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Chapter 12 Organic Compounds w/ Oxygen & Sulfur
12.1 Alcohols, Phenols, and Thiols Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 groups 3 groups H CH CH | | | CH3—C—OH CH3—C—OH CH3—C—OH | | | H H CH3
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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
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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
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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
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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 propanol OH │ CH3─CH─CH2─CH butanol CH OH │ │ CH3─CH─CH2─CH2─CH─CH methyl-2-hexanol
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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.
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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—CH methyl-2-pentanol cyclopentanol
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Learning Check Write the structure of the following: A. 3-pentanol
B. ethyl alcohol C methylcyclohexanol
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Solution Write the structure of the following: A. 3-pentanol OH |
CH3—CH2—CH—CH2—CH3 B. ethyl alcohol CH3 —CH2 —OH C methylcyclohexanol
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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 chlorophenol bromophenol (m-chlorophenol) (p-bromophenol)
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Phenols in Medicine Phenol
Is the IUPAC name for benzene with a hydroxyl group. Is used in antiseptics and disinfectants. phenol resorcinol hexylresorcinol
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Derivatives of Phenol Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint. Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Learning Check Write the structure of each of the following:
A pentanol B. ethyl alcohol C. p-methylphenol
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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
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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.
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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
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Thiols Thiols Often have strong odors. Are used to detect gas leaks.
Are found in onions, oysters, and garlic. Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Learning Check Draw the structure of each compound. A. 2-butanethiol
B. 2-methyl-1-butanol
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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
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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
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Solution Name each of the following compounds: OH |
A. CH3—CH2 —CH—CH butanol CH3 B. CH3—CH2—CH—CH2—CH2—OH 3-methyl-1-pentanol C. CH3—CH2—CH2—SH 1-propanethiol
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Ethers Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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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
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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 Numbering the longer alkane gives 1-methoxypropane
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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
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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.
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Learning Check Draw the structure of each compound. A. diethyl ether
B. ethyl methyl ether C. 2-methoxybutane
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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
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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 ,3,7,8-tetrachlorodibenzodioxin (2,4,5-T; agent orange) (TTCC, “dioxin”)
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Learning Check Name each of the following: 1.
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Solution methoxy cyclopentane (cyclopentyl methyl ether)
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Physical Properties of Alcohols,
12.2 Physical Properties of Alcohols, Phenols, and Ethers Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Comparing Solubility and Boiling Points
Compound Molar Boiling Soluble Mass Point (°C) in Water? Alkane CH3─CH2─CH No Ether CH3─O─CH Yes Alcohol CH3─CH2─OH Yes
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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+
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Learning Check Which compound would have the higher boiling
point? Explain. ethyl methyl ether or 1-propanol
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Solution 1-propanol would have the higher boiling point because
an alcohol can form hydrogen bonds, but the ether cannot.
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Learning Check Which compound would be more soluble in water? Explain.
ethanol or 2-pentanol
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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.
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Reactions of Alcohols and Thiols
12.3 Reactions of Alcohols and Thiols Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Combustion of Alcohols
Combustion is the reaction of an alcohol with O2 to produce CO2 and H2O. 2CH3OH + 3O CO H2O + Heat Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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
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Learning Check Write the equations for the reactions when
2-propanol undergoes: 1. combustion 2. dehydration
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Solution OH │ CH3─CH─CH3 = 2-propanol = C3H8O 1. combustion
2C3H8O + 9O CO H2O 2. dehydration │ H+ CH3─CH─CH CH3─CH=CH2 + H2O
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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.
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Oxidation and Reduction
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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)
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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—CH CH3—C—CH3 + H2O │ H 2-propanol (isopropyl alcohol) propanone(dimethyl ketone, “acetone”)
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Oxidation of Tertiary (3)Alcohols
Tertiary alcohols do not readily oxidize [O] Tertiary alcohol no reaction OH │ [O] CH3─C─CH3 no product │ CH no H on the C-OH to oxidize 2-methyl-2-propanol
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Learning Check Select the compound that would result for each reaction
of CH3—CH2—CH2—OH. O || 1) CH3—CH=CH ) CO2 + H2O ) CH3—CH2—C—H A. H+, heat B. [O] C. O2, heat
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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
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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
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Ethanol CH3─CH2─OH 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. Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Effect of Alcohol on the Body
TABLE 13.2 Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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—CH ) CH3—C—CH2 —CH3 │ 3) CO2 + H2O ) CH3—CH—CH2—CH3
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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
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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—CH CH3—S—S—CH3 + H2O
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12.4 Aldehydes and Ketones Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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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.
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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)
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Naming Aldehydes Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Aldehydes in Flavorings
Several naturally occurring aldehydes are used as flavorings for foods and fragrances. Benzaldehyde (almonds) Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings Cinnamaldehyde (cinnamon)
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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−CH CH3−C−CH2−CH3 propanone butanone (dimethyl ketone) (ethyl methyl ketone)
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Ketones in Common Use Butter flavoring Nail polish remover, Solvent
Propanone, Dimethylketone, Acetone Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Learning Check Classify each as 1) aldehyde or 2) ketone. O O || ||
|| || A. CH3—CH2—C—CH B. CH3—C—H CH O | || C. CH3—C—CH2—C—H D. | CH3
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Solution A. 2) ketone B. 1) aldehyde C. 1) aldehyde D. 2) ketone
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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 CH O OH │ ║ │ C. CH3─C─CH2─C─H D. CH3─CH─CH3 │ CH3
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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 CH O OH │ ║ │ C. CH3─C─CH2─C─H D. CH3─CH─CH3 │ CH3 (1) aldehyde (3) alcohol
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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
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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
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Learning Check Name the following compounds. O ||
A. CH3—CH2—CH2—C—CH B. CH O | || C. CH3—C—CH2—C—H | CH3
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Solution A. 2-pentanone; methyl propyl ketone B. cyclohexanone
C, 3,3-dimethylbutanal
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Learning Check Draw the structural formulas for each:
A. 4-methylpentanal B. 2,3-dichloropropanal C. 3-methyl-2-butanone
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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
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12.5 Properties Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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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.
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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.
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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.
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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
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Solution A. CH3—CH2—OH B. C. CH3—CH2—OH
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Solubility in Water The electronegative O atom of the carbonyl group in aldehydes and ketones forms hydrogen bonds with water. Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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
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Solution A. CH3—CH2—CH3 insoluble B. CH3—CH2—OH soluble O ||
C. CH3—CH2—CH2—C—H soluble D. CH3—C—CH soluble
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Oxidation and Reduction
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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Oxidation Aldehydes are easily oxidized to carboxylic acids. O O
CH3—C—H CH3—C—OH Acetaldehyde Acetic acid
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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
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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.
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Addition Reactions | + + | —C=O X—Y —C—O—X | Y
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Chiral Molecules Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc Publishing as Benjamin Cummings
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Some Everyday Chiral and Achiral Objects
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Enantiomers Have same mp, bp, same chemistry
Except: reaction with other chiral molecules
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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)
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Enantiomers Have same mp, bp, same chemistry
Except: reaction with other chiral molecules Except: rotation of plane of polarized light
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Learning Check Identify each as a chiral or achiral compound.
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Solution Identify each as a chiral or achiral compound.
chiral achiral chiral
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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.
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Drawing Fischer Projections
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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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 © by Pearson Education, Inc Publishing as Benjamin Cummings
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Learning Check Indicate whether each pair is a mirror image that
cannot be superimposed.
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Solution Indicate whether each pair is a mirror image that
cannot be superimposed Yes No
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