Chapter 12 Organic Compounds with Oxygen and Sulfur 12.1 Alcohols, Ethers, and Thiols Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Alcohols An alcohol contains a hydroxyl group (—OH) attached to a carbon chain. A phenol contains a hydroxyl group (—OH) attached to a benzene ring. water alcohol phenol Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming Alcohols The names of alcohols in IUPAC replace the -e with -ol. with common names use the name of the alkyl group followed by alcohol. Formula IUPAC Common Name CH4 methane CH3─OH methanol methyl alcohol CH3─CH3 ethane CH3─CH2─OH ethanol ethyl alcohol

More Names of Alcohols IUPAC names for longer chains number the chain from the end nearest the -OH group. CH3─CH2─CH2─OH 1-propanol OH │ CH3─CH─CH2─CH3 2-butanol CH3 OH │ │ CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-hexanol 6 5 4 3 2 1

Some Typical Alcohols | “rubbing alcohol” CH3—CH—CH3 2-propanol (isopropyl alcohol) antifreeze HO—CH2—CH2—OH 1,2-ethanediol (ethylene glycol) glycerol HO—CH2—CH—CH2—OH 1,2,3-propanetriol

Learning Check Name the following compounds. 1. CH3—CH2—CH2—CH2—OH OH CH3 | | 2. CH3—CH—CH—CH2—CH3 3.

Solution OH CH3 | | 2. CH3—CH—CH—CH2—CH3 3-methyl-2-pentanol 1. CH3—CH2—CH2—CH2—OH 1-butanol OH CH3 | | 2. CH3—CH—CH—CH2—CH3 3-methyl-2-pentanol 3. cyclopentanol

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

Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint.

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. 1 1 3 4 3-chlorophenol 4-bromophenol

Learning Check Write the structure of each of the following. A. 3-pentanol B. ethyl alcohol C. 4-methylphenol

Solution Write the structure of the following. A. 3-pentanol OH | CH3—CH2—CH—CH2—CH3 B. ethyl alcohol CH3—CH2—OH C. 4-methylphenol O H C 3

Classification of Alcohols Classification of alcohols is determined by the number of alkyl groups attached to the carbon bonded to the hydroxyl. primary (1°), secondary (2°), or tertiary(3). Primary (1º) Secondary (2º) Tertiary (3º) 1 group 2 groups 3 groups H CH3 CH3 | | | CH3—C—OH CH3—C—OH CH3—C—OH | | | H H CH3

Learning Check 1) primary, 2) secondary, or 3) tertiary. OH | Classify each alcohol as 1) primary, 2) secondary, or 3) tertiary. OH | A. CH3—CH—CH2—CH3 B. CH3—CH2—CH2—OH C. CH3—CH2—C—CH2—CH3 CH3

Solution | A. CH3—CH—CH2—CH3 secondary B. CH3—CH2—CH2—OH primary C. CH3—CH2—C—CH2—CH3 tertiary CH3

Thiols 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. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Thiols Thiols often have strong odors. are used to detect gas leaks. are found in onions, oysters, and garlic.

Ethers An ether contains an ─O─ between two carbon groups. has a common name that gives the alkyl names of the attached groups followed by ether. CH3─O─CH3 CH3─CH2─O─CH3 dimethyl ether ethyl methyl ether

Learning Check Write the structure of the following. A. 3-pentanol B. diethyl ether

Solution OH | A. 3-pentanol CH3─CH2─CH─CH2─CH3 B. diethyl ether CH3─CH2─O─CH2─CH3

Ethers as Anesthetics Anesthetics inhibit pain signals to the brain. like diethyl ether CH3─CH2─O─CH2─CH3 were used for over a century, but caused nausea and were flammable. developed by the 1960’s were nonflammable. Cl F F Cl F H │ │ │ │ │ │ H─C─C─O─C─H H─C─C─O─C─H F F F H F H Ethane(enflurane) Penthrane

MTBE Methyl tert-butyl ether CH3 │ CH3─O─C─CH3 is second in production of organic chemicals. is an additive used to improve gasoline performance. use is questioned since the discovery that MTBE has contaminated water supplies.

Chapter 12 Organic Compounds with Oxygen and Sulfur 12.2 Properties of Alcohols, Ethers, and Thiols Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Boiling Points of Alcohols contain polar OH groups. form hydrogen bonds with other alcohol molecules. have higher boiling points than alkanes and ethers of similar mass. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Boiling Points of Ethers do not have a polar group. have an O atom, but there is no H attached. cannot form hydrogen bonds between ether molecules. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Solubility of Alcohols and Ethers in Water are more soluble in water than alkanes because the oxygen atom can hydrogen bond with water. with 1-4 C atoms are soluble, but not with 5 or more C atoms.

