Theoretical Studies On The External Electric Field Acted On The Hydroboration And Hydrosilylation Reactions Of The Unsaturated C-X(X = C/N/O)bonds

Recent literatures show that external electric field,as a new and green catalyst,can selectively catalyze chemical reactions and obtain different products.Hydroelementation reaction is a traditional and efficient method for the synthesis of organic compounds containing heteroatoms,for example,the hydroboration reactions and hydrosilylation reactions of unsaturated compounds is the direct method of producing boron-containing and silicon-containing compounds.Due largely to mostly of the organic reactions needing external catalysts to improve reaction efficiency or selectivity,the operations for the separation of corresponding products are bound to many problems of the extra economic cost and environmental pollution.Consequently,in present paper,the external electric field is introduced into the hydroboration and hydrosilylation reactions,which is expected to solve the above problems.The aim of this paper is to study the influences of external electric field on catalyzing the hydroboration and hydrosilylation reactions of unsaturated C-X（X = C/N/O）bonded compounds,with expecting to achieve green hydroelementation reaction on the basis of reducing the economic cost.This paper mainly contains four parts: the hydroboration reactions of olefins,the hydroboration reactions of imine and nitrile,the hydroboration reactions of carbonyl compounds,and the hydrosilylation reactions of alkenes and alkynes.1.Using the theoretical method,we studied the effects of external electric field on the hydroboration reactions of ethylene and propylene with borane,respectively.For the hydroboration reaction of nonpolar ethylene molecule,the external electric field changed the reaction barriers when it was oriented along the direction of C=C double bond.While for the hydroboration of polar propylene molecule,the external electric field not only changed the reaction barrier,but also made the Markovnikov addition to be the main reaction channel,that is the reaction selectivity was reversed.2.The hydroboration reactions of imines and nitriles were studied respectively under the action of external electric field in the level of theory.The calculated results demonstrated that the electric field along the direction of C=N double bond influenced the reaction barrier.What’s more,it changed the reaction selectivity,that is the hydroboration reaction of imine occurred according to the Markovnikov addition under the same direction of external electric field.The other directions of electric field generated a little effect on this reaction.For the hydroboration of benzonitrile,which containing the C≡N triple bond,the external electric field reduced the Markovnikov reaction barriers,but this reaction takes place by manner of anti-Markovnikov addition still.3.The effects of external electric field on the hydroboration reactions of benzaldehyde and benzophenone with pinacolborane were theoretically investigated,respectively.Even though the electric field lowered the reaction barriers of Markovnikov addition,these reactions occurred by way of anti-Markovnikov addition.Different directions of the external electric field induced different influences on the hydroboration reactions of carbonyl compounds,in which the directions oriented parallel and perpendicular to the bond axis of C=O bond had the largest effects on these reactions.4.The Markovnikov hydrosilylation reactions of alkenes and alkynes with phenylsilane were explored through the external electric field as their catalyst in the level of theory,respectively.The calculation results indicated that when the electric field were oriented along the direction of reaction axis,the barriers of hydrosilylation reactions were lowered largely.To be specific,the reaction barrier of hydrosilylation of styrene reduced by 22.9 kcal mol^-1when the field strength is up to 180(×10^-4)a.u.,while it lowered by 19.3 and 37.2 kcal mol^-1for the hydrosilylation of acetylene and phenylacetylene,respectively.This phenomenon revealed that the synergistic effect of external electric field and phenyl substitute of reactant played an important role in catalyzing hydrosilylation reactions of alkynes.