Studies On The Clean Processes For The Production Of 3,3-Dimethyl-2-Oxobutyric Acid

Electrochemical synthetic mthod is the key research aspect of green chemistry,which has been widely applied in the fields of organic synthesis,inorganic synthesis,waste water treatment,etc.3,3-dimethyl-2-oxobutyric acid is a basic chemical raw materials,which is mainly used in medicine,farm chemical,genetic engineering reagent,coating materials,etc.The traditional chemical synthetic routes using potassium permanganate,sodium hypochlorite etc as oxidant had been limited by the serious pollution problems.In this thesis,we attempt to resolve these limitations by developing a green synthetic way using electrochemical method and rebuilding the traditional Fenton reagent oxidation process by using an in situ H₂O₂generating technique by electrochemical reduction of oxygen.The factors influence the hydrolysis reaction of dichloropinacolone in sodium hydroxide aqueous solution were investigated in detail in the first part of the thesis.The optimized reaction condtions are as following:molar ratio of dichloropinacolone and sodium hydroxide was 1:3.2,mixing speed was 800 r/min,adding the sodium hydroxide solution dropwisely into dichloropinacolone solution,temperature was 80^oC and reaction time was 3.5 h.Under this condition,the yield of hydrolysis reaction is 86%and the conversion of dichloropinacolone reaches 89%.Based on the hydrolysis reaction,the electrochemical oxidation of the hydrolysis product was studied using the constant current electrolysis method.The experimental results show that good yield of 3,3-dimethyl-2-oxobutyric acid,76%,can be obtained using Ti/RuO₂ as anode,graphite plate as cathode,mixing the solution at 450r/min,and electrolysising the sodium hydroxide solution containing 0.1mol/L?-hyroxy acid with the current density of 50mA/cm²,then cutting-off when2F/mol charge passed.The repeat experiments demonstrate the results are reproduciable,which hints the practical prospect of this process.Due to the waste water treated by the traditional biochemical process can not meet the requirement of the local regulations;the operation of the cooperative company is confronted with the difficulty.In the second part of the thesis,we constructed a H₂O₂ electrochemical generator based on the two-electron reduction of oxygen by electrochemical method.Using this generator,the transportation and storage of dangerous H₂O₂ can be avoided when using Fenton reagent oxidation method in the waste water treating.An efficient gas diffusion electrode was prepared using 2-ethyl anthraquinone as electrocatalyst for synthesis of H₂O₂.The generator using the as-prepared gas diffusion electrode was undergoing 18 days intermittent operation with the current density of 750A/m² and 2 times of theoretical air flow rate.The average current efficiency of 83%was obtained.After that,a pilot scale waste water treating process was constructed containing a H₂O₂ electrochemical generator and a ferric-carbon micro-electrolysis device.In this pilot process,the Fenton's reagents were generated in situ.After thirty days continuous operation,the results showed that the quality of effluent was stability,and compared with the original treatment process,whether quality of the effluent or processing speed had been significantly improved,reaching the local sewer standard.The results indicated that the method for in situ generation of Fenton's reagent was an effective technical means for the pretreatment of the refractory organic wastewater,fully equipped with the practical possibility and broad application prospects.