AQA Chemistry A-level 3.3.7: Optical Isomers PDF
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This document provides detailed notes on optical isomers, a type of stereoisomerism in organic chemistry. It explains the concept of chiral centers and how they lead to the formation of enantiomers. The notes also cover racemic mixtures and nucleophilic addition reactions. It is suitable for A-level Chemistry students.
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AQA Chemistry A-level 3.3.7: Optical Isomers Detailed Notes This work by PMT Education is licensed under https://bit.ly/pmt-cc https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0...
AQA Chemistry A-level 3.3.7: Optical Isomers Detailed Notes This work by PMT Education is licensed under https://bit.ly/pmt-cc https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc 3.3.7.1 - Optical Isomers Optical isomerism is a type of stereoisomerism where molecules have the same molecular formula but a different spatial arrangement of atoms in space. It occurs when there is an asymmetrical carbon within an organic molecule known as a chiral centre. Chiral Centres A chiral centre is a carbon atom with four different groups bonded around it so there is no line of symmetry to the molecule. Example: The chiral centre is commonly indicated using * next to the asymmetric carbon. Optical Isomers The presence of a chiral centre leads to the presence of two possible isomers that are mirror images of each other. These are optical isomers. Example: The two different isomers are called enantiomers and are unique due to their effect on plane polarised light. Each enantiomer causes the rotation of plane polarised light by 90o in opposite directions. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Example: Racemic Mixtures A racemate is formed when optical isomers are produced as a pair of enantiomers in a 1:1 ratio. The optical rotational effect on polarised light caused by each enantiomer causes the overall effect to be zero as the opposite directions of rotation cancel out. As a result the mixture produced is optically inactive, known as a racemic mixture. These two isomers are able to form in this way due to a nucleophilic addition reaction. Nucleophilic Addition In these reactions, nucleophiles are able to attack a molecule with a carbonyl group from above or below the carbon-oxygen double bond. This means the two possible products of the reaction are mirror images and therefore optical isomers. Mechanism https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc
