7/8 Flashcards
what is the stereospecificity of sn2 reactions
if the alpha carbon is chiral, during substitution, configuration switches
r turns to s (wedge switches to back)
strong base, weak nucleophile results
E2
strong base, strong nucleophile results
1: some E2, most SN2
2: most E2, some SN2
3: E2
weak base, strong nucleophile results
1: SN2
2: SN2
3: SN1
strong base, strong nucleophile solutions
NaOH, NaOCH3, CN, NaEtOH, NaOMe
weak base, strong nucleophile solutions
NaBr, NaI, NaSH, NaCl
what is the difference between zaitsev and hoffmann products
e2 products
zaitsev is more substituated, stable, common
hofmann is minor product unless bulky base used
when do key players need to be in periplanar positions
E2 when B positions are chiral
in cyclohexenes, the leaving group has to be ____ than the halide
OPPOSITE (one up, one down)
why do alcohols need an acidic solution for reactions
OH is really unstable and needs to pair with another H to become H2O
OH does proton transfer to become H2O+, loss of leaving group, attack from nucleophile
what are polar aprotic solutions
do not have H
best for SN2 because of no hydrogen bonding
nucleophiles free to react
acetone, DMF, DMSO
what are polar protic solutions
contain H that bond with substrate
best for SN1 because they stabilize carbocation
H2O, ethanol, ammonia
what is added in hydrohalogenation
H + X
markovnikov
racemic mixture (both syn and anti)
may do carbocation rearrangements
what is added in hydration
H + OH
3 types
what is added in hydogenation
H + H
what is added in halogenation
X + X
anti (one wedge, one behind) bc backside attack
may have meso so watch out
what is added in halohydrin
OH + X
bromonium ion (Br bridge intermediate) + H2O
anti additon
what is added in dihydroxylation
OH + OH
anti addition: RCO3H, H3O
syn addition: OsO4/KMnO4, H2O
markovnikov vs anti markovnikov
markovnikov: regiochemical preferences (Cl goes to more substituted spot rather than H)
anti is opposite
what are racemic mixtures
the 2 enantiomers produced appear in equal amounts 50/50 that X is on wedge or behind
why does it matter to do carbocation rearrangements
not the most stable molecule so it shifts
not a racemic mixture of results anymore, some will bond before shift happens
what is acid catalyzed hydration
addition of H + OH across a double bond in presence of catalyst (acid (H, H2SO4, H30)
markovnikov
racemic mixture
what happens in acid catalyzed reactions with dilute H2SO4 and more H20
addition
what happens in acid catalyzed reactions with concentrated H2SO4 and less H20
elimination
what is oxymercuration/demercuration
markovnikov addition of H + OH across an alkene without carbocation rearrangement
HgOAc
what is hydroboration oxidation
H + OH in presence of BH3, THF
anti markovnikov
syn addition
what is catalytic hydrogenation
H + H in with catalyst (Pt)
syn addition when applicable (2 chiral centers), sometimes no need to worry bc 0 or 1 chiral center
what is ozonolysis
reactions that add across an alkene and cleave C=C bond
