Sep 24, 2023 · So, the carbons in vinyl group is "vinylic" carbon and the carbon in the extra methylene bridge is the "allylic" carbon. (Picture source) Regarding the origin of the word, the respective Wikipedia page has a good information. In short: allyl comes from the scientific name for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl ...

Carbo-cations may be stabilized by: (a) π-bonds only at allylic position (b) π-bonds only at vinylic position (c) π-bonds at allylic and benzylic position also (d) -I effect While the answer is obviously not (d), I am really confused about what 'allylic', 'vinylic' and 'benzylic' positions actually mean.

Mar 13, 2018 · For a positive center to be attached to a more electronegative group is destabilizing. Hence the vinylic cation is less stable than a typical alkyl cation. Things are even worse with the aryl carbocation on the right. Here the positive carbon is attached to 2 $\ce{sp^2}$ carbons. Destabilizing the aryl cation even further is its geometry.

Oct 31, 2023 · Clarification: If I wasn't completely clear, my main question is why vinylic carbocations have an empty sp2 orbital while tertiary carbocations have an empty p orbital. I think my problem here is that I have a misunderstanding of "rehybridization" during the formation of a carbocation that I explain above.

Apr 30, 2018 · This is why rearrangements in vinylic carbocations don't occur. (There is a Russian Chemical Reviews article that explains all this, but it's hard to get a copy of this, and their PDFs seem to be corrupted.) References. Shchegolev, A. A.; Kanishchev, M. I. Rearrangements in Vinyl Cations. Russ. Chem. Rev. 1981, 50 (6), 553–564.

May 11, 2013 · when searching in the internet about why are alkenes more polar than alkanes (but still they are non-polar), they are always saying that the double bond is more polarizable , i understood the whole story about how the sp2 attract electrons from the sp3 and forming london forces, but they always said that vinylic bonds are slightly polar but i ...

Oct 2, 2015 · On the other hand, the elimination reaction at a vinylic carbon is quite facile. Here as the base removes a proton we build up negative charge on an $\ce{sp^2}$ hybridized carbon. An $\ce{sp^2}$ orbital has more s-character than an $\ce{sp^3}$ orbital; the more s-character in an orbital the lower the energy of an electron in that orbital.

May 4, 2021 · No, aryl halides are not a type of vinyl halides. A compound is called an aryl halide when it contains a halogen group directly attached to an aromatic system.

The lone pair on the benzene is in the plane of the ring and hence orthogonal to the conjugated $\pi$-system so that it cannot interact with it. It is $\ce{sp^2}$ hybridized just like the vinylic carbanion, which also cannot resonate. Furthermore, both compounds lack an electron withdrawing group, so there is no inductive effect either.

The larger the electron affinity, the more tightly the electron was held. Stable carbanions hold their electron more tightly than less stable carbanions. The electron affinity of the allyl anion was measured as 0.481 eV. For the vinylic carbanion, the EA was measured as 0.667 eV.