In E2 elimination, which factor influences the major product, and what does a bulky base favor?

• A. Base bulkiness; bulky bases favor the Hofmann product (less substituted alkene).
• B. Base strength; stronger bases favor the Hofmann product.
• C. Solvent polarity; polar solvents favor the Hofmann product.
• D. Temperature; higher temperatures favor the Hofmann product.

Answer: (A)

In E2 elimination, the regioselectivity is governed mainly by steric effects in the transition state: which β-hydrogen the base can access while the leaving group departs anti to it. A bulky base interacts with the substrate in a more hindered way, so it preferentially abstracts the less hindered β-hydrogen. This leads to the formation of the less substituted alkene, known as the Hofmann product.

So the factor being tested is base bulkiness, and a bulky base favors the Hofmann product (the less substituted alkene). Base strength, solvent polarity, and temperature can influence reaction rate or general conditions, but they don’t dictate the regioselectivity as much as the steric size of the base does.