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Basic concepts of organic chemistry

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Question 1

(a) Thiols and dithiols are sulfur-containing organic compounds widely studied for their reactivity, which mimics that of alcohols but with distinct chemical properties due to the lower electronegativity of sulfur.

a.

Benzenethiol (C6H5SH\text{C}_6\text{H}_5\text{SH}C6​H5​SH) behaves as a weak acid in aqueous solution. Write the expression for the acid dissociation constant, KaK_{\text{a}}Ka​, for benzenethiol.

[1]
b.

Thiols react with carboxylic acids in a condensation reaction to form thioesters. Write a balanced chemical equation for the reaction between ethane-1-thiol and butanoic acid (CH3CH2CH2COOH\text{CH}_3\text{CH}_2\text{CH}_2\text{COOH}CH3​CH2​CH2​COOH). Use structures for all organic compounds with their functional groups clearly displayed.

[2]
c.

Draw the skeletal formula for 3-methylbut-2-ene-1-thiol.

[1]
d.

Propane-1,3-dithiol (HSCH2CH2CH2SH\text{HSCH}_2\text{CH}_2\text{CH}_2\text{SH}HSCH2​CH2​CH2​SH) reacts with carbonyl compounds to form a cyclic thioacetal in a condensation reaction. Write a balanced chemical equation for the reaction of propane-1,3-dithiol with propanone (CH3COCH3\text{CH}_3\text{COCH}_3CH3​COCH3​). Use structures for all organic compounds.

[2]
Markscheme

Basic concepts of organic chemistry Questions

  1. A Level
  2. /Chemistry
  3. /Basic concepts of organic chemistry

18 exam-style questions on OCR A A Level Chemistry Basic concepts of organic chemistry. Each one has a worked solution and a mark scheme showing where the marks go.

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