Phenylalanine, $$$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{NH}_{2}\right) \mathrm{COOH}$$$, is an amino acid with an isoelectric point of 5.5. (i) State what is meant by isoelectric point. ....................................................................................................................................... . ................................................................................................................................. (ii) Draw the structure of $$$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{NH}_{2}\right) \mathrm{COOH}$$$ at pH 10 .

Chemistry

IGCSE&ALevel

CAIE

Exam No：9701_s24_qp_42 Year：2024 Question No：8(e)

Answer:

Knowledge points:

34.3.1.1 the reaction between ammonia and an acyl chloride at room temperature

34.3.1.2 the reaction between a primary amine and an acyl chloride at room temperature

34.3.2.1 hydrolysis with aqueous alkali or aqueous acid

34.3.2.2 the reduction of the CO group in amides with LiAl H4 to form an amine

34.3.3 state and explain why amides are much weaker bases than amines

34.4.1 describe the acid / base properties of amino acids and the formation of zwitterions, to include the isoelectric point

34.4.2 describe the formation of amide (peptide) bonds between amino acids to give di- and tripeptides

34.4.3 interpret and predict the results of electrophoresis on mixtures of amino acids and dipeptides at varying pHs (the assembling of the apparatus will not be tested)

Answer:

Knowledge points:

Solution:

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