Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 12 Organic Compounds with Oxygen and Sulfur 12.3 Reactions of Alcohols and Thiols 1

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Dehydration of Alcohols Alcohols undergo dehydration when heated with an acid catalyst the loss of –H and –OH from adjacent carbon atoms, producing an alkene H OH | | H +, heat H—C—C—H H—C=C—H + H 2 O | | H H H H alcohol alkene 2

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation of 1  Alcohols Alcohols undergo oxidation, increasing the number of carbon and oxygen bonds. Primary alcohols are oxidized to produce an aldehyde. 1 bond to O 2 bonds to O H OH H O | | oxidation | || H—C—C—H | | | H H H 1  alcohol aldehyde 3

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation of 1  Alcohols Alcohols undergo oxidation, increasing the number of carbon and oxygen bonds. Aldehydes can further oxidize to produce a carboxylic acid. 1 bond to O 2 bonds to O H O H O | || oxidation | || H—C—C—H H—C—C—OH | H aldehyde carboxylic acid 4

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation of 2  Alcohols Secondary alcohols are oxidized to produce a ketone. To indicate the process of oxidation, [O] is placed over the reaction arrow. 1 bond to O 2 bonds to O H OH H H O H | | | [O] | || | H—C—C—C—H | | | | | H H H H H 2  alcohol ketone 5

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation of Tertiary 3  Alcohols Tertiary (3  ) alcohols do not readily oxidize. OH CH 3  C  CH 3 [O]no product CH 3 no H to oxidize 3  alcohol no reaction 6

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. 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 a decrease in the number of C–O bonds there is a gain of H 7

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation and Reduction 8

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Methanol Poisoning Methanol is also known as methyl alcohol is highly toxic and found in windshield washer fluid, Sterno, and paint strippers is rapidly absorbed and oxidized to formaldehyde and then formic acid O O [O] [O] CH 3 OH H  CH H  COH methyl alcohol formaldehyde formic acid 9

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Ethanol, CH 3 CH 2 OH Ethanol acts as a depressant and kills or disables more people than any other drug is metabolized at a rate of 12–15 mg/dL per hour by a social drinker is metabolized at a rate of 30 mg/dL per hour by an alcoholic 10

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Effect of Alcohol on the Body 11

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Oxidation of Thiols When thiols undergo oxidation, an H atom is lost from each of two –SH groups the product is a disulfide protein in hair is cross-linked by disulfide bonds found in the amino acid cysteine 12

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Select the product for the oxidation of OH [O] CH 3  CH  CH 2  CH 3 O A. CH 3  CH=CH  CH 3 B. CH 3  C  CH 2  CH 3 OH C. CO 2 + H 2 O D. CH 3  CH  CH 2  CH 3 13

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Select the product for the oxidation of OH [O] CH 3  CH  CH 2  CH 3 O The answer is B. CH 3  C  CH 2  CH 3 14

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Select the product when CH 3 –CH 2 –CH 2 –OH undergoes each of the following reactions: [O] [O] CH 3 —CH 2 —CH 2 OH B. C. 1) CH 3 —CH=CH 2 2) CO 2 + H 2 O O || 3) CH 3 —CH 2 —C—H O || 4) CH 3 —CH 2 —C—OH 15

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Select the product when CH 3 –CH 2 –CH 2 –OH undergoes each of the following reactions: O [O] B. 3) || CH 3 —CH 2 —CH 2 OH CH 3 —CH 2 —C—H [O] O C. 4) || CH 3 —CH 2 —C—OH 16

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Give the primary product for the reaction of 2-propanol when it undergoes A. oxidation B. dehydration 17

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution OH CH 3  CH  CH 3 = 2-propanol = C 3 H 8 O A. oxidation OH O [O] 2CH 3  CH  CH 3 + 9O 2 CH 3  C  CH 3 + 6CO 2 + 8H 2 O B. dehydration OH H +, heat CH 3  CH  CH 3 CH 3  CH=CH 2 + H 2 O 18