Process of making a stable solution of poly(hydroxystyrene) functionalized with t-butyloxycarbonyl groups
AssigneeHoechst Celanese Corporation
InventorDinesh N. Khanna
Life of this patent
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Abstract
Poly(hydroxystyrene) resins in which a portion of the hydroxyl groups are functionalized with t-butyloxycarbonyl groups ("t-Boc") tend to decompose during drying of the wet solid and on storage in the solid state. Solutions that are more stable than the solid material can be made from the wet freshly synthesized solid by dissolving the wet solid in a solvent that forms an azeotrope with water and then distilling the azeotrope of water and solvent from the solution until the solution contains less than about 1% by weight of water.
Claims20
A method of making a stable solution of a t-Boc PHS resin from wet t-Boc PHS resin, wherein said t-Boc PHS resin comprises monomer units I having the formula ##STR5## wherein A, B, and C are alike or different and are selected from the group consisting of H, Cl, F, C.sub.1 to C.sub.4 alkyl groups and mixtures thereof;
- wherein some or all of the groups R are represented by the formula ##STR6## and the remainder of the groups R are H;
- said method comprising the steps of:
- (a) dissolving said wet t-Boc PHS resin in a solvent capable of forming an azeotrope with water to form a solution;
- and
- (b) distilling said azeotrope of water and said solvent from said solution until said solution contains less than about 1% by weight of water.
A solution consisting essentially of (a) about 5% to about 50% by weight of a resin that consists essentially of monomer units I, where I has the formula ##STR11## and wherein some or all of the groups R have the formula ##STR12## and the remainder of the groups R are H;
- (b) less than about 1% by weight of water;
- and (c) about 50% to about 95% by weight of propylene glycol methyl ether acetate.
Dependencies are inferred from the claim text.