula: <FORM:0849541/IV(b)/1> are prepared by reacting ethylene-urea or trimethylene-urea with an aldehyde RR1CH, CHO, R being H, phenyl, tolyl, benzyl, cyclohexyl or C1-C8 alkyl, R1 being H or C1-C4 alkyl, and n being 1 or 2. The reaction may be carried out with or without a solvent such as water or a C1-C4 alcohol. It is preferable to work at a temperature of 15 DEG -220 DEG C. and to add an acid to bring the pH to 1-6,5. The first stage of the reaction probably produces an N-(a -hydroxy-alkyl) compound which self-condenses to give a polymer. On heating to 185 DEG -300 DEG C. the polymer decomposes and the N-vinyl compound distils over; this stage is aided by the addition of alkali to bring the pH to 7-8. When a C1-C4 alcohol (e.g. methanol or isopropanol) is used as solvent the aldehyde initially forms a hemiacetal which reacts with the cyclic urea to give the N-(a -alkoxyalkyl) and N: N1-bis-(a -alkoxy-alkyl) compounds as well as the polymer. The alkoxy compounds can be distilled off separately before pyrolysis of the polymer, but if an alkali alkoxide is added they too yield the desired vinyl compound on heating and then need not be separated. In examples, the aldehydes used are acetaldehyde, propionalde hyde, capric aldehyde, phenylacetaldehyde, cyclohexyl-acetaldehyde and hydrocinnamaldehyde.