Question

What is a bulky base in regards to elimination reactions? Other than t-BuO . Looking for instances where I would apply Hoffman with a base other than t-BuO. Is NaOEt an example. Just want to know how to deterimine it. Is it just a bigger base? What's the cutoff? Thank you

Answer 1

Lithium di-isopropyl amide (LDA) is another base.

NaOEt is not a bulky base as t-BuO^-. NaOEt will give Zaitsev product.

Cutoff is just a trival word and doesn't have any correlation.

t-butoxide – is an extremely bulky base, and the proton we want to remove to form the Zaitsev product from a tertiary carbon. As the oxygen from the base draws nearer to this proton, a steric clash occurs. In essence the electron clouds around the methyl groups are interacting with each other, and the repulsion between these clouds will raise the energy of the transition state (remember – opposite charges attract, like charges repel).