Reactive Intermediates
In chemistry, reactive intermediates are termed as short-lived, highly reactive atoms with high energy. They rapidly transform into stable particles during a chemical reaction. In specific cases, by means of matrix isolation and at low-temperature reactive intermediates can be isolated.
Hydride Shift
A hydride shift is a rearrangement of a hydrogen atom in a carbocation that occurs to make the molecule more stable. In organic chemistry, rearrangement of the carbocation is very easily seen. This rearrangement can be because of the movement of a carbocation to attain stability in the compound. Such structural reorganization movement is called a shift within molecules. After the shifting of carbocation over the different carbon then they form structural isomers of the previous existing molecule.
Vinylic Carbocation
A carbocation where the positive charge is on the alkene carbon is known as the vinyl carbocation or vinyl cation. The empirical formula for vinyl cation is C2H3+. In the vinyl carbocation, the positive charge is on the carbon atom with the double bond therefore it is sp hybridized. It is known to be a part of various reactions, for example, electrophilic addition of alkynes and solvolysis as well. It plays the role of a reactive intermediate in these reactions.
Cycloheptatrienyl Cation
It is an aromatic carbocation having a general formula, [C7 H7]+. It is also known as the aromatic tropylium ion. Its name is derived from the molecule tropine, which is a seven membered carbon atom ring. Cycloheptatriene or tropylidene was first synthesized from tropine.
Stability of Vinyl Carbocation
Carbocations are positively charged carbon atoms. It is also known as a carbonium ion.
![27. Explain why in this reaction an increase in temperature does not cause a different product to
form.
HI
-50 °C
28. Give the major product of each reaction. Assume 1 equivalent of reactant in each case.
HBr
HCI
a.
-78 °C
-78 °C
HBr
HCI
b.
25 °C
50 °C
29. Give the major product of each Diels Alder reaction. Show stereochemistry where needed
(cis/trans, endo/exo). Indicate if a racemic mixture is formed.
CH;0
160
a.
H.
heat
b.
heat
OCH, +
C.
CI](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc4c42384-b7f2-4727-bf03-6b339e288722%2F5761c779-c504-47af-b8bb-bd095d940750%2Flak71yx_processed.jpeg&w=3840&q=75)
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