Chapter 9.SE, Problem 42AP

Interpretation Introduction

a)

Interpretation:

How to synthesize 1-pentyne from acetylene using any alkyl halide with four or fewer number of carbons is to be shown.

Concept introduction:

Terminal alkynes can be converted into their acetylides by treating with NaNH₃ in liquid NH₃. The acetylides when treated with alkyl halides with the required number of carbons yield the higher alkyne needed.

To state:

How to synthesize 1-pentyne from acetylene using any alkyl halide with four or fewer number of carbons.

Interpretation Introduction

b)

Interpretation:

How to synthesize 3-hexyne from acetylene using any alkyl halide with four or fewer number of carbons is to be shown.

Concept introduction:

Terminal alkynes can be converted into their alkynides by treating with NaNH₃ in liquid NH₃. The alkynides when treated with alkyl halides with the required number of carbons yield the higher alkyne needed. Acetylene has two acidic hydrogens. Both hydrogens can be replaced by alkyl groups through this process.

To state:

How to synthesize 3-hexyne from acetylene using any alkyl halide with four or fewer number of carbons.

Interpretation Introduction

c)

Interpretation:

How to synthesize 4-methyl-1-pentene from acetylene using any alkyl halide with four or fewer number of carbons is to be shown.

Concept introduction:

Terminal alkynes can be converted into their alkynides by treating with NaNH₃ in liquid NH₃. The alkynides when treated with alkyl halides with the required number of carbons yield the higher alkyne needed. The alkyne can be reduced to the corresponding alkene by reduction with H₃ in the presence of Lindlar catalyst or by using Li in liquid ammonia.

To state:

How to synthesize 4-methyl-1-pentene from acetylene using any alkyl halide with four or fewer number of carbons.

Interpretation Introduction

d)

Interpretation:

How to synthesize 4-octanone from acetylene using any alkyl halide with four or fewer number of carbons is to be shown.

Concept introduction:

Terminal alkynes can be converted into their alkynides by treating with NaNH₃ in liquid NH₃. The alkynides when treated with alkyl halides with the required number of carbons yield the higher alkyne needed. The alkyne undergoes hydration when treated with dilute H₃SO₄ in the presence of HgSO₄ to yield an enol which tautomerizes to a ketone.

To state:

How to synthesize 4-octanone from acetylene using any alkyl halide with four or fewer number of carbons.

Interpretation Introduction

e)

Interpretation:

How to synthesize hexanal from acetylene using any alkyl halide with four or fewer number of carbons is to be shown.

Concept introduction:

Terminal alkynes can be converted into their alkynides by treating with NaNH₃ in liquid NH₃. The alkynides when treated with alkyl halides with the required number of carbons yield the higher alkynes needed. The alkynes yield enols with OH on terminal carbon in hydroboration-oxidation reaction which tautomerize to yield aldehydes.

To state:

How to synthesize hexanal from acetylene using any alkyl halide with four or fewer number of carbons.