**Exercise: Identifying the Major Product in a Chemical Reaction** In this exercise, you are tasked with selecting the major product of a given chemical reaction. The reaction is initiated by bromination in the presence of light (\(Br_2 / h\nu\)). The structure of the starting compound is an alkene: \[ \text{Reactant: } \] A simple alkene structure is shown where a double bond is present. The choices for the major product are depicted as follows: 1. **Option 1:** - An alkane structure with a bromine atom attached to a terminal carbon. 2. **Option 2:** - An alkene structure with a bromine atom attached to the second carbon. 3. **Option 3:** - An alkene structure with a bromine atom attached to the first carbon adjacent to the double bond. 4. **Option 4:** - An alkene structure with a bromine atom on a carbon that supports a branching point. 5. **Option 5:** - None of these. **Task:** Analyze the given options and determine which one represents the major product of this bromination reaction under the given conditions. Consider the stability of carbocation intermediates and the likelihood of bromine addition in your reasoning.
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.
![**Exercise: Identifying the Major Product in a Chemical Reaction**
In this exercise, you are tasked with selecting the major product of a given chemical reaction. The reaction is initiated by bromination in the presence of light (\(Br_2 / h\nu\)). The structure of the starting compound is an alkene:
\[ \text{Reactant: } \]
A simple alkene structure is shown where a double bond is present.
The choices for the major product are depicted as follows:
1. **Option 1:**
- An alkane structure with a bromine atom attached to a terminal carbon.
2. **Option 2:**
- An alkene structure with a bromine atom attached to the second carbon.
3. **Option 3:**
- An alkene structure with a bromine atom attached to the first carbon adjacent to the double bond.
4. **Option 4:**
- An alkene structure with a bromine atom on a carbon that supports a branching point.
5. **Option 5:**
- None of these.
**Task:**
Analyze the given options and determine which one represents the major product of this bromination reaction under the given conditions. Consider the stability of carbocation intermediates and the likelihood of bromine addition in your reasoning.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F2a35b697-38d2-4033-9241-845115dff029%2Fc82e864a-0b65-4222-98f5-b683954f55e6%2Fp17mjzf.jpeg&w=3840&q=75)
Allylic bromination is carried out in the presence of light (hv). In presence of light this reaction produces the free radical intermediates.
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