Research On Ultrasonic Preparation Of Grignard Reagent Of Pentaerythrityl Tetrabromide And The Design Method Of A Novel Expansion Monomer Spiro Tetra Acid Di-anhydride

During the curing process，thermosetting resins will inevitably happen volumeshrinkage, generally the curing shrinkage rate of epoxy resin is2%~5%. Huge volumeshrinkage defects will be taken in the use of the composite materials of epoxy resinbecause of this tiny shrinkage of volume. For example, volume shrinkage will reducethe fracture strength of materials based on epoxy resin, it will cause the materialsurface crack and even producing cracking,also it can make the size instablity ofepoxy resin as the electronic component substrate.Of course thisdisadvantage will bring the serious bad influence on the development of epoxyresin in practical application. In order to solve this kind of curing volume shrinkageproblem of epoxy resin, theoretically, adding a known as expansion compoundmonomer is the effective way to solve fundamentally.But so far, the expandingmonomer has been found is limited with bicyclic ortho ester, spiro orthoester, spiroorthocarbonate and the compounds with such similar structure.This paper started fromthe common materials pentaerythritol，adopating the method of ultrasonic to prepareGrignard reagent, then with the Grignard reagent,we designed pathway to preparespiro four formic acid anhydride.Theoretically,this polymer can overcome thedifficulties which existed in the application with expansion monomer, it may havebetter application value in epoxy resin matrix composites and epoxy resin pottingmaterials.The main research contents are as follows:(1)Pentaerythritol,benzene sulfonyl chloride, sodium bromide were used as rawmaterial to composite Pentaerythritylbromide by two step;and based on existingreports, we focuses on the optimal technological conditions of the synthesis ofpentaerythrityl tetrabromide,and there is a result showed us that when otherconditions are the same, the raw material feeding sequence play an important role onthe yield of the product and have important influence on purification.In theexperiment of synthesis of neopentyl bromide: reaction time20h, reactiontemperature150℃, dosage of catalytic agent PEG-600is5%, and the ratio of rawmaterials is1:6.2,the yield of pentaerythrityl tetrabromide is up to90.85%.(2)Study the principle of ultrasonic method to the synthesis of Grignard reagent.In the synthesis experiment of1,3-magnesium dibromide (magnesium methylic-2,2- methyl magnesium bromide) propane, ultrasonic method has been used to prepare theGrignard reagent firstly. This method has the advantages such as simple process, thecondition is mild,and Grignard reaction initiation period is shortened obviously,theyield of grignard product is increased.The process condition of Grignard reagent1,3-magnesium dibromide (magnesium methylic-2,2-methyl magnesium bromide is:reaction time1.5h, reaction temperature55℃, reactant ratio1:6, the yield of theproduct is up to79%.(3)Designed the process route by using Grignard reagent to synthsis spiro fourformic acid anhydride.Firstiy,we can take advantage of the Grignard reagent can reactwith CO2or dry ice to get multi atomic number of carbon compounds, it can considerthe Grignard reagent react with dry ice or carbon dioxide to prepare1,3-twocarboxyl-(2,2)-twoacetoxy propane.The reaction is simple, mild operationcondition.Then we can use1,3-two carboxyl-(2,2)-two acetoxy propane as rawmaterial,acetic acid as solvent, reacted with acetic anhydride to prepare the finalproduct spiro four formic acid anhydride.