3.7.1

Nature & Preparation of Amines

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Nature of Amines

Amines are organic compounds that contain nitrogen. They can be thought of as alkylated forms of ammonia (e.g. NRH2). You can have both aliphatic and aromatic amines.

Illustrative background for Aliphatic aminesIllustrative background for Aliphatic amines ?? "content

Aliphatic amines

  • Aliphatic amines are amines containing aliphatic -R groups, such as alkyl chains.
  • The alkyl chain may be as short as methyl, or much longer.
Illustrative background for Aromatic aminesIllustrative background for Aromatic amines ?? "content

Aromatic amines

  • Aromatic amines share the same general formula as aliphatic amines.
  • But aromatic amines must have an aromatic -R group.
Illustrative background for AmidesIllustrative background for Amides ?? "content

Amides

  • Amides are different to amines but we must also be able to identify them - they crop up throughout this course.
  • An amide contains a -RCONH2 group, as shown above.

Classification of Amines

Amines, both aliphatic and aromatic, can be classified into primary, secondary and tertiary amines.

Illustrative background for Primary aminesIllustrative background for Primary amines ?? "content

Primary amines

  • Primary amines contain ONE -R group and TWO -H groups.
    • NRH2.
Illustrative background for Secondary aminesIllustrative background for Secondary amines ?? "content

Secondary amines

  • Secondary amines contain TWO -R groups and ONE -H group.
    • NR2H.
Illustrative background for Tertiary aminesIllustrative background for Tertiary amines ?? "content

Tertiary amines

  • Tertiary amines contain THREE -R groups and NO -H groups.
    • NR3.
Illustrative background for Ammonium ionsIllustrative background for Ammonium ions ?? "content

Ammonium ions

  • Under certain conditions, there is a possibility of a fourth group being added through a dative covalent bond.
    • This is possible because of the lone pair on the nitrogen.
    • An example is methylamine, N(CH3)H2. in acid; N(CH3)H3+
  • These molecules are called ammonium ions and are often found as ammonium salts - as the ion is much more stable in this form (e.g. (CH3)H3N+Cl−).

Preparation of Amines

We will consider ways to prepare aliphatic and aromatic amines.

Illustrative background for Halogenoalkane and ammoniaIllustrative background for Halogenoalkane and ammonia ?? "content

Halogenoalkane and ammonia

  • We can produce amines by heating halogenoalkanes with excess ammonia.
  • Above shows the mechanism of how this happens.
  • The overall reaction is:
    • NH3 + CH3Cl → CH3NH2 + HCl
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Illustrative background for Halogenoalkane and ammoniaIllustrative background for Halogenoalkane and ammonia ?? "content

Halogenoalkane and ammonia

  • There is one issue with this method.
  • The primary amine produced is also nucleophilic because it too has a lone pair of electrons and can react with the halogenoalkane itself to produce a secondary amine.
    • This process can happen again to produce a tertiary amine and a quaternary ammonium ion - as shown above.
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Illustrative background for Reducing a nitrileIllustrative background for Reducing a nitrile ?? "content

Reducing a nitrile

  • You can form an amine by the reduction of a nitrile in two ways.
  • First method:
    • LiAlH4.
    • Dilute acid.
  • In the equation above the [H] term represents the reducing agent which is LiAlH4!
Illustrative background for Reducing a nitrileIllustrative background for Reducing a nitrile ?? "content

Reducing a nitrile

  • The previous method is good but LiAlH4 is expensive.
  • Instead, the second method is catalytic hydrogenation.
  • You need:
    • Hydrogen gas.
    • Metal catalyst e.g. platinum or nickel.
    • High temperature and pressure.
Illustrative background for Preparing aromatic aminesIllustrative background for Preparing aromatic amines ?? "content

Preparing aromatic amines

  • These are produced by reducing nitrobenzene, a two step process.
  • First step:
    • Tin.
    • Conc. HCl.
    • Under reflux.
  • This forms an ionic salt. To obtain the amine we carry out the second step:
    • Add NaOH, a base.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.1.1Relative Masses

