elimination reactions Flashcards
what is the E2 mechanism
a base attacks a hydrogen atom on the adjacent carbon to the one carrying the leaving group.
the base forms a new bond to the H atom _____ as the C-X bond is broken
at the same time
in E2 the halogenoalkane adopts an _____ conformation
anti-periplanar
what is antiperplanar
the 2 groups of atoms are positioned opposite to each other on either side of the single bond
what is a E isomer
if the 2 highest priority groups on each carbon atom are on opposite sides of the double bond
what is a z isomer
if the 2 highest
what isomer is the most stable
E, as it has less steric strain
what happens in the E2 transition state
the C=C bond is partially formed
unlike the E2 reaction, the E1 does not require …
the molecule to take a certain configuration
in the E1 reaction we use a _____ base compared to the E2
weaker
The number of alkyl groups bonded to the carbon atom in the C-X bond influences the _____ of an E1 reaction
rate
the greater the number of substituents on the C-X bond for E1, the _____ the reaction
faster
is P, S or T best for E1
Tertiary Is best
for E1, which conformation is preferred (E or Z)
E
what is Zaitsev’s rule
The major elimination product is the one produced by deprotonating the carbon atom initially attached to the fewest hydrogen atoms.
what is regioselectivity
the preference of chemical bonding or breaking in one direction over all other possible directions.
when choosing what H to bond to we want to pick the one with the _____ energy hill
lowest
the more alkyl groups there are around the double bond there is an ______ in stability
increase
trans alkenes are ____ stable then cis
more
E2 reaction can exhibit anti-Zaitsev Regiochemistry with a strong, bulky base. So, we form an _____
hafmann product
To much steric bulk causes the _____ transition state.
higher
Increasing the concentration of the base or changing the base with greater basic strength increases the rate of an __ reaction, but not that of an ___ reaction
E2, but not E1
Changing from a poor leaving group to a good leaving group in a halogenoalkane increases the rates of ___
both E2 and E1 reactions.
strong bases tend to favour ___
E2
