The Double and Triple Role of L-(+)-tartaric Acid and Dimethyl Urea: A Prevailing Green Approach in Organic Synthesis

The deep eutectic mixtures (DESs), introduced as a novel alternative to usual volatile organic solvents for organic transformations, have attracted tremendous attention of the research community because of their low cost, negligible vapour pressure, low toxicity, biodegradability, recyclability, insensitivity towards moisture, and ready availability from bulk renewable resources. Although the low melting mixture of dimethyl urea (DMU)/L-(+)- tartaric acid (TA) is still in infancy, it is very effective as it plays multiple roles such as solvent, catalyst and/or reagent in the same pot for many crucial organic transformations. These unique properties of the DMU/TA mixture prompted us to provide a quick overview of where the field stands presently and where it might be going in the near future. To our best knowledge, no review dealing with the applications of a low melting mixture of DMU/TA appeared in the literature except the one published in 2017, describing only the chemistry of indole systems. Therefore, we intended to reveal the developments of this versatile, low melting mixture in the modern organic synthesis since its first report in 2011 by Köenig’s team to date. Hopefully, the present review article will be useful to the researcher working not only in the arena of synthetic organic chemistry but also to the scientists working in other branches of science and technology.