Which of the following is secondary radical:

A) CH2 = CH

B) (C H3)3C -

C) C6 H5

D) CH3 (CH2)2 - CH2 -

To determine which of the given options is a secondary radical, we first need to understand what a secondary radical is. A secondary radical is a type of free radical where the unpaired electron is located on a carbon atom that is bonded to two other carbon atoms. This is in contrast to primary radicals, which are bonded to only one carbon, and tertiary radicals, which are bonded to three carbons.

Analyzing the Options

Let’s break down each of the options provided:

• A) CH2 = CH: This is an alkene, specifically ethylene. It does not have a radical structure as it does not contain an unpaired electron.
• B) (C H3)3C -: This represents a tertiary radical. The central carbon is bonded to three methyl groups (CH3), making it a tertiary radical, not secondary.
• C) C6 H5: This is a phenyl group. While it can participate in radical reactions, it is not a radical by itself in this form.
• D) CH3 (CH2)2 - CH2 -: This structure represents a carbon chain where the terminal carbon is bonded to two other carbons (the two CH2 groups). If we consider the radical formed by removing a hydrogen from the terminal CH2, we find that the unpaired electron is on a carbon that is bonded to two other carbons, making it a secondary radical.

Identifying the Secondary Radical

From our analysis, option D (CH3(CH2)2-CH2-) can indeed form a secondary radical. When a hydrogen atom is removed from the second carbon in the chain (the one that is bonded to two other carbons), the resulting radical has the unpaired electron on that carbon, confirming it as a secondary radical.

Conclusion

Therefore, the correct answer is D) CH3(CH2)2-CH2-. This structure can form a secondary radical due to the positioning of the unpaired electron on a carbon that is bonded to two other carbons. Understanding the structure of radicals is crucial in organic chemistry, especially when predicting the behavior of molecules in reactions.