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首页> 外文期刊>Journal of Applied Polymer Science >Effects of solvent polarity on the reaction of phenol with tolylene-2,4-diisocyanate
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Effects of solvent polarity on the reaction of phenol with tolylene-2,4-diisocyanate

机译：溶剂极性对苯酚与甲苯-2,4-二异氰酸酯反应的影响

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摘要

Using tolylene-2,4-diisocyanate as standard compound, the relationship between -NCO absorbance and concentration was studied with in situ FTIR. The linear relationship appeared correct only for concentrations lower than 0.4 mol L~(-1). Then, the urethane reaction kinetics of phenol with tolylene-2,4-diisocyanate were investigated in different solvents, such as dimethyl sulfoxide, cyclohexanone, n-butyl acetate, 1,4-dioxane, and xylene. It showed that solvents largely affected reaction rates. The reaction was largely accelerated in polar solvents, following the order of dimethyl sulfoxide > cyclohexanone > n-butyl acetate > 1,4-dioxane > xylene. It was in contrast to the alcohol-diisocyanate reaction. Finally, an appropriate reaction mechanism was proposed. The H-O bond in phenol was polarized under the influence of solvents, which made the combination of hydrogen to nitrogen and alkoxyl group to carbenium easier. After that the solvent was dissociated and the carbamate generated. The kinetic equation could be derived as v = k′K·[S:] [ROH]·[R′NCO].
机译：以甲苯-2,4-二异氰酸酯为标准化合物，用原位FTIR研究了-NCO吸光度与浓度的关系。线性关系仅在浓度低于0.4 mol L〜（-1）时才显示正确。然后，在不同的溶剂（如二甲亚砜，环己酮，乙酸正丁酯，1,4-二恶烷和二甲苯）中研究了苯酚与甲苯2,4-二异氰酸酯的氨基甲酸酯反应动力学。结果表明，溶剂在很大程度上影响反应速度。在二甲基亚砜>环己酮>乙酸正丁酯> 1,4-二恶烷>二甲苯的顺序下，在极性溶剂中大大促进了反应。这与醇-二异氰酸酯反应相反。最后，提出了合适的反应机理。苯酚中的H-O键在溶剂的影响下被极化，这使得氢到氮和烷氧基到碳正离子的结合更容易。之后，将溶剂解离并生成氨基甲酸酯。动力学方程可推导为v = k'K·[S：] [ROH]·[R'NCO]。

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