Polycarbonate polyols

A method of synthesizing a polycarbonate polyol, comprising:

• contacting an epoxide monomer and carbon dioxide in the presence of a polymerization system to form a crude polycarbonate product in solution,
• wherein the polymerization system comprises an initiator including a mono- or multi-functional carboxylate or carbonate salt of tetrabutylammonium, an optional protic compound, and a borane compound;
• and
• precipitating a polycarbonate polyol product out of the solution.

A method of recovering an activator and initiator from a solution for use or re-use in the synthesis of polycarbonate polyols, the method comprising:

• quenching a polymer solution containing a crude polycarbonate with a solution comprising a Lewis base and Lewis acid in water, said crude polycarbonate having an activator-organic cation complex at a chain end;
• reacting the organic cation with an anion to form an initiator that is extracted into a first layer;
• reacting the activator with a Lewis base to form an activator-Lewis base complex that is extracted into a second layer, said second layer being immiscible with said first layer;
• separating the first layer from the second layer;
• contacting the second layer with an isocyanate compound to disassociate the activator from the Lewis base and processing the second layer to recover the activator;
• and
• contacting the first layer with a non-solvent to separate the initiator from the polymer and processing the first layer to recover the initiator.