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Ch. 12: Compounds with O and S

Chem 20

El Camino College

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Alcohols, Thiols, Ethers

H3C

O

H H3C

S

H H3C

O

CH3

methanol methanethiol dimethyl ether

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Naming Alcohols

Name the longest carbon chain containing the OH group, use the –ol suffix

Number the chain to give the OH the lowest number

Give the location and name of other substituents in alphabetical order.

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Name These

1-butanol 2-butanol 3-pentanol

H3C CH2 CH2 CH2 OH

OH

OH

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Name These

3-methyl-2-pentanol

2,2-dimethyl-1-butanol

2-bromo-2-chloro-1-butanol

OH OH

Cl Br

OH

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Draw These

3-methyl-2-butanol

2,2-dibromo-1-propanol

cyclopentanol

OH

CH3

Br Br

OH

OH

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Naming Ethers

Write the name of each group attached to the O Use alphabetical order If the groups are the same, use the prefix “di”

H3C

O

CH2

CH3H3C CH2 O CH2 CH3 O CH3

ethyl methyl etherdiethyl ether

cyclopropyl methyl ether

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Solubility “Like dissolves like” explains solubility Alkanes are nonpolar

they are insoluble in water Ethers are slightly polar

ethers with small carbon chains are water solubleethers with long carbon chains are water insoluble

Alcohols are polaralcohols with small/medium C chains are solublealcohols with large C chains are water insoluble.

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Give Name: Solubility

O

O

OH

OH

OH

propane: insoluble in water

dimethyl ether: soluble in water

dibutyl ether: insoluble in water

ethanol: soluble in water

1-hexanol: soluble in water

1-octanol: insoluble in water

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Aldehyde and Ketone

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Oxidation Reaction

In one kind of oxidation rxn of alcohols, the carbon bearing the OH turns into a C=O groupIf the C bearing the OH is attached to one other carbon or less, an aldehyde formsIf the C bearing the OH is attached to two other carbons, a ketone formsIf the C bearing the OH is attached to three other carbons, no reaction happens.

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H3C

O

H

[ O ]

H

C

H

O

aldehyde

CH2

O

H

[ O ]

H3C

C

H

O

H3Caldehyde

CH

O

H

[ O ]

H3C

C

CH3

O

H3C

H3C

ketone

C

O

H

[ O ]H3C

H3C CH3

no reaction

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Draw the product: aldehyde, ketone, or NR?

OH

HO

OH

[ O ]

[ O ]

[ O ]

Oketone

O

aldehyde

H

O

ketone

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Naming Aldehydes

Name the longest carbon chain containing the carbonyl (C=O)

Use the suffix “al” Name any substituents by numbering the

carbonyl carbon as number 1

H

C

H

O

methanal(formaldehyde)

H3C

C

H

O

ethanal

H

O

propanal

O

2-methylpropanal

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Name These

pentanal 2,3-dibromobutanal

O

H

O

H

Br

Br

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Naming Ketones Name the longest carbon chain containing the

carbonyl (C=O) Use the suffix “one” Number the main chain from the end nearest the

carbonyl. Name and number any substituent

H3C

C

CH3

O

propanone(acetone)

H3C

C

CH2CH3

O

butanone

CH3

O

3-methylbutanone

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Name These

pentanal 2-pentanone 3-pentanone

O

H

O

O

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Name These

cyclopentanone 3-heptanone

3,3-dichlorobutanone

O

O

CH3

O

Cl Cl

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Properties Aldehydes and ketones are slightly polar They tend to have similar bps to ethers of the

same molar mass They tend to have much lower bps than

alcohols, because alcohols are much more polar Aldehydes and ketones of 5 C atoms or less are

soluble in water

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Chemical Tests

In Tollens’ test, an aldehyde is oxidized to a carboxylic acid. Silver also forms.

CH3CHO + 2 Ag+ 2 Ag(s) + CH3COOH

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Chemical Tests

In Benedict’s test, an aldehyde that has an OH group on the next carbon forms a carboxylic acid. Red ppt also forms.

RCHO + 2Cu2+ Cu2O(s) + RCOOH

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Isomers Isomers are compounds with the same formula, but the atoms are attached

differently “Stereoisomers” have the atoms arranged differently in space--they are related

as mirror images.

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Chiral Carbons

Chiral carbons are tetrahedral carbons with four different attachments

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