Chapter 15, Problem 20P

Suggest appropriate methods for preparing each of the following organometallic compounds from the starting material of your choice.

Interpretation Introduction

Interpretation:

The appropriate method of preparation for each of the given organometallic compounds is to be suggested.

Concept introduction:

The reaction of a metal with an organic halide is an oxidation–reduction in which the metal is the reducing agent.

lithium metal and magnesium metal in the presence of dry ether as a solvent, reacts with alkyl halides to produce the corresponding organo lithium and magnesium compounds respectively.

Organolithium reagents are used to prepare organometallic compounds analogous of terminal alkynes.

Organolithium compounds are strongly basic and react with terminal alkynes by abstracting the acidic proton and forming an alkane.

Answer to Problem 20P

Solution:

Explanation of Solution

Alkyl halides react with lithium metal in the presence of dry ether as a solvent to produce the corresponding organo lithium compound.

The product given is cyclopentyl lithium. Reaction of cyclopentyl bromide with lithium metal in the presence of diethyl ether as a solvent will produce this cyclopentyl lithium.

The reaction is shown below:

The product given is tert-butyl magnesium bromide. Tert-butyl bromide react with magnesium metal in the presence of diethyl ether as a solvent will produce this tert-butyl magnesium bromide.

The reaction is shown below:

Organolithium reagents are used to prepare organometallic compounds analogous of terminal alkynes.

Organolithium compounds are strongly basic and react with terminal alkynes by abstracting the acidic proton and forming an alkane.

Thus, phenyl acetylene reacts with an organo lithium reagent like butyl lithium to produce lithium phenylacetylide and butane.