Polycondensations of Substituted Maleic Anhydrides and 1,6-Hexanediol Catalyzed by Metal Triflates

Abstract

Polycondensations of methylmaleic anhydride (citraconic anhydride, CiAh), bromomaleic anhydride (BMaAh), and dichloromaleic anhydride (DCMaAh) with 1,6-hexanediol were conducted in bulk. For polycondensations of CiAh, the triflates of aluminum, bismuth, lanthanum, magnesium, samarium, and scandium were used as catalysts and the best results were obtained with Bismuth triflate. MALDI-TOF mass spectra indicated that the chain growth was limited by cyclization and incomplete conversion, but temperatures above 100°C were not advantageous due to side reactions. Bismuth and samarium triflate catalyzed polycondfensations of BMaAh and DCMaAh were less successful than polycondensations of CiAh. For polycondensations of CiAh, BMaAh, and DCMaAh, only a low extent of isomerization to trans isomers (1–3%) was observed at 100°C, but considerably higher extent at 140°C.

Keywords:

• Bismuth
• citraconic anhydride
• polyesters
• polycondensation
• cyclization

Notes

^a Measured at 20°C with c = 0.05mol/L in H₂O.

^b Measured at 20°C with c = 2 g/L in CH₂Cl₂.

^c SEC measurements in chloroform at 25°C calibrated with polystyrene.

^a Measured at 20°C with c = 0.05mol/L in H₂O.

^b Measured at 20°C with c = 2 g/L in CH₂Cl₂.

^a Measured at 20°C with c = 2 g/L in CH₂Cl₂.

^a mass of the repeat unit: 212.246.

^a mass of the repeat unit: 267.112.

^a Measured at 20°C with c = 0.05mol/L in H₂O.

^b Measured at 20°C with c = 2 g/L in CH₂Cl₂.