Catalytic Synthesis Of Alicyclic Dicarbamate And Ethyl Bromide

The catalytic synthesis of three alicyclic dicarbamate and ethyl bromide was studied in this thesis. These alicyclic dicarbamates were synthesized from the reaction of three alicyclic diamines with dimethylcarbonate (DMC) catalyzed by various metal-containing compounds, composite catalysts consisting of inorganic salts or metal oxides, alcoholized inorganic salts and supported molecular sieve catalysts. From those researches, we found that anhydrous Pb(OAc)2showed a better catalytic activity. The effects of the ratio of reactants, the reaction temperature and time, the solvent, the formylation reagent and the catalyst content on the yield of alicyclic dicarbamates were investigated. All the products were widely characterized by melting-point test, IR,1H and13C NMR spectra.Firstly, the synthesis of4,4’-methylene bis (cyclohexylamine)(H12MDC) was studied, with dimethylcarbonate (DMC) and4,4’-methylene bis (cyclohexylamine)(H12MDA) as raw reagents, in which Pb(OAc)2was used as the catalyst. Under the optimal experimental conditions followed by atmospheric pressure, DMC/H12MDA molar ratio of12:1, Pb(OAc)2/H12MDA molar ratio of1:6.9, reaction temperature of80℃, and reaction time of24h, the yield of H12MDC could reach74.8%. But, under the conditions from ambient pressure to8atm, DMC/H12MDA molar ratio of12:1, Pb(OAc)2/H12MDA molar ratio of1:6.9, reaction temperature of150℃, and reaction time of8h, the yield of H12MDC could reach79.1%. When cyclohexane was added as a co-solvent, the amount of DMC was decreased. The yield of H12MDC could reach79.6%at the DMC/H12MDA molar ratio of4:1.Secondly, the optimal condition for the synthesis of IPDC from isophorone and diamine was obtained with Pb(OAc)2catalyst, ambient pressure-8atm, DMC/IPDA molar ratio of15:1, Pb(OAc)2/IPDA molar ratio of1:10, reaction temperature of180℃, and reaction time of2h. The highest yield of IPDC could reach79.7%.Thirdly, the yield of H10NDC could reach only38.9%, under the conditions of Zn(OAc)2, DMC/H10NDA molar ratio of6:1, reaction temperature of70℃, and reaction time of10h,.Ethyl bromide was synthesized from sodium bromide and ethanol catalyzed by β-phosphotungstic acid, Zn(OAc)2,2.4%CO-SiO2, SO42-/ZrO2, SnO2etc. The reaction conditions were optimized, inclusive of different catalysts, different reaction time and temperature. The results indicated that stannic oxide was a suitable catalyst for the yield of ethyl bromide from a mixture of NaBr:C2H5OH:H2SO4under mild conditions, in which the highest yield of78.2%was achieved at80℃within4h.