Chapter 12 Organic Compounds w/ Oxygen & Sulfur 12.1 Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

Classification of Alcohols 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 CH3 CH3 | | | CH3—C—OH CH3—C—OH CH3—C—OH | | | H H CH3

Learning Check (P) primary, (S) secondary, or (T) tertiary. OH | Classify each alcohol as (P) primary, (S) secondary, or (T) tertiary. OH | 1. CH3—CH—CH2—CH3 2. CH3—CH2—CH2—OH 3. CH3—CH2—C—CH2—CH3 CH3

Solution | 1. CH3—CH—CH2—CH3 (S) secondary OH | 1. CH3—CH—CH2—CH3 (S) secondary 2. CH3—CH2—CH2—OH (P) primary 3. CH3—CH2—C—CH2—CH3 (T) tertiary CH3

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. Formula IUPAC Common Name CH4 methane CH3─OH methanol methyl alcohol CH3─CH3 ethane CH3─CH2─OH ethanol ethyl alcohol

More Names of Alcohols In IUPAC names for longer carbon chains, the chain is numbered 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 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Give the IUPAC name for each of the following: 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

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

Solution Write the structure of the following: A. 3-pentanol OH | CH3—CH2—CH—CH2—CH3 B. ethyl alcohol CH3 —CH2 —OH C. 3-methylcyclohexanol

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)

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

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

Solution Write the structure of each of the following: A. 3-pentanol OH | CH3—CH2—CH—CH2—CH3 B. ethyl alcohol CH3—CH2—OH C. p-methylphenol

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.

Naming Thiols In thiols with long carbon chains, the chain is numbered to locate the –SH group. CH3—CH2—CH2—SH 1-propanethiol SH | CH3—CH—CH3 2-propanethiol

Thiols 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

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

Solution Draw the structure of each compound. A. 2-butanethiol SH | CH3—CH—CH2—CH3 B. 2-methyl-1-butanol CH3 HO—CH2—CH—CH2—CH3

Learning Check Name each of the following compounds: OH | A. CH3—CH2 —CH—CH3 CH3 B. CH3—CH2—CH—CH2—CH2—OH C. CH3—CH2—CH2—SH

Solution Name each of the following compounds: OH | A. CH3—CH2 —CH—CH3 2-butanol CH3 B. CH3—CH2—CH—CH2—CH2—OH 3-methyl-1-pentanol C. CH3—CH2—CH2—SH 1-propanethiol

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

Ethers Ethers Contain an ─O─ between two carbon groups. That are simple are named by listing the alkyl names in alphabetical order followed by ether CH3─O─CH3 CH3─CH2─O─CH3 dimethyl ether ethyl methyl ether

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 CH3—O—CH2—CH2—CH3 1 2 3 Numbering the longer alkane gives 1-methoxypropane

Ethers as Anesthetics Anesthetics Inhibit pain signals to the brain. Such as ethyl ether CH3─CH2─O─CH2─CH3 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─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 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.

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

Solution Draw the structure of each compound. A. diethyl ether CH3—CH2—O—CH2—CH3 B. ethyl methyl ether CH3—CH2—O—CH3 C. 2-methoxybutane O—CH3 | CH3—CH—CH2—CH3

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”)

Learning Check Name each of the following: 1.

Solution 1. methoxy cyclopentane (cyclopentyl methyl ether)

Physical Properties of Alcohols, 12.2 Physical Properties of Alcohols, Phenols, and Ethers Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Boiling Points of 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

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

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

Comparing Solubility and Boiling Points Compound Molar Boiling Soluble 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 the skin. + H2O + H3O+

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

Solution 1-propanol would have the higher boiling point because an alcohol can form hydrogen bonds, but the ether cannot.

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

Solution Ethanol. An alcohol with two carbons in its carbon chain is more soluble than one with 5 carbons. The longer alkyl chain diminishes the effect of the –OH group.

Reactions of Alcohols and Thiols 12.3 Reactions of Alcohols and Thiols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Combustion of Alcohols Combustion is the reaction of an alcohol with O2 to produce CO2 and H2O. 2CH3OH + 3O2 2CO2 + 4H2O + Heat Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

Learning Check Write the equations for the reactions when 2-propanol 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 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.

