Synthesis Of Cyclic Functional Organic Boric Acid Ester By Non-acid Catalyst

Organic boric acid ester has attracted more attention recent years because of its non-toxicity, odorless, environmental compatibility, excellent antiwear and antifriction characteristics. This research developed a new process for synthesizing a new cyclic functional organic boric acid ester—cyclic 2-methyltrimethylene 3-hydroxy-2-methyl-propyl boric acid ester, which 2-methyl-l,3 -propanediol(MPO) and boric acid were used as the main materials in the presence of non-acid catalyst. It is important not only to science research but also to industrial application, for the new process eliminated a large amount of waste water disposal. The synthesis conditions and kinetics were also studied.At first, cyclic 2-methyltrimethylene 3-hydroxy-2-methylpropyl boric acid ester was synthesized by using 2-methyl-1,3-propanediol(MPO) and boric acid as the main materials, improved non-acid catalyst, toluene as water-carrier and organic-water separator. The structure of synthesized product was characterized by MS, IR and H-NMR. The optimum esterifying conditions were obtained through Orthogonal Test Design and single factor experiments: n(MPO)/n(acid)=2.1:1, w(cata.)/w(total)=0.1%, 2.5h and within 180℃, v(water-carrier)/v(MPO)=25%. The esterification ratio was 99.16%.Nonisothermal esterification kinetics was studied by means of the relationship between temperature, reaction time and reaction processing to determine the kinetic parameters. The results showed that the MPO esterification follows different kinetics rules during different reaction stages. There is a turning-point before and after the boric acid dissolved completely, appeared at about 14%of the reaction progress degree. Before the boric acid dissolved completely, the esterification is the rate-controlling step, and the reaction can be seen as quasi-one-order. After the boric acid dissolved completely, the esterification is two-order, one-order for liquid boric and one-order for MPO respectively. The apparent activation energy was 100±3.0kJ·mol^-1 and the frequency factor was 0.656×10⁶ L·mol^-1·s^-1.Moreover, vapor-liquid equilibrium of pure liquid MPO, MPO-H₂O and MPO-BDO (1,4-butanediol) binary systems were studied under atmospheric pressure. Vapor pressure of MPO from 298.15K to 484.95K was measured by using static-method, the changing of vapor pressure of MPO with temperatures follows Clapeyron-Clausis equation. The average enthalpy of vaporization of MPO was 37.68kJ·mol^-1. Vapor-liquid equilibrium data for MPO-H₂O and MPO-BDO binary systems were measured by improved ROSE kettle under atmospheric pressure. The results showed that there was an azeotropic point (215℃, x(BDO)=0.121) for MPO-BDO system, while no azeotropic point for MPO-H₂O. The consistency of thermodynamics was also verified for experimental equilibrium data.