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A carbanion is one of several reactive intermediates in organic chemistry. In organic synthesis, organolithium reagents and Grignard reagents are commonly treated and referred to as "carbanions." This is a convenient approximation, although these species are generally clusters or complexes containing highly polar, but still covalent bonds metal ...
[5] [22] For instance, a modification of this analysis is still viable, even if the lone pairs of H 2 O are considered to be inequivalent by virtue of their symmetry (i.e., only s, and in-plane p x and p y oxygen AOs are hybridized to form the two O-H bonding orbitals σ O-H and lone pair n O (σ), while p z becomes an inequivalent pure p ...
For the hydrogen fluoride molecule, for example, two F lone pairs are essentially unhybridized p orbitals, while the other is an sp x hybrid orbital. An analogous consideration applies to water (one O lone pair is in a pure p orbital, another is in an sp x hybrid orbital).
Enolate anions are electronically related to allyl anions. The anionic charge is delocalized over the oxygen and the two carbon sites. Thus they have the character of both an alkoxide and a carbanion. [5] Although they are often drawn as being simple salts, in fact they adopt complicated structures often featuring aggregates. [6]
Hyperconjugation can be used to rationalize a variety of chemical phenomena, including the anomeric effect, the gauche effect, the rotational barrier of ethane, the beta-silicon effect, the vibrational frequency of exocyclic carbonyl groups, and the relative stability of substituted carbocations and substituted carbon centred radicals, and the thermodynamic Zaitsev's rule for alkene stability.
Cinnamaldehyde is a naturally-occurring compound that has a conjugated system penta-1,3-diene is a molecule with a conjugated system Diazomethane conjugated pi-system. In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability.
However, the three hydrogen atoms are repelled by the electron lone pair in a way that the geometry is distorted to a trigonal pyramid (regular 3-sided pyramid) with bond angles of 107°. In contrast, boron trifluoride is flat, adopting a trigonal planar geometry because the boron does not have a lone pair of electrons.
They can attack lone pairs, but their primary synthetic utility arises from attacks on π bonds, which give cyclopropanes; and on σ bonds, which cause carbene insertion. Other reactions include rearrangements and dimerizations. A particular carbene's reactivity depends on the substituents, including any metals present.