How many different heptenes result by partial hydrogenation of all possible, unbranched heptynes?Correct answer is '5'. Can you explain this answer?

Question

Answer

The correct answer is 5.
C=C-C-C-C-C-C , no geometrical isomerism so 1
C-C=C-C-C-C-C 2 , geometrical cis trans
C-C-C=C-C-C-C , cis trans again so 2
∴ 2+2+1=5

Answer

Answer

Little dirty c//c-ccccc no geometrical isomerism so 1
c-c//c-cccc 2 geometrical cis trans
c-c-c//c-ccc cis trans again so 2
2+2+1=5,where
// denotes double bond

Answer

There are several possible heptynes (C7H12) that can undergo partial hydrogenation to form different heptenes (C7H14). Let's analyze the process step by step to determine how many different heptenes can be obtained.

1. Unbranched heptynes:
Unbranched heptynes are those with a linear carbon chain of seven carbon atoms and a triple bond. The general formula for an unbranched heptyne is C7H12. There are several possible structural isomers of heptynes, including:

- 1-Heptyne
- 2-Heptyne
- 3-Heptyne
- 4-Heptyne
- 5-Heptyne

2. Partial hydrogenation:
Partial hydrogenation is a chemical reaction where hydrogen gas (H2) is added to a molecule, typically in the presence of a catalyst. This reaction converts the triple bond of the heptyne into a double bond, resulting in the formation of heptenes.

3. Different heptenes:
To determine the number of different heptenes that can be obtained, we need to consider the various possibilities of adding hydrogen atoms across the double bond. The position of the double bond in the heptene molecule can vary, resulting in different structural isomers. The possible positions for the double bond in a heptene are:

- Between carbon atoms 1 and 2
- Between carbon atoms 2 and 3
- Between carbon atoms 3 and 4
- Between carbon atoms 4 and 5
- Between carbon atoms 5 and 6
- Between carbon atoms 6 and 7

4. Analysis:
Now, let's analyze the possible combinations of heptynes and heptenes:

- For 1-Heptyne, the double bond can be formed between carbon atoms 1 and 2.
- For 2-Heptyne, the double bond can be formed between carbon atoms 1 and 2 or between carbon atoms 2 and 3.
- For 3-Heptyne, the double bond can be formed between carbon atoms 1 and 2, between carbon atoms 2 and 3, or between carbon atoms 3 and 4.
- For 4-Heptyne, the double bond can be formed between carbon atoms 1 and 2, between carbon atoms 2 and 3, between carbon atoms 3 and 4, or between carbon atoms 4 and 5.
- For 5-Heptyne, the double bond can be formed between carbon atoms 1 and 2, between carbon atoms 2 and 3, between carbon atoms 3 and 4, between carbon atoms 4 and 5, or between carbon atoms 5 and 6.

5. Conclusion:
By analyzing the possible combinations, we find that there are five different heptenes that can be obtained through the partial hydrogenation of all possible unbranched heptynes. Hence, the correct answer is '5'.

To summarize:
The possible unbranched heptynes are 1-Heptyne, 2-Heptyne, 3-Heptyne, 4-Heptyne, and 5-Heptyne. The number of different heptenes that can be obtained through partial hydrogenation is determined by the possible

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