1 chapter 12 organic compounds w/ oxygen & sulfur 12.1 alcohols, phenols, and thiols copyright...
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Chapter 12 Organic Compounds w/ Oxygen & Sulfur
12.1
Alcohols, Phenols, and Thiols
Copyright © 2007 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.
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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
Classification of Alcohols
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Classify each alcohol as (P) primary, (S) secondary, or (T) tertiary.
OH |
1. CH3—CH—CH2—CH3
2. CH3—CH2—CH2—OH
OH |
3. CH3—CH2—C—CH2—CH3 |
CH3
Learning Check
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OH |
1. CH3—CH—CH2—CH3 (S) secondary
2. CH3—CH2—CH2—OH (P) primary
OH |
3. CH3—CH2—C—CH2—CH3 (T) tertiary |
CH3
Solution
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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 IUPACCommon 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 1-propanol
OH │CH3─CH─CH2─CH3 2-butanol
CH3 OH │ │CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-
hexanol6 5 4 3 2 1
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Some Typical Alcohols
OH |“rubbing alcohol” CH3—CH—CH3
2-propanol (isopropyl alcohol)
antifreeze HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol) OH
| glycerolHO—CH2—CH—CH2—OH
1,2,3-propanetriol
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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.
OH
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Solution
1. CH3—CH2—CH2—CH2—OH 1-butanol
OH CH3 | |2. CH3—CH—CH—CH2—CH3 3-methyl-2-pentanol
3. cyclopentanol OH
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Write the structure of the following:
A. 3-pentanol
B. ethyl alcohol
C. 3-methylcyclohexanol
Learning Check
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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. 3-methylcyclohexanol
CH3
OH
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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.
OH
Cl
OHOH
Br
Phenol 3-chlorophenol 4-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 4-hexylresorcinol
OH
OH
CH2CH2CH2CH2CH2CH3
OH OH
OH
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Derivatives of Phenol
Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint.
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Write the structure of each of the following:
A. 3-pentanol
B. ethyl alcohol
C. p-methylphenol
Learning Check
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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 OH
CH3
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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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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
Naming Thiols
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Thiols
Thiols Often have
strong odors. Are used to
detect gas leaks. Are found in
onions, oysters, and garlic.
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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—CH3 2-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
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
1 2 3
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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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.
Cl
Cl Cl
OCH2 OHC
O
Cl
Cl
O
O
Cl
Cl
2,4,5-trichlorophenoxyacetic acid 2,3,7,8-tetrachlorodibenzodioxin(2,4,5-T; agent orange) (TTCC, “dioxin”)
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Learning Check
Name each of the following:
1. O
CH3
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Solution
1. methoxy cyclopentane
(cyclopentyl methyl ether)O
CH3
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12.2
Physical Properties of Alcohols,
Phenols, and Ethers
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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.
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Boiling Points of Ethers
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.
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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.
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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
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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.
OH O-
+ 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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12.3
Reactions of Alcohols and Thiols
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Combustion of Alcohols
Combustion is the reaction of an alcohol
with O2 to produce CO2 and H2O.
2CH3OH + 3O2 2CO2 + 4H2O + Heat
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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+, heatH—C—C—H H—C=C—H + H2O
| | | | H H H H
alcohol alkene
Dehydration of Alcohols
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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 + 9O2 6CO2 + 8H2O
2. dehydration OH │ H+
CH3─CH─CH3 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
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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 Primary (1) Alcohols
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Oxidation of Secondary (2) AlcoholsWhen 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”)
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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 │ CH3 no H on the C-OH to oxidize
2-methyl-2-propanol
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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
Learning Check
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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
Solution
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Oxidation of Ethanol in the Body
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 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.
Ethanol CH3─CH2─OH
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Effect of Alcohol on the Body
TABLE 13.2
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Learning Check
Select the product for the oxidation of OH │ [O]
CH3—CH—CH2—CH3
O ║
1) CH3—CH=CH—CH3 2) CH3—C—CH2 —CH3
OH │
3) CO2 + H2O 4) CH3—CH—CH2—CH3
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Solution
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—CH3 CH3—S—S—CH3 + H2O
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12.4
Aldehydes and Ketones
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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
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Aldehydes in Flavorings
Several naturally occurring aldehydes are used as flavorings for foods and fragrances.
H
O
C
H
O
CCH=CH
Benzaldehyde(almonds)
Cinnamaldehyde (cinnamon)
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68
Naming KetonesKetones 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)
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Ketones in Common Use
Nail polish remover, Solvent
Propanone, Dimethylketone, Acetone
Butter flavoring
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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
Learning Check
O
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A. 2) ketone
B. 1) aldehyde
C. 1) aldehyde
D. 2) ketone
Solution
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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
CH3 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 CH3 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
O
║ 2. Cl─CH2─CH2─C─H O ║ 3. CH3─CH2─C─CH3
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Solution
O ║
1. CH3─CH2─CH2─CH2─C─H pentanal
O ║
2. Cl─CH2─CH2─C─H 3-chloropropanal
O ║
3. CH3─CH2─C─CH3 2-butanone;
ethyl methyl ketone
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Name the following compounds. O
||A. CH3—CH2—CH2—C—CH3 B.
CH3 O
| ||C. CH3—C—CH2—C—H
| CH3
Learning Check
O
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A. 2-pentanone; methyl propyl ketone
B. cyclohexanone
C, 3,3-dimethylbutanal
Solution
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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
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81
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
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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
or
O
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Solution
A. CH3—CH2—OH
B.
C. CH3—CH2—OH
O
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Solubility in Water
The electronegative O atom of the carbonyl group in aldehydes and ketones forms hydrogen bonds with water.
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87
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
O ||
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
O ||
D. CH3—C—CH3 soluble
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Oxidation and Reduction
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90
Oxidation
Aldehydes are easily oxidized to carboxylic acids. O 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.
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92
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).
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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
3. 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 notoxidized by Tollen’s reagent.
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Addition Reactions
| + - + - | —C=O + X—Y —C—O—X
| Y
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Chiral Molecules
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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 © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
98
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.
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99
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.
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100
Some Everyday Chiral and Achiral Objects
101
Enantiomers
Have same mp, bp, same chemistry
Except: reaction with other chiral molecules
102
Smell:Smell:S-(+)-carvoneS-(+)-carvone
Caraway(Dill)(Manderine Orange Peel)
Caraway(Dill)(Manderine Orange Peel)
R-(-)-carvoneR-(-)-carvone
SpearmintSpearmint
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Have same mp, bp, same chemistry
Except: reaction with other chiral molecules
Enantiomers
•Except: rotation of plane of polarized light
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Learning Check
Identify each as a chiral or achiral compound.
A
CH2CH3
H CH3
Cl
C
B
H
H CH3
Cl
C
C
Br
H CH3
Cl
C
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Solution
Identify each as a chiral or achiral compound.
chiral achiral chiral
A
CH2CH3
H CH3
Cl
C
B
H
H CH3
Cl
C
C
Br
H CH3
Cl
C
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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.
107
Drawing Fischer Projections
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108
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.
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109
Learning Check
Indicate whether each pair is a mirror image that
cannot be superimposed.
B.
A.
and
and
Br
CH3 H
CH2OH
C
H
CH3 H
Cl
C
Br
H CH3
CH2OH
C
H
H CH3
Cl
C
110
Solution
Indicate whether each pair is a mirror image that
cannot be superimposed
Yes
No
B.
A.
and
and
Br
CH3 H
CH2OH
C
H
CH3 H
Cl
C
Br
H CH3
CH2OH
C
H
H CH3
Cl
C