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A quantum chemical investigation of reaction mechanisms of isocyanate group with water and the function of water-blowing tertiary amine catalyst on the mechanisms

机译：异氰酸酯基团与水反应机理的量子化学研究及注水叔胺催化剂的作用机理

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The reaction between isocyanate group and water with releasing carbon dioxide is widely applied to manufacturing of water-blown polyurethane foams. Many of the tertiary amine catalysts are utilized to control the processability during foam production and the other properties of the foam produced. However, even in case of non-catalytic reaction, the actual reaction mechanisms still have not been sufficiently revealed. The elucidation of the non-catalytic and also catalytic reaction mechanisms is very important for development of a new type of catalyst and for manufacturing of water-blown foams. The reaction mechanisms of non-catalytic and catalytic reactions between isocyanate and water were investigated in terms of quantum chemical methods. At first, detailed mechanisms of non-catalytic reaction between isocyanate and water were investigated. The reaction has been generally considered to be two-step reaction, i.e. amine and carbon dioxide formation and followed by the attack of the generated amine on another isocyanate. However, the results of quantum chemical calculation indicated that many complicated routes consisted of a number of elemental reactions are possible to reach urea and carbon dioxide. The most reasonable non-catalyzed route from the viewpoint of relative energy balance is not via amine formation but carbamic acid directly reacts with isocyanate and produce urea and carbon dioxide. This result indicates that carbon dioxide would be released simultaneously with the polymerization by urea linkage in non-catalyzed reaction of polyisocyanate and water. The catalytic reaction mechanism of a tertiary amine catalyst TOYOCAT-ETS~?(Bis(2-dimethylaminoethyl)ether) which is considered to be suiting for water-blowing was also investigated. A transition state structure, which consists of isocyanate, two molecules of water and the catalyst, was discovered. Carbamic acid can be produced easily by participation of the catalyst because the activation energy through the transition state is extremely low. Furthermore, it was found that the same catalyst activates the reaction of carbamic acid and water producing amine and carbon dioxide. It is concluded that the catalyst can greatly accelerate the water-blowing reaction because the activation energies via the newly discovered transition states are extremely low. Moreover, the catalyst can control the processability of foaming by hastening of blowing because carbon dioxide is released simultaneously with the amine formation
机译：异氰酸酯基团与释放二氧化碳的反应广泛应用于制造水吹塑的聚氨酯泡沫。许多叔胺催化剂用于控制泡沫生产过程中的可加工性，并产生的泡沫的其他性质。然而，即使在非催化反应的情况下，即使在非催化反应的情况下，实际的反应机制仍然没有充分露出。阐明非催化剂和催化反应机理对于开发新型催化剂和制造水吹塑的泡沫非常重要。在量子化学方法方面研究了异氰酸酯与水之间的非催化和催化反应的反应机制。首先，研究了异氰酸酯和水之间的非催化反应的详细机制。该反应通常认为是两步反应，即胺和二氧化碳形成，然后在另一个异氰酸酯上进行产生的胺。然而，量子化学计算结果表明，许多由许多元素反应组成的复杂途径是可以达到尿素和二氧化碳的。从相对能量平衡的观点来看，最合理的非催化路线不是通过胺形成，但氨基甲酸直接与异氰酸酯反应并产生尿素和二氧化碳。该结果表明，二氧化碳将通过尿素键在多异氰酸酯和水的非催化反应中的尿素键同时释放二氧化碳。还研究了叔胺催化剂Toyocat-ETS的催化反应机制~~~~~~~~~~醚类的乙醚）也被认为是适用于水吹制的。发现了由异氰酸酯，两种水和催化剂组成的过渡状态结构。通过催化剂的参与可以容易地制造氨基甲酸，因为通过过渡状态的激活能量极低。此外，发现相同的催化剂激活氨基甲酸和产生胺和二氧化碳的反应。得出结论是，催化剂可以大大加速水吹气反应，因为通过新发现的过渡状态的激活能量非常低。此外，催化剂可以通过加速吹割来控制发泡的可加工性，因为二氧化碳与胺形成同时释放

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