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  2. Mesomeric effect - Wikipedia

    en.wikipedia.org/wiki/Mesomeric_effect

    The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant resonance structures and is symbolized by the letter M. [2] The mesomeric effect is negative (–M) when the substituent is an electron-withdrawing group, and the effect is positive (+M) when the substituent ...

  3. Hammett equation - Wikipedia

    en.wikipedia.org/wiki/Hammett_equation

    The data also show that for these substituents, the meta effect is much larger than the para effect, due to the fact that the mesomeric effect is greatly reduced in a meta substituent. With meta substituents a carbon atom bearing the negative charge is further away from the carboxylic acid group (structure 2b).

  4. Electrophilic aromatic directing groups - Wikipedia

    en.wikipedia.org/wiki/Electrophilic_aromatic...

    However, another effect that plays a role is the +M effect which adds electron density back into the benzene ring (thus having the opposite effect of the -I effect but by a different mechanism). This is called the mesomeric effect (hence +M) and the result for fluorine is that the +M effect approximately cancels out the -I effect.

  5. Ether cleavage - Wikipedia

    en.wikipedia.org/wiki/Ether_cleavage

    In organic chemistry, ether cleavage is an acid catalyzed nucleophilic substitution reaction. Depending on the specific ether, cleavage can follow either S N 1 or S N 2 mechanisms. Distinguishing between both mechanisms requires consideration of inductive and mesomeric effects that could stabilize or destabilize a potential carbocation in the S ...

  6. Mesoionic compounds - Wikipedia

    en.wikipedia.org/wiki/Mesoionic_compounds

    A completely uncharged structure cannot be written and mesoionic compounds cannot be represented satisfactorily by any one mesomeric structure. [1] Mesoionic compounds are a subclass of betaines. [1] Examples are sydnones and sydnone imines (e.g. the stimulant mesocarb), münchnones, [1] [2] and mesoionic carbenes.

  7. Fries rearrangement - Wikipedia

    en.wikipedia.org/wiki/Fries_rearrangement

    In the first reaction step a Lewis acid for instance aluminium chloride AlCl 3 co-ordinates to the carbonyl oxygen atom of the acyl group. This oxygen atom is more electron rich than the phenolic oxygen atom and is the preferred Lewis base .

  8. Republican Senator Mitch McConnell suffers minor injury in ...

    www.aol.com/news/republican-senator-mitch...

    WASHINGTON (Reuters) -U.S. Senator Republican leader Mitch McConnell fell at the U.S. Capitol on Thursday, sustaining minor injuries, but was cleared to resume work, his office said in a statement.

  9. COSMO-RS - Wikipedia

    en.wikipedia.org/wiki/COSMO-RS

    Quantum chemical effects like group-group interactions, mesomeric effects and inductive effects also are incorporated into COSMO-RS by this approach. The COSMO-RS method was first published in 1995 by A. Klamt. [1] A refined version of COSMO-RS was published in 1998 [5] and is the basis for newer developments and reimplementations. [6] [7] [8 ...