how-would-you-describe-the-nucleophilic-addition-of-an-alcohol-to-an-isocyanate-

Question

How would you describe the nucleophilic addition of an alcohol to an isocyanate in urethane formation?

Accepted Answer

The alcohol acts as a nucleophile, attacking the electrophilic carbon of the isocyanate.

Answer

The isocyanate acts as a nucleophile, attacking the electrophilic oxygen of the alcohol.

Answer

The isocyanate forms a radical with the alcohol.

Answer

The alcohol deprotonates the nitrogen of the isocyanate.