7-Aklyl Halides and Nucleophilic Substitution Flashcards
boiling point of alkyl halides (increase/decrease) as the size of R increases
INCREASE
Melting point of alkyl halides (increase/decrease) as the size of R increases
INCREASE
Boiling point of alkyl halides (increase/decrease) as the size of
X increases
increase
Melting point of alkyl halides (increase/decrease) as the size of X increases
increase
alkyl halides are (insoluble/soluble) in organic solvents
soluble
alkyl halides are (insolble/insoluble) in water
insoluble
alkyl halides undergo ______ reactions with NUCLEOPHILES
substitution
alkyl halides undergo ______ reactions with BRONSTED-LOWRY BASES
elimination
The better leaving group is the (weaker/stronger) base
weaker
across a row, basicity (increases/decreases)
decreases
across a row, leaving group ability (increases/decreases)
increases
Down a column, basicity (increases/decreases)
decreases
Down a column, leaving group ability (increases/decreases)
increases
Good leaving groups have (high/low) pKa
low
When the leaving group is a weaker base than the nucleophile the (reactants/products) are favored?
products
Nucleophiles normally attack?
carbons
nucleophilicity (increases/decreases) as basicity (increases/decreases)
increase-increase or decrease-decrease
As the number of R groups on the carbon with the leaving group increases, the rate of the SN2 reaction (increases/decreases)
decreases
Rate of SN2 reactions (substitution of R group)
(fastest)CH3-X > RCH2-X > R2CH-X > R3C-X (slowest)
SN2 Mechanism
kinetics
second order
rate=k[RX][Nu:-]
SN2 Mechanism
mechanism
one step
SN2 Mechanism
stereochemistry
backside attack of the nucleophile
inversion of configuration at a stereogenic center
SN2 Mechanism
identity of R and rate
CH3-X > RCH2X > R2CHX > R3CX
SN2 reactions have ___ step(s)
one
SN1 reactions have ___ step(s)
two
______ are formed as a reactive intermediate in an SN1 reaction
cabocations
As the number of R groups on the carbon with the leaving group increases, the rate of the SN1 reaction (increases/decreases)
increases
Rate of SN1 reactions (substitution of R group)
(slowest) CH3-X < RCH2-X < R2CH-X < R3C-X(fastest)
SN1 Mechanism
kinetics
first order
rate=k[RX]
SN1 Mechanism
mechanism
two steps
SN1 Mechanism
stereochemistry
trigonal planar carbocation intermediate
racemization at a single stereogenic center
SN1 Mechanism
identity of R and rate
R3CX > R2CHX > RCH2X > CH3X
carbocation stability
(least stable)CH3 < RCH2 < R2CH < R3C(most stable)
Vocab:
spreading our charge by the overlap of an empty p orbital with an adjacent sigma bond is called
hyperconjugation
as alkyl substitution increases, dispersal of positive charge (increases/decreases)
increases
rate of an SN1 reaction (increases/decreases) as the stability of the carbocation (increases/decreases)
increase-increase or decrease-decrease
increasing alkyl substitution favors ___
SN1
decreasing alkyl substitution favors ___
SN2
strong nucleophiles favor (SN1/SN2)
SN2
weak nucleophiles favor (SN1/SN2)
SN1
SN1 reactions favor polar (protic/aprotic) solvents
protic
SN2 reactions favor polar (protic/aprotic) solvents
aprotic
solvent that contains an O-H or N-H bond
polar protic
solvent does NOT contain an O-H or N-H bond
polar aprotic
