Deep Eutectic Solvents for Simple and Sustainable Organometallic Catalysis

溶剂在合成中起着重要的作用。不幸的是，许多常用的挥发性有机溶剂（VOS）对人类和/或环境有害。一些卤化溶剂和极性非质子溶剂，如二甲基甲酰胺、n -甲基-2-吡咯烷酮和1,2-二氯乙烷，已被REACH列为“高度关注物质”。然而，寻找合适的替代品是一项挑战。寻找对环境无害的溶剂是当前可持续化学研究的热点。近年来，深共晶溶剂（DES）作为一种新型反应介质出现。DES与离子液体（ILs）有关，通常主要由离子组成。它们通常由季铵盐（如氯化胆碱，ChCl）与金属盐（如ZnCl2）或氢键供体（如尿素）结合形成共晶混合物。它们的蒸气压低，热稳定性好，能溶解各种溶质。然而，与许多il相比，它们便宜、无毒、可生物降解，并且从潜在的可再生原料中合成的路线相对较短。因此，它们具有许多理想的特性，可以作为VOS的可持续替代品。已经证明，使用DES作为溶剂，即使在有水存在的情况下，也可以发生涉及高活性有机金属试剂（例如格氏或烷基锂试剂）的反应。这是非常令人惊讶的，因为这些条件会在传统溶剂中迅速降解有机金属。该项目将进一步研究这些观察结果，并在温和条件下开发新的催化反应，使用DES作为可持续溶剂，不受大气湿度或氧气的保护。

Solvents play a fundamental role in synthesis. Unfortunately, many commonly used volatile organic solvents (VOS) are harmful to humans and/or the environment. Some halogenated and polar aprotic solvents such as dimethylformamide, N-Methyl-2-pyrrolidone and 1,2-dichloroethane are already categorised as "substances of very high concern" under REACH. However, suitable alternatives are challenging to find. The search for environmentally benign solvents is currently a hot topic in sustainable chemistry. Recently, deep-eutectic solvents (DES) have emerged as novel reaction media. DES are related to ionic liquids (ILs) and are usually composed predominantly of ions. They are often formed by combination of a quaternary ammonium salt (e.g. choline chloride, ChCl) with a metal salt (e.g. ZnCl2) or hydrogen-bond donor (e.g. urea) to form eutectic mixtures. They have low vapour pressures, good thermal stabilities and are able to dissolve a range of solutes. However, in contrast to many ILs, they are cheap, non-toxic, biodegradable and have relatively short synthetic routes from potentially renewable feedstocks. As such, they have many desirable characteristics as sustainable alternatives to VOS.It has been shown that using DES as solvents allows reactions involving highly reactive organometallic reagents (e.g. Grignard or alkyllithium reagents) to take place even in the presence of water. This is very surprising, as these conditions would rapidly degrade the organometallic in conventional solvents. This project will take these observations further and develop novel catalytic reactions using DES as sustainable solvents under mild conditions, with no protection from atmospheric moisture or oxygen.