CAIE A-Level Chemistry 34.1 Primary and Secondary Amines

Practise amine synthesis, acylation and basicity using reagents, product structures and nitrogen lone pairs.

Exam points

select halogenoalkane substitution or nitrile/amide reduction routes to a target primary or secondary amine
draw the N-substituted amide formed when an amine attacks an acyl chloride
explain basicity by proton acceptance at the nitrogen lone pair and compare alkyl electron-donating effects

Covered syllabus points

34.1.1—Preparation of primary and secondary amines 34.1.2—Amide formation from amines 34.1.3—Basicity of aq. solutions of amines

[Maximum number: 2]

Phenylamine, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}$ , and propylamine, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$ , can be produced by different reduction reactions.

Identify an organic compound that can be converted into $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$ by a reduction reaction. State the reagent for this reaction.
organic compound
reagent

M1: propylamide / propenamide / $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{CONH}_{2} \mathrm{OR}$ propanenitrile / $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{CN}$

M2: $\mathrm{LiAlH}_{4}$

[Maximum number: 3]

Asparagine and aspartic acid are two naturally occurring amino acids. Their structures and isoelectric points are shown in Table 8.1.

Table 8.1

(a)

Propanedioic acid, $\mathrm{HOOCCH}_{2} \mathrm{COOH}$ , is treated with an excess of thionyl chloride, $\mathrm{SOCl}_{2}$ . Propanedioyl chloride, $\mathrm{ClOCCH}_{2} \mathrm{COCl}$ , is formed.

[ 3 ]

(i)

Write an equation for this reaction.

[ 1 ]

$\mathrm{HOOCCH}_{2} \mathrm{COOH}+2 \mathrm{SOCl}_{2} \rightarrow \mathrm{ClOCCH}_{2} \mathrm{COCl}+2 \mathrm{SO}_{2}+2 \mathrm{HCl}$

(ii)

Propanedioyl chloride reacts with an excess of asparagine to form compound G with molecular formula $\mathrm{C}_{11} \mathrm{H}_{16} \mathrm{~N}_{4} \mathrm{O}_{8}$ .

Each molecule of compound G has four amide groups.
Draw the structure of compound G.

\text { Compound G, } \mathrm{C}_{11} \mathrm{H}_{16} \mathrm{~N}_{4} \mathrm{O}_{8}

[ 2 ]

Figure for Answer to Question (ii) — CAIE A-Level Chemistry A2

$\mathrm{HOOCCH}\left(\mathrm{CH}_{2} \mathrm{CONH}_{2}\right) \mathrm{NHCOCH}_{2} \mathrm{CONHCH}\left(\mathrm{CH}_{2} \mathrm{CONH}_{2}\right) \mathrm{COOH}$

M1: three molecules joined, with four correct amide groups only

M2: whole structure correct as above, displayed formula accepted, skeletal formula as below accepted

[Maximum number: 3]

Copper is a transition element and has atomic number 29.

(a)

Ethane-1,2-diamine is a useful reagent in organic chemistry.

[ 3 ]

(i)

Explain how the amino groups in ethane-1,2-diamine allow the molecule to act as a Brønsted-Lowry base.

[ 2 ]

(ii)

Write an equation for the reaction of ethane-1,2-diamine with an excess of hydrochloric acid.

[ 1 ]

$\ce{H2NCH2CH2NH2 + 2HCl -> ClH3NCH2CH2NH3Cl}$

OR $\ce{H2NCH2CH2NH2 + 2H+ -> H3N+CH2CH2N+H3}$

1

All question bank results loaded

Covered syllabus points

34.1 Primary and secondary amines question 1

34.1 Primary and secondary amines question 2

Question (a)

Question (i)

Question (ii)

34.1 Primary and secondary amines question 3

Question (a)

Question (i)

Question (ii)