ch 2 ch 2 o u2014 and u2014 ch 2 chro u2014 or u2014 chrch 2 o u2014 groups may be used according to the invention in another embodiment of the present invention the cation x consists of one or more alkyl ammonium cation compounds of formula iii wherein r 2 represents a linear or branched alkyl a linear alkenyl or a linear alkynyl group having 6 to 24 carbon atoms preferably 10 to 18 carbon atoms r 3 represents a linear or branched alkyl group having 1 to 5 carbon atoms preferably a methyl group r 4 represents a linear or branched alkyl group having 1 to 5 carbon atoms preferably a methyl group or a linear or branched alkyl a linear alkenyl or a linear alkynyl group having 6 to 24 carbon atoms preferably from 10 to 18 carbon atoms in another embodiment of the present invention the ionic liquid of formula i preferably comprises an ethercarboxylate anion of formula ii wherein r 1 represents a linear or branched alkyl or a linear alkenyl group having 6 to 22 carbon atoms preferably 8 to 18 carbon atoms more preferably having 12 to 18 carbon atoms the n in the u2014 ch 2 ch 2 o u2014 units represents a number from 2 to 8 more preferably from 2 to 6 and the m.