| 摘要 |
<p>Carbamic acid esters are prepared by mixing a C1- 8 monohydroxy aliphatic alcohol with urea in a proportion of at least two moles of alcohol per mole of urea and heating the mixture for not more than 1 1/2 hours in the absence of a reaction catalyst to a temperature in the range 180 DEG to 230 DEG C., while maintaining a pressure at least equal to the vapour pressure of said heated mixture and venting by-product ammonia gas from said heated mixture at a rate such that the pressure does not fall below the said vapour pressure. The above process may be adapted for continuous working. Specified alcohol reactants are methanol, ethanol, 2-methoxy-methanol, 2-chloroethanol, propanol, allyl alcohol, isopropanol, butanol, isobutanol, secondary-butanol, and primary and secondary amyl and octyl alcohols. Carbamic ester product may be separated from unreacted material by cooling to between - 70 DEG and - 20 DEG C.</p> |
