炫酷化学动画做化学的你值得拥有.pptx

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1、第1页/共15页What are the building blocks?第2页/共15页sp2 orbitalsp orbitals bondsp3 orbitals hydrogens第3页/共15页 hydrogens hydrogensSites for Sites for nucleophilic nucleophilic attacksattacksHigh Electronegativity of Oxygen第4页/共15页Resonance Energy“Stabilization energy”第5页/共15页Ethyl propanoateFormation of the

2、 enolate Condensationwith ethyl benzoate to form-keto esterEt-O-C-CH2 CH3 O|Loss of 2nd alpha hydrogen on-keto esterEt-O-C-CH CH3 O|-第6页/共15页Ethyl Propanoate0.04pKa of alpha hydrogens 24 or Ka 10-24第7页/共15页Bond Angles120osp2 orbitals109.5osp3 orbitals180osp orbitals90op orbitals第8页/共15页Overview of t

3、he Claisen Condensation ReactionEthyl PropanoateEthoxide ionEthyl Benzoate1.Ethoxide ion acting as a strong base deprotonates ethyl propanoate.2.The enolate of ethyl propanoate is formed.3.The enolate of ethyl propanoate is a strong nucleophile that attacks the partially positive carbon of the carbo

4、nyl group on ethyl benzoate.4.The alpha substitution makes this a carbonyl condensation reaction.5.A-keto ester is formed.+6.The driving force for this reaction is the transfer of the second alpha hydrogen to the ethoxide ion.This is exothermic.第9页/共15页Deprotonation of Ethyl PropanoateResonanceThe e

5、nolate ion is a strong nucleophile and will attack the partially positive carbon of a carbonyl group.+Ethyl PropanoateEthyl PropanoateEthyl BenzoateEnolate ofEnolate of第10页/共15页Self condensation of ethyl propanoate第11页/共15页第12页/共15页第13页/共15页Rainer Ludwig Claisen(1851-1930)Developed the“Claisen Condensation”in 1887第14页/共15页感谢您的观看！第15页/共15页