CIE A Level Chemistry

Revision Notes

Syllabus Edition

First teaching 2020

Last exams 2024

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3.4.1 Production of Alcohols

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Production of Alcohols

  • Alcohols are compounds that contain at least one hydroxy (-OH) group
  • The general formula of alcohols is CnH2n+1OH
  • Alcohols can be prepared by a wide range of chemical reactions

Electrophilic addition of alkenes

  • When hot steam is reacted with an alkene, using concentrated phosphoric(VI) acid (H3PO4)as a catalyst, electrophilic addition takes place to form an alcohol

 

Hydroxy Compounds Electrophilic Addition, downloadable AS & A Level Chemistry revision notes

Electrophilic addition of steam to alkenes to form an alcohol

Oxidation of alkenes

  • Cold, dilute KMnO4 is a mild oxidising agent and oxidises alkenes
  • The C-C double bond is not fully broken and a diol is formed
    • A diol is a compound with two hydroxy, -OH, groups

 

Hydroxy Compounds Oxidation, downloadable AS & A Level Chemistry revision notes

Oxidation of alkenes using cold, dilute KMnO4 to form a diol

Nucleophilic substitution of halogenoalkanes

  • The halide atom in halogenoalkanes can be substituted when heated with aqueous NaOH in a nucleophilic substitution reaction

 Hydroxy Compounds Nucleophilic Substitution, downloadable AS & A Level Chemistry revision notes

Nucleophilic substitution of halogenoalkanes using NaOH to form an alcohol

Reduction of aldehyde & ketones

  • Aldehydes and ketones can be reduced by reducing agents such as NaBH4 or LiAlH4 
  • Aldehydes are reduced to primary alcohols
    • The carbon attached to the hydroxy group is bonded to one other alkyl group

  • Ketones are reduced to secondary alcohols
    • The carbon attached to the hydroxy group is bonded to two other alkyl groups

 Hydroxy Compounds Reduction, downloadable AS & A Level Chemistry revision notes

Reduction of aldehydes and ketones to form primary and secondary alcohols

Reduction of carboxylic acids

  • Similarly, carboxylic acids are reduced by NaBH4 or LiAlH4 to primary alcohols

 

copy-of-3-4-hydroxy-compounds-reduction-2-new

Reduction of carboxylic acids to primary alcohols

Hydrolysis of ester

  • Esters are made by a condensation reaction between an alcohol and a carboxylic acid
  • When an ester is heated with dilute acid or alkali, hydrolysis will take place and the carboxylic acid and alcohol will be reformed

 

Hydroxy Compounds Hydrolysis, downloadable AS & A Level Chemistry revision notes

Hydrolysis of esters to form alcohols

Alcohol production reactions table

3-4-hydroxy-compounds-table-1-production-of-alcohols-new

Exam Tip

The symbol [O] is used to represent oxygen provided by an oxidising agent.

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Fran studied for a BSc in Chemistry with Forensic Science, and since graduating taught A level Chemistry in the UK for over 11 years. She studied for an MBA in Senior Leadership, and has held a number of roles during her time in Education, including Head of Chemistry, Head of Science and most recently as an Assistant Headteacher. In this role, she used her passion for education to drive improvement and success for staff and students across a number of subjects in addition to Science, supporting them to achieve their full potential. Fran has co-written Science textbooks, delivered CPD for teachers, and worked as an examiner for a number of UK exam boards.