High temperature liquid water(HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid(GA) and pyrogallol(PY) are under investigation in our laboratory. In this study,the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.
The decomposition kinetics of glucose was studied in high-temperature liquid water （HTLW） from 180 to 220℃ under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylfurfural （5-HMF） and levulinic acid （LA）. The decomposition kinetics of 5-HMF and stability of LA in HTLW were further investigated. A kinetic model for glucose decomposition was proposed accordingly. In the model, a series of first-order reactions with the consideration of parallel by-reactions were used to illustrate the decomposition of glucose. The decomposition activation energies of glucose, 5-HMF, and LA were evaluated as 118.85, 95.40, and 31.29 kJ·mol^-1, respectively.
Adenine is an important chemical material widely used in the fields of medicine,organic synthesis and so on.Presently,adenine is produced from the condensation of diethyl malonate with formamide,which has serious pollution problems.To achieve the green production of adenine,non-catalyzed hydrolysis of adenosine in high temperature liquid water was carried out.The effects of initial concentration,agitating speed and temperature on adenosine hydrolysis were studied and the kinetics of adenosine hydrolysis was investigated at temperatures from 150℃ to 190℃.Rate constants were evaluated with the zeroth-order reaction assumption and the activation energy was 134.1 kJ·mol-1.The experimental results demonstrated that high selective preparation of adenine by non-catalyzed hydrolysis of adenosine in high temperature liquid water was possible.
