orgo question attached

[HdK]

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Which works best for this reaction?

The answer is C: Here the base is big, strong, and very sterically hindered. If a 1degree halide reacts, we get the E2 product but the less substituted alkene!

I know that tert butoxide, the bulky base results in the hoffman product. However I thought the answer here would be OH-, because why would you need the bulky base when there is no choice of "less substituted alkene"... If you look at the actual structure, there isn't hoffman or antihoffman product (as in you don't even have a choice), so wouldn't you just go with strong base, strong nucleophile?

 

[Koalafied]

Which works best for this reaction?

The answer is C: Here the base is big, strong, and very sterically hindered. If a 1degree halide reacts, we get the E2 product but the less substituted alkene!

I know that tert butoxide, the bulky base results in the hoffman product. However I thought the answer here would be OH-, because why would you need the bulky base when there is no choice of "less substituted alkene"... If you look at the actual structure, there is hoffman or antihoffman product (as in you don't even have a choice), so wouldn't you just go with strong base, strong nucleophile?

For E2 reactions you should be concerned with strong bases more so than nucleophilicity.

E2 reaction is regioselective; meaning there is a side of preference on the alkene bond during the reaction, especially if you're dealing with an asymmetric alkene bond.

Zaitsev's rules predominates when more bulkier stronger bases are used as the starting reagents which forms highly substituted alkene products (Zaitsev product). Hoffman's rule on-the-other-hand yields generous amounts of less substituted alkene product (Hoffman product) when less bulkier stronger bases are used as the starting reagents. The hydroxide ion is not as stronger of a base than the ethoxide ion; the substituted ethyl group donates election density to the oxygen atom of the entire compound.

 

[FeralisExtremum]

Look, don't make this question more complicated than it needs to be. You know that this reaction can only happen one way: E2. If you use the strong bases besides tert butoxide, such as OH- or OR-, you'd end up with the SN2 product since it's a primary halide and those are strong nucleophiles. Tert butoxide is biased to E2 since it is a strong base but weak nucleophile on account of its bulk. E1 would give us a different product and wouldn't even be an option here since it's a primary halide, so you can knock out the weak base answer choices.

The shortcut to this is identifying an E2 reaction took place, and then going straight for tert butoxide, which is our go-to for causing an E2 reaction.

 

[gtbROX]

Look, don't make this question more complicated than it needs to be. You know that this reaction can only happen one way: E2. If you use anything besides tert butoxide, such as OH- or OR-, you'd end up with the SN2 product since it's a primary halide and those are strong nucleophiles. Tert butoxide is biased to E2 since it is a strong base but weak nucleophile on account of its bulk.

The shortcut to this is identifying an E2 reaction took place, and then going straight for tert butoxide, which is our go-to for causing an E2 reaction.

This hits the nail on the head. The post above it, while accurate and helpful, does not answer the question.

 

[HdK]

Thank you everyone, and ferralis!!