1.1.2The Mole

1.1.3Mass Spectrometry

1.1.4Empirical & Molecular Formulae

1.1.5Balanced Equations

1.1.6Molar Volume

1.1.7End of Topic Test - Amount of Substance

1.2Atomic Structure

1.2.1Fundamental Particles

1.2.2Isotopes & Mass Number

1.2.3Electron Shells, Sub-Shells & Orbitals

1.2.4Electron Configuration

1.2.5Ionisation Energy

1.2.6Factors Affecting Ionisation Energies

1.2.7Trends of Ionisation

1.2.8Specific Impacts on Ionisation Energies

1.2.9Electron Affinity

1.2.10End of Topic Test - Atomic Structure

1.2.11A-A* (AO2/3) - Atomic Structure

1.3Chemical Bonding

1.3.1Ionic Bonding

1.3.2Covalent & Dative Bonding

1.3.3Shapes of Molecules

1.3.4Intermolecular Forces

1.3.5Intermolecular Forces 2

1.3.6Electronegativity

1.3.7Bond Length, Bond Energy, & Bond Polarity

1.3.8Metallic Bonding

1.3.9Physical Properties

1.3.10End of Topic Test - Bonding

1.3.11A-A* (AO2/3) - Bonding

1.4States of Matter

1.4.1Simple Covalent Molecules

1.4.2The Ideal Gas Equation

1.4.3States of Matter

1.4.4Particle Diagrams

1.4.5The Liquid State

1.4.6Giant Ionic Lattices

1.4.7Giant Metallic Lattices

1.4.8Giant Covalent Structures

1.4.9Graphene & Fullerene

1.4.10Recycling

1.5Chemical Energetics

1.5.1Calorimetry

1.5.2Bond Enthalpies

1.5.3Enthalpy Changes

1.5.4Hess' Law

1.5.5Born-Haber Cycles

1.5.6Born-Haber Cycle Calculations

1.5.7Entropy

1.5.8Free Energy

1.5.9End of Topic Test - Energetics

1.6Electrochemistry

1.6.1Electrochemical Cells

1.6.2Electrochemical Series

1.6.3Commercial Application

1.6.4Nernst Equation

1.6.5Redox

1.7Equilibria

1.7.1Dynamic Equilibrium & Le Chatelier

1.7.2Kc

1.7.3Kp

1.7.4pH

1.7.5The Ionic Product of Water

1.7.6Weak Acids & Bases

1.7.7Introduction to Solubility Equilibria

1.7.8Solubility Equilibria Calculations

1.7.9Free Energy of Dissolution

1.7.10pH and Solubility

1.7.11Common-Ion Effect

1.7.12End of Topic Test - Kp & Electrochemistry

1.7.13A-A* (AO2/3) - Electrochemical Cells

1.8Partition Coefficient

1.8.1Kpc

1.9Reaction Kinetics

1.9.1Collision Theory

1.9.2Orders, Rate Constants & Equations

1.9.3Rate Graphs

1.9.4Rate Determining Step

1.9.5Maxwell-Boltzmann Distribution

1.9.6Catalysts

1.9.7Homogeneous Catalysts

1.9.8Heterogeneous Catalysts

1.9.9End of Topic Test - Kinetics

1.9.10End of Topic Test - Rate Equations

1.9.11A-A* (AO2/3) - Rate Equations

2Inorganic Chemistry

2.1The Periodic Table

2.1.1The Periodic Table

2.1.2Trends in the Periodic Table

2.1.3End of Topic Test - Periodicity & Trends

2.1.4Ceramics

2.1.5Period 3 Elements & Oxides

2.1.6Period 3 Oxides

2.1.7End of Topic Test - Period 3

2.2Group 2

2.2.1Group 2 Chemistry

2.3Group 17

2.3.1Introduction to Halogens

2.3.2Reactions of Halogens

2.3.3Chlorine & Chlorate(I)

