6.5.1

Nature & Preparation of Amines (A2 Only)

Test yourself

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. This is because the ion is much more stable in this form.

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
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.
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. platinium 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

1.1Atomic Structure

1.1.1Fundamental Particles

1.1.2Isotopes & Mass Number

1.1.3Mass Spectrometry

1.1.4Electron Shells, Sub-Shells & Orbitals

1.1.5Electron Configuration

1.1.6Ionisation Energy

1.1.7Factors Affecting Ionisation Energies

1.1.8Trends of Ionisation

1.1.9Specific Impacts on Ionisation Energies

1.1.10End of Topic Test - Atomic Structure

1.1.11A-A* (AO3/4) - Atomic Structure

1.2Amount of Substance

1.2.1Relative Masses

1.2.2The Mole

1.2.3The Ideal Gas Equation

1.2.4Empirical & Molecular Formulae

1.2.5Balanced Equations

1.2.6Percentage Yield

1.2.7A-A* (AO3/4) - Percentage Yield

1.2.8Atom Economy

1.2.9End of Topic Test - Amount of Substance

1.2.10A-A* (AO3/4) - Substances & Yield

1.3Bonding

1.3.1Ionic Bonding

1.3.2Covalent & Dative Bonding

1.3.3Carbon Structures

1.3.4Metallic Bonding

1.3.5Physical Properties

1.3.6Shapes of Molecules

1.3.7Polarity

1.3.8Intermolecular Forces

1.3.9Intermolecular Forces 2

1.3.10End of Topic Test - Bonding

1.3.11Exam-Style Question - Shape of Molecules

1.3.12A-A* (AO3/4) - Bonding

1.4Energetics

1.4.1Enthalpy Changes

1.4.2Calorimetry

1.4.3Hess' Law

1.4.4Bond Enthalpies

1.4.5End of Topic Test - Energetics

1.5Kinetics

1.5.1Collision Theory

1.5.2Maxwell-Boltzmann Distribution

1.5.3Increasing Rates

1.5.4End of Topic Test - Kinetics

1.6Equilibria

1.6.1Le Chatelier

1.6.2Equilibrium Constants

1.6.3A-A* (AO3/4) - Energetics, Kinetics, Equilibria

1.6.4End of Topic Test - Equilibria

1.7Redox

1.7.1Redox

1.7.2End of Topic Test - Redox

2Physical Chemistry 2 (A2 Only)

2.1Thermodynamics (A2 Only)

2.1.1Born-Haber Cycles (A2 Only)

2.1.2Born-Haber Cycle Calculations (A2 Only)

2.1.3Entropy (A2 Only)

2.1.4Free Energy (A2 Only)

2.1.5End of Topic Test - Thermodynamics

2.1.6A-A* (AO3/4) - Thermodynamics

2.2Rate Equations (A2 Only)

2.2.1Rate Equations (A2 Only)

2.2.2Rate Equations 2 (A2 Only)

2.2.3The Arrhenius Equation (A2 Only)

2.2.4Experimental Methods for Rates (A2 Only)

2.2.5End of Topic Test - Rate Equations

2.2.6Exam-Style Question - Rates

2.2.7A-A* (AO3/4) - Rate Equations

2.3The Equilibrium Constant Kp (A2 Only)

2.3.1Properties of Kp (A2 Only)

2.4Electrochemical Cells (A2 Only)

2.4.1Electrochemical Cells (A2 Only)

2.4.2Electrochemical Series (A2 Only)

2.4.3Commercial Application (A2 Only)

2.4.4End of Topic Test - Kp & Electrochemistry

2.4.5A-A* (AO3/4) - Electrochemical Cells

2.5Acids & Bases (A2 Only)

2.5.1Brønsted-Lowry Acids & Bases (A2 Only)

2.5.2pH (A2 Only)

2.5.3The Ionic Product of Water (A2 Only)

2.5.4Weak Acids & Bases (A2 Only)

2.5.5pH Curves & Titrations (A2 Only)

2.5.6pH Curves & Titrations 2 (A2 Only)

2.5.7Buffer Solutions (A2 Only)

2.5.8End of Topic Test - Acids & Bases

2.5.9Exam-Style Question - Weak Acids

2.5.10A-A* (AO3/4) - Acids & Bases

3Inorganic Chemistry

3.1Periodicity & Trends

3.1.1The Periodic Table

3.1.2Trends in the Periodic Table

3.1.3End of Topic Test - Periodicity & Trends

3.2Group 2

3.2.1Group 2 Chemistry

3.2.2End of Topic Test - Group 2

3.3Group 7

3.3.1Introduction to Halogens

3.3.2Reactions of Halogens

3.3.3Chlorine & Chlorate(I)

3.3.4End of Topic Test - Group 7

3.3.5Exam-Style Question - Group 7

3.3.6A-A* (AO3/4) - Periodicity, Group 2 & 7

4Inorganic Chemistry 2 (A2 Only)

4.1Period 3 (A2 Only)

4.1.1Period 3 Elements & Oxides (A2 Only)

4.1.2Period 3 Oxides (A2 Only)

4.1.3End of Topic Test - Period 3

4.2Transition Metals (A2 Only)

4.2.1General Properties (A2 Only)

4.2.2Substitution Reactions (A2 Only)

4.2.3Shapes of Complex Ions (A2 Only)

4.2.4Colours of Ions (A2 Only)

4.2.5Variable Oxidation States (A2 Only)

4.2.6Titrations (A2 Only)

4.2.7Homogeneous Catalysts (A2 Only)

4.2.8Heterogeneous Catalysts (A2 Only)

4.2.9End of Topic Test - Transition Metals

4.2.10A-A* (AO3/4) - Transition Metals

4.3Reactions of Ions in Aqueous Solutions (A2 Only)

4.3.1Acidity (A2 Only)

4.3.2Identification (A2 Only)

4.3.3End of Topic Test - Reactions of Ions in Solution

5Organic Chemistry 1

5.1Introduction

5.1.1Naming Conventions

5.1.2Mechanism

5.1.3Isomerism

5.1.4End of Topic Test - Introduction to Organic Chem

5.2Alkanes

5.2.1Fractional Distillation

5.2.2Cracking

5.2.3Combustion

5.2.4Chlorination

5.2.5End of Topic Test - Alkanes

5.3Halogenoalkanes

5.3.1Substitution Reactions

5.3.2Elimination Reactions

5.3.3Ozone Depletion

5.3.4End of Topic Test - Halogenoalkanes

5.4Alkenes

5.4.1Introduction to Alkenes

5.4.2Reactions of Alkenes

5.4.3Polymerisation Reactions

5.4.4Properties of Polymers

5.4.5End of Topic Test - Alkenes

5.5Alcohols

5.5.1Production of Alcohols

5.5.2Oxidation of Alcohols

5.5.3Oxidation of Alcohols - 2

5.5.4Elimination Reactions

5.5.5End of Topic Test - Alcohols

5.5.6Exam-Style Question - Alcohols

5.6Organic Analysis

5.6.1Reactions

5.6.2Reactions 2

5.6.3Mass Spectrometry

5.6.4Infrared Spectroscopy

5.6.5End of Topic Test - Organic Analysis

5.7A-A* (AO3/4) - Organic 1

5.7.1A-A* (AO3/4) - Organic 1

6Organic Chemistry 2 (A2 Only)

6.1Optical Isomerism (A2 Only)

6.1.1Optical Isomerism (A2 Only)

6.1.2End of Topic Test - Optical Isomerism

6.2Aldehydes & Ketones (A2 Only)

6.2.1Aldehydes & Ketones (A2 Only)

6.2.2End of Topic Test - Aldehydes & Ketones

6.3Carboxylic Acids & Esters (A2 Only)

6.3.1Acids & Esters (A2 Only)

6.3.2Acylation (A2 Only)

6.3.3End of Topic Test - Carboxylic Acids & Esters

6.4Aromatic Chemistry (A2 Only)

6.4.1Structure & Reactivity (A2 Only)

6.4.2Reactions of Benzene (A2 Only)

6.4.3End of Topic Test - Aromatic Chemistry

6.5Amines (A2 Only)

6.5.1Nature & Preparation of Amines (A2 Only)

6.5.2Basicity & Nucleophilicity (A2 Only)

6.5.3End of Topic Test - Amines

6.6Polymers (A2 Only)

6.6.1Condensation Polymers (A2 Only)

6.6.2Biodegradability (A2 Only)

6.7Biological Organic (A2 Only)

6.7.1Amino Acids (A2 Only)

6.7.2Proteins (A2 Only)

6.7.3DNA (A2 Only)

6.7.4Anti-Cancer Drugs (A2 Only)

6.7.5End of Topic Test - Biological Organic

6.8Organic Synthesis (A2 Only)

6.8.1Organic Synthesis (A2 Only)

6.8.2Examples of Synthetic Routes (A2 Only)

6.8.3End of Topic Test - Polymers & Organic Synthesis

6.9NMR Spectroscopy (A2 Only)

6.9.1Understanding NMR (A2 Only)

6.9.2Carbon-13 NMR (A2 Only)

6.9.3Hydrogen-1 NMR (A2 Only)

6.9.4Hydrogen-1 NMR 2 (A2 Only)

6.9.5End of Topic Test - NMR

6.10Chromatography (A2 Only)

6.10.1Overview of Chromatography (A2 Only)

6.10.2Thin-Layer Chromatography (A2 Only)

6.10.3Column Chromatography (A2 Only)

6.10.4Gas Chromatography (A2 Only)

6.10.5End of Topic Test - Chromatography

6.11A-A* (AO3/4) - Organic 2

6.11.1A-A* (AO3/4) - Organic 2

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End of Topic Test - Aromatic Chemistry

Basicity & Nucleophilicity (A2 Only)