1 Lecture 4 Alcohols, Phenols, and Thiols Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Midterm II Outcome Class Average: 75 High Score: 103 Low Score: 32

3 Alcohols and Phenols An alcohol contains  A hydroxyl group (—OH) attached to a carbon chain. A phenol contains  A hydroxyl group (—OH) attached to a benzene ring. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

4 Alcohols are classified  By the number of alkyl groups attached to the carbon bonded to the hydroxyl.  As primary (1°), secondary (2°), or tertiary (3°). Primary (1º) Secondary (2º) Tertiary (3º) 1 group 2 groups 3 groups H CH 3 CH 3 | | | CH 3 —C—OH CH 3 —C—OH CH 3 —C—OH | | | H H CH 3 Classification of Alcohols

5 Classify each alcohol as (P) primary, (S) secondary, or (T) tertiary. OH | 1. CH 3 —CH—CH 2 —CH 3 2. CH 3 —CH 2 —CH 2 —OH OH | 3. CH 3 —CH 2 —C—CH 2 —CH 3 | CH 3 Learning Check

6 Naming Alcohols The names of alcohols  In the IUPAC system replace -e of alkane name with - ol.  that are common names use the name of the alkyl group followed by alcohol. FormulaIUPACCommon Name CH 4 methane CH 3 ─OH methanol methyl alcohol CH 3 ─CH 3 ethane CH 3 ─CH 2 ─OH ethanol ethyl alcohol

7 More Names of Alcohols In IUPAC names for longer carbon chains, the chain is numbered from the end nearest the ─OH group. CH 3 ─CH 2 ─CH 2 ─OH 1-propanol OH │ CH 3 ─CH─CH 2 ─CH 3 2-butanol CH 3 OH │ CH 3 ─CH─CH 2 ─CH 2 ─CH─CH 3 5-methyl-2-hexanol

8 Some Typical Alcohols OH | “rubbing alcohol”CH 3 —CH—CH 3 2-propanol (isopropyl alcohol) antifreeze HO—CH 2 —CH 2 —OH 1,2-ethanediol (ethylene glycol) OH | glycerolHO—CH 2 —CH—CH 2 —OH 1,2,3-propanetriol Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

9 Learning Check Give the IUPAC name for each of the following: 1. CH 3 —CH 2 —CH 2 —CH 2 —OH OH CH 3 | | 2. CH 3 —CH—CH—CH 2 —CH 3 3.

10 Write the structure of the following: A. 3-pentanol B. ethyl alcohol C. 3-methylcyclohexanol Learning Check

11 Naming Phenols To name a phenol with two substituents,  Assign C-1 to the carbon attached to the –OH.  Number the ring to give the lowest numbers.  Use prefixes o, m, and p for common names. Phenol 3-chlorophenol 4-bromophenol (m-chlorophenol) (p-bromophenol)

12 Phenols in Medicine Phenol  Is the IUPAC name for benzene with a hydroxyl group.  Is used in antiseptics and disinfectants. phenol resorcinol 4-hexylresorcinol

13 Derivatives of Phenol  Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

14 Write the structure of each of the following: A. 3-pentanol B. ethyl alcohol C. p-methylphenol Learning Check

15 Thiols  Are carbon compounds that contain a –SH group.  Are named in the IUPAC system by adding ­thiol to the alkane name of the longest carbon chain.

16  In thiols with long carbon chains, the chain is numbered to locate the –SH group. CH 3 —CH 2 —CH 2 —SH 1-propanethiol SH | CH 3 —CH—CH 3 2-propanethiol Naming Thiols

17 Thiols  Often have strong odors.  Are used to detect gas leaks.  Are found in onions, oysters, and garlic. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

18 Learning Check Draw the structure of each compound. A. 2-butanethiol B. 2-methyl-1-butanol

19 Learning Check Name each of the following compounds: OH | A. CH 3 —CH 2 —CH—CH 3 CH 3 | B. CH 3 —CH 2 —CH—CH 2 —CH 2 —OH C.CH 3 —CH 2 —CH 2 —SH

20 Pause: Group Activity Do the following problems on ALE 4  Problem # 1, parts A to F  Problem # 2, parts A to D

21 Ethers  Contain an ─O─ between two carbon groups.  That are simple are named by listing the alkyl names in alphabetical order followed by ether CH 3 ─O─CH 3 CH 3 ─CH 2 ─O─CH 3 dimethyl ether ethyl methyl ether

22 IUPAC Names for Ethers  In the IUPAC system, the shorter alkyl group and the oxygen are named as an alkoxy group attached to the longer alkane. methoxy propane CH 3 —O—CH 2 —CH 2 —CH  Numbering the longer alkane gives 1-methoxypropane

23 Ethers as Anesthetics Anesthetics  Inhibit pain signals to the brain.  Such as ethyl ether CH 3 ─CH 2 ─O─CH 2 ─CH 3 were used for over a century, but caused nausea and were flammable.  Developed by 1960s were nonflammable. Cl F F Cl F H │ │ │ │ │ │ H─C─C─O─C─HH─C─C─O─C─H │ │ │ │ │ │ F F F H F H Ethane(enflurane) Penthrane

24 MTBE Methyl tert-butyl ether CH 3 │ CH 3 ─O─C─CH 3 │ CH 3  Is one of the most produced organic chemicals.  Is a fuel additive  Is used to improve gasoline combustion.  Use is questioned since the discovery that MTBE has contaminated water supplies.

25 Learning Check Draw the structure of each compound. A. diethyl ether B. ethyl methyl ether C. 2-methoxybutane

26 Cyclic Ethers A cyclic ether  Contains an O atom in a carbon ring.  Is called a heterocyclic compound.  Typically has 5 (furan) or 6 atoms (pyran) in the ring. furan tetrahydrofuran pyran 1,4-dioxane

27 Dioxins Dioxins are  A group of ethers that are highly toxic.  Formed during forest fires and as industrial by- products.  Often carcinogenic. 2,4,5-trichlorophenoxyacetic acid 2,3,7,8-tetrachlorodibenzodioxin (2,4,5-T; agent orange) (TTCC, “dioxin”)

28 Learning Check Name each of the following: 1. 2.

29 Pause: Group Activity Do the following problems on ALE 4  Problem # 1, parts G to I  Problem # 2, parts E to F

30 Lecture Physical Properties of Alcohols, Phenols, and Ethers Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

31 Boiling Points of Alcohols Alcohols  Contain a strongly electronegative O in the OH groups.  Form hydrogen bonds between alcohol molecules.  Have higher boiling points than alkanes and ethers of similar mass. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

32 Boiling Points of Ethers Ethers  Have an O atom, but no H is attached.  Cannot form hydrogen bonds between ether molecules. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

33 Solubility of Alcohols and Ethers in Water  Alcohols and ethers are more soluble in water than alkanes because the oxygen atom hydrogen bonds with water.  Alcohols with 1-4 C atoms are soluble, but alcohols with 5 or more C atoms are not. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

34 Comparing Solubility and Boiling Points CompoundMolarBoiling Soluble Mass Point (°C) in Water? Alkane CH 3 ─CH 2 ─CH No Ether CH 3 ─O─CH Yes Alcohol CH 3 ─CH 2 ─OH Yes

35 Solubility of Phenol Phenol  Is soluble in water.  Has a hydroxyl group that ionizes slightly (weak acid).  Is corrosive and irritating to the skin. + H 2 O + H 3 O +

36 Learning Check Which compound would have the higher boiling point? Explain. ethyl methyl ether or 1-propanol

37 Learning Check Which compound would be more soluble in water? Explain. ethanol or 2-pentanol

38 Pause: Group Activity Do the following problems on ALE 4  Problem # 3  Problem # 4

39 Lecture Reactions of Alcohols and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

40 Combustion of Alcohols Combustion is the reaction of an alcohol with O 2 to produce CO 2 and H 2 O. 2CH 3 OH + 3O 2 2CO 2 + 4H 2 O + Heat Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

41 Dehydration of an alcohol occurs  When heated with an acid catalyst.  With 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

42 Learning Check Write the equations for the reactions when 2-propanol undergoes: 1. combustion 2. dehydration

43 Formation of Ethers  Ethers form when dehydration takes place at low temperature. H + CH 3 —OH + HO—CH 3 CH 3 —O—CH 3 + H 2 O two methanol dimethyl ether

44 Oxidation and Reduction In the oxidation of an organic compound  There is an increase in the number of C—O bonds.  There is a loss of H. In the reduction of an organic compound  There is an decrease in the number of C—O bonds.  There is a gain of H.

45 Oxidation and Reduction Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

46 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

47 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-propanone(dimethyl ketone, “acetone”)

48 Oxidation of Tertiary (3)  Alcohols Tertiary 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

49 Select the compound that would result for each reaction of CH 3 —CH 2 —CH 2 —OH. O || 1) CH 3 —CH=CH 2 2) CO 2 + H 2 O 3) CH 3 —CH 2 —C—H A. H +, heat B. [O] C. O 2, heat Learning Check

50 Oxidation of Ethanol in the Body In the body,  Ethanol is oxidized by enzymes in the liver.  Aldehyde product impairs coordination. O ║ ║ CH 3 ─CH 2 ─OH CH 3 ─C─H CH 3 ─C─OH ethyl alcohol acetaldehyde acetic acid 2CO 2 + H 2 O

51 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 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

52 Effect of Alcohol on the Body TABLE 13.2 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

53 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

54 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

55 Pause: Group Activity Do the following problems on ALE 4  Problem # 5