中性及近中性溶剂促进席夫碱C=N双键转移的研究

Study on Schiff base C=N double bond transfer promoted by neutral and near-neutral solvents

研究了常用溶剂促进的C N双键[1,3]-质子转移。以醛或酮与芳胺形成的席夫碱为底物,通过多种中性或近中性溶剂、自由基抑制剂、理论计算对质子转移过程进行了研究。结果表明,质子转移首先在溶剂的协助下活泼氢从底物1上离解下来,然后再结合到底物1的3位碳上,完成了[1,3]-质子。不同溶剂对质子转移速率的影响很大。醛、醇等溶剂具有较好的促进C=N双键转移的作用,归因于它们可以与底物1形成氢键和π-π堆叠,使C=N双键转移的活化能大大降低。溶剂与底物分子的弱相互作用越强则C=N双键转移速率越大。反应温度越高,双键转移的速率越大。工业上该方法特别适用于醛或酮转化为胺的反应,环境友好、成本低、后处理操作简单。

This paper studies the C=N double bond[1,3]-proton transfer promoted by commonly used solvent.Using the Schiff base formed by aldehydes or ketones with aromatic amines as substrates,the proton transfer process was studied through a variety of neutral or near-neutral reaction solvent,free radical inhibitors,and theoretical calculations.The results show that the proton transfer is firstly dissociated from substrate 1 with the assistance of the solvent,and then binds to the 3-position carbon of substrate 1 to complete[1,3]-proton.Different solvents have a great influence on the proton transfer rate.The Solvents such as aldehydes and alcohols have a good effect of promoting transfer of C=N double bonds,due to their ability to form hydrogen bonds andπ-πstacking with substrate 1,greatly reducing the activation energy of C=N double bond transfer.The stronger the weaker interaction between the solvent and the substrate molecule,the greater the C=N double bond transfer rate.The higher the reaction temperature,the greater the rate of double bond transfer.This method is especially suitable for the conversion of aldehydes or ketones to amines in industry,which is environmentally friendly,low cost and simple in post-treatment.