Which has the highest BP? The lowest?

Which has the highest BP? The lowest?

Which will be miscible with each other?

HO

H

O

Alkenes

Addition Reactions

Synthesis

Which is the Nucleophile? The Electrophile?

Addition Reaction is a Two-Step Mechanism

Markovnikov’s Rule

The addition of H-X across a double bond results in the more

highly substituted alkyl halide as the major product.

Addition of HBr or HClMarkovnikov Addition

Markovnikov

Br

C CH

H

HCH3

CH3

HBr

CH3

CH3

C

H

H

C

CH3

CH3C

H

H

Br

C

H

not formed

Regiochemistry Determined by Stability of Intermediate

H-BrBr

H

HBr Br H

3o carbocation

Hyperconjugation

Carbocation Stabilitymore highly substituted, lower energy

3o Carbocation forms Preferentially

What Alkenes are Needed to form these Alkyl Halides?

HBr Addition with RO-ORAnti-Markovnikov

HBr

RO-OR, h

H Br

Free-Radical Mechanism

Initiation:

Propagation: i)

ii)

RO-OR 2 RO

RO + HBr Br + ROH

+ BrBr

Br+ H-Br

H Br+ Br

.

. .

. .

. .

HydrationAddition of H2O

C CH

H

CH3

CH3

H2SO4 (aq)

CH3

CH3C

H

H

H

C

OH

H

C CH

H

HCH3

CH3

H2O

OH

H

C CH

H

HCH3

CH3

H2O

-H

catalytic

Addition of Br2

Br

Br

Br2

A Similar Mechanism to the Addition of HBr?

Trans is formed exclusively(No cis is formed)

Bromonium ion intermediate is formed

Bromonium Ion is Opened Equally from Both Sides

Br2

Br Br Br Br

Br

Br

Br

Br

Br Br + -

Bromonium Ion Intermediate

Bromonium ion

- Br

Br

Br

BrBr

+ BrBr

Catalytic Hydrogenationsyn addition

Mechanism – Syn Addition

Syn Addition of H2

CH3CH3

H2, 1% Pt/C

75 psi

CH3 CH3H H

cis only

Hydrogenationall alkene bonds are reduced

H2, Pt/C

Three mol equivalents of hydrogen gas are consumed.

Hydrogenated Vegetable Oil

Oxymercuration HydrationMarkovnikov additionRegiospecific Reaction

1) Hg(OAc)2 inTHF/H2O

2) NaBH4

OH

H

Oxymercuration Mechanism

OH H

(H )NaBH4

organomercurial alcohol

HgOAc

OH

OAc

HgOAc

OH

H

OAcHgOAc

in H2O

OH2

+

+

Hg

OAc

Hg(OAc)2

Predict the Oxymercuration Hydration Products

What Alkene would you use to Make These Alcohols?

Hydroboration Hydration Anti-Markovnikov

Syn addition

31) BH3-THF

2) H2O2, NaOH

H OH3

BH3 adds to Alkene

Hydroboration

BH3H BH2 H B

HH2

B

H

H H

Trialkylborane

H2O2

OH-

H OH3

3

Alkylborane

Regiochemistry is Anti-Markovnikov

2 Complementary Hydration Reactions

CH3

1) BH3, THF

2) H2O2, NaOH

OH

CH3

H

1) Hg(OAc)2, H2O-THF

2) NaBH4

OH

CH3

Oxymercuration – the more highly substituted alcohol forms

Hydroboration – the less highly substituted alcohol forms

Predict Both Oxymercuration and Hydroboration Products

Epoxidation of Alkenes

Mechanism of Epoxide Formation

Epoxide opens to form a trans-1,2-diol

Alkenes react with basic KMnO4 or OsO4 to form cis-1,2-diols

Oxidation of Alkenes: Draw the major product(s)

KMnO4, NaOH

MCPBA H3O+

Alkenes can be cleaved with acidic KMnO4

Alkenes can be cleaved with acidic KMnO4

Olefinic carbons with H are converted to carboxylic acids.

Olefinic carbons w/out H are converted to ketones.

Terminal olefinic carbons are converted to CO2.

KMnO4, H3O+

O + O

OH

KMnO4, H3O+

O + O C O

Fill in the missing compounds.KMnO4, H3O+

A + B

KMnO4, H3O+

KMnO4, H3O+

D (with a cyclohexyl ring)

O

O

O

OH

+ CO2

C

Problem

The sex attractant of the common housefly is a hydrocarbon named muscalure, with the formula C23H46. On treatment with aqueous acidic KMnO4, two products are obtained, CH3(CH2)12CO2H and CH3(CH2)7CO2H. Propose a structure for muscalure.

Molecular Form ula = C 23H 46

Form ula W eight = 322.61134Com position = C(85.63%) H(14.37%)

OH

O

OH

O

KMnO4, H3O+

Problem

A symmetrical unknown compound A, C8H16, reacts with H2 on a 1% Pt/C catalyst

to form B (C8H18). Treatment of A with

acidic permanganate affords butanone only. Identify A and B.

CH3CCH2CH3

O

butanone

O

butanone

O

HH

H2

O3

A

B

KMnO4, H3O+

Conjugated Dienes

Which of these compounds are conjugated alkenes?

B and C only.

Looking at Buta-1,3-diene

Addition to Conjugated Dienes

resonance forms of the allylic carbocation

The 1,2-addition product is typical Markovnikov.

The 1,4-addition product is due to the resonance forms of the allylic carbocation intermediate.