Organic Chemistry: Halogenoalkanes (Edexcel International AS Chemistry): Exam Questions

Ammonia reacts with 1‐chlorobutane.

State the type and mechanism of this reaction.

A student drew the first step of the mechanism for the reaction.

i) Identify two omissions in the student’s mechanism.

(2)

ii) To obtain butylamine, sodium hydroxide solution is added. Complete the next step of the mechanism to form butylamine, showing curly arrows, relevant lone pairs and the reaction products.

(3)

The reactions of ammonia and of hydroxide ions with halogenoalkanes are similar.

Compare the rate of reaction of ammonia with 1‐chlorobutane and with 2‐bromo‐2‐methylpropane. Justify your answer.

This question is about halogenoalkanes.

The rates of hydrolysis of 1-chloropropane, 1-bromopropane and 1-iodopropane in reactions with aqueous silver nitrate solution were compared.

i) State what would be measured in the experiment to compare the rates of hydrolysis.

(1)

ii) State which of these halogenoalkanes would hydrolyse the fastest. Justify your answer.

(2)

The equation for the hydrolysis of 1-chloropropane by aqueous hydroxide ions is shown.

CH₃CH₂CH₂Cl + OH⁻ → CH₃CH₂CH₂OH + Cl⁻

Give the mechanism for this hydrolysis. Include curly arrows, and relevant dipoles and lone pairs.

The boiling temperatures of some halogenoalkanes are shown.

Explain the trend in boiling temperature of these halogenoalkanes by comparing the intermolecular forces involved.

Detailed explanations of the forces involved are not required.

In another experiment, 2-bromobutane is heated with ethanolic potassium hydroxide and an elimination reaction occurs.

Draw the skeletal formulae of the three possible organic products, giving their names.

The compound DMAA was originally synthesised as a decongestant.

A suggested synthetic route for DMAA is shown.

i) Give the systematic name of compound A.

(1)

ii)  Identify, by name or formula, a suitable reagent for Step 1.

(1)

iii) Give the mechanism for the reaction in Step 2.

Include curly arrows, and any relevant dipoles and lone pairs.

(4)

DMAA is only slightly soluble in water but dissolves readily in hydrochloric acid to form an aqueous solution.

i) Explain the type of bonding that occurs between the nitrogen atom and the hydrogen ion, when the positive ion forms.

(3)

ii) Complete the diagrams to show how the ions formed in the reaction between DMAA and hydrochloric acid interact with water molecules.

(3)