Chapter 9: Alcohols, Ethers, and Amines

Alcohol

A compound in which an –OH group is connected to a hydrocarbon

Hydroxy group:

The –OH functional group.

Phenol:

A compound in which an –OH group is connected to a benzene ring. The parent compound is also called phenol.

• Alcohols and phenols may also be considered to be derived from water by the replacement of one of its hydrogen atoms with an alkyl group or an aromatic ring:

Naming of Alcohols

Step 1: Number the longest chain to give the lower

number to the carbon with the attached hydroxy

group.

• Step 2: Name the longest chain to which the hydroxy

group is attached. The chain name is obtained by

dropping the final -e from the name of the

hydrocarbon that contains the same number of

carbon atoms and adding the ending -ol.

• Step 3: Locate the position of the hydroxy group by the

number of the carbon atom to which it is attached.

• Step 4: Locate and name any groups attached to the

chain.

• Step 5: Combine the name and location for other

groups, the hydroxy group location, and the longest

chain into the final name

Naming of Alcohols: Phenol

• Substituted phenols are usually named as derivatives of the parent

compound phenol.

• Locate the position of the hydroxy group and number the carbon

atom to which it is attached