Organic Chemstry Chapter 8 - Alkene Addition Reactions

Conditions of addition

low temperature, decreased entropy

Conditions of elimination

High temperature, increased entropy

What hydrohalogenation rxn looks like

hydrohalogenation markovnikov or anti?

Markovnikov if H-X

Anti if H-X & ROOR

hydrohalogenation reagents (markovnikov)

H-X (HCl, HI, HBr)

hydrohalogenation reagants (antimarkovnikov)

H-X & ROOR (peroxide)

hydrohalogenation steps for reaction mechanism

proton transfer

carbocation rearrangement/hydride shift (if possible)

nucleophilic attack

hydrohalogenation stereoselectivity

not stereoselective, will form racemic mixture

what hydration is

adding components of water (H & OH) over pi bond (double bond/alkene)

3 kinds of hydration

acid-catalyzed

oxymercuation-demurcuration

hydroboration-oxidation

what acid-catalyzed hydration rxn looks like

acid-catalyed hydation markovnikov or anti?

markovnikov

acid-catalyzed hydration reagents

something with H2O, often —

H3O+

dilute H2SO4

steps of acid-catalyzed hydration reaction

proton transfer (forms carbocation)

carbocation rearrangement (MAY occur)

nucleophilic attack (forms oxonium ion)

proton transfer again

order of reagents used in acid-catalyzed hydration for mechanisms

H3O+, H2O, H2O

stereoselectivity of acid-catalyzed hydration

forms racemic mixture, not stereoselective

when are acid-catalyzed hydration reactions fastest

with more substituted alkenes (form more stable carbocations)

what oxymercuration demercuration rxn looks like

oxymercuration demercuration reagents

1: Hg(OAc)2 & H2O OR alcohol

2: NaBH4

steps in oxymercuration demercuration rxn

oxymercuration (Add Hg(OAc)2)

demercuration (get rid of Hg(OAc)2 using NaBH4)

oxymercuration demercuration markovnikov or anti markovninov?

markovnikov

oxymercuration demercuration stereoselectivity

syn addition 

what does hydroboration oxidation reaction look like

reagents used for hydroboration oxidation

1: BH3 * THF

2: N2O2 & NaO

hydroboration oxidation markovnikov or antimarkovnikov

anti markovnikov

hydroboration oxidation stereospecificity

syn addition

hydroboration oxidation steps

boron added to most crowded C, hydride added to other C of alkene simulatanesouly, syn addition

Boron is oxidized, loss of leaving group off boron gives product

what does catalytic hydrogenation rxn look like

catalytic hydrogenation reagents

H2

Pd, Pt, Ni, or Wilkinson’s catalyst

catalytic hydrogenation markovnikov or antimarkovnikov

neither - H is added to both carbons on alkene

catalytic hydrogenation stereospecificity

syn addition

what does halogenation rxn look like

halogenation reagents

Cl2, Br2

CHCl3 (non-nucleophilic solvent)

halogenation markovnikov or anti

neither

halogenation stereoselectivity

anti addition

what does halohydrin formation look like

halohydrin formation reagents

Br2/Cl2

H2O

halohydrin order that reagents are used

Br2/Cl2

H2O

H2O

halohydrin markovnikov/antimarkovnikov

neither

halohydin stereoselectivity

anti addition

halohydrin regioselectivity

OH added to most substituted carbon

what does anti dihydroxylation rxn look like

anti dihydroxylation reagents

epoxy acid (RCO3H/MCBPA)

H3O+

anti dihydroxylation mechanism steps

formation of epoxide intermediate

epoxide protonated and nucleophilic attack opens ring (simultaneous)

anti dihydroxylation stereospecificity

anti addition (duh)

what does syn dihydroxylation look like

syn dihydroxylation steps

2 OHs added across pi bond & forms cyclic esters

cyclic esters hydrolyzed

syn dihydroxylation reagents

options

1) OsO4, Na2SO3/H2O

OR catalytic amount of OsO4 & NMO

2) KMnO4, NaOH

3) CH3CO3H & H3O

syn dihydroxylation stereospecificity

syn addition (duh)

what does ozonolysis look like

ozonolysis steps

ozonide formed

ozonide reduced

ozonolysis reagents

1) O3

2) DMS (CH3-S-CH3) or Zn/H2O

types of alkene addition

hydrohalogenation

acid-catalyzed hydration

oxymercuration - demercuration hydration

hydroboration - oxidation hydration

catalytic hydrogenation

halogenation

hydride formation

anti dihydroxylation

syn dihydroxylation

ozonolysis