Related Experiment Video
Updated: May 2, 2026

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
On the configurational stability of chiral, nonracemic fluoro- and iodo-[D(1)]methyllithiums
Dagmar C Kail1, Petra Malova Krizkova, Anna Wieczorek
1PharmBioTec GmbH, Saarland University, Campus C2.2, Room 31, 66123 Saarbrücken (Germany).
Abstract:
Enantiomerically pure fluoro-[D1]methyllithium and iodo-[D1]methyllithiums of up to 92% ee were generated by transmetalation of the corresponding stannanes with MeLi in THF at various temperatures. The intermediate halo-[D1]methyllithiums were trapped with benzaldehyde or acetophenone already present in excess in the reaction mixture to either give halohydrins or to disintegrate to carbene. The fluoro-[D1]methyllithiums were found to be microscopically configurationally stable within the tested range of -95 to 0 °C, but chemically only stable at temperatures below -95 °C due to a rapidly increasing portion disintegrating to carbene. The iodo-[D1]methyllithiums were configurationally labile relative to the rate of addition to PhCHO at all temperatures tested (-95 to -30 °C). Disintegration to carbene interfered as well.
Related Concept Videos
Radical Halogenation: Stereochemistry
Halogenation to form a new chiral center:
Stereoisomerism of Cyclic Compounds
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Alkyl Halides
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...

