Biomaterial Database

Relative basicities of ortho-, meta-, and para-substituted aryllithiums. 2009

Joanna Gorecka-Kobylinska, and Manfred Schlosser

Institute of Chemical Sciences and Engineering, Ecole Polytechnique Federale (EPFL-BCh), CH-1015 Lausanne, Switzerland.

The relative basicities of aryllithiums bearing methoxy, chlorine, fluorine, trifluoromethyl and trifluoromethoxy substituents at the ortho, meta, and para positions have been assessed. To this end, two aryllithiums of comparable basicity were equilibrated together with the corresponding bromo- or iodoarenes in a 1:2 mixture of pentanes with tetrahydrofuran at -50, -75, or -100 degrees C. The "basicity" (protodelithiation) increments DeltaDeltaG derived from the equilibrium constants are linearly correlated with the relative protonation enthalpies of the corresponding aryl anions in the gas phase. However, the correlation factor proves to be position-dependent. Compared with "naked" aryl anions, the basicity of aryllithiums mirrors the effects of ortho, meta, and para substituents to the extent of 36%, 30%, and 25%, respectively.

UI	MeSH Term	Description	Entries
D008094	Lithium	An element in the alkali metals family. It has the atomic symbol Li, atomic number 3, and atomic weight [6.938; 6.997]. Salts of lithium are used in treating BIPOLAR DISORDER.	Lithium-7,Lithium 7
D009942	Organometallic Compounds	A class of compounds of the type R-M, where a C atom is joined directly to any other element except H, C, N, O, F, Cl, Br, I, or At. (Grant & Hackh's Chemical Dictionary, 5th ed)	Metallo-Organic Compound,Metallo-Organic Compounds,Metalloorganic Compound,Organometallic Compound,Metalloorganic Compounds,Compound, Metallo-Organic,Compound, Metalloorganic,Compound, Organometallic,Compounds, Metallo-Organic,Compounds, Metalloorganic,Compounds, Organometallic,Metallo Organic Compound,Metallo Organic Compounds
D013237	Stereoisomerism	The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Molecular Stereochemistry,Stereoisomers,Stereochemistry, Molecular,Stereoisomer
D015394	Molecular Structure	The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.	Structure, Molecular,Molecular Structures,Structures, Molecular