Rank the following carbon radicals in order of decreasing stability: ${\mathrm{CH}}^3\cdot$ (methyl radical), $\mathrm{CH}{3}_2\mathrm{CH}\cdot$ (secondary radical), $\mathrm{CH}{3}_{3}C\cdot$ (tertiary radical), $\mathrm{CH}{3}_1\mathrm{CH}\cdot$ (primary radical).

• A. ${\mathrm{CH}}^3\cdot$ > $\mathrm{CH}{3}_1\mathrm{CH}\cdot$ > $\mathrm{CH}{3}_2\mathrm{CH}\cdot$ > $\mathrm{CH}{3}_{3}C\cdot$
• B. $\mathrm{CH}{3}_2\mathrm{CH}\cdot$ > $\mathrm{CH}{3}_{3}C\cdot$ > $\mathrm{CH}{3}_1\mathrm{CH}\cdot$ > ${\mathrm{CH}}^3\cdot$
• C. $\mathrm{CH}{3}_1\mathrm{CH}\cdot$ > $\mathrm{CH}{3}_2\mathrm{CH}\cdot$ > ${\mathrm{CH}}^3\cdot$ > $\mathrm{CH}{3}_{3}C\cdot$
• D. $\mathrm{CH}{3}_{3}C\cdot$ > $\mathrm{CH}{3}_2\mathrm{CH}\cdot$ > $\mathrm{CH}{3}_1\mathrm{CH}\cdot$ > ${\mathrm{CH}}^3\cdot$

Answer: (D)

Verified step by step guidance

1. Identify the types of carbon radicals given: methyl radical (\( \mathrm{CH_3\cdot} \)), primary radical (\( \mathrm{CH_3CH_2\cdot} \)), secondary radical (\( \mathrm{(CH_3)_2CH\cdot} \)), and tertiary radical (\( \mathrm{(CH_3)_3C\cdot} \)).
2. Recall that the stability of carbon radicals generally increases with the number of alkyl groups attached to the radical center due to hyperconjugation and inductive effects. Alkyl groups donate electron density and help stabilize the unpaired electron.
3. Rank the radicals by considering the degree of substitution: tertiary radicals are the most stable because they have three alkyl groups donating electron density, secondary radicals are next, followed by primary radicals, and finally methyl radicals are the least stable as they have no alkyl substituents.
4. Express the stability order as: \( \mathrm{(CH_3)_3C\cdot} > \mathrm{(CH_3)_2CH\cdot} > \mathrm{CH_3CH_2\cdot} > \mathrm{CH_3\cdot} \).
5. Understand that this order is supported by both experimental data and theoretical considerations involving hyperconjugation and the inductive effect, which stabilize the radical center by delocalizing the unpaired electron.