Urgent! ! Reaction conditions for dimethyl terephthalate-hexamethylenediamine-polyethylene glycol
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The laboratory is carrying out a reaction involving polymers: the esterification of dimethyl terephthalate with hexamethylenediamine. An excess of the ester is used, and then an ester exchange reaction is carried out with polyethylene glycol 1000. I am responsible for the first step, which involves using polyethylene glycol and DMF as solvents; the mixture is heated to 110°C and allowed to react for 2 hours. After that, p-toluenesulfonic acid is added as a catalyst, and the temperature is raised to 140°C to carry out the ester exchange reaction. In the end, I wanted to obtain a water-soluble polymer, but it seems the reaction conditions were not right, and what was produced was insoluble in water. Help! ! HELP!!!
Why does ester exchange occur after aminolysis? Is only one molecule of methanol aminolyzed?