A mechanism for the given reaction (sulphur ylides react with ketone to give epoxides ) has to be suggested. Concept introduction: The functional group in the aldehydes and Ketones are carbonyl group. Electrophile: It is positively charged species which seeks for negative charge and hence accepts pair of electrons from negatively charged species (Nucleophiles) which results in the formation of chemical bond ’ Nucleophile: It is negatively charged species which seeks for positive charge and hence donate pair of electrons to positively charged species (electrophiles) which results in the formation of chemical bond. Mechanism of the reaction is the step-by-step description of the process by which reactants are changed into products. Curved arrows show the bonds that are formed and the bonds that are broken in a reaction. Curved arrows used to understand a reaction mechanism. Curved arrows are drawn to show how the electrons move as new covalent bonds are formed existing covalent bonds are broken. Wittig reaction is a reaction in which a nucleophilic elimination occurs after nucleophilic addition reaction. In this reaction an aldehyde or ketone reacts with a triphenyl phosphonium ylide (Wittig reagent) to give an alkene and triphenylphosphine oxide. The reaction can be represented as shown below, Mechanism:

Question

Show how alkylation and acylation of enamines and lithium enolates are usedsynthetically. Give mechanisms for these reactions.

Answer 1

Question

Chapter 16, Problem 16.27P

Interpretation Introduction

Interpretation:

A mechanism for the given reaction (sulphur ylides react with ketone to give epoxides) has to be suggested.

Concept introduction:

The functional group in the aldehydes and Ketones are carbonyl group.

Electrophile: It is positively charged species which seeks for negative charge and hence accepts pair of electrons from negatively charged species (Nucleophiles) which results in the formation of chemical bond’

Nucleophile: It is negatively charged species which seeks for positive charge and hence donate pair of electrons to positively charged species (electrophiles) which results in the formation of chemical bond.

Mechanism of the reaction is the step-by-step description of the process by which reactants are changed into products.

Curved arrows show the bonds that are formed and the bonds that are broken in a reaction.

Curved arrows used to understand a reaction mechanism.

Curved arrows are drawn to show how the electrons move as new covalent bonds are formed existing covalent bonds are broken.

Wittig reaction is a reaction in which a nucleophilic elimination occurs after nucleophilic addition reaction. In this reaction an aldehyde or ketone reacts with a triphenyl phosphonium ylide (Wittig reagent) to give an alkene and triphenylphosphine oxide.

The reaction can be represented as shown below,

Mechanism:

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