The Chemistry of Rotational Isomers [Paperback]

Rotation about the Carbon-Carbon single bond is generallyregarded to be unrestricted. About 50 years ago, rotationalisomers were found to exhibit optical activity: substitutedbiphenyl derivatives. However, the author has investigatedother classes of compounds that have stable rotationalisomers at room temperature. These compounds can serve asmodels for studying very weak intermolecular interactions,that are difficult to observe. Even diastereotopic groupsshow different chemical reactivity.From the contents: The Free Rotation Concept - RotamerPopulations - Barriers to Rotation - Reactivity ofRotational Isomers.Rotation about the Carbon-Carbon single bond is generallyregarded to be unrestricted. About 50 years ago, rotationalisomers were found to exhibit optical activity: substitutedbiphenyl derivatives. However, the author has investigatedother classes of compounds that have stable rotationalisomers at room temperature. These compounds can serve asmodels for studying very weak intermolecular interactions,that are difficult to observe. Even diastereotopic groupsshow different chemical reactivity.From the contents: The Free Rotation Concept - RotamerPopulations - Barriers to Rotation - Reactivity ofRotational Isomers.1 Introduction.- 1.1 The Free Rotation Concept.- 1.2 Recognition of Rotational Isomers.- 1.3 Atropisomers.- 1.4 Isolation of Rotational Isomers.- 1.4.1 Factors Affecting Barrier Heights.- 1.4.2 Triptycene Derivatives.- 1.4.3 9-Arylfluorenes.- 1.5 Concepts That Need Modification.- 1.5.1 Are There Dextrorotatory and Levorotatory Groups?.- 1.5.2 Reactivity of Rotational Isomers.- 1.6 References.- 2 Rotamer Populations.- 2.1 Estimation of Rotamer Populations.- 2.1.1 Vibration Spectroscopy.- 2.1.2 Nuclear Magnetic Resonance Spectroscopy.- 2.2 Factors That Affect Rotamer Populations.- 2.3 Information on Molecular Interactions Obtained from Rotamer PolcĄ