carbon atoms such as methyl ethyl propyl butyl octyl vinyl butenyl and hexadecenyl groups and 2 monovalent hydrocarbon groups having an aromatic ring such as phenoxy propylphenoxy octylphenoxy and benzyl groups however preference is given to methyl groups known processes may be applied to the synthesis of such polyether compounds b and c for instance use may be made of a process wherein an alkyl halide reacts with a metal complex salt of the polyether compound a in the polyether compounds d and e the acyl group corresponding to a in formula 1 for instance includes 1 aliphatic acyl groups having 2 to 22 carbon atoms such as acetyl propanoyl butanoyl hexnoyl heptanoyl oxtanoyl nonanoyl decanoyl hexadecanoyl octadecanoyl hexadecenoyl eicosenoyl and octadecenoyl groups and 2 acyl groups having an aromatic ring such as benzoyl toluoyl and naphthoyl groups among which decanoyl and octadecenoyl groups are preferred known processes may be applied to the synthesis of such polyether compounds d and e for instance use may be made of a process wherein an acyl halide reacts with a metal complex salt of the polyether compound a for the hydrocarbon group corresponding to a in formula 1 in the polyether compounds f and g the same as referred to in conjunction with the polyether compounds b and c may hold true and for the acyl group corresponding to a in formula 1 the same as referred to in conjunction with the polyether compounds d and e may go true known processes may be applied to the synthesis of such poylyether compounds f and g for instance use may be made of processes wherein an alkyl halide reacts with a.