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Chapter 13 Organic Compounds with Oxygen and Sulfur

13.4 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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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)

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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 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

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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

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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

Name each of the following: 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

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