Organic Chemistry 2: Chapter 19

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Define: Umpolung Reaction

General idea of reversing a charge at a particular atom
Umpolung reactions are used to form bonds between ______ & _______
Give an example (it'll help)
- 2 atoms with a similar charge/ polarity
- Like 2 electron poor Carbon atoms
How is the synthesis of a Wittig Reagent an Umpolung reaction?
- In the Alkyl halide reactant, the carbon that is attached to the halogen is electron poor and by the end of the reaction, that same carbon is attached to Wittig reagent becomes electron rich.
- That charge partial(+) has been changed to a partial (-)
How is the synthesis of an organometallic reagent (from an alkyl halide) an Umpolung reagent
Ex) the formation of a grignard reagent

The electron poor carbon where the halogen (Br) is attached, bears a partial (+) charge as an alkyl bromide and after being attached to the metallic reagent bears a partial (-) charge
In a wittig reaction, the reagent used in step 1 is ________?

(C₆H₅)₃P
In a wittig reaction, the reagent used in step 2 is ________?

CH₂(CH₂)₃Li
What are the necessary reagent for Step 1.

KCN or HCN
What are the necessary reagent for Step 2?

Acidic water
What are the necessary reagent to transform a ketone/ Aldehyde to a cyanohydrin Step1 & Step2
- 1. HCN or NaCN (Cyanide anion)
- 2. H₃O⁺
What are the necessary reagent to transform a Keytone/ Aldehyde to a Cyanohydrin

A Cyanide anion ^-CN
What are the necessary reagent to transform a Keytone/ Aldehyde to an Alkene

Wittig Reagent: (C₆H₅)₃P & CH₂(CH₂)₃Li
What are the necessary reagent to transform a Keytone/ Aldehyde to a β-Hydroxy carbonyl

Enolate ion
What are the necessary reagent to transform an α, β Keytone/ Aldehyde to a β-Cyano ketone/ aldehyde

Cyanide ion
What are the necessary reagent to transform an α 1,5-Dicarbonyl?

Enolate ion

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Organic Chemistry 2: Chapter 19

Description

Reactions and their Reagents

Updated

2018-03-14T08:27:36Z