Reaction SMILES: C([O-])(=O)C1C=CC(C([O-])=O)=CC=1.COC(=O)C1C=CC(C(OC)=O)=CC=1.C[C:28]1[C:33]([C:34]([O-:36])=[O:35])=[C:32]([S:37]([OH:40])(=[O:39])=[O:38])[C:31]([C:41]([O-:43])=[O:42])=[C:30](C)[CH:29]=1.[Na+:45].[Na+].[CH2:47]([OH:51])[CH:48]([OH:50])[CH3:49].CCCC[Sn](O)=O>O1CCCC1.C(O)COCCO>[S:37]([C:32]1[C:33]([C:34]([O-:36])=[O:35])=[CH:28][CH:29]=[CH:30][C:31]=1[C:41]([O-:43])=[O:42])([OH:40])(=[O:39])=[O:38].[Na+:45].[Na+:45].[CH2:47]([OH:51])[CH:48]([OH:50])[CH3:49]
Reactant: Cc1cc(C)c(C(=O)[O-])c(S(=O)(=O)O)c1C(=O)[O-]
Agent: CCCC[Sn](=O)O
Agent: COC(=O)c1ccc(C(=O)OC)cc1
Agent: O=C([O-])c1ccc(C(=O)[O-])cc1
Solvent: CC(O)CO
Solvent: C1CCOC1
Solvent: OCCOCCO
Product: O=C([O-])c1cccc(C(=O)[O-])c1S(=O)(=O)O
Temperature: 165 °C
Reaction time: 3 h

Procedure:
A linear sulfonated random copolyester resin comprised of, on a mol percent, approximately 0.465 of terephthalate; 0.035 of sodium sulfoisophthalate, 0.475 of 1,2-propanediol, and 0.025 of diethylene glycol was prepared as follows. In a one liter Parr reactor equipped with a bottom drain valve, double turbine agitator, and distillation receiver with a cold water condenser were charged 388 grams of dimethylterephthalate, 44.55 grams of sodium dimethylsulfoisophthalate, 310.94 grams of 1,2-propanediol (1 mole excess of glycol), 22.36 grams of diethylene glycol (1 mole excess of glycol), and 0.8 gram of butyltin hydroxide oxide as the catalyst. The reactor was then heated to 165° C. with stirring for 3 hours whereby 115 grams of distillate were collected in the distillation receiver, and which distillate was comprised of about 98 percent by volume of methanol and 2 percent by volume of 1,2-propanediol as measured by the ABBE refractometer available from American Optical Corporation. The mixture was then heated to 190° C. over a one hour period, after which the pressure was slowly reduced from atmospheric pressure to about 260 Torr over a one hour period, and then reduced to 5 Torr over a two hour period with the collection of approximately 122 grams of distillate in the distillation receiver, and which distillate was comprised of approximately 97 percent by volume of 1,2-propanediol and 3 percent by volume of methanol as measured by the ABBE refractometer. The pressure was then further reduced to about 1 Torr over a 30 minute period whereby an additional 16 grams of 1,2-propanediol were collected. The reactor was then purged with nitrogen to atmospheric pressure, and the polymer discharged through the bottom drain onto a container cooled with dry ice to yield 460 grams of the 3.5 mol percent sulfonated polyester resin, copoly(1,2-propylene-diethylene)terephthalate-copoly(sodium sulfoisophthalate dicarboxylate). The sulfonated polyester resin glass transition temperature was measured to be 59.5° C. (onset) utilizing the 910 Differential Scanning Calorimeter available from E.I. DuPont operating at a heating rate of 10° C. per minute. The number average molecular weight was measured to be 3,250 grams per mole, and the weight average molecular weight was measured to be 5,290 grams per mole using tetrahydrofuran as the solvent. A particle size of 57 nanometers (volume weighted) was measured using a Nicomp particle sizer.