Orgo 1 reactions and reactants

Elimination reactions to prepare alkenes

E2 and E1 reactions

Hydrohalogenation

Reagents: HX

- Markovnikov product

- watch for carbocation rearrangements

Hydration (acid-catalyzed)

Reagents: H2O, H2SO4

Stereochem: racemic

- Markovnikov product (rearrangements possible)

Hydration (oxymercuration)

Reagents: 1) Hg(OAc)2, H2O 2) NaBH4

- Markovnikov product (no rearrangement)

Halogenation (w/o peroxides)

Reagents: X2

- anti addition of X2

Sterochem: anti addition

Halohydrin formation

Reagents: X2 + H2O

- H2O on more substituted

- Anti addition

Hydroboration-oxidation

Reagents: 1) BH3 2) H2O2, NaOH

- Anti Markovnikov product

- Syn addition of H and OH

Reduction of alkenes to give alkanes

- Hydrogenation

Reagents: H2 + metal catalyst (Pd, Pt, Ni)

- alkene -> alkane

- syn addition of H2

Oxidative cleavage of alkenes

- Ozonolysis

Reagents: 1) O3 2) DMS or Zn

- breaks double bond into 2 carbonyls (aldehydes or ketones)

Epoxidation of alkenes

Reagent: mCPBA (or peracids like RCO3H)

- alkene -> epoxide

- Syn addition of oxygen

Reduction of alkynes to give alkanes

Reagents: H2 + metal catalyst (Pt, Pd, Ni)

- alkyne -> alkane

- adds 2x equiv of H2

Reduction of alkynes to give alkenes

Reagent: H2 / Lindlar catalyst

- Cis (Z) alkene

Reagent: Na or Li metal / NH3 (l)

Oxidative cleavage of alkynes

Reagents: O3 / H2O or KMnO4 (hot, conc.)

- internal alkyne -> 2 carboxylic acids

- terminal alkyne -> carboxylic acid + CO2

Hydration of alkynes

Reagents: HgSO4, H2SO4, H2O

- Markovnikov ketone

- first enol -> tautomerizes -> ketone

- terminal alkyne -> methyl ketone

- internal alkyne -> mixture of ketones

Hydroboration/oxidation of alkynes

Reagents: 1) BH3 2) H2O2, OH(-)

- Anti Markovnikov

- Terminal alkyne -> anti mark aldehyde (always aldehyde, never ketone)

- internal alkyne -> mixture of ketones

- enol -> tautomerizes -> aldehyde

Addition of HX to alkynes

Reagents: HX

- 1 equiv -> vinyl halide (Markovnikov)

- 2 equiv - geminal dihalide (both halogens on same C) (Markovnikov)

Addition of X2 to alkynes

- Halogenation

Reagents: X2

- 1 equiv -> Trans dihalide alkene (anti addition)

- 2 equiv -> tetrahalide

Alkynes homologation (with alkyl halides)

1) Reagent: NaNH2

- forms acetylide anion

2) Reagent: R-X (primary)

- extends carbon chain (SN2)

Alkynes homologation (with alkyl tosylates)

1) Reagent: NaNH2

- forms acetylide anion

2) Reagent: R-OTs (primary)

- extends carbon chain (SN2)

Alkynes homologation (with epoxides)

Reagents: 1) Acetylide anion 2) H2O

- forms alcohol after ring opening

- attack happens at less substituted carbon

NaH

- strong base (non nu)

- Deprotonates alcohols (ROH -> RO-)

- Deprotonates terminal alkynes

H2SO4

- Acid catalyst / dehydrating acid

- Alcohol -> Alkene (E1; rearrangements possible)

- hydration of alkenes (alkene + H2O -> alcohol) (E1 or acid-catalyzed addititon - Zaitsev, rearrangements possible)

TsOH

- strong acid like H2SO4

- Dehydrates alcohols -> alkenes (E1)

POCl3, pyridine

- dehydration of alcohols w/o rearrangement

- Alcohol -> Alkene (E2; Zaitsev)

HX

- Alcohol + HX -> Alkyl halide (SN1 or SN2)

- Alkene + HX -> Markovnikov alkyl halide

- Alkyne + HX -> vinyl halide or geminal dihalide (Markovnikov)

ZnCl2

- alcohols -> alkyl halides

- makes OH a good LG

SOCl2

- OH -> Cl

- alcohol -> alkyl chloride

- usually with pyridine

PBr3

- OH -> Br

- alcohol -> alkyl bromide

- usually with pyridine

TsCl

- makes tosylate

- ROH -> ROTs (good LG)

H20/H2SO4

-Hydration

- Alkene + water -> alcohol (Markovnikov)

X2, H2O

- halohydrin formation

- anti addition (Markovnikov OH)

1) BH3, 2) H2O2, OH(-)

- Hydroboration-oxidation

- Alkene -> alcohol (anti-Markovnikov, syn add.)

- Alkyne -> aldehyde (anti-Markovnikov hydration, syn add.)

NaNH2

- very strong base

- alkyne deprotonation -> acetylide ion

- double elimination of vicinal/geminal halides -> alkyne

- E2 and deprotonation

KOC(CH3)3 in DMSO

- t-BuOK

- bulky base -> Hofmann elimination

- E2 elimination (Hofmann)

H2O, H2SO4, HgSO4

- oxymercuration for alkynes

- Markovnikov hydration of alkynes

- terminal alkyne -> ketone

- enol -> keto tautomerization

1) R2BH 2) H2O2, HO(-)

- Hydroboration-oxidation of alkynes

- anti-Markovnikov hydration

- terminal alkyne -> aldehyde (via enol -> keto) (syn add.)