Calorimetric Studies On Several Drug Intermediates

Calorimetry and thermal analysis are widely used techniques to investigate thethermodynamic properties of substances. DSC and TG are usually used to testthe thermal stability of substances. Adiabatic calorimetry are frequently applied tomeasure the heat capacities of substances and thus obtain important information inmany aspects such as structures and phase transitions. Combustion calorimetrycan obtain the enthalpies of formation of substances and thus calculate the heatsof reaction, which could be used to analyse the energetics during the reactionprocesses.However, only a few laboratories in the world are conducting the research onthe basic thermodynamic properties of substances, so the thermodynamic data ofmany important compounds are unavailable till now, which causes great trouble torelevant research work. This thesis focuses on calorimetric studies of severalimportant drug intermediates as follows. N,N-Dimethyl-4-aminopyridine,5-Nitro-2-aminopyridine, 2-Benzoylpyridine, 2,6-Dicarboxypyridine,endo-TDCP, 2-chlorine-5-trichlorinemethylpyridine are widely used drugintermediates, and, monuron and arelon are both important pesticides and can beused as intermediates to synthesize more effective pesticides. However, thethermodynamic properties of these compounds have not been studied adequately.With the high precision adiabatic calorimeter, molar heat capacities and phasetransition temperatures of these compounds were measured; the enthalpies,entropies of phase transitions, the thermodynamic function data (based on thestandard state at 298.15 K) were calculated. By means of the high precisionoxygen bomb calorimeter the heats of combustion were determined. From theexperimental results of combustion calorimetry the standard enthalpies offormation were derived. The thermal stability of these compounds was furtherinvestigated with TG and DSC. The relationship between the structures andproperties of the studied compounds was discussed based on the obtainedthermodynamic data. The research work of this thesis filled the blank of the thermodynamic data ofthese substances. These fundamental data will increase our understanding aboutthese substances and be helpful to the design of industrial devices, the control ofprocesses and refinement of production conditions concerned with these importantsubstances.