The catalytic decarbonylation reaction mechanisms of 2-methyl-2-propenal in the presence of hydrogen chloride (HCl), water (H2O), or sulfuric acid (H2SO4) have been investigated theoretically for the first time. Both concerted and stepwise mechanisms have been considered. Compared with uncatalyzed reaction, the transition state energy is decreased by 90.46, 26.35, or 146.74 kJ/mol when the reaction is carried out with HCl, H2O, or H2SO4 as a catalyst, respectively. Our calculations demonstrate that the presence of HCl can reduce the transition state energy dramatically and make the decarbonylation of 2-methyl-2-propenal to be carried out at much lower temperatures, which is consistent with the experimental result. Moreover, the lowest activation energy assisted by H2SO4 suggests that H2SO4 may have better catalytic ability than that of HCl for the decarbonylation of 2-methyl-2-propenal, and our calculational results may be useful for future experimental studies on the title reaction.

中文翻译：

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氯化氢、水或硫酸辅助2-甲基-2-丙烯醛脱羰反应机理研究

首次从理论上研究了在氯化氢 (HCl)、水 (H2O) 或硫酸 (H2SO4) 存在下 2-甲基-2-丙烯醛的催化脱羰反应机理。已经考虑了协调和逐步机制。与未催化反应相比，以HCl、H2O或H2SO4为催化剂进行反应时，过渡态能分别降低90.46、26.35或146.74 kJ/mol。我们的计算表明，HCl 的存在可以显着降低过渡态能量，并使 2-甲基-2-丙烯醛的脱羰在更低的温度下进行，这与实验结果一致。而且，