Today we covered both the E1 and E2 reactions. In both cases, we use a Lewis base to abstract a proton from the substrate (at a carbon next to the carbon with the leaving group) and form an alkene. There are differences, however: The E2 is a single-step reaction and the stereochemistry of the product is determined at the beginning of the reaction. The E1 reaction is two steps and the presence of the intermediate allows for C-C bond rotation, therefore the stereochemistry is not set until the second step of the reaction.
We started to look at how to determine which of the four possible reactions (SN1,SN2, E1, E2) would take place under a particular set of reaction conditions, with the promise of more to come next Monday and Wednesday.
Over the weekend a copy of last year's exam will be posted, along with a podcast of the material from today's lecture and an elimination problem set. I am also hoping to get some more substitution problems posted to give you more practice with drawing arrows.
The picture shows what it is all about -- a pair of electrons is moved according to the direction of an arrow, from Lewis base to Lewis acid.
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