6.7 Extending Carbon Chains

Propylamine, shown in Figure 1, can be synthesised from ethene.

Figure 1

A student suggests that ethene should be reacted with hydrogen cyanide to produce propylamine.

Figure 2 shows the outline of a reaction scheme to convert ethene into propylamine.

Figure 2

Ethene  Compound A  Compound B  Propylamine

Identify which step of the reaction scheme could use the student’s suggestion of hydrogen cyanide. Justify your answer.

Draw the skeletal structure of compound A, from part a), and state the reagents required for its formation.

The final step of the reaction scheme will form the desired amine.

Benzene undergoes a substitution reaction to form compounds X and Y. This is shown in Figure 1.

Figure 1

State the formulas of the reagents required for reaction 1.

Using curly arrows, describe the mechanism which will generate the electrophile.

Using curly arrows, describe the mechanism for the formation of compound Y. In your answer show how AlCl₃ is regenerated. 

State the type of reaction that occurs in both reactions in part a).

Lactic acid, CH₃CH(OH)COOH, can be formed from compound X in three steps as shown below.

Compound X  Ethanal  Compound Y  Lactic acid

Compound X undergoes oxidation to form ethanal. 

Using curly arrows, describe the mechanism for step 2.

State the reagents required for step 3.

Propanal reacts with potassium cyanide, followed by dilute acid, to form the hydroxynitrile CH₃CH₂CH(OH)CN.

Give the IUPAC name of CH₃CH₂CH(OH)CN. 

Name the mechanism for the reaction between potassium cyanide and propanal.

Propanone undergoes the same reaction with HCN as propanal to form a hydroxynitrile.

Outline the mechanism for the reaction.

Suggest why carbonyl compounds are likely to undergo nucleophilic attack. 

Benzene is a useful in the production of pharmaceuticals, however due to the stability of the benzene ring it is fairly unreactive with electrophiles. Instead stronger electrophiles can be made by using a halogen carrier such as aluminium chloride, AlCl₃ with ethanoyl chloride. 

Give an equation to show the generation of an electrophile using aluminium chloride.

Outline the mechanism for the reaction of the electrophile with benzene to produce 1-phenylethanone.

Outline the mechanism for the reaction of the ethanoyl chloride with the catalyst to form the acylium ion needed for electrophilic substitution.

Aluminium chloride is used as the catalyst in the reaction between benzene and ethanoyl chloride. Explain how the catalyst reforms.

A reaction pathway to produce a carboxylate salt, Compound M, which contains three carbon atoms is shown below.

Bromoethane → Compound L → Compound M

Give the correct reagents to form compound L from bromoethane.

Name and outline the mechanism for the formation of Compound L from bromoethane.

State the reagents required for the formation of Compound M from Compound L and give an equation for the reaction.

A chemist reacted Compound L with hydrogen gas in the presence of a nickel catalyst. Name and draw the structure of the compound produced.