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Study on the Environmentally Friendly Reactions of Organozinc Halides with Carbonyl Compounds

Author: ZhangYuMei
Tutor: WangJinXian
School: Northwest Normal University
Course: Polymer Chemistry and Physics
Keywords: Reaction Supported catalysts Microwave radiation Cinnamaldehyde Zinc bromide Alkenyl Polymer carrier Chloromethyl polystyrene Solvent-free Functional groups
CLC: O621.25
Type: PhD thesis
Year: 2005
Downloads: 256
Quote: 2
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Abstract


Organozincs are an important class of organometallics for the formation of C-C bonds. A variety of functional groups may be tolerated in these organometallic reagents because of their moderate reactivity. But, just for their low reactivity ,the application of organozinc reagent in organic synthesis have been limited for a long time. Many methods have been developed to active organozinc. Such as transition metal catalysts ,especially those containg Cu,Pd and Ni has converted otherwise unreactive or sluggishly reactive organozincs into higherly reactive reagents .Herein we use polymer-supported palladium( Ⅱ ) catalyst, microwave irradiation ,and solvent-free to improve the reaction of organozincs and carbonyl compounds. Under microwave irradiation or solent-free conditions, organozincs rapidly reacted with carbonyl compounds to give second alcohol in the absent of TMSCL and polymer-supported palladium(Ⅱ) catalyst , while cabonyl olefmation products were synthesized in the presence of TMSCL and polymer-supported palladium( Ⅱ) catalyst.This thesis including three chapters:Chapter one: Transition metal Pd catalyzed organic reactionsWe review herein the progress of organic reaction in microwave-assisted homogeneous palladium catalysis in the liquid phase and heterogeneous polymer-supported palladium catalysis.Chapter two: Study on the olefination of functionalized benzylzinc halides with cinnamic aldehyde under polymer-supported palladium catalysis.In this section, the polymer-supported palladium( Ⅱ ) is prepared under ultrasound. The preparation of polymer-supported catalyst using ultrasound is direct, rapid, and highly efficient. A comparative study shows that this catalyst is as efficient as PdCl2(PPh3)2 .The polymeric catalyst can be easily separated from a reaction mixture and reused more than 5 times with no decrease in activity.polymer-supported palladium( Ⅱ) was applied in the reaction of the olefination of benzylzinc halides with cinnamic aldehyde in the present of TMSCL undermicrowave irradiation.The experimental results showed that this reaction proceeded effectively and rapidly. The catalyst can be recovered from the reaction mixture by simple filtration and reused in the next reaction.The elimination of volatile organic solvents in organic synthesis is a most important goal in "green" chemistry. Solvent-free polymer-supported palladium( Ⅱ) catalyzed the olefination of benzylzinc halides with cinnamic aldehyde was more milder, simpler, save energy and prevent solvent waste.Chapter three: The addition reaction of organozinc and aldehydes without any catalysts.In this section, we investigated the 1,2-addition reaction of organozincs and aldehyde under MW or solvent-free conditions.Under microwave irradiation, allylzinc reacted with all kinds of aldehyde in THF to give alcohols without any catalyst ; while other inactive organozinc, such as benzylzinc, alkylzinc, and propargyl did not react with aldehyde very well.The reactivity of organozincs could be enhanced dramatically after solvent was evaporated , allylzinc and benzylzinc can react with aldehyde to give second alcohols at room temperature in 10 min without any catalyst. The yield and selectivity was high, and the reaction need not any catalyst.

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CLC: > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Organic Chemistry general issues > Properties of organic compounds > Chemical properties of organic reactions
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