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Influence of Substituents on the Rotational Energy Barrier of Axially Chiral Biphenyls, II

✍ Scribed by Wolf, Christian ;Hochmuth, Detlev H. ;A. König, Wilfried ;Roussel, Christian

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
701 KB
Volume
1996
Category
Article
ISSN
0947-3440

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✦ Synopsis

The influence of substituents on the rotational energy barrier of a series of 2,2'-bis(trifluoromethy1)-and 2,2'-diisopropylbiphenyl derivatives with various substitution patterns was investigated by dynamic gas chromatography (DGC) with selectively modified cyclodextrins and by high-performance li- quid chromatography (HPLC) on microcrystalline cellulose triacetate combined with polarimetry. Investigation of the steric effect of substituents was possible by gradually increasing the bulkiness of substituents in the ortho positions of 2,2'-disubstituted biphenyls and determination of the corresponding energy barriers. The buttressing effect of alkyl groups adjacent to the ortho substituents is discussed. Comparison of the energy barriers of 2,2'-bis(trifluoromethy1)biphenyl (1) with its derivatives possessing alkyl groups in po-

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