Synthetic Study Of Monomers Of Poly 3-Hydroxybutyrate

Methyl 3-hydroxybutyrate is the main monomer for producing PHB, an important biodegradable plastic. By far, it has not been produced on commercial scale. Therefore, the synthesis of PHB monomers is of great importance.Preparation of methyl 3-hydroxybutyrate from 3-hydroxybutyric acid and methanol was studied. The yield of methyl 3-hydroxybutyrate could reach 66.5% under the following conditions: 3-hydroxybutyric acid 0.2 mol, methanol 1.0mol , paratoluenesulfonic acid 2.0 g, cyclohexane 60 g, time 4 h.The density and viscosity were measured by a vibrating densimeter(model DA-505U) and a Ubbelohde suspended-level viscometer at atmospheric pressure for ethyl crotonate + ethanol,crotonic acid + ethanol. The excess molar volumes(VE )and deviations of viscosity(?η)were calculated. The VE and ?ηwere fitted by Redlich-Kister equation respectively.The chemical standard equilibrium constants of the preparation of methyl 3-hydroxybutyrate and ethyl 3-hydroxybutyrate were also calculated in this paper.