Styrene → Styrene

Beteiligte Stoffe

Reaktionsschritte

A 5 g sample of poly(styrene [50 mol %], isopropyl hydrogen maleate [32 mol %], maleic anhydride [18 mol %]) was suspended in 75 mL of 3,4-dihydro-2H-pyran and treated with 0.1 g of pyridine hydrochloride. The mixture was stirred at reflux for 18 hours, during which time a homogeneous solution was formed. After cooling to room temperature, the solution was stirred for 1 hour with crosslinked poly(dimethylaminomethylstyrene) to remove the catalyst. After filtration, the product was isolated from the filtrate by precipitation in methanol and dried to give 3 g of poly(styrene, isopropyl tetrahydropyranyl maleate, maleic anhydride). Titration of the starting material with 0.1N sodium hydroxide shows 4.32 meq/g of anhydride and acid. Titration of the product shows 2.49 meq/g of anhydride. IR analysis of the product shows absorption characteristic of anhydride (1855 and 1780 cm-1), but no absorption characteristic of carboxylic acid. Differential scanning calorimetry (DSC) of the product shows a sharp decomposition endotherm peaking at 153.9° C. (104.1 J/g) which is absent from the starting material. Thermal gravimetric analysis (TGA) shows a 13.36% weight loss centered at 154.54° C. which is not seen in the TGA of the starting material. The thermal event at 154° C. is the thermal loss of dihydropyran to form polymeric carboxylic acid groups.

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