Question about E2

[Impulse155]

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I thought E2 favored 1 degree > 2nd > 3rd?
Im looking at a destroyer question (62) and it shows 5 molecules and says to rate them.

It says for E2 that 3 degree is the most reactive? Isnt that for E1?

 

[jwest88]

You need a weak base for an E1 reaction to occur. Steric hindrance isn't a problem with E2 reactions b/c protons are pretty easily pulled off. If you have a strong base, E2 is actually the reverse of your order of reactivity. 3 > 2 > 1. Your order of reactivity is correcti for SN2 reactions where steric hindrance is more of a problem. If your base can act as a nucleophile, it will more likely act as a nucleophile when site of attack is less sterically hindered. If more sterically hindered, then your base will act more as a base.