| 摘要 |
The level of 2-oxazoline or an oxazine impurity in an isocyanatoalkyl ester of an organic carboxylic acid is reduced by (i) reacting the impurity with an organic acid chloride, a chloroformate, a thiochloroformate, a sulfonyl chloride, phosphoryl chloride, sulfuryl chloride or thionyl chloride and (ii) fractionally distilling the reaction mixture to recover the isocyanatoalkyl ester. As an example, crude 2-isocyanatoethyl methacrylate (IEM) containing 0.19 weight percent 2-isopropenyl-2-oxazoline (IPO) is contacted with terephthaloyl chloride for 0.5 hour at 90 DEG C. The reaction mixture is fractionally distilled to recover 97 weight percent of the IEM containing only 0.02 weight percent IPO. |
