Transition Metal Compounds Catalyze The Hydration Reaction Of Alkynes

In organic synthesis,ketones are regarded as necessary industrial raw materials and versatile functional groups ideally suited for a variety of chemical manipulations.The large amount of ketones needed in industrial production or our daily life encourages people to pay close attention to the preparation of ketones.The addition of water to the alkynes is one of the most important methods for the synthesis of ketones.The 100%atom economy in this pocesses completely interprets the concept of sustainable development of green chemistry.Though large numbers of catalysts were developed for hydration of alkynes,they still suffer the disadvantages,such as environment-unfriendly,low activities,harsh reaction conditions and limited substrate scope.Therefore,development of environment friendly,effective catalyst system under mild reaction conditions for hydration of alkyne is still an important task both in academic and application areas.In this thesis,a Lewis/Bronsted acid system was developed for the hydration of phenylacetylene,after the screening of two constituents,ZnSO4·7H2O and TsOH were chose to be the best Lewis acid and Bronsted acid,respectively.With the optimized conditions,ZnSO4·7H2O(10 mol%),TsOH(20 mol%)were added to 1 mL methanol in a sealed tube,then heated up to 120 ? and stirred at refluxing for 18 h,the yield of acetophenone reached 93.5%.What is more,the Lewis/Bronsted acid system showed good reactivity in the research of different substrates.Possible mechanism was proposed based on the results of experiments and relevant literatures.The transition metal compounds were solely used as a catalyst without acid assistant in the addition of water to the alkynes,SnCl4·5H2O was shown the best catalytic performance.It exhibited excellent catalytic performance in various alkynes under the appropriate conditions(the amount of SnCl4·5H2O was 15 mol%?1 mL MeOH?120 ?,18 h).Then the probable mechanism was discussed.Aiming at developing reused catalyst system,heteropolyacid ionic liquids were prepared easily and used as a catalyst for the hydration of alkynes.The influence of different structures of ionic liquid on the catalytic performance was investigated and the[SO3H-Bmim]H2PW12O40 was found to be the most suitable catalyst.Under the optimized conditions,the amount of catalyst was reduced(2.5 mol%)and the reaction time was shorter(5 h),the yield of target product still be 92%.A slight decrease of the catalytic activity was observed after it was reused for 4 times.