Ch. 6 Flashcards
Alkyl Halides are _____ leving groups and ______ nucleophiles with the exception of ______SN1
great
great
Fluorine
Do vinyl halides do SN1, SN2, or neither
Neither
Do aryl halides do Sn2, SN1 or neither
Neither
Nomenclature (Halogens)
- Find the longest carbon chain, even if the halogen is not bonded to any of those carbons
Geminal dihalide
The two halogens are bonded to the same carbon
Vicinal dihalide
The two halogens are bonded to adjacent carbons
What two properties indicate higher boiling points
Greater mass, greater intermolecular forces
Spherical shape ______ boiling point
decreases
Which halogens are denser than water
Alkyl chlorides with two or more chlorines
Alkyl bromides
Alkyl iodides
(alkyl fluorides ARE NOT)
When adding Br, remove the ______ CH
weakest
Resonance stabilization of a radial makes it ______ to lose an H
easier
A radical wants to be on a tertiary/secondary/primary carbon
tertiary
Nucleophilic substitution
Halide leaving group is replaced by a nucleophile
Elimination
Halide leaving group leaves and electrophile removes a H
Nucleophilic substitution requires an _____ hybridized carbon
sp3
A good leaving group has a ______ pKa of its conjugate acid
Low
Common electrophiles
R-Cl, R-OH, R-OH2+, R-H, R-CH3
Common leaving groups
Cl-, HO-, H2O, H-, CH3-
Common nucleophiles/bases
Cl-, OH-, H2O, CH3-, NH2, NH3
Polar Protic Solvents (Rank F- to I-)
Solvates I- best, then Br-, then Cl-, then F-
Polar aprotic Solvents (Rank F- to I-)
Solvates F- best, then Cl-, then Br-, then I-
Sn2 Rate Law
Rate = k[Nuc][Elect]
SN2 performs a ________ attack
backside atack
Backside Attack
the nucleophile attacks the electrophilic center on the side that is opposite to the leaving group; Inverts stereochemistry
SN2 needs a _______ nucleophile/electrophile
good
What degree of carbon is fastest with Sn2? Which degree doesn’t react? How does steric impact speed
1º is faster than 2º
3º doesn’t react
More sterics, slower rate
A negatively charged nucleophile is ________ that its neutral counterpart
stronger
Nucleophilicty _____ from left to right
decreases`
Nucleophilicity ______ down the periodic table as size and polarizability increase
increases
What is the polarizability effect?
Bigger atoms are more polarizable and better nucleophiles than expected based on pKa alone
SN1 Rate Law
Rate = k[Electrophile]
Which reaction produces both stereoisomers
SN1
Delete
3º > 2º > 1º > Methyl
Polar protic solvnts are best for _____. Why?
SN1, solvates ions through hydrogen bonding
Hammond Postulate
The transition state most closely resembles the starting material/product/intermediate that it is closest to in space
SN1 can react with ____ nucleophiles, SN2 needs ____ nucleophiles
weak
Strong
Do Csp2-X halides react?
NO!
What is a hydride shift? When can it occur?
Shift the H atom and 2 electrons in a bond, when it makes an equally or more stable carbocation
How many carbons can you move over in a hydride shift?
One
Which solvent doesnt have any H bonds
Polar Aprotie
A good nucleophile is a _______ base
strong
