4. Substitution Reactions Flashcards
what happens in a substitution reaction and when does it occur
one group is exchanged for another
occurs when an electrophile is treated with a nucleophile
what is an electrophile known as and what must it contain
substrate
contain a good leaving group
what are 3 common leaving groups
Br, I, Cl
what are halogenated compounds are used as in substitution reactions
electrophiles
what is an alpha carbon
carbon atoms connected directly to halogen
what are beta carbons
carbons connected to the alpha carbon
what are the 2 mechanisms that occur during a substitution reaction
concerted process
stepwise process
what is a concerted process
nucleophilic attack and loss of leaving group occur at the same time
what is a stepwise process
leaving group is lost first and then the nucleophile attacks
what is the rate equation of an SN2 reactions
rate = k[substrate][nucleophile]
what order is the rate equation of SN2 reactions
why
second order
rate is linearly dependent on conc of 2 different compounds
is SN2 a concerted process
yes
when a SN2 reaction occurs what happens to the configuration
inversion of configuration
why does the configuration invert in a SN2 reaction
nucleophile can only attack from the side opposite the leaving group
what alkyl halide is most reactive
how does reactivity decrease
methyl alkyl halide most reactive
reactivity decreases when moving from primary to secondary to tertiary halides
what is steric hindrance responsible for in reactivity and reaction rate of SN2 reactions and why
from extra side chains
decrease in reactivity and reaction rate
why are SN2 reactions slow
steric hindrance
why does SN1 reactions likely to occur
as SN2 is very slow
what is the rate equation for SN1
rate = k[substrate]
what is the SN1 reaction rate dependent on
only the conc of the substrate
will a change in nucleophile conc affect the reaction rate of SN1
no
for SN1 reaction what are the 2 steps involved and which is the rate determining reaction
leaving group leaves first (rate determining step)
nucleophile attacks the carbocation formed
what process does SN1 reaction follow
stepwise process
what is the trend for SN1 compared to SN2
trend for SN1 and SN2 reverse of each other
