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CAIE A-Level Chemistry AS 17.1.3 Reactions of Hydrogen Cyanide Questions

Practise CAIE 9701 HCN addition to aldehydes and ketones, drawing the CN− attack, tetrahedral intermediate, proton transfer and regenerated catalyst.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • draw CN− attacking the δ+ carbonyl carbon while the C=O electron pair moves to oxygen
  • show the tetrahedral O− intermediate with the new C–CN bond and all relevant charges
  • protonate O− using HCN and show regeneration of CN− as the catalyst

CAIE A-Level Chemistry AS 17.1.3 Reactions of Hydrogen Cyanide Questions question 1

[Maximum number: 3]

4(CH3)3CCHO4\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO} is used in the synthesis of some antibiotics.

X, Y and Z are all isomers of (CH3)3CCHO\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO}.

A summary of some of the reactions and properties of X, Y and Z is shown in the table.

Table for Question CAIE A-Level Chemistry AS 17.1.3 Reactions of Hydrogen Cyanide Questions question 1 — CAIE A-Level Chemistry AS

X contains a carbonyl group. X reacts with HCN , in the presence of a small amount of NaCN , to form (C2H5)2C(OH)CN\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{C}(\mathrm{OH}) \mathrm{CN} as shown.

X+HCN→(C2H5)2C(OH)CN\mathbf{X}+\mathrm{HCN} \rightarrow\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{C}(\mathrm{OH}) \mathrm{CN}

Draw the mechanism of the reaction of X with HCN .
- Draw the structure of X and the intermediate.
- Include all charges, partial charges, lone pairs and curly arrows.

Figure for Question CAIE A-Level Chemistry AS 17.1.3 Reactions of Hydrogen Cyanide Questions question 1 — CAIE A-Level Chemistry AS
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