Abstract
For the urethane formation reaction of isocyanate with alcohol, orientation of approach of alcohol toward isocyanate was investigated theoretically by means of MO method. As a result of EHT and CNDO/2 calculations, it was found that the reaction proceeding via 4-centered mechanism, in which ROH is coplanar with isocyanate plane was energetically favored. It was also shown that the oxygen of ROH attacks the isocyanate carbon prior to the formation of 4-center complex. The reaction was found to be a charge controlled one.
이소시안산 에스테르와 알코올이 反應하는 우레탄 形成反應에서 알코올分子가 이소시안산 에스테르에 접근하는 配向成을 MO論的으로 고찰하였다. EHT 및 CNDO/2 계산결과에 의하면 알코올이 이소시안 산에스테르 平面과 同一한 平面으로 접근하는 4-중심 메카니즘으로 진행되는 것이 유리함을 알 수 있었다. 또한 알코올의 O-H基에 있는 산소가 수소보다 먼저 이소시안산 에스테르의 탄소에 접근함을 알 수 있었고 이 反應은 전하조절반응임을 밝혔다.