Potassium tert-butoxide is a common base for E2 reactions because it is
_______.
A. weak base
B. an organic base
C. a strong base
D. a bulky base
Potassium tert-butoxide is a common base for E2 reactions because it is:
D. a bulky base.
The tert-butoxide ion (OCH3CH2) has a bulky tert-butyl group attached to the oxygen atom. This bulky group hinders the formation of strong ionic interactions with the reaction substrate, making the base less likely to participate in SN2 reactions. Instead, it favors E2 reactions, which involve the elimination of a leaving group and a proton in a concerted manner. The bulky tert-butyl group helps to minimize steric hindrance during the elimination process, making potassium tert-butoxide an effective base for E2 reactions.
To determine the correct answer, we need to understand the characteristics and reactivity of potassium tert-butoxide.
Potassium tert-butoxide, or potassium \( t \)-butylate (\( \text{K}^+\text{C}(CH_3)_3^-\)), is commonly used as a base in E2 (elimination, bimolecular) reactions. E2 reactions involve the elimination of a leaving group and a proton from adjacent carbon atoms, resulting in the formation of a double bond. Steric hindrance is an important consideration in deciding the appropriate base for an E2 reaction.
A. Weak base: Potassium tert-butoxide is not a weak base. In fact, it is a strong base, meaning it readily accepts protons.
B. An organic base: Potassium tert-butoxide is indeed an organic base, as it contains carbon atoms bonded to hydrogen.
C. Strong base: This is the correct answer. Potassium tert-butoxide is a strong base. Strong bases readily abstract protons and promote the elimination required in E2 reactions due to their high reactivity.
D. Bulky base: This is also a correct statement. Potassium tert-butoxide is a bulky base due to the large tert-butyl group. The sterically hindered nature of this base enables it to preferentially eliminate the least sterically hindered hydrogen atom during an E2 reaction.
Therefore, the answer is C. Potassium tert-butoxide is a strong base.