Question

The alkane from below having two secondary hydrogens is:

• A. 2,2,4,4-Tetramethylhexane
• B. 2,2,3,3-Tetramethylpentane
• C. 4-Ethyl-3,4-dimethyloctane
• D. 2,2,4,5-Tetramethylheptane

Hint:

When identifying secondary hydrogens, look for the carbon atoms attached to two other carbon atoms. These positions will have the secondary hydrogens.

Answer 1

The Correct Option is B

Identifying secondary hydrogens in alkanes involves understanding the structure of each carbon atom and its connected hydrogen atoms. A secondary hydrogen atom is attached to a secondary carbon. A secondary carbon is bonded to two other carbon atoms. Let's analyze each option:

1. 2,2,4,4-Tetramethylhexane: The structure of this alkane does not have any secondary carbons, as all carbons hosting hydrogens are either primary or quaternary.
2. 2,2,3,3-Tetramethylpentane: This alkane has a structure where the 2nd and the 3rd carbon in the parent chain are secondary, each bonded to two other carbons. Therefore, it houses secondary hydrogens.
3. 4-Ethyl-3,4-dimethyloctane: Although it has complex branching, secondary hydrogens are minimal and scattered, not fulfilling the requirement of having two secondary hydrogens effectively derived from a single parent carbon chain.
4. 2,2,4,5-Tetramethylheptane: This alkane predominantly contains primary and tert-carbon atoms, with limited secondary hydrogen accessibility.

Given these insights, the alkane 2,2,3,3-Tetramethylpentane is the correct answer as it distinctly contains two secondary hydrogens due to the presence of adequate secondary carbon atoms in its structure.