Chapter 9, Problem 54P

(a)

Interpretation Introduction

Interpretation:

Synthesis of n-pentane from 1-Bromo propane should be shown.

Concept Introduction:

Target molecule is nothing but the desired product.

Terminal alkynes are unusual for simple hydrocarbons in that they can be deprotonated (pK_a = 26) using an appropriate base to generate a carbanion.

The acetylide carbanion is a good nucleophile and can undergo nucleophilic substitution reactions (usually ${\text{S}}_{\text{N}}\text{2}$ ) with 1^o or 2^o alkyl halides (Cl, Br or I) which can produce an internal alkyne.

3^o alkyl halides are more likely to undergo elimination.

One or both of the terminal H atoms in ethylene (acetylene) $\text{H-C}\equiv \text{C-H}$ can be susbtituted providing access to monosubstituted $\text{(H-C}\equiv \text{C-R)}$ and symmetrical ($\text{R = R'}$) or unsymmetrical (R not equal to R') disubstituted alkynes $\text{R-C}\equiv \text{C-R'}$

The product is also an alkyne; it can also undergo the other reactions.

(b)

Interpretation Introduction

Interpretation:

Synthesis of 2-pentanone from 1-Bromo propane should be shown.

Concept Introduction:

Target molecule is nothing but the desired product.

Terminal alkynes are unusual for simple hydrocarbons in that they can be deprotonated (pK_a = 26) using an appropriate base to generate a carbanion.

The acetylide carbanion is a good nucleophile and can undergo nucleophilic substitution reactions (usually ${\text{S}}_{\text{N}}\text{2}$ ) with 1^o or 2^o alkyl halides (Cl, Br or I) which can produce an internal alkyne.

3^o alkyl halides are more likely to undergo elimination.

One or both of the terminal H atoms in ethylene (acetylene) $\text{H-C}\equiv \text{C-H}$ can be susbtituted providing access to monosubstituted $\text{(H-C}\equiv \text{C-R)}$ and symmetrical ($\text{R = R'}$) or unsymmetrical (R not equal to R') disubstituted alkynes $\text{R-C}\equiv \text{C-R'}$

The product is also an alkyne; it can also undergo the other reactions.

(c)

Interpretation Introduction

Interpretation:

Synthesis of Pentanal from 1-Bromo propane should be shown.

Concept Introduction:

Target molecule is nothing but the desired product.

Terminal alkynes are unusual for simple hydrocarbons in that they can be deprotonated (pK_a = 26) using an appropriate base to generate a carbanion.

The acetylide carbanion is a good nucleophile and can undergo nucleophilic substitution reactions (usually ${\text{S}}_{\text{N}}\text{2}$ ) with 1^o or 2^o alkyl halides (Cl, Br or I) which can produce an internal alkyne.

3^o alkyl halides are more likely to undergo elimination.

One or both of the terminal H atoms in ethylene (acetylene) $\text{H-C}\equiv \text{C-H}$ can be susbtituted providing access to monosubstituted $\text{(H-C}\equiv \text{C-R)}$ and symmetrical ($\text{R = R'}$) or unsymmetrical (R not equal to R') disubstituted alkynes $\text{R-C}\equiv \text{C-R'}$

The product is also an alkyne; it can also undergo the other reactions.

(d)

Interpretation Introduction

Interpretation:

Synthesis of 1, 2-epoxypentane from 1-Bromo propane should be shown.

Concept Introduction:

Target molecule is nothing but the desired product.

Terminal alkynes are unusual for simple hydrocarbons in that they can be deprotonated (pK_a = 26) using an appropriate base to generate a carbanion.

The acetylide carbanion is a good nucleophile and can undergo nucleophilic substitution reactions (usually ${\text{S}}_{\text{N}}\text{2}$ ) with 1^o or 2^o alkyl halides (Cl, Br or I) which can produce an internal alkyne.

3^o alkyl halides are more likely to undergo elimination.

One or both of the terminal H atoms in ethylene (acetylene) $\text{H-C}\equiv \text{C-H}$ can be susbtituted providing access to monosubstituted $\text{(H-C}\equiv \text{C-R)}$ and symmetrical ($\text{R = R'}$) or unsymmetrical (R not equal to R') disubstituted alkynes $\text{R-C}\equiv \text{C-R'}$

The product is also an alkyne; it can also undergo the other reactions.