2.3.4End of Topic Test - Group 17

2.3.5A-A* (AO2/3) - Periodicity, Group 2 & 17

2.4Transition Metals

2.4.1General Properties

2.4.2Titrations

2.4.3Shapes of Complex Ions

2.4.4Variable Oxidation States

2.4.5Ligands

2.4.6Colours of Ions

2.4.7Stereoisomerism of Complex Ions

2.4.8Cisplatin

2.4.9Ligand Substitutions & Kstab

2.4.10End of Topic Test - Transition Metals

2.4.11A-A* (AO2/3) - Transition Metals

2.5Nitrogen & Sulfur

2.5.1Nitrogen & Ammonia

2.5.2Formulated vs Manure Fertilisers

2.5.3Nitrogen Containing Fertilisers

2.5.4Fertilizers & Eutrophication

2.5.5Common Atmospheric Pollutants & Their Properties

2.5.6Catalytic Converters

2.5.7Atmospheric Oxides

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.1.1Naming Conventions

3.1.2Mechanism

3.1.3Isomerism

3.1.4End of Topic Test - Introduction to Organic Chem

3.2Hydrocarbons

3.2.1Fractional Distillation

3.2.2Cracking

3.2.3Combustion

3.2.4Chlorination

3.2.5End of Topic Test - Alkanes

3.2.6Introduction to Alkenes

3.2.7Reactions of Alkenes

3.2.8Polymerisation Reactions

3.2.9End of Topic Test - Alkenes

3.2.10Arenes

3.2.11Evidence for Structure of Arenes

3.2.12Reactions of Benzene

3.2.13End of Topic Test -Arenes

3.3Halogen Derivatives

3.3.1Properties of Haloalkanes

3.3.2Substitution Reactions of Haloalkanes

3.3.3Environmental Impacts of Haloalkanes

3.3.4End of Topic Test - Halogenoalkanes

3.4Hydroxy Compounds

3.4.1Types of Alcohol

3.4.2Oxidation 1

3.4.3Oxidation 2

3.4.4Elimination

3.4.5Acids & Esters

3.4.6Acyl Chlorides & Acylation

3.4.7Phenols & Their Reactions

3.4.8End of Topic Test - Alcohols

3.5Carbonyl Compounds

3.5.1Carbonyls

3.5.2Hydrogen Bonding & Carbonyls

3.5.3Aldehydes & Ketones

3.5.4Tri-Iodomethane Reaction

3.5.5End of Topic Test -Carbonyls

3.6Carboxylic Acids & Derivatives

3.6.1Properties of Carboxylic Acids

3.6.2Esters

3.6.3Acyl Chlorides

3.6.4End of Topic Test - Carboxylic Acids

3.7Nitrogen Compounds

3.7.1Nature & Preparation of Amines

3.7.2Basicity & Nucleophilicity

3.7.3Amides

3.7.4Reactions of Amino Acids

3.7.5Amino Acids

3.8Polymerisation

3.8.1Properties of Addition Polymers

3.8.2Condensation Polymerisation

3.8.3Effects of Side-Chains on Polymers

3.8.4Hydrolysis of Ester & Amide Groups

3.8.5Proteins

3.8.6DNA

3.8.7Adhesive & Conducting Polymers

3.8.8End of Topic Test - Amines & Proteins

3.9Analytical Techniques

3.9.1Chromatography

3.9.2High-Performance Liquid Chromatography

3.9.3Gas Chromatography

3.9.4IR Spectroscopy

3.9.5Uses of IR Spectroscopy

3.9.6Mass Spectrometry

3.9.7Mass Spectrometry Analysis

3.9.8Nuclear Magnetic Resonance

3.9.9Carbon-13 NMR

3.9.10Proton NMR I

3.9.11Proton NMR II

3.9.12End of Topic Test - Analytical Techniques

3.9.13A-A* (AO2/3) - Analytical Techniques

3.10Organic Synthesis

3.10.1Chirality & Drug Synthesis

3.10.2Organic Synthesis

3.10.3Examples of Synthetic Routes

3.10.4End of Topic Test - Organic Synthesis

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End of Topic Test - Carboxylic Acids

Basicity & Nucleophilicity