Interfacial sythesis of polyphosphonate and polyphosphate ester. VII. Temperature effects and reaction loci in polycondensations of hydroquinone with phenylphosphonic dichloride and 4-methythiophenyl phosphorodichloridate

Polyphosphate and polyphosphonate esters of molecular weights > 10,000 were synthesized by base-promoted, liquid-vapor and liquid-liquid interfacial polycondensations of hydroquinone (HQ) with 4-methylthiophenyl phosphorodichloridate (MTPP) and phenylphosphonic dichloride (PPD). The barium hydroxide-initiated liquid-vapor polycondensation of PPD and HQ in the temperature range of 15–95°C shows that [η] increases with reaction temperature and unfractionated yields exhibit a maximum at about 45°C. The analogous liquid-vapor polycondensation of MTPP and HQ between 25 and 85⁴C also shows a maximum yield at 45°C, whereas [η] decreases with increase in reaction temperature. The results are contrasted with temperature dependencies of base-catalyzed, liquid-liquid polycondensation of HQ with MTPP and PPD. A different insight is obtained by analyzing the temperature effects on fractionated products. The relative importance of degradative saponification reactions are ranked as attack on chain ester linkages > phosphorus chloride reactant > end groups of growing chains.