7.3.3
Hydrogen-1 NMR
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.
1Structure - Models of the Particulate of Matter
1.1Introduction to the Particulate Model of Matter
1.2The Nuclear Atom
1.3Electron Configuration
1.4Counting Particles by Mass: The Mole
1.6Elements, Compounds & Mixtures
1.7States of Matter & Changes of State
1.8Reacting Masses &. Volumes
1.9Solutions
2Structure - Models of Bonding & Structure
2.1The Ionic Model
2.2The Covalent Model
2.3Covalent Structures
2.4The Metallic Model
2.5From Models to Materials
2.6Valence Electrons & Ionic Compounds
2.7Molecular Shape
3Structure - Classification of Matter
3.1The Periodic Table: Classification of Elements
3.2Periodic Trends
3.3Group 1 Alkali Metals
3.4Halogens
3.5Noble gases, group 18
3.6Functional Groups: Classification of Organic
3.7Functional Group Chemistry
3.8Alkanes
3.9Alcohols
4Reactivity - What Drives Chemical Reaction?
4.1Endothermic & Exothermic Reactions
4.2Enthalpy of Reaction, Formation, & Hess' Law
5Reactivity - How Much, How Fast & How Far?
5.1Kinetics
5.2Rates of Reaction
5.3Stoichometry
5.4Le Châtelier’s Principle
5.5Introduction to Equilibrium
5.6Equilibrium Constant
5.7Reaction Quotient & Equilibrium Constant
6Reactivity - The Mechanisms of Chemical Change
6.1Proton Transfer Reactions
6.2The pH Scale
6.3Strong & Weak Acids and Bases
6.4Acid Deposition
6.5Types of Organic Reactions
6.6Oxidation & Reduction
6.7Electrochemical Cells
6.9Acid-Base Titrations
6.9.1Titration Calculation Weak Acid & Strong Base
6.9.2Titration Experimental Detail
6.9.3Extended Response - Titration
6.9.4Titration Calculations
6.9.5Titration Curves
6.9.6Titration Calculation Strong Acid & Weak Base
6.9.7IB Multiple Choice - Titrations
6.9.8Polyprotic Acids
6.9.9Titration Calculations Strong Acid & Strong Base
6.9.10Titrations Curves 2
7Measurement, Data Processing & Analysis
7.1Uncertainties & Errors in Measurements & Results
7.2Graphical Techniques
7.3Spectroscopic Identification of Organic Compounds
7.4Infrared Spectroscpy
Jump to other topics
1Structure - Models of the Particulate of Matter
1.1Introduction to the Particulate Model of Matter
1.2The Nuclear Atom
1.3Electron Configuration
1.4Counting Particles by Mass: The Mole
1.6Elements, Compounds & Mixtures
1.7States of Matter & Changes of State
1.8Reacting Masses &. Volumes
1.9Solutions
2Structure - Models of Bonding & Structure
2.1The Ionic Model
2.2The Covalent Model
2.3Covalent Structures
2.4The Metallic Model
2.5From Models to Materials
2.6Valence Electrons & Ionic Compounds
2.7Molecular Shape
3Structure - Classification of Matter
3.1The Periodic Table: Classification of Elements
3.2Periodic Trends
3.3Group 1 Alkali Metals
3.4Halogens
3.5Noble gases, group 18
3.6Functional Groups: Classification of Organic
3.7Functional Group Chemistry
3.8Alkanes
3.9Alcohols
4Reactivity - What Drives Chemical Reaction?
4.1Endothermic & Exothermic Reactions
4.2Enthalpy of Reaction, Formation, & Hess' Law
5Reactivity - How Much, How Fast & How Far?
5.1Kinetics
5.2Rates of Reaction
5.3Stoichometry
5.4Le Châtelier’s Principle
5.5Introduction to Equilibrium
5.6Equilibrium Constant
5.7Reaction Quotient & Equilibrium Constant
6Reactivity - The Mechanisms of Chemical Change
6.1Proton Transfer Reactions
6.2The pH Scale
6.3Strong & Weak Acids and Bases
6.4Acid Deposition
6.5Types of Organic Reactions
6.6Oxidation & Reduction
6.7Electrochemical Cells
6.9Acid-Base Titrations
6.9.1Titration Calculation Weak Acid & Strong Base
6.9.2Titration Experimental Detail
6.9.3Extended Response - Titration
6.9.4Titration Calculations
6.9.5Titration Curves
6.9.6Titration Calculation Strong Acid & Weak Base
6.9.7IB Multiple Choice - Titrations
6.9.8Polyprotic Acids
6.9.9Titration Calculations Strong Acid & Strong Base
6.9.10Titrations Curves 2
7Measurement, Data Processing & Analysis
7.1Uncertainties & Errors in Measurements & Results
7.2Graphical Techniques
7.3Spectroscopic Identification of Organic Compounds
7.4Infrared Spectroscpy
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