Lithiation often occurs at a position ? to electron withdrawing groups, since they are good at stabilizing the electron-density of the anion.
12.
With three electron withdrawing groups, the negative charge in the complex is located at one of the nitro groups according to the quinoid model.
13.
The molecular orbitals of electron withdrawing groups at C7 overlap with the HOMO Walsh orbitals of the cyclopropane ring causing a shortening of the C1-C6 bond.
14.
In real applications the CX4 atoms would need to be defined more precisely to prevent matching against electron withdrawing groups such as CF3 that would render the amine insufficiently basic to protonate at physiological pH.
15.
The same dienes were shown to react in both [ 6 + 4 ] and [ 4 + 2 ] cycloadditions when the reacting tropone has at least one electron withdrawing group ( EWG ).
16.
If the nucleophile is negatively charged ( e . g . cyanide ) the electron withdrawing group will increase the rate due to stabilization of the extra charge which is put on the carbon in the transition state.
17.
The presence of one moderate electron withdrawing group ( bromine atom ) and two moderate donating groups ( alkyl substituents ) are responsible for bromothymol blue's active indication range from a pH of 6.0 to 7.6.
18.
On the other hand, if the nucleophile is not charged ( e . g . triphenylphosphine ), electron withdrawing group is going to slow down the reaction by decreasing the electron density in the anti bonding orbital of leaving group in the transition state.
19.
If a substituent on the ?-carbon is sufficiently electron withdrawing, the nucleophile will add " anti-" relative to the electron withdrawing group, even if the substituent is not the largest of the 3 bonded to the ?-carbon.
20.
When they possess an electron withdrawing group and an electron donating group at opposite ends of the resonance structure, they have a large shift in charge distribution across the molecule, which causes the solvent molecules to reorient to a less energetic arrangement, called solvent relaxation.
