enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Carbanion - Wikipedia

    en.wikipedia.org/wiki/Carbanion

    Formally, a carbanion is the conjugate base of a carbon acid: R 3 CH + B − → R 3 C − + HB. where B stands for the base. The carbanions formed from deprotonation of alkanes (at an sp 3 carbon), alkenes (at an sp 2 carbon), arenes (at an sp 2 carbon), and alkynes (at an sp carbon) are known as alkyl, alkenyl , aryl, and alkynyl anions ...

  3. Carbenium ion - Wikipedia

    en.wikipedia.org/wiki/Carbenium_ion

    The stability of alkyl-substituted carbocations follows the order 3° > 2° > 1° > methyl. This trend can be inferred by the hydride ion affinity values (231, 246, 273, and 312 kcal/mol for (CH 3) 3 C +, (CH 3) 2 CH +, CH 3 CH + 2, and CH + 3). [9] The effect of alkyl substitution is a strong one:

  4. Hydrogen isotope biogeochemistry - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_isotope...

    The trend of carbocation stability. Note the stabilization effects from adjacent carbons that donate electrons to the positive charge. The opposite trend is seen in carbanion stability. In isotopes, a tertiary bound hydrogen is more likely to be lost because the resulting carbocation is the most stable species. Radical reactions that cleave C ...

  5. Horner–Wadsworth–Emmons reaction - Wikipedia

    en.wikipedia.org/wiki/Horner–Wadsworth–Emmons...

    The Horner–Wadsworth–Emmons (HWE) reaction is a chemical reaction used in organic chemistry of stabilized phosphonate carbanions with aldehydes (or ketones) to produce predominantly E-alkenes. [1] The Horner–Wadsworth–Emmons reaction. In 1958, Leopold Horner published a modified Wittig reaction using phosphonate-stabilized carbanions.

  6. Pyramidal inversion - Wikipedia

    en.wikipedia.org/wiki/Pyramidal_inversion

    In chemistry, pyramidal inversion (also umbrella inversion) is a fluxional process in compounds with a pyramidal molecule, such as ammonia (NH 3) "turns inside out". [1] [2] It is a rapid oscillation of the atom and substituents, the molecule or ion passing through a planar transition state. [3]

  7. List of elements by stability of isotopes - Wikipedia

    en.wikipedia.org/wiki/List_of_elements_by...

    An even number of protons or neutrons is more stable (higher binding energy) because of pairing effects, so even–even nuclides are much more stable than odd–odd. One effect is that there are few stable odd–odd nuclides: in fact only five are stable, with another four having half-lives longer than a billion years.

  8. Negative hyperconjugation in silicon - Wikipedia

    en.wikipedia.org/wiki/Negative_hyperconjugation...

    The continued presence of second-row type stability in certain organosilicon compounds is known as the silicon α and β effects, after the corresponding locants. These stabilities occur because of a partial overlap between the C–Si σ orbital and the σ* antibonding orbital at the β position, lowering the S N reaction transition state's energy.

  9. Enolate - Wikipedia

    en.wikipedia.org/wiki/Enolate

    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]