Reaction Mechanisms

SN1

• rate: k[AH]

• substrate: tertiary AH

• stereochemistry: equal R and S

• favors: low temps, polar protic

E1

• rate: k[AH]

• substrate: 3 > 2 > 1 AH

• stereochemistry: E-favored

• favors: high temps, polar protic

SN2

• rate: k[AH][Nu]

• substrate: 1 or 2 AH

• stereochemistry: 100% inverted

• favors: SN/WB, polar aprotic

E2

• rate: k[AH][B]

• substrate: 3>2>1 AH

• stereochemistry: needs anti periplanar

• favors: WN/SB, ltemps, polar aprotic

hydrohalogenation (alkene)

• reagents: HX

• CCR possible

• alkene → alkyl halide

• R: mark; S: —

modified hydrobromination (alkene)

• reagents: HBr, ROOR

• alkene → alkyl halide (only Br)

• R: anti-mark; S: —

acid-catalyzed hydration (alkene)

• reagents: H3O+ or H2SO4+H2O

• CCR possible

• alkene → alcohol

• R: mark; S: —

acid-catalyzed ether formation (alkene)

• reagents: HOR, H+

• CCR possible

• alkene → ether

• R: mark; S: —

oxymercuration-demercuration (alkene)

• reagents:

1. Hg(OAC)2, H₂O

2. NABH4

• alkene → alcohol

• R: mark; S: —

modified oxymercuration-demercuration (alkene)

• reagents:

1. Hg(OAC)2, HOR

2. NABH4

• alkene → ether

• R: mark; S: —

alkene halogenation

• adds two halogens across a double bond

• reagents: X₂, CCl₄ (or any NPS like CH2Cl2)

• R: mark; S: anti

alkene halohydrin formation

• adds a halogen to one side, an alcohol to the other (Mark) side

• reagents: X₂, H2O

• R: mark; S: anti

alkene haloether formation

• adds a halogen to one side, an ether to the other (Mark) side

• reagents: X₂, HOR

• R: mark; S: anti

alkene hydroboration-oxidation

• adds alcohol to anti-mark side

• reagents:

1. BH3/BBN-9, THF

2. H2O2, HO-

• R: anti-mark; S: syn

alkene syn dihydoxlation

• makes syn diols; adds OH to both sides of a double bond

• reagents:

1. OSO4, pyr/NMO/tBuOOH/NaOH

2. NAHSO3, H2O

• R: —; S: syn

alkene epoxide formation via peroxyacid

• makes an epoxide (three ringed thing with an oxygen)

• reagents:

• RCO3H or mCPBA

• R: —; S: syn

alkene epoxide formation via halohydrin

• makes an epoxide (three ringed thing with an oxygen)

• reagents:

1. X2, H2O

2. NaOH/any strong base

• R: —; S: syn

alkene anti dihydoxylation

• opens up an epoxide, with one alcohol being wedged and the adjacent one dashed

• reagents:

1. RCO3H (makes epoxide)

2. H3O+ (opens epoxide)

• R: —; S: anti

alkene hydrogenation

• alkene → alkane (deletes pi bond except for in arenes)

• reagents: H2, Pt or Pd/C or Ni or Pd

• R: —; S: syn

alkene ozonolysis

• cuts a pi bond down the middle. the carbon on each end turns into a ketone, aldehyde, or formaldehyde

• reagents:

1. O3

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

• R: —; S: —

alkyne hydrohalogenation

• alkyne → alkene → two halogens on one carbon

• reagents: 1eq HX twice

• R: mark; S: —

alkyne modified hydrobromination

• alkyne → alkene → two bromines on one carbon

• reagents: 1eq HBr and ROOR twice

• R: mark; S: —

• mixture of E/Z isomers

alkyne halogenation

• alkyne → trans alkene with halogen on both sides → two halogens on each side

• reagents: 1eq X₂ twice

• R: mark; S: anti

alkyne acid-catalyzed hydration

• alkyne → alkene with alcohol → ketone

• reagents: H2O, H2SO4, HgSO4, then tautomerization

• R: mark; S: —

alkyne hydroboration-oxidation

• alkyne → alkene with alcohol → aldehyde

• reagents:

1. R2BH, THF or 9-BBN

2. HO-, H2O2

• R: anti-mark; S: —

alkyne catalytic hydrogenation

• alkyne → alkane

• reagents: H2, Pt/Pd/Pd on C/Ni

• R: — ; S: syn

alkyne poisoned catalytic hydrogenation

• alkyne → alkene

• reagents: H2, Lindlar’s catalyst

• R: —; S: syn

alkyne dissolving metal reduction

• alkyne → alkene

• reagents: Na or Li, NH3

• R: —; S: anti

alkyne ozonolysis

• alkyne → alcohol + CO2

• reagents:

1. O3

2. H2O

• R: —; S: —

alkyne chain extension

• the only one that you can use to add a C!!

• alkyne → alkyne with charge at end → alkyne with R at end

• reagents:

1. NaNH2, NH3

2. R—Br

• R: —; S: —