# This reaction involves two step mechanism.
# This is characteristic reaction of olifiens whose unsaturated double bond e- density is good enough for attach.
MECHANISM AND STEREO CHEMISTRY:
#This reaction's first step involves attach of electrophyl in order to result an cyclic cationic intermediate.
#In the second step the anionic part of reagent attaches on one of the two carbons of cyclic cation in trans manner.
\#Hence this reaction is stereo selective.
REACTIVITY OF ALKYNES TOWARDS E+ ADDITION:
#Though this reaction very much favorable for olifiens , the alkynes are less reactive towards this reaction. This is due to the pi electrons in the triple bond are tightly held by SP hybridized C atoms. Hence they are not available for the attach of electrophyl.
#How ever this reactivity of alkynes increased by Hg2+ like metal ions which can attack on that triple bond.
The mechanism as follow.
ENERGY-PROFILE DIAGRAM:
#Since this reaction involves two types of transitions there will be two peaks in energy-profile diagram.
REACTIVITY OF ALKENES:
#Aalkenes which can capable to form stable carbo cation are more reactive towards this reaction.
For example consider the following alkanes,
Reactivity is in the order 1>2>3>4.
This is because of decreasing of stability of intermediate cation in the given order , because of inductive and hyper conjugation effects.
SOME EXAMPLE REACTIONS:
\*** If u unable to see any diagram just click on that so that u will see complete one.
****For any doubts on this topic contact pavan@chem.iitb.ac.in
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