Condensed OCHEM1 Exam 4

E2

WN/SB, all substitutions

SN/SB, secondary and tertiary

Sn2

SN/SB, primary

SN/WB, primary and secondary

Sn1

SN/WB, tertiary

WN/WB, secondary and tertiary

solvolysis

E1

SN/WB with heat, tertiary

WN/WB with heat, secondary and tertiary

stereospecific

100% inversion

Sn2 and E2

anti or syn

stereoselective

racemic mix with slightly more inversion

Sn1 and E1

regioselective

1 carbon over the other

Markovnikov or Anti-Markovnikov

chemoselective

only one functional group reacts

TsCl/MsCl/TfCl, pyr

converting an alcohol to be a better leaving group

OH to OTs/OMs/OTf, nothing else changes

HX (X=Cl, Br, I)

hydrohalogenation

mark, no pref

carbocation intermediate

forms alkyl halide

HBr and ROOR

modified hydrobromination

anti-mark, no pref

forms alkyl halide with bromine attached

H3O+ or H2SO4 and H2O

acid catalyzed hydration

mark, no pref

forms an alcohol

carbocation intermediate

HOR, H+

acid catalyzed ether formation

mark, no pref

forms an ether

carbocation intermediate

1. Hg(OAC)2, H20

2. NaBH4

oxymercuration demercuration

mark, anti/no pref

forms an alcohol

1. Hg(OAC)2, HOR

2. NaBH4

modified oxymer-demer

mark, no pref

forms an ether

X2, CCl4/CH2Cl2 (X = Br or Cl)

halogenation

mark, anti

vicinal dihalide (X gets added to each side of double bond)

X2, H2O (X = Br or Cl)

halohydrin formation

mark, anti

alcohol on mark side, X on other side

X2, HOR (X = Br or Cl)

haloether formation

mark, anti

ether on mark side, X on other side

1. BH3/R2BH/9-BBN, THF

2. H2O2, -OH

hydroboration-oxidation

anti-mark, syn

alcohol on anti-mark side

1. OsO4, pyr/NMO/tBuOOH

2. NaHSO3, H2O

or KMNO4, NaOH, cold

syn dihydroxylation

no regioselectivity, syn

forms a syn diol (two alcohols on each side of bond facing the same direction)

RCO3H/mCPBA

epoxide formation via peroxyacid

no regioselectivity, syn

forms epoxide (O attached to both sides of bond in a ring facing the same direction)

1. X2, H2O

2. NaOH/any strong base

epoxide formation via halohydrin

no regioselectivity, syn

forms epoxide (O attached to both sides of bond in a ring facing same direction)

1. RCO3H

2. H3O+

anti dihydroxylation

no regioselectivity, anti

step one makes an epoxide, second step opens it and adds H

forms trans diol (two alcohols on each side of bond facing opposite directions)

H2, Pt/Ni/Pd/Pd on C

hydrogenation/catalytic hydrogenation for alkynes

no regioselectivity, syn

forms an alkane

H added on either side of bond facing same direction, will NOT reduce double bond in an arene

1. O3

2. Zn, H+/(CH3)2S

ozonolysis

no regioselectivity or stereospecificity

splits double bonds down the middle, product often multiple fragments or a long chain

“most reactive” or “react fastest”

what kind of reaction? → what kind of substitution is ideal

leaving group ability → weak bases

“react fastest with dilute acid”

most stable carbocation intermediate (double tertiary for example)

“which starting material would produce product in highest yields”

largest difference in substitutions

or obvi see where product was formed and put double bond between it and the alpha carbon

rate limiting step

when carbocation is formed

optically active

chiral

non meso

non racemic

largest heat of hydrogenation

most unstable alkene

lowest heat of hydrogenation

most stable alkene

excess HX (Br, Cl, I)

hydrohalogenation of an alkyne

mark, no pref

forms two X attached to mark side of alkyne

excess HBr, ROOR

modified hydrobromination of alkyne

anti mark, no pref

vinyl halide intermediate formed w eq HBr and ROOR will be mix of E/Z

final product is two Br attached to anti-mark side of alkyne

excess X2 (Br or Cl)

halogenation of an alkyne

mark, anti

2 X on each side of alkyne

H2O, H2SO4, HgSO4

acid catalyzed hydration of alkyne

initially forms alcohol with double bond, tautomerized to a ketone

mark, n/a

HgSO4 necessary for terminal alkynes but can be used for internal too

1. R2BH/9-BBN, THF

2. HO-, H2O2

hydroboration oxidation of an alkyne

initially forms alcohol with a double bond, tautomerizes into an aldehyde

anti-mark, n/a

H2, Lindlar’s Catalyst

poisoned catalytic hydrogenation of an alkyne

n/a, syn

forms alkene only

Na/Li, NH3 at -78C

dissolving metal reduction of an alkyne

forms an alkane

n/a, anti

avoid terminal alkynes

1. O3

2. H2O

ozonolysis of an alkyne (cleaves down the triple bond)

no regioselectivity or stereospecificity

forms a carboxylic acid and/or CO2

1. NaNH2, NH3 at -78C

2. R-Br

chain extension of an alkyne

intermediate is acetylide anion, alkylated by primary alkyl halide, extending the chain

no regioselectivity or stereospecificity