Strongly eutectic solvent

As Stark eutectic solvent ( DES of English Deep Eutectic Solvents ) multicomponent be eutectic salt melts referred whose melting point , as that of ionic liquids is close to or below room temperature. The term is misleading insofar as there is no special mechanism that causes a particularly strong lowering of the melting point compared to other eutectics.

Known eutectic solvents are based on a mixture of quaternary ammonium compounds with hydrogen bond donors (e.g. amines ) and carboxylic acids . In 2003 the phenomenon of a strongly eutectic mixture of choline chloride (2-hydroxy- N , N , N -trimethyl-ethanaminium chloride) and urea in a molar ratio of 1: 2 was described. The melting point of this strongly eutectic mixture is 12 ° C, while that of choline chloride is 302 ° C and that of urea is 133 ° C.

DES have been studied for their applicability on a laboratory scale and for industry. In this case, it was found that the eutectic described (see above) various metal salts such as lithium chloride ( solubility of 2.5 mol · L ^-1 ), and copper (II) oxide (solubility 0.12 mol·L ^-1 dissolves). An application in metal cleaning processes ( electroplating ) seems possible. DES can also be used as electropolishes as they are electrically conductive . DES can also be used as solvents in the field of organic chemistry , e.g. B. for benzoic acid (solubility 0.82 mol·L ⁻¹ ) or even for cellulose .

Compared to conventional solvents, DES are non-volatile , i.e. they have no vapor pressure, and are therefore only very difficult to ignite ( flammability ). Other DESs based on choline chloride are formed with malonic acid (m.p. 0 ° C), phenol (−40 ° C) or glycerol (−35 ° C).

Compared to ionic liquids, which, like DES, are composed of ions and therefore have similar properties, DES can be produced more cheaply because they are simply mixtures of common laboratory chemicals. Further advantages compared to common ILs are the absence of fluorine and the good or well-known biodegradability .

Individual evidence

↑ Andrew P. Abbott, Glen Capper, David L. Davies, Raymond K. Rasheed, Vasuki Tambyrajah: Novel solvent properties of choline chloride / urea mixtures . In: Chemical Communications . No. 1, 2003, pp. 70-71. doi : 10.1039 / b210714g .
↑ Abbott, AP; Boothby, D .; Capper, G .; Davies, DL; Rasheed, RK: Deep Eutectic Solvents Formed between Choline Chloride and Carboxylic Acids: Versatile Alternatives to Ionic Liquids . In: J. Am. Chem. Soc. . 126, No. 29, 2004, pp. 9142-9147. doi : 10.1021 / ja048266j . PMID 15264850 .
^ Richard F. Miller. 2010. Deep eutectic solvents and applications. Patent number: 8022014. Filing date: Mar 25, 2009. Issue date: Sep 20, 2011. Application number: 12 / 410,662.

[1] Andrew P. Abbott, Glen Capper, David L. Davies, Raymond K. Rasheed, Vasuki Tambyrajah: Novel solvent properties of choline chloride / urea mixtures . In: Chemical Communications . No. 1, 2003, pp. 70-71. doi : 10.1039 / b210714g .

[2] Abbott, AP; Boothby, D .; Capper, G .; Davies, DL; Rasheed, RK: Deep Eutectic Solvents Formed between Choline Chloride and Carboxylic Acids: Versatile Alternatives to Ionic Liquids . In: J. Am. Chem. Soc. . 126, No. 29, 2004, pp. 9142-9147. doi : 10.1021 / ja048266j . PMID 15264850 .

[3] Richard F. Miller. 2010. Deep eutectic solvents and applications. Patent number: 8022014. Filing date: Mar 25, 2009. Issue date: Sep 20, 2011. Application number: 12 / 410,662.