Chapter 22 – Alcohols, Ethers, Phenols, and Thiols Name____________________

• The various classes of compounds are identified by the presence of certain characteristic groups called functional groups. Through the chemical reactions of functional groups, it is possible to create or synthesize new substances.

Compare and contrast:

water alcohol ether phenol thiol

ALCOHOLSClassification of alcohols

• Alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) depending on whether the carbon atom to which the –OH group is attached is directly bonded to one, two, or three other carbon atoms respectively.

Ex:

1

Polyhydroxy alcohols (aka __________________ )

Structural Representations of Alcohols

An alcohol such as 2-butanol can be written in a single-line formula by enclosing the –OH group in parentheses and placing it after the carbon to which it is bonded.

Applications to biochemistry:

Blood sugar (glucose) contains five alcohol groups. Using the structure of glucose shown here, label each group as 1°, 2°, or 3°.

2

Naming alcohols

1. Select the longest continuous chain of carbon atoms containing the –OH group.

2. Number the carbon atoms in this chain so that the one bearing the -OH group has the lowest possible number.

Name each:

CH3CH2CH2CH2OH

Physical Properties of Alcohols

• The physical properties of alcohols are related to those of _______________________________________

• An alcohol molecule is made up of a ________________________________________________________.

Boiling Points of Alcohols

• Alcohols have _____________________________________________________________________

• The boiling points of the normal alcohols ________________________________________________

• Branched-chain alcohols have _________________________________________________________

Ex:

3

OH

CHH3C

CH3

CHH3CCH3 CH2CH2OH

OH OHHO

2-propanol(isopropyl alcohol)

3-methyl-1-butanol

cyclohexanol 1,3-cyclohexanediol

OH

CHH3C

CH3

CHH3CCH3 CH2CH2OH

OH OHHO

2-propanol(isopropyl alcohol) 3-methyl-1-butanol

cyclohexanol 1,3-cyclohexanediol

• Alcohols containing up to three carbon atoms are ____________________________________________

• The –OH group on the alcohol molecule is responsible for ____________________________________

___________________________________________________________________________________

Hydrogen Bonding in Alcohols

Hydrogen bonding definition:_________________________________________________________________

_________________________________________________________________________________________

Ex:

4

Glucose is one of the most important carbohydrates in biochemistry. Draw it and find its molar mass. How would you predict the water solubility of glucose to differ from that of 1-hexanol?

Chemical Properties of Alcohols

• Acidic and Basic Properties

• Oxidation

• Dehydration

• Esterification

Acidic properties:

• Alcohols can act as Brønsted-Lowry acids (proton donors).

• The resulting anion in the alcohol reaction is known as an alkoxide ion (RO-).

Basic properties:

• Alcohols can act as Brønsted-Lowry bases (proton acceptors)

• If an alcohol is mixed with a strong acid, it will accept a proton (act as a Brønsted-Lowry base) to form a protonated alcohol or oxonium ion.

Reactivity of alcohols with Na or K

5

• The order of reactivity of alcohols with sodium or potassium is:

• Reactivity decreases with ______________________________________________________________ ___________________________________________________________________________________

Oxidation

• Oxidation is the ____________________________________________________________________

• Carbon atoms ______________________________________________________________________

Calculate the oxidation state of carbon in:

Methane methanol methanol methanoic acid carbon dioxide

The –OH group gives an organic compound the capability of forming an __________________, ______________________________, or ____________________________________

What is the product of oxidizing each?

1. 1-propanol

2. 2- propanol

3. 2-methyl-2-propanol

Common Oxidizing Agents:

Dehydration

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Alkanes Alcohols AldehydesKetones

CarboxylicAcids

Carbon dioxide

increasing oxidation state

• Alcohols can be dehydrated with sulfuric acid to form alkenes.

Intramolecular dehydration: (within the same molecule)

• For many alcohols, there is more than one way to remove water. Therefore the double bond can be located in different positions.

• The major product in such cases is the alkene in which ____________________________________

___________________________________________________________________________________

Saytzeff’s rule:

During intramolecular dehydration, if there is a choice of positions for the carbon-carbon double bond,

_________________________________________________________________________________________

_________________________________________________________________________________________

Intermolecular Dehydration: (between two different molecules)

• Primary alcohols can be dehydrated with sulfuric acid to form __________________

• A condensation reaction is when

Esterification (Conversion of Alcohols to Esters)

• An alcohol can react with a carboxylic acid to form _________________________________________

Ex of esterification:

7

Utility of the Hydroxyl Functional Group

Three General Methods for Making Alcohols (ie; “lab preps of alcohols”)

8

1. Hydrolysis of an ester.

2. Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).

3. Catalytic reduction of aldehydes and ketones.

Hydrolysis of an ester

Hydrolysis is

Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).

