Synthesis And Characterization Of Organosilicon Grignard Reagent And Hydroxylpropyl Disiloxane

Compared with carbon atoms,silicon atoms have more uniqueness than similarity.Carbon Grignard reagent is a crucial intermediate in organic chemistry,moreover there are scarcely any reports of silicon magnesium bonds among the silicon metallic bonds.Hence,we proposed the research idea of preparation of Organosilicon Grignard reagents.We prepared four kinds of Organosilicon Grignard reagents with different alkyl groups,including trimethylsilyl magnesium chloride,dimethylphenylsilyl magnesium chloride,methyldiphenylsilyl magnesium chloride and triphenylsilyl magnesium chloride,using magnesium chips and chlorosilane as reactants,hexamethylphosphoramide(HMPA)as solvent.In the meantime,we investigated the effects on the yield of the products under different conditions.We not only got the best reaction temperature,reactant ratio,catalyst of each reaction,but performed 1H NMR,29Si NMR for each product.We found the colorless transparent acicular crystal in the Organosilicon Grignard reagents,which was gradually cooled through a certain way.The crystal structure was obtained by testing and we found the formula of the complex to be MgCl2·2HMPA.We speculate from the crystal that the Schlenk equilibrium also exists in the Organosilicon Grignard reagent,which is present in the Carbon Grignard reagent.Hydroxyalkyl disiloxane plays an increasing role in synthesizing silicone-modified polyurethane materials and silicone-modified polyurea materials.1,3-bis(?-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane is one of the most useful blocking agents.The main preparation methods of the blocking agent are hydrosilylation and organometallic synthesis.Hydroxyl protection is needed in the hydrosilylation,however,which makes the reaction process cumbersome.Organometallic synthesis is not suitable for industrial production because of high operation requirement.Much to our delight,we found a new way to prepare 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane.We designed the route of 2-propenyl acetate to react with dimethylchlorosilane.Carbon functional silylcarboxlates,which is made after hydrosilylation,are hydrolyzed under condition of acid,and then the product,1,3-bis(?-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane can easily be obtained by simple purification.This route makes the steps simple and easy to operate and few side reactions took place,product is of high yield and high purity as well.