| 摘要 |
1282342 Xylylene dicarbamates JAPAN GAS-CHEMICAL CO Inc 9 April 1970 [10 April 1969 20 Oct 1969] 17027/70 Heading C2C The invention comprises compounds of the formula where R is an alkyl C 1-4 group and n is 0 or an integer from 1 to 4. They are prepared by reacting the appropriate xylylene glycol with urea at 135-160‹ C. or with a lower alkyl C 1-4 carbamate at 120-180‹ C. In (a) a stoichiometric amount of urea is employed, an optional catalyst is an organotin compound and the reaction product is extracted with an aromatic hydrocarbon C 6-9 and the xylylene dicarbamate in the residue is extracted therefrom with nitrobenzene. In (b) a stoichiometric amount of carbamate is employed, the reaction may occur in a solvent comprising an aromatic hydrocarbon of boiling point above 115‹ C., a chlorobenzene or an alkoxybenzene, an optional catalyst is an aluminium alkoxide or a tetra-alkyl ester of titanic acid.
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