Search results
Results from the WOW.Com Content Network
The +M effect, also known as the positive mesomeric effect, occurs when the substituent is an electron donating group. The group must have one of two things: a lone pair of electrons, or a negative charge. In the +M effect, the pi electrons are transferred from the group towards the conjugate system, increasing the density of the system.
Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.
This effect is depicted in scheme 3, where, in a para substituted arene 1a, one resonance structure 1b is a quinoid with positive charge on the X substituent, releasing electrons and thus destabilizing the Y substituent. This destabilizing effect is not possible when X has a meta orientation. Scheme 3. Hammett Inductive Mesomeric Effects
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.
Other structural factors that influence the magnitude of the acid dissociation constant include inductive effects, mesomeric effects, and hydrogen bonding. Hammett type equations have frequently been applied to the estimation of pK a. [3] [4] The quantitative behaviour of acids and bases in solution can be understood only if their pK a values ...
The more you earn, the more you pay. Since 2007, a beneficiary’s Part B monthly premium is based on his or her income. About 8% of Medicare users earn too much to qualify for the standard Part B ...
It is often said the resonance stability of phenol makes it a stronger acid than that of aliphatic alcohols such as ethanol (pK a = 10 vs. 16–18). However, a significant contribution is the greater electronegativity of the sp 2 alpha carbon in phenol compared to the sp 3 alpha carbon in aliphatic alcohols.
Lizzo's name has been dropped from a harassment lawsuit that rocked the singer's reputation last year when it alleged a hostile work environment on her 2023 European tour, according to reports.. A ...