Method for preparing copolyether glycols

In a process for preparing a copolyether glycol by copolymerizing an alkylene oxide or a cyclic acetal and tetrahydrofuran using water or an alkanediol as a chain terminator, the improvement comprising using as a catalyst a polymer of monoethylenically unsaturated monomers, the polymer containing groups of the formula ##STR7## where represents the polymer chain or a segment thereof;

• D is hydrogen, an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms, a halogen or a segment of the polymer chain;
• X and Y are hydrogen, an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms, or fluorine, but at least one of X and Y must be fluorine;
• R is a linear or branched linking group having up to 40 carbon atoms in the principal chain;
• and
• Z is hydrogen, an aliphatic or aromatic hydrocarbon radical of 1 to 10 carbon atoms, or halogen;
• the polymer being effectively free of functional groups which interfere with the reaction.