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Alcohols and Ethers

Alcohols and Ethers. AH Chemistry Unit 3(b). Alcohols. Physical properties. When comparing the boiling point of ethanol with an alkane, which alkane would you compare it with? Which would have the higher boiling point? Why?. Alcohols exhibit hydrogen bonding .

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Alcohols and Ethers

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  1. Alcohols and Ethers AH Chemistry Unit 3(b)

  2. Alcohols

  3. Physical properties • When comparing the boiling point of ethanol with an alkane, which alkane would you compare it with? • Which would have the higher boiling point? • Why?

  4. Alcohols exhibit hydrogen bonding. • As a result, they exhibit higher boiling points than (most) other organic compounds of similar molecular mass.

  5. Which is more soluble in water: ethanol or hexan-1-ol? • Why?

  6. The lower alcohols are miscible with water but as their chain length increases their solubility in water decreases.

  7. Preparation of alcohols • There are 2 principle methods for producing alcohols in industry. What are they? • Acid-catalysed hydration of alkenes (electrophilic addition) • Nucleophilic substitution of halogenoalkanes

  8. Reactions of alcohols • With metals • produces alkoxides • Dehydration • produces alkenes • With carboxylic acids • produces esters, slowly • With acid chlorides • produces esters, more vigorously

  9. Acid chlorides

  10. Carboxylic acids can be converted into acid chlorides by reaction with: • Thionyl chloride • Phosphorus(III) chloride • Phosphorus(v) chloride

  11. Producing esters • Use full structural formulae to illustrate how ethyl propanoate can be produced from an alcohol and an acid chloride. • What type of reaction is this?

  12. Ethers

  13. General formula

  14. Uses • Solvents • Reasons: • Dissolve many organic compounds • Volatile (so removed easily by distillation)

  15. Preparation of ethers • Q:How can you prepare an ether in the lab? • A:Reaction of a halogenoalkane with a metal alkoxide. • Q: What type of reaction is this? • A:Nucleophilic substitution

  16. Naming ethers Methoxyethane Methoxymethane Ethoxypropane

  17. Naming Ethers • Name the longest continuous chain e.g. pentane • Name the alkoxy group by removing “yl” from the substituent name and adding “oxy” e.g. propyl becomes propoxy • Add the appropriate number in front of the substituent if the ether is branched e.g. 3

  18. Name a halogenoalkane and metal alkoxide combination you could use to prepare ethoxybutane. • Name a halogenoalkane and metal alkoxide combination you could use to prepare 2-ethoxybutane. • Name the ether produced by reacting 1-chloropropane with sodium ethoxide.

  19. Physical properties – mp / bp • How do the melting and boiling points of ethers compare to alcohols? • Why?

  20. Physical properties - solubility • Why are ethers of low molecular mass soluble in water?

  21. Chemical properties • Flammable • Form peroxides on exposure to air / light (these are unstable and explosive) e.g. ethoxyethane peroxide

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