A mechanism of alkali metal carbonates catalysing the synthesis of β-hydroxyethyl sulfide with mercaptan and ethylene carbonate
作者:Dongliang Liu、Tiju Thomas、Hong Gong、Fei Li、Qiang Li、Lijuan Song、Tamil Azhagan、Heng Jiang、Minghui Yang
DOI:10.1039/c9ob01816f
日期:——
The reaction of β-hydroxyethylation is essential to the current practice of organic chemistry. Here, we proposed a new and green route to synthesize 2-hydroxyethyl n-alkyl sulfide with n-alkyl mercaptan and ethylene carbonate (EC) in the presence of alkali carbonates as catalysts and revealed the mechanism by experiments and theoretical calculations. The reaction reported proceeds rapidly with high
β-羟乙基化反应对于当前有机化学的实践是必不可少的。在这里,我们提出了一种新的绿色路线,在碱金属碳酸盐存在的情况下,用正烷基硫醇和碳酸亚乙酯(EC)合成2-羟乙基正烷基硫醚,并通过实验和理论计算揭示了机理。当报道的反应在120°C进行且催化负载量约为1 mol%时,该反应以高收率快速进行。该方案适用于其他硫醇合成相应的β-羟乙基硫醚。基于密度泛函理论的计算显示了反应路径的能量分布。速率确定步骤是EC的开环。在氢键的影响下,碱金属碳酸盐带负电的O原子接近-SH的S原子。带有更多负电荷的活化S原子充当亲核试剂,并通过降低EC中C1-O1键的Mayer键顺序来帮助EC开环。碱阳离子也有助于C1-O1键的裂解。EC的开环能垒随着碱金属阳离子电负性的降低而降低。H原子的随后转移导致β-羟乙基硫的形成,CO 2的离解和K 2 CO 3的还原。