Method for the preparation of polythioethers from thiodiethanol using heterogeneous mixed metal oxide catalysts

Claim 1

A method for the preparation of polycondensation oligomers of thiodiethanol with a molecular weight of about 300 to about 4100 which comprises condensing thiodiethanol or a mixture of a major proportion of thiodiethanol and one or more aliphatic diols at a temperature ranging from about 150° to about 200° C in the presence of about 0.5 to 20 percent by weight of a heterogeneous, acid acting, metal oxide catalyst consisting essentially of silica-alumina; admixtures of silica, alumina, or silica-alumina with calcium oxide, magnesium oxide, boron oxide, molybdenum oxide or tungsten oxide; acid washed acidic clays or acid acting metal oxides having acidic groups on their surface structure; said metal oxide catalyst being such that the pH of an aqueous slurry of a 5 gram portion of the catalyst in 50 ml. of water after stirring for 5 minutes is the same or lower than the pH of a 1 gram portion of the catalyst in 50 ml. of water after stirring for 5 minutes.

Claim 2

A method for the preparation of polycondensation oligomers of thiodiethanol with a molecular weight of about 300 to about 4100 which comprises condensing thiodiethanol or a mixture of a major proportion of thiodiethanol and one or more aliphatic diols at a temperature ranging from about 150° to about 200° C in the presence of about 0.5 to 20 percent by weight of a heterogeneous, acid acting, metal oxide catalyst consisting essentially of silica-alumina; admixtures of silica, alumina, or silica-alumina with calcium oxide, magnesium oxide, boron oxide, molybdenum oxide or tungsten oxide; acid washed acidic clays or acid acting metal oxides having acidic groups on their surface structure; said metal oxide catalyst being such that the pH of an aqueous slurry of a 5 gram portion of the catalyst in 50 ml. of water after stirring for 5 minutes is the same or lower than the pH of a 1 gram portion of the catalyst in 50 ml. of water after stirring for 5 minutes.