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

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-propanone(dimethyl ketone, “acetone”)

Oxidation of Tertiary (3)Alcohols Tertiary 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

Learning Check Select the compound that would result for each reaction of CH3—CH2—CH2—OH. O || 1) CH3—CH=CH2 2) CO2 + H2O 3) CH3—CH2—C—H A. H+, heat B. [O] C. O2, heat

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

Oxidation of Ethanol in the Body Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. O O ║ ║ CH3─CH2─OH CH3─C─H CH3─C─OH ethyl alcohol acetaldehyde acetic acid 2CO2 + H2O

Ethanol CH3─CH2─OH 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. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

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

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

12.4 Aldehydes and Ketones Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

Aldehydes in Flavorings Several naturally occurring aldehydes are used as flavorings for foods and fragrances. Benzaldehyde (almonds) Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Cinnamaldehyde (cinnamon)

Naming Ketones Ketones are named In the IUPAC system by replacing the -e in the alkane name with ­one. The carbonyl carbon is indicated by a number. With a common name by indicating the alkyl groups attached to the carbonyl group in alphabetical order followed by ketone. O O ║ ║ CH3−C−CH3 CH3−C−CH2−CH3 propanone 2-butanone (dimethyl ketone) (ethyl methyl ketone)

Ketones in Common Use Butter flavoring Nail polish remover, Solvent Propanone, Dimethylketone, Acetone Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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 aldehyde (1), ketone (2), alcohol (3), or ether (4). 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 Classify each as an aldehyde (1), ketone (2), alcohol (3), or ether (4). 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 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 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

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

Polar Carbonyl Group The polar carbonyl group Provides dipole-dipole interactions. + - + - C=O C=O Does not have H on the oxygen atom. 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 Aldehydes and ketones have Higher boiling points than alkanes and ethers of similar mass. Lower boiling points than alcohols of similar mass.

Learning Check Select the compound in each pair that would have the Higher boiling point. A. CH3—CH2—CH3 or CH3—CH2—OH B. C. CH3—CH2—OH or CH3—O—CH3

Solution A. CH3—CH2—OH B. C. CH3—CH2—OH

Solubility in Water The electronegative O atom of the carbonyl group in aldehydes and ketones forms hydrogen bonds with water. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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 A. CH3—CH2—CH3 insoluble B. CH3—CH2—OH soluble O || C. CH3—CH2—CH2—C—H soluble D. CH3—C—CH3 soluble

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

Oxidation Aldehydes are easily oxidized to carboxylic acids. O O CH3—C—H CH3—C—OH Acetaldehyde Acetic acid

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

Benedict’s Test In the Benedict’s Test, Cu2+ reacts with aldehydes that have an adjacent OH group. Aldehydes are oxidized to carboxylic acids. Cu2+ is reduced to give Cu2O(s). Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Write the structure and name of the oxidized product when each is mixed with Tollens’ reagent. 1. butanal 2. acetaldehyde ethyl methyl ketone

Solution 1. butanal O || CH3—CH2—CH2—C—OH butanoic acid 2. acetaldehyde O CH3—C—OH acetic acid 3. ethyl methyl ketone None. Ketones are not oxidized by Tollen’s reagent.

Addition Reactions | + - + - | —C=O + X—Y —C—O—X | Y

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

Chiral Compounds Chiral compounds Have the same number of atoms arranged differently in space. Have one or more chiral carbon atoms bonded to four different groups. Are mirror images like your hands. Try to superimpose your thumbs, palms, back of hands, and little fingers. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Mirror Images The mirror images of Chiral compounds cannot be superimposed. Two compounds of bromochloroiodomethane can align the H and I atoms, which places the Cl and Br atoms on opposite sides. Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings

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

Some Everyday Chiral and Achiral Objects

Enantiomers Have same mp, bp, same chemistry Except: reaction with other chiral molecules

Smell: Caraway Spearmint R-(-)-carvone S-(+)-carvone (Dill) (Manderine Orange Peel) Spearmint Pass around models: Are they the same or different? Pass around spearmint & caraway oils: Are they the same or different? Explain receptors (G-protein) and how enantiomers fit (hand in glove)

Enantiomers Have same mp, bp, same chemistry Except: reaction with other chiral molecules Except: rotation of plane of polarized light

Learning Check Identify each as a chiral or achiral compound.

Solution Identify each as a chiral or achiral compound. chiral achiral chiral

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

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 © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings

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

Solution Indicate whether each pair is a mirror image that cannot be superimposed Yes No