Which Is More Stable Vinyl Carbocation Or A Primary Carbocation

Vinyl carbocation is unstable.

Which is more stable vinyl carbocation or a primary carbocation.

The difference in stability can be explained by considering the electron withdrawing inductive effect of the ester carbonyl. In a secondary 2 carbocation the carbon with the positive charge is attached to two other alkyl groups which may be the same or different. Carbon with two other atoms attached prefers sp hybridization and a linear geometry. One way of determining carbocation stabilities is to measure the amount of energy to form the carbocation by dissociation of the corresponding alkyl halide while the tertiary alkyl halide dissociates to give carbocations more easily than secondary or primary ones which result in tri substituted carbocations are found to be more stable than di.

It is possible to demonstrate in the laboratory see section 16 1d that carbocation a below is more stable than carbocation b even though a is a primary carbocation and b is secondary. A secondary carbocation has the general formula shown in the box. The alkyl group friend reaches over with an orbital hug but it s not enough to stabilize the burden on the primary carbocation. But carbocation 5 is vinylic carbocation positively charged carbon is sp 2 hybridized i e.

We have one more case in this example with primary carbocations 1 and 5. The hybridization of a vinyl carbocation is sp hybirdized. Carbon of the. In our example the carbocation 4 is more stable than the carbocation 3.

Using the symbol r for an alkyl group a primary carbocation would be written as in the box. The primary carbocation is not stable. Primary phenyl vinyl methyl allyl benzyl methoxymethyl most stable least stable important note. The carbocation 1 is a saturated carbocation which is stabilized by hyperconjugation.

The vinyl cations are less stable due to the difference in hybridization of the carbon bearing. Due to this reason the stability of a primary vinylic carbocation is less than a primary alkyl carbocation. A vinyl cation is a positively charged molecule a cation where the positive charge is located on a vinyl group ch ch2. Vinyl and aryl carbocations are very rare to find due to their low stability.

You will not see a primary carbocation forming under standard conditions.