A trick question!!!

[annygirl]

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When optically pure 2,3-dimethyl-2-butanol was subjected to dehydration, a mixture of 2 alkenes was obtained. Hydrogeneation of these alkenes gave 2,3-dimethylbutane which was 50% optically pure. What were the two alkenes formed in the elimination reaction and what were the reletive amounts of each?

okay, now, I know the two products are 2,3 dimethyl 2 butene, and 2,3 dimethyl 1 butene. the thing i really would love to know are what are the freakin' amounts? I know the 2,3 dimethyl 2 butene should be more highly favored because it is the more substituted alkene, but i would still love to know what the hell the amounts are. please? 😳

many thanks in advance...🙂

 

[annygirl]

ummm, bump?

 

[HBomb]

Where did you get this question? First, it is whacked because neither the reactant or the products are optically active....so there's no optically pure/impure anything. How do I know this? Because they don't have chiral centers!!! But that's not answering your question. The answer to your question depends on the reaction conditions and there is no way for you to tell without experimentation. So my point is that you don't need to know the amounts...none of us know it unless we look it up (or do the experiment). I do agree that the internal alkene is more thermodynamically favorable then the terminal alkene, but you already know that, so you're in good shape for the DAT!!!