Catalytic Reduction of Aldehydes and Ketones

Common Alcohols

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Methanol

• Methanol is synthesized by ________________________________________________

• The most economical nonpetroleum source of carbon monoxide for making methanol is ____________

• Reaction:

Uses of methanol:

1. Conversion to ____________________________________

2. Manufacture of ______________________________________________

3. Denaturing ___________________________________________________

4. ____________________________________________________________

Ethanol

• Large quantities of ethanol are prepared by _______________________________

– ___________________________________________________________________

• Industrially, ethanol is made by ________________________________________________

– Reaction:

Uses of ethanol:

• An intermediate in the ______________________________________________________________

• A solvent for ______________________________________________________________________

• A compounding ingredient for ________________________________________________________

• An essential ingredient in ____________________________________________________________

2-Propanol (Isopropyl Alcohol)

2-Propanol is made from propene:

Uses of isopropyl alcohol:

1. To manufacture ________________________________________________________________

2. As an ________________________________________________________________________

3. As the principal ingredient ________________________________________________________

Ethylene Glycol (1,2-Ethanediol)

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Industrial synthesis:

Uses of ethylene glycol:

1. In the preparation of the _____________________________________________________________

2. As a major ingredient _______________________________________________________________

3. As a solvent in ____________________________________________________________________

4. In the formulations of _______________________________________________________________

Glycerol (aka ___________________________________________)

• Glycerol (also known as _____________) is an important ____________________________________

• It is obtained as a ____________________________________________________________________

• It is synthesized commercially from ______________________________.

Uses of glycerol: (each is directly related to ___________________________)

1. As a raw material in _____________________________________________________________

2. As an ________________________________________________________________________

3. As a _________________________________________________________________________

4. As a ______________________________________________.

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PHENOLS• The term phenol is used for the class of compounds that ________________

____________________________________________________

• The parent compound is also called phenol, C6H5OH.

Naming phenols: Many phenols are named as derivatives of the parent compound, via the general methods for naming aromatic compounds

Common phenols with special names:

Physical /chemical properties of phenols

• _________________________________________________

• _________________________________________________

• _________________________________________________

• Reaction:

Industrial production of phenol

• Phenol is obtained from _________________________________

• Several commercial methods ________________________________________________.

ETHERS

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OH OH

Br

OH

NH2

phenol m-bromophenol

p-aminophenol

OH OH

Br

OH

NH2

phenol m-bromophenol

p-aminophenolHO

OH OH

HO

OH

OHcatechol(o-dihydroxybenzene)

resorcinol(m-dihydroxybenzene)

hyrdroquinone(p-dihydroxybenzene)

HO

OH OH

HO

OH

OHcatechol(o-dihydroxybenzene)

resorcinol(m-dihydroxybenzene)

hyrdroquinone(p-dihydroxybenzene)

Ethers have the general formula:

Naming ethers

Individual ethers may be known by some common names:

dimethyl ether ethyl methyl ether

IUPAC naming rules for ethers:

1. Select the longest carbon continuous chain and label it with the name of the corresponding alkane.

2. Change the –yl ending of the other hydrocarbon group to –oxy to obtain the alkoxy group name.

e.g. CH3O- is called methoxy.

3. Combine the two names from Steps 1 and 2, giving the alkoxy name and its position on the longest carbon chain first, to form the ether name.

Examples:

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H3C O CH2CH3

CH3O- is the alkoxy group(methoxy)

This is the longest C-C chain, so call it ethane.

methoxyethane

H3CH2CH2C O CH2CH2CH2CH3

1-propoxybutane

H3CHC O CHCH2CHCH3

2-isopropoxy-4-methylpentane

CH3 CH3 CH3

H3CH2CH2C O CH2CH2CH2CH3

1-propoxybutane

H3CHC O CHCH2CHCH3

2-isopropoxy-4-methylpentane

CH3 CH3 CH3

Structure and properties of ethers:

• Ethers are somewhat more polar than ___________, but are much less polar than _____________.

• The more polar a compound, ___________ _________________________________

• Ethers – especially diethyl ether – are exceptionally good solvents for organic compounds.

Formation of peroxides from ethers

Oxygen of the air slowly reacts with ethers to form unstable peroxides that are subject to explosive decomposition

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Preparation of ethers: The Williamson Ether Synthesis

Reaction:

• The alkyl halide, RX, may be ____________________________, but NOT a _____________________

___________________________________________________________________

• The alkoxide, R’ONa, may be __________________________________________________________.

Ex:

THIOLS

Organic compounds that contain the -SH group are known as thiols or mercaptans

Properties of thiols:

1. ___________________________

2. Oxidation to __________________________

Reaction:

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CH2CH3

SH

H3CS

Hmethanethiol(methyl mercaptan)

H3C

2-propanethiol

CH2CH3

SH

H3CS

Hmethanethiol(methyl mercaptan)

H3C

2-propanethiol