amines
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Substance Reagent ObservationPrimary alcohol
Cr2O72-
Secondary alcohol
Cr2O72-
Tertiary alcohol
Cr2O72-
Ketone Cr2O72-
Aldehydes Cr2O72-
Acids Cr2O72-
AminesAmines
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
Ammonia and some common amines
N-methyl propylamine
The shortest alkyl contain one carbon atom connected to the N atom, so N-methyl is added as the prefix.
N,N-diethylpropylamine
The four kinds of amines
Primary amine: only one carbon chain attached to the nitrogen.
Secondary amine: nitrogen attached to 2 carbon chains
Why are amines basic?
Amines are weak bases. They are proton acceptors.
Reaction of methylamine as a base
Reaction of phenylamine and nitric acid
Making primary aliphatic amines
• Halogenoalkanes are gently warmed in a an alcohol solvent with excess ammonia.
• The reaction proceeds by a nucleophilic substituion mechanism.
Steps involved in making aliphatic amines
• Step 1: Reacting ammonia with the halogenoalkane
• Step 2: Removing halogen ions with excess ammonia
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
Qs
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.
azo dyes
Made in two steps:1)Formation of diazonium ion2)coupling
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
Coupling
Notice that the reaction conditions are alkaline!
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]
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)