1 Chapter 13 Organic Compounds with Oxygen and Sulfur 13.3 Reactions of Alcohols and Thiols Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Combustion of Alcohols Alcohols undergo combustion with O 2 to produce CO 2 and H 2 O. 2CH 3 OH + 3O 2 2CO 2 + 4H 2 O + Heat Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 Alcohols undergo dehydration when heated with an acid catalyst. the loss of —H and —OH from adjacent carbon atoms. H OH | | H +, heat H—C—C—H H—C=C—H + H 2 O | | H H H H alcohol alkene Dehydration of Alcohols

4 Learning Check Write the equations for the reaction of 2-propanol when it undergoes 1. combustion. 2. dehydration.

5 Solution OH │ CH 3 ─CH─CH 3 = 2-propanol = C 3 H 8 O 1. combustion 2C 3 H 8 O + 9O 2 6CO 2 + 8H 2 O 2. dehydration OH │ H + CH 3 ─CH─CH 3 CH 3 ─CH=CH 2 + H 2 O

6 Oxidation and Reduction In an oxidation, there is an increase in the number of C-O bonds. there is a loss of H. In a reduction, there is an decrease in the number of C-O bonds. there is a gain of H.

7 Oxidation and Reduction

8 When a primary alcohol is oxidized, [O], one H is removed from the –OH. another H is removed from the carbon bonded to the OH. an aldehyde is produced. [O] Primary alcohol Aldehyde OH O | [O] || CH 3 —C—H CH 3 —C—H + H 2 O | H Ethanol Ethanal (ethyl alcohol) (acetaldehyde) Oxidation of Primary (1  ) Alcohols

9 Oxidation of Secondary (2  ) Alcohols When a secondary alcohol is oxidized, [O], one H is removed from the –OH. another H is removed from the carbon bonded to the OH. a ketone is produced. [O] secondary alcohol ketone OH O │ [O] ║ CH 3 ─C─CH 3 CH 3 ─C─CH 3 + H 2 O │ H 2-propanol (isopropyl alcohol) 2-propanol (dimethyl ketone)

10 Oxidation of Tertiary ( 3)  Alcohols Tertiary 3  alcohols do not readily oxidize. [O] Tertiary alcoholno reaction OH │ [O] CH 3 ─C─CH 3 no product │ CH 3 no H on the C-OH to oxidize 2-methyl-2-propanol

11 Oxidation of Ethanol in the Body In the body, enzymes in the liver oxidize ethanol. aldehyde product impairs coordination. blood alcohol over 0.4% can be fatal. O O ║ ║ CH 3 CH 2 OH CH 3 CH CH 3 COH 2CO 2 + H 2 O ethyl alcohol acetaldehyde acetic acid

12 Ethanol acts as a depressant. kills or disables more people than any other drug. is metabolized at a rate of mg/dL per hour by a social drinker. is metabolized at a rate of 30 mg/dL per hour by an alcoholic. Ethanol CH 3 CH 2 OH

13 Effect of Alcohol on the Body

14 % EthanolProduct 50%Whiskey, rum, brandy 40%Flavoring extracts 15-25%Listerine, Nyquil, Scope 12%Wine, Dristan, Cepacol 3-9%Beer, Lavoris Alcohol Contents in Common Products

15 Oxidation of Thiols When thiols undergo oxidation, an H atom is lost from each of two –SH groups. the product is a disulfide. [O] CH 3 ─SH + HS─CH 3 CH 3 ─S─S─CH 3 + H 2 O

16 Learning Check Select the product for the oxidation of OH │ [O] CH 3 ─CH─CH 2 ─CH 3 O ║ 1) CH 3 ─CH=CH─CH 3 2) CH 3 ─C─CH 2 ─CH 3 OH │ 3) CO 2 + H 2 O 4) CH 3 ─CH─CH 2 ─CH 3

17 Solution Select the product for the oxidation of OH │ [O] CH 3 ─CH─CH 2 ─CH 3 O ║ 2) CH 3 ─C─CH 2 ─CH 3

18 Select the product when CH 3 —CH 2 —CH 2 —OH undergoes each of the following reactions: A) H +, heatB) [O]C) + O 2 1) CH 3 —CH=CH 2 2) CO 2 + H 2 O O || 3) CH 3 —CH 2 —C—H Learning Check

19 A. H +, heat 1) CH 3 —CH=CH 2 O [O] || B. 3) CH 3 —CH 2 —C—H C. + O 2 2) CO 2 + H 2 O Solution