Alcohol Reactions

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 Cr2O7

2–] ®• 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-catalyzedReferred 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: bB. I: a, d, e; II: c, f; III: bC. I: c, d, e; II: a, f; III: bD. I: c, f; II: a, d, e; III: bE. I: c, e;II: a, d, f; III: b

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