Which of the following has the highest value of pKa?
Correct answer: D. CH3 - CH(CH3) - CH2OH
- A. CH3 - CH2OH
- B. CI - CH2 - CH2OH
- C. F3C - CH2 - OH
- D. CH3 - CH(CH3) - CH2OH
Explanation
To find which compound has the highest pKa, we need to identify the weakest acid among the choices. pKa is inversely related to acidity: a higher pKa indicates a weaker acid. In this case:Option A (ethanol) has a moderate acidity.Option B (2-chloroethanol) has increased acidity due to the electronegative chlorine atom, resulting in a lower pKa.Option C (trifluoroethanol) is even more acidic due to the presence of three fluorine atoms, which significantly stabilize the conjugate base, leading to a very low pKa.Option D (2-propanol) is a tertiary alcohol, which is less acidic than both ethanol and the halogenated alcohols, making it the correct answer with the highest pKa.Thus, the correct answer is Option D.
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