Electrocatalytic Carboxylation Of Aliphatic Ketene In The Presence Of Carbon Dioxide

In order to protect our environment and take the stainable development as our goal, green chemistry has been proposed to reduce and prevent pollutionat its cource. Therefore green chemistry is also called environmental friendly chemistry and sustainable chemistry.The basic principle of green chemistry is to maximize atom economy, which is to design synthetic methods to maximize the incorporation of all materials used in the process into the final product. Comparing with the traditional organic chemistry, electron has been used as the reagent in the electroorganic synthesis avoiding the use of other toxic reagents. Besides, acquire pure products with highly selectivity could be abtained by electrochemical synthesis, which is advantage to the industry.Carbon dioxide is the largest contributor to the green house effect, and has certain pollution to the environment. Fixing CO2 through electroorganic synthesis and getting corresponding carboxylated products are very meaningfull.Electrocarboxylation of unsaturated orgnic compounds is proceeding with galvanostatic electrolysis. From electrocarboxylation of aliphatic ketene, we find that C=C bond is more liable to react with CO2 than C=O.There are three parts about the experiments in the paper. The details are given as follows: Firstly:Electrocarboxylation of 2-cyclohexen-lone and 3-methyl-2-cyclohexen-1-one were carried out in an undivided cell in the N,N-dimethylformamide(DMF) by galvanostatic electrolysis. The influence of reaction conditions, such as the electrode materials, the supporting electrolytes, the current densities, the quantity of electric charge, temperature, has been investigated. Under the optimized condition, the largest yields of electrocarboxylation of 2-cyclohexen-l-one and 3-methyl-2-cyclohexen-l-one are 36% and 20.5% respectively. The electrochemical reduction behaviours of 2-cyclohexen-l-one and 3-methyl-2-cyclohexen-l-one are studied by cyclic voltammetry on the glass carbon electrode and other different metal electrodes. Finally the mechanisms of electrocarboxylation of 2-cyclohexen-l-one and 3-methyl-2-cyclohexen-l-one were presumed according to the experiments. Secondly:Electrocarboxylation of methyl crotonate was carried out in an undivided cell in the acetonitrile at room temperature and under normal pressure by galvanostatic electrolysis. The yield of elecarboxylated products was influenced by the working electrodes, supporting electrolytes, the current densities, the quantity of electric charge and the temperature. The highest yield is 71.6%. The electrochemical reduction behavior of methyl crotonate on different electrodes was studied by cyclic voltammetry. At last, the mechanism of the electrocarboxylation of methyl crotonate was proposed on the basis of the experiment.Finally:Electrocarboxylation of 2-cyclopent enone and 3-methyl-2-cyclopent enone were carried out in an undivided cellby galvanostatic electrolysis. Also some key factors that influence the experiment were investigated, such as solvent, the electrode materials, the supporting electrolytes, the current densities, the quantity of electric charge, temperature. Under the optimized condition, the largest yields of electrocarboxylation of 2-cyclopent enone and 3-methyl-2-cyclopent are 43.2% and 39.6% respectively. The electrochemical reduction behaviours of 2-cyclopent enone and 3-methyl-2-cyclopent enone were studied by cyclic voltammetry on the glass carbon electrode and other different metal electrodes. Finally the mechanisms of electrocarboxylation of 2-cyclopent enone and 3-methyl-2-cyclopent were pursumed according to the results of experiments.