addition reactions Flashcards
Alkenes and alkynes tend to act as nucleophiles as ____
its easier to break PI bonds than sigma
what happens when we add a strong acid across a alkene
it adds across the double bond
what is the rate determining step in addition reactions
the formation of the carbonation intermediate (breaking the double bond)
benzene rings do not readily undergo additions of ____
why?
acids
The Pi electrons that would be used to form the new bond to H are too heavily stabilised by delocalization.
what is maokovnikov’s rule
the addition of a hydrogen halide to an alkene favours the product in which the proton adds to the alkene carbon that is initially bonded to the greater number of hydrogen atoms.
what is the most stable carbocation
a tertiary one
what do we need to use at a catylist to allow for water to take part in an addition reaction
acid
what acid does not work in an acid-catylsed hydration.
why?
HCl
chlorine is a better nucleophile than water, therefore the Cl would add instead
what happens when we add to a conjugated system
we see 2 different products, two different resonance structures of the SAME carbocation intermediate (look different tho)
what happens when you add an electrophile to a alkene
forms a 3 membered ring
what happens when you add a molecular halogen to an alkene
undergoes anti-addition, this forms a trans product
when reacting an alkene with a molecular halogen we must not …
form a carbocation intermediate, otherwise both syn and anti addition will take place
what happens when we add a molecular halogen with water as a solvent
regular addition reaction with Br on one carbon and OH on the other. it will produce 2 of these, one with bromine at the front and the other at the back
why does water attack instead of bromine even though bromine is a better nucleophile?
water is used as a solvent and is therefore in excess
what type of reaction is forming an epoxide
nucleophile substitution
what happens when we have an unsymmetrical epoxide
the ring opens
Under neutral or basic conditions, a nucleophile attacks an epoxide at the ___ highly alkyl-substituted C atom of the ring, from the side opposite the O atom.
less
the backside attack of epoxides leads to
walden inversion
where does the nucleophile attack the epoxide under acidic conditions?
more highly alkyl-substituted C atom
what is an oxymercuration-reduction reaction
an alternative method of adding water across a double bond.
how do we add H2 across an alkene
it works when its in the presence of either palladium, platinum, or nickel.
what is a poisoned catalyst
a metal catalyst that has been specially treated to decrease its catalytic ability, thus making a slower and more controlled reaction.
what is an example of a poisoned catalyst
lindler’s catalyst
if we use lindlers catalyst we get ____ addition
syn
