Manufacture of polytrimethylene ether glycol

1. A process of manufacture of polytrimethylene ether glycol comprising the steps of:

(a) polycondensing reactant comprising diol selected from the group consisting of 1,3-propanediol, 1,3-propanediol dimer and 1,3-propanediol trimer or mixtures thereof, in the presence of acid polycondensation catalyst to form polytrimethylene ether glycol;

(b) adding water to the polytrimethylene ether glycol and hydrolyzing the acid esters formed during the polycondensation to form a hydrolyzed mixture containing the polytrimethylene ether glycol and the hydrolyzed acid esters;

(c) adding one or more water-soluble, inorganic compounds to the hydrolyzed mixture to form an aqueous-organic mixture comprising (i) an organic phase containing polytrimethylene ether glycol and residual acid polycondensation catalyst from the polycondensing, and (ii) an aqueous phase, wherein the water-soluble, inorganic compounds are selected from the group consisting of an inorganic salt and an inorganic base;

(d) separating the aqueous phase and the organic phase;

(e) optionally adding base to the separated organic phase to neutralize the residual acid polycondensation catalyst by forming salts of the residual acid polycondensation catalyst;

(f) removing residual water from the organic phase;

(g) separating the organic phase into (i) a liquid phase comprising polytrimethylene ether glycol, and (ii) a solid phase comprising the salts of the residual acid polycondensation catalyst and the base which is unreacted.

2. The process of claim 1 wherein the water-soluble, inorganic compound comprises a salt comprising a cation selected from the group consisting of ammonium ion, Group IA metal cations, Group IIA metal cations and Group IIIA metal cations; and an anion selected from the groups consisting of fluoride, chloride, bromide, iodide, carbonate, bicarbonate, sulfate, bisulfate, phosphate, hydrogen phosphate, and dihydrogen phosphate.

3. The process of claim 1 wherein the water-soluble, inorganic compound comprises an inorganic base comprising hydroxide anion and a cation selected from the group consisting of ammonium ion, Group IA metal cations, Group IIA metal cations and Group IIIA metal cations.

4. The process of claim 1 wherein the water-soluble inorganic compound is selected from the group consisting of lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, sodium sulfate, sodium phosphate, ammonium chloride, ammonium hydroxide and mixtures thereof.

5. The process of claim 1 wherein the water-soluble inorganic compound comprises sodium chloride.

6. The process of claim 1 wherein the water-soluble inorganic compound is added in an amount of from about 1 to about 20 wt %, based on the weight of the water added to the polytrimethylene ether glycol.

7. The process of claim 1 wherein the water-soluble inorganic compound is added in an amount of from about 1 to about 10 wt %, based on the weight of the water added to the polytrimethylene ether glycol.

8. The process of claim 1 wherein the water-soluble inorganic compound is added in an amount of from about 2 to about 8 wt %, on the weight of the water added to the polytrimethylene ether glycol.

9. The process of claim 1 wherein the water-soluble inorganic compound is added in aqueous solution.

10. The process of claim 1 wherein the adding water to the polytrimethylene ether glycol is carried out by adding from about 10 to about 200 wt % water, based on the weight of the polytrimethylene ether glycol.

11. The process of claim 1 wherein separating the water phase and the organic phase comprises the steps of allowing the aqueous-organic mixture to stand without agitation at a temperature of from about 85 to about 100° C. for a time sufficient for the organic and water phases to separate, and then draining or decanting the water phase.