Alcohol Reactions

Alcohol Reactions

Conversions to esters (Acetate Lab)

Reactions with hydrogen halides

Acid-catalyzed hydrations

Esterification

condensation

Fischer esterification

acid catalyzed

reversible

Esterification

ROH H2O+

H+

+R'COH

O

R'COR

O

Example of Fischer Esterification

H2O+

CH3OH+COH

O

COCH3

O

H2SO4

0.1 mol 0.6 mol

70% yield based on benzoic acid

High yields

Not reversible when carried outin presence of pyridine.

Reaction of Alcohols with Acyl Chlorides

ROH HCl+ +R'CCl

O

R'COR

O

pyridine

+ CClO2N

OCH3CH2

CH3

OH

(63%)

NO2

CH3CH2

CH3

OC

O

Example

analogous to acyl chlorides

Reaction of Alcohols with Acid Anhydrides

ROH + +R'COR

OO

R'COCR'

O

R'COH

O

pyridine

(83%)

+C6H5CH2CH2OH

O

F3CCOCCF3

O

C6H5CH2CH2OCCF3

O

Example

Reactions of Alcohols

“Poor”

Reactions of Alcohols

Oxidation

Conversion to ethers

Oxidation of Alcohols

Primary alcohols

from H2O

Oxidation of Alcohols

RCH2OH

O

RCH

O

RCOH

Secondary alcohols

O

RCR'RCHR'

OH

In aqueous solution:

Mn(VII) Cr(VI)

KMnO4 CrO3/ H2SO4 = H2CrO4

K2Cr2O7 / H2SO4 = H2Cr2O7

Strong Oxidizing Agents

Oxidize 1o alcohols to carboxylic acids.

Cannot stop at aldehydes.

Aqueous Cr(VI)

FCH2CH2CH2CH2OH

K2Cr2O7

H2SO4

H2O

FCH2CH2CH2COH

(74%)

O

Na2Cr2O7

H2SO4

H2O

(85%)

H

OH

O

Question

• Treatment of 1-propanol with K2Cr2O7,

H2SO4, and heat will produce:

• A) B)

• C) D)

A.

B.

C.

D.

H2CrO4, acetone 35o C

OH

OH

O

O

OH

O

OH

O

H

O

O

O

What is the product of the following reaction?

Question

Used in CH2Cl2

Pyridinium dichromate (PDC)

(C5H5NH+)2 Cr2O7

2–

Pyridinium chlorochromate (PCC)

C5H5NH+ ClCrO3–

“Collins Reagent”

Specialized Oxidizing Agents[Nonaqueous Sources of Cr(VI)]

Jones Reagent:

CrO3/ H2SO4 acetone

(does not affect Carbon=Carbon double bonds;

oxidizes 2o alcohols to ketones)

Example: Oxidation of a Primary Alcohol with PCC

CH3(CH2)5CH2OHPCC

CH2Cl2

O

CH3(CH2)5CH

(78%)

ClCrO3–

N

H

+

Question

• What is the product of the reaction of 1-butanol with PCC in CH2Cl2?

• A) B)

• C) D)

A.

B.

C.

D.

xs PCC, CH2Cl2, 25o C

OH

OH

O

O

OH

O

OH

O

H

O

O

O

 What is the product of the following reaction?

Question

PDC CH2Cl2

O

(94%)

CH2OH(CH3)3C

CH(CH3)3C

Example: Oxidation of a Primary Alcohol with PDC

Question• For the following reaction, select the statement that

best describes it.

RCH2OH + PDC [(C5H5NH+)2 Cr2O72–] ®

• A) The alcohol is oxidized to an acid, and the Cr(VI) is reduced.

• B) The alcohol is oxidized to an aldehyde, and the Cr(VI) is reduced.

• C) The alcohol is reduced to an aldehyde, and the Cr(III) is oxidized.

• D) The alcohol is oxidized to a ketone, and the Cr(VI) is reduced.

Conversion of Alcohols to Ethers

RCH2O

H

CH2R

OH

H+

RCH2O CH2R H OH+

Conversion of Alcohols to Ethers

Acid-catalyzed

Referred to as a "condensation"

Equilibrium; most favorable for primary alcohols

Example

2CH3CH2CH2CH2OH

H2SO4, 130°C

CH3CH2CH2CH2OCH2CH2CH2CH3

(60%)

Intramolecular Analogue

HOCH2CH2CH2CH2CH2OH

H2SO4 130°

O

(76%)

via:

O

H

+O

H

H

••••••

Reaction normally works well only for5- and 6-membered rings.

Question • When 1-propanol is treated with

Na2Cr2O7/H2SO4 followed by treatment with

CH3OH, H2SO4 the product isolated is:

• A) propanal B) propanoic acid

• C) propanol D) methyl propanoate

Question

I. Oxidation

II. Reduction

III. Neither oxidation or

reduction

A. I: a, c, d; II: e, f; III: b

B. I: a, d, e; II: c, f; III: b

C. I: c, d, e; II: a, f; III: b

D. I: c, f; II: a, d, e; III: b

E. I: c, e;II: a, d, f; III: b

Classify the following as oxidation, reduction or neither oxidation or reduction