EduNinja

[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.

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(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}

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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

CAIE A-Level Chemistry A2 34.1.2 Amide Formation From Amines Topic Practice

Question 1

Question (a)

Question (i)

Question (ii)