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Amines

Amines. L.O: Explain basicity of amines. Preparation of aliphatic amines by substitution of halogenoalkanes. Preparation of aromatic amines by reduction of nitroarenes Synthesis of azo dyes by diazotisation and coupling. Amphetamine, phenylephrine and adrenaline are all amines.

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Amines

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  1. Amines L.O: Explain basicity of amines. Preparation of aliphatic amines by substitution of halogenoalkanes. Preparation of aromatic amines by reduction of nitroarenes Synthesis of azo dyes by diazotisation and coupling.

  2. Amphetamine, phenylephrine and adrenaline are all amines

  3. Ammonia and some common amines

  4. N-methyl propylamine The shortest alkyl contain one carbon atom connected to the N atom, so N-methyl is added as the prefix.

  5. N,N-diethylpropylamine

  6. The four kinds of amines Primary amine: only one carbon chain attached to the nitrogen. Secondary amine: nitrogen attached to 2 carbon chains

  7. Why are amines basic? Amines are weak bases. They are proton acceptors.

  8. Reaction of methylamine as a base

  9. Reaction of phenylamine and nitric acid

  10. Making primary aliphatic amines • Halogenoalkanes are gently warmed in a an alcohol solvent with excess ammonia. • The reaction proceeds by a nucleophilic substituion mechanism.

  11. Steps involved in making aliphatic amines • Step 1: Reacting ammonia with the halogenoalkane • Step 2: Removing halogen ions with excess ammonia

  12. Making a secondary amine • The lone pair of electrons on the N atom can still attack the δ+ carbon attached to the halogen on another halogenoalkane • Tertiary and quaternary amines are likewise also possible

  13. Qs

  14. Reduction of nitrobenzene to make phenylamine (aniline) Nitroarenes can be reduced using a mixture of Sn and concentrated HCl, heated under reflux, followed by neutralisation. [H] represents the reducing agent.

  15. azo dyes • Made in two steps: • Formation of diazonium ion • coupling

  16. 1) Diazotisation reaction Nitrous acid (HNO2) is made by reacting sodium nitrite (NaNO2) with excess HCl The phenylamine and nitrous acid are then mixed at temps below 10 °C

  17. Coupling Notice that the reaction conditions are alkaline!

  18. E110 is a yellow colouring agent that is commonly added to a variety of foods. E110 contains an azo dye made from an amine and a phenol. Describe how you would prepare a sample of an azo dye in the laboratory from an amine, a phenol and any other necessary reagents. Include in your answer •essential reagents and conditions for each stage •names of any functional groups formed during the process [7]

  19. 1st stagearomatic amine / named aromatic amine / structure (1)sodium nitrite / nitrous acid (1)HCl/H2SO4 (but not conc) /H+ (1)at <10°C (1) which forms a diazonium salt / ion (1) if more than four are given, mark any wrong reagents, conditions first 2nd stagethe product from the first stage mixed with the phenol (1)(in excess) hydroxide / alkali (1)

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