6.9.3
Hydrogen-1 NMR (A2 Only)
1H Environments
1H Environments
1H NMR is the next type of NMR we will study. It is slightly harder than 13C NMR but the basic principles are the same.
Chemical shifts
Chemical shifts
- As in 13C NMR, 1H NMR spectra display signals at different chemical shift values.
- These chemical shift values represent different 1H environments.
- E.g. If the spectrum has four peaks, there are four different chemical environments with an unknown number of 1H's in each environment.
- We can use chemical shift tables to identify 1H environments and functional groups from the signals in spectra.
Tetramethylsilane
Tetramethylsilane
- As in 13C NMR, 1H NMR's reference is tetramethylsilane (TMS).
- TMS has a chemical shift of 0 ppm.
- TMS produces a single peak because each 1H in TMS is in the same environment.
Signal ratios
Signal ratios
- An extra piece of information that 1H NMR gives us over 13C NMR is based around the ratio of the areas underneath the signals.
- The ratio of the areas reflects the ratio of how many protons are in that same environment.
- E.g. If there are two singlet peaks and one peak is twice as big as the other, this means that the chemical environment of the bigger peak has twice as many 1H's as the other environment.
Splitting Patterns
Splitting Patterns
1H NMR gets slightly harder than 13C NMR when we consider splitting patterns. But, this pays off because it gives us lots of useful information.
Signals splitting
Signals splitting
- In 1H NMR, the main signals that represent different chemical environments have fine splitting patterns.
- The main signal may be split into a number of fine peaks. Peaks have different names depending on how many splits they have:
- No splittings = singlet.
- Split into two = doublet.
- Split into three = triplet.
- Split into four = quartet.
- On the AQA spec, anything split into five or more = multiplet.
Information from splittings
Information from splittings
- Signal splitting helps us work out the number of 1H's in different environments. Beware, this is not straightforward!
- Number of fine splittings = number of 1H's on adjacent carbon + 1
- This is called the n+1 rule.
- Number of fine splittings = number of 1H's on adjacent carbon + 1
Example: Diethyl ether
Example: Diethyl ether
- There are only two different proton environments in diethyl ether.
- The adjacent CH2 and CH3 groups creates the splitting patterns seen above.
Example: Propanol
Example: Propanol
- CH3 group: split into a triplet due to adjacent CH2 group.
- Middle CH2 group: split into a multiplet () due to adjacent CH2 group on one side and CH3 group on the other side.
- CH2 group next to -OH: split into a triplet due to adjacent CH2 group.
- OH group: is a singlet as no adjacent carbons.
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
1.3Bonding
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
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
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
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
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)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
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
1.3Bonding
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
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
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
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
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)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
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