© 2013 pearson education, inc. chapter 13, section 1 general, organic, and biological chemistry...

© 2013 Pearson Education, Inc. Chapter 13, Section 1

General, Organic, and Biological Chemistry

Fourth EditionKaren Timberlake

13.1Alcohols, Phenols, and

Thiols

Chapter 13Alcohols, Phenols, Thiols,

and Ethers

© 2013 Pearson Education, Inc.Lectures


Alcohols, Phenols, and Thiols

An alcohol contains a hydroxyl group (–OH) attached to a carbon chain.

A phenol contains a hydroxyl group (–OH) attached to a benzene ring.

A thiol contains a thiol group (–SH) attached to a carbon chain.

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Guide to Naming Alcohols

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Naming Alcohols

The names of alcohols in the IUPAC system, replace -e of the 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 alcohol4


Naming Alcohols

In IUPAC names for longer carbon chains, the chain isnumbered from the end nearer the –OH group.

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Naming Alcohols

We can also draw skeletal structures for alcohols.

CH3─CH2─CH2─OH CH3─CH─CH2─CH3

OH

1-Propanol 2-Butanol

OH

OH

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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-Hexylresoricinol

OH

OH

CH2CH2CH2CH2CH2CH3

OH OH

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 substituents the lowest

numbers. use prefixes o, m, and p for common names.

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Phenol 3-chlorophenol 3-methylphenol (m-chlorophenol) (m-cresol)


Thiols

Thiols are organic 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 give the −SH group the lowest possible number.

Naming Thiols

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Ethers

Ethers consist of an oxygen atom that is connected by single bonds to two carbon groups (alkyl or aromatic).

Simple ethers are named by listing the alkyl names in alphabetical order followed by ether

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CH3─O─CH3 CH3─CH2─O─CH3

methyl methyl ethyl methyl


Cyclic Ethers

A cyclic ether contains an O atom in a carbon ring. is called a heterocyclic compound. typically has 5 (furan) or 6 atoms (pyran) in the

ring.

O O O

Furan Tetrahydrofuran Pyran 1,4-Dioxane

O

O

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Dioxins

Dioxins are a six-atom ring with two oxygen atoms and two double

bonds. a group of ethers that are highly toxic and often

carcinogenic. formed during forest fires and as industrial by-

products.

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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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Guide to Naming Ethers

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Classifying Alcohols

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Boiling Points of Alcohols

Alcohols form hydrogen bonds

between alcohol molecules. have higher boiling points

than alkanes and ethers of similar mass.

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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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Boiling Points of Ethers


Solubility of Alcohols and Ethers in WaterAlcohols and ethers are more soluble in water than are alkanes because the oxygen atom can form hydrogen bonds with water.

Alcohol Solubility in H2O

1–3 carbon atoms completely soluble

4 carbon atoms slightly soluble

5 or more carbon atoms insoluble

Ethers containing up to 4 carbon atoms are slightly soluble in water.

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Solubility of Alcohols and Ethers in Water

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Comparing Solubility and Boiling Points

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Combustion of Alcohols

Combustion is the reaction of an alcohol with O2 toproduce CO2, H2O and energy.

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Dehydration of an alcohol occurs when heated with an acid catalyst, H+

with the loss of –H and –OH from adjacent carbon atoms to form water

Dehydration of Alcohols

alcohol alkene

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Saytzeff’s Rule

According to Saytzeff’s rule, the dehydration of a secondary alcohol favors the product in which hydrogen is removed from the carbon atom in the chain with the smaller number of H atoms

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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 a decrease in the number of C–O bonds. there is a gain of H.

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Oxidation and Reduction

An alcohol is more oxidized than an alkane; an aldehyde or ketone is more oxidized than an alcohol; a carboxylic acid is more oxidized than an aldehyde.

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Primary alcohols are oxidized to form aldheydes.

Oxidation of Primary (1) Alcohols

Ethanol (ethyl alcohol) Ethanal (acetaldehyde)

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Oxidation of Secondary (2) AlcoholsSecondary alcohols are oxidized to form ketones.

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2-Propanol (isopropyl alcohol) 2-Propanone(dimethyl ketone,“acetone”)


Oxidation of Tertiary (3) AlcoholsTertiary alcohols do not readily oxidize.

There is no H on the C–OH to oxidize.

2-Methyl-2-propanol

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© 2013 pearson education, inc. chapter 13, section 1 general, organic, and biological chemistry...

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