Comparing Solubility and Boiling Points Molar Boiling Soluble Compound Mass Point (°C) in Water? Alkane CH3─CH2─CH3 44 -42 No Ether CH3─O─CH3 46 -23 Yes Alcohol CH3─CH2─OH 46 78 Yes

Solubility of Phenol Phenol is soluble in water. has a hydroxyl group that ionizes slightly (weak acid). is corrosive and irritating to skin. + H2O + H3O+

Chapter 12 Organic Compounds with Oxygen and Sulfur 12.3 Reactions of Alcohols and Thiols Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Combustion of Alcohols Alcohols undergo combustion with O2 to produce CO2 and H2O. 2CH3OH + 3O2 2CO2 + 4H2O + Heat Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Dehydration of Alcohols 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 + H2O | | | | H H H H alcohol alkene

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

Solution OH │ CH3─CH─CH3 = 2-propanol = C3H8O 1. combustion 2C3H8O + 9O2 6CO2 + 8H2O 2. dehydration │ H+ CH3─CH─CH3 CH3─CH=CH2 + H2O

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.

Oxidation and Reduction

Oxidation of Primary (1) Alcohols 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] || CH3—C—H CH3—C—H + H2O | H Ethanol Ethanal (ethyl alcohol) (acetaldehyde)

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] ║ CH3─C─CH3 CH3─C─CH3 + H2O │ H 2-propanol (isopropyl alcohol) 2-propanol (dimethyl ketone)

Oxidation of Tertiary ( 3)Alcohols Tertiary 3alcohols do not readily oxidize. [O] Tertiary alcohol no reaction OH │ [O] CH3─C─CH3 no product │ CH3 no H on the C-OH to oxidize 2-methyl-2-propanol

Oxidation of Ethanol in the Body enzymes in the liver oxidize ethanol. aldehyde product impairs coordination. blood alcohol over 0.4% can be fatal. O O ║ ║ CH3CH2OH CH3CH CH3COH 2CO2 + H2O ethyl alcohol acetaldehyde acetic acid

Ethanol CH3CH2OH Ethanol acts as a depressant. 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.

Effect of Alcohol on the Body

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

Oxidation of Thiols When thiols undergo oxidation, an H atom is lost from each of two –SH groups. the product is a disulfide. [O] CH3─SH + HS─CH3 CH3─S─S─CH3 + H2O

Learning Check OH │ [O] CH3─CH─CH2─CH3 O ║ Select the product for the oxidation of OH │ [O] CH3─CH─CH2─CH3 O ║ 1) CH3─CH=CH─CH3 2) CH3─C─CH2 ─CH3 │ 3) CO2 + H2O 4) CH3─CH─CH2─CH3

Solution OH │ [O] CH3─CH─CH2─CH3 O ║ 2) CH3─C─CH2 ─CH3 Select the product for the oxidation of OH │ [O] CH3─CH─CH2─CH3 O ║ 2) CH3─C─CH2 ─CH3

Learning Check A) H+, heat B) [O] C) + O2 1) CH3—CH=CH2 2) CO2 + H2O O Select the product when CH3—CH2—CH2—OH undergoes each of the following reactions: A) H+, heat B) [O] C) + O2 1) CH3—CH=CH2 2) CO2 + H2O O || 3) CH3—CH2—C—H

Solution O [O] || B. 3) CH3—CH2—C—H C. + O2 2) CO2 + H2O A. H+, heat 1) CH3—CH=CH2 O [O] || B. 3) CH3—CH2—C—H C. + O2 2) CO2 + H2O

Chapter 12 Organic Compounds with Oxygen and Sulfur 12.4 Aldehydes and Ketones

Carbonyl Group in Aldehydes and Ketones A carbonyl group in an aldehyde is attached to at least one H atom. in a ketone is attached to two carbon groups.

Naming Aldehydes An aldehyde has an IUPAC name in which the -e in the alkane name is changed to –al. has a common name for the first four aldehydes that use the prefixes: form (1C), acet (2C), propion (3C), and butyr (4C), followed by aldehyde. O O O ║ ║ ║ H─C─H CH3─C─H CH3─CH2─C─H methanal ethanal propanal (formaldehyde) (acetaldehyde) (propionaldehyde)

Naming Aldehydes

Aldehydes in Flavorings Several naturally occurring aldehydes are used as flavorings for foods and fragrances. Benzaldehyde (almonds) Cinnamaldehyde (cinnamon)

Naming Ketones In naming ketones as IUPAC, the -e in the alkane name is replaced with –one. With a common name, the alkyl groups attached to the carbonyl group are named alphabetically followed by ketone. O O ║ ║ CH3 ─C─CH3 CH3─C─CH2─CH3 propanone 2-butanone (dimethyl ketone) (ethyl methyl ketone)

Ketones in Common Use Nail polish remover, solvent Propanone, Dimethylketone, Acetone Butter flavoring

Learning Check Classify each as 1) aldehyde or 2) ketone. O O || || || || A. CH3—CH2—C—CH3 B. CH3—C—H CH3 O | || C. CH3—C—CH2—C—H D. | CH3

Solution A. 2 ketone B. 1 aldehyde C. 1 aldehyde D. 2 ketone

Learning Check Classify each as an 1) aldehyde 2) ketone 3) alcohol or 4) ether. O ║ A. CH3─CH2─C─CH3 B. CH3─O─CH3 CH3 O OH │ ║ │ C. CH3─C─CH2─C─H D. CH3─CH ─CH3 │ CH3

Solution O ║ A. CH3─CH2─C─CH3 B. CH3─O─CH3 2) ketone 4) ether CH3 O OH │ ║ │ C. CH3─C─CH2─C─H D. CH3─CH─CH3 │ CH3 1) aldehyde 3) alcohol

Learning Check Name each of the following. O ║ 1. CH3─CH2─CH2─CH2─C─H 2. Cl─CH2─CH2─C─H 3. CH3─CH2─C─CH3

Solution Name each of the following: O ║ 1. CH3─CH2─CH2─CH2─C─H pentanal 2. Cl─CH2─CH2─C─H 3-chloropropanal 3. CH3─CH2─C─CH3 2-butanone; ethyl methyl ketone

Learning Check Name the following compounds. O || A. CH3—CH2—CH2—C—CH3 B. CH3 O | || C. CH3—C—CH2—C—H | CH3

Solution A. 2-pentanone; methyl propyl ketone B. cyclohexanone C, 3,3-dimethylbutanal

Learning Check Draw the structural formulas for each: A. 4-methylpentanal B. 2,3-dichloropropanal C. 3-methyl-2-butanone

Solution Draw the structural formulas for each: CH3 O │ ║ A. 4-methylpentanal CH3─CH─CH2─CH2─C─H Cl O │ ║ B. 2,3-dichloropropanal Cl─CH2─CH─C─H CH3 O C. 3-methyl-2-butanone CH3─CH─C─CH3

Chapter 12 Organic Compounds with oxygen and Sulfur 12.5 Properties of Aldehydes and Ketones

Physical Properties The polar carbonyl group provides dipole-dipole interactions. + - + - C=O C=O Without an H on the oxygen, aldehydes and ketones cannot form hydrogen bonds.

Boiling Points + - + - + - Aldehydes and ketones have polar carbonyl groups (C=O). + - C=O attractions between polar groups. + - + - C=O C=O higher boiling points than alkanes and ethers of similar mass. lower boiling points than alcohols of similar mass.

Comparison of Boiling Points 58

Solubility in Water The electronegative O atom of the carbonyl group of aldehydes and ketones forms hydrogen bonds with water.

Learning Check Indicate if each is soluble or insoluble in water. A. CH3—CH2—CH3 B. CH3—CH2—OH O || C. CH3—CH2—CH2—C—H D. CH3—C—CH3

Solution Indicate if each is soluble or insoluble in water. A. CH3—CH2—CH3 insoluble B. CH3—CH2—OH soluble O || C. CH3—CH2—CH2—C—H soluble D. CH3—C—CH3 soluble

Tollens’ Test In Tollens’ test, Tollens’ reagent, which contains Ag+, oxidizes aldehydes, but not ketones. Ag+ is reduced to metallic Ag, which appears as a “mirror” in the test tube.

Benedict’s Test In the Benedict’s test, Benedict’s reagent, which contains Cu2+, reacts with aldehydes that have an adjacent OH group. An aldehyde is oxidized to a carboxylic acid, while Cu2+ is reduced to give red Cu2O(s).

Learning Check Write the structure and name of the oxidized product when each is mixed with Tollens’ reagent. A. butanal B. acetaldehyde C. ethyl methyl ketone

Solution A. butanal O || CH3—CH2—CH2—C—OH butanoic acid B. acetaldehyde O CH3—C—OH acetic acid C. ethyl methyl ketone None. Ketones are not oxidized by Tollen’s reagent.

Chapter 12 Organic Compounds with Oxygen and Sulfur 12.6 Chiral Molecules Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Chiral Objects Chiral objects have the same number of atoms arranged differently in space. have one or more chiral carbon atoms each of which is bonded to four different groups. are like your hands. Try to superimpose your thumbs, palms, back of hands, and little fingers. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Mirror Images The mirror images of chiral compounds cannot be superimposed. When the H and I atoms are aligned, the Cl and Br atoms are on opposite sides.

Achiral Structures are Superimposable When the mirror image of an achiral structure is rotated, the structure can be aligned with the initial structure. Thus this mirror image is superimposable.

Some Everyday Chiral and Achiral Objects

Learning Check Identify each as a chiral or achiral compound. A C H 2 3 l B r

Solution chiral achiral chiral A C H l B r Identify each as a chiral or achiral compound. chiral achiral chiral A C H 2 3 l B r

Fischer Projections A Fischer projection is a 2-dimensional representation of a 3-dimensional molecule. places the most oxidized group at the top. uses vertical lines in place of dashes for bonds that go back. uses horizontal lines in place of wedges for bonds that come forward.

Drawing Fischer Projections

D and L Notations By convention, the letter L is assigned to the structure with the —OH on the left. The letter D is assigned to the structure with the —OH on the right. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers).

Solution Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers). Yes No