dehydration Flashcards
what are the key features of a dehydration
protonation of oh creates a good leaving group
what is the key features of an E1 mechanism
loss of water produces carbocation intermediate
alcohols leading to more stable carbocation will react faster
carbocations may undergo rearrangement
most stable alkene forms as the major product
what is the key requirement of an E2 mechanism
it requires an anti-periplanar geometry
what makes a good catalyst?
must be strong enough to protonate alchohol
must not be nucleophillic
alcohols that form more stable carbocations react
faster
Benzylic, allylicm and tertiary alcohols undergo what type of mechanism and whats the rate
they undergo rapid elimination
what type of conditions are required for secondary and primary alcohols to undergo E1
heat and extreme condtions
what is the rate limiting step in an E1
the loss of water leading to a carbocation
what is zaitsev’s rule
it is the formation of the most stable alkene that is thermodynamically favorable
what do the relative percentages of major and minor products depend on
the substrate and the reaction temperature
what is a rearrangement
less stable carbocations can readily rearrange to more stable carbocations through 1,2 hydride or methyl shifts
when will a ring expansion occur
when a carbocation of equal stability is rearranged to form a more stable overall compound
when do rearrangements to less stable carbocations occur
when there is a subsequent carbocation rearrangement that leads to a more stable one
when will an E2 occur
when the substrate cannot form a stable intermediate
why do we wash the fractions with h2O, NaHCO3, and dry
to remove traces of acid
