Recently, a new generation of green solvents, namely deep eutectic solvents (DESs), have emerged as a suitable alternative to hazardous organic solvents in various applications, they were introduced as a low-cost alternative to ionic liquids (ILs) [1]. DESes are be made of mixture a hydrogen-bond acceptors (HBA) and hydrogen-bond donors (HBD). Generally, a DES is a type of solvent composed of a mixing two or more components under simple operation of that forms an eutectic with a much lower melting point than either of the individual components [2]. Substituted acridines and acridine-1,8-dione have been successfully used as antimalarials for many years, and several of them have shown excellent results such as anticancer activity, antimicrobial activity and cytotoxicity [3]. Due to their structural similarity with 1,4- dihydropyridines, these substances are used as intermediates for the synthesis of some drugs, such as drugs for the treatment of cardiovascular diseases and high blood pressure [4]. In this study, a novel, efficient, and recoverable DES was designed and made from a mixture of triphenylphosphonium derivative as HBA and Gentisic acid as HBD with ration 1:1 and it characterized using fourier transform infrared spectroscopy (FT-IR), thermal analysis/differential thermal analysis (TGA/DTA), densitometry, and 1HNMR. This DES used as catalyst for the synthesis of piperidine derivatives.
