| 摘要 |
<p>Prodn. of urethanes (I) comprises reacting chloroformates of formula RO.CO.Cl (II) (R=opt. branched alkyl, cycloalkyl or aryl opt. substd. esp. by phosphonate, phosphine oxide, sulphone or ether functions) with amines of formula R1NHRM (III) (R1=H, opt. branched 7C alkyl or hydroxyalkyl, or is aryl.R2 is as R1 but not H, or R1+R2 together complete a ring) in the presence of an acid acceptor in a 2-phase heterogeneous liq. -solid medium. The liq. phase comprises (I)-(III) dissolved in an organic solvent of b.pt. below that of (I), while the solid phase initially comprises anhydrous alkali or alkaline earth carbonate of which at least om(y+1)/2y moles are used (m=- moles of (II); y=max. number of moles of water which the carbonate can fix as a solid hydrate). After reaction the mixt. is filtered through a glass frit and (I) recovered by evaporating the solvent. (I) are used in the pharmaceutical and plant-protection industries. High yields (generally 90-100%) of very pure (I) are achieveD. The HCl formed is completely transferred to the solid phase; no water is present (to dissolve (I) or hydrolyse (II) and no fractional distillations in vacuo are required.</p> |
