Why do the researchers think these are SN2 and E2, rather than SN1 and E1?.Researchers have developed ways to study competition between two reactions in the gas phase by using mass spectrometry. Does that match what you know about this reaction? Explain.Based on the KIE shown above, would you expect this reaction to be:.Assuming that k 13 has a rate of 100 s -1, what would the k 12 rate be?.For the KIE given for this reaction, which reaction is faster?.In this case, small α-carbon KIEs near 1% are indicative of a carbocation reaction, while larger KIEs of up to 8% for a concerted substitution mechanism. This isotope effect is different from the earlier example in the workbook because we are looking a different reaction than the nucleophilic substitution at a carbonyl. Draw the two possible mechanisms for this reaction.Matsson, Dybala-Defratyka, Rostkowski, Paneth and Westaway, J. The kinetic isotope effect can help determine mechanism type. Kinetic isotope effect (KIE) is the ratio of rate constants for a reaction run with a light (k L) isotope in the and the rate constant for the same reaction with a heavy (k H) isotope: Overall, the _ stable alkene is obtained unless it is too _.If one product is obtained via removal of a more accessible proton, circle it.Sometimes, the least stable alkene forms instead. In most cases, formation of the most stable alkene is favoured. If one product is more stable, circle it.In the following cases, more than one elimination product is possible. Fill in the MO interaction diagram for this interaction with electrons.In the following diagram, show how a conjugation effect can stabilize the alkene.It could form stabilizing overlap with a (filled / empty) orbital. A pi bond is a (filled / empty) orbital.Propose a structural factor that seems to correspond with this trend.įormally, this trend is sometimes explained via hyperconjugation.In alkenes, the order of stability is given below: When faced with two different products, it can be useful to evaluate their relative stability. Circle two protons that could be removed, leading to two different elimination products.Regiochemistry refers to where in the molecule a reaction takes place.įrom the following alkyl halide, two different eliminations could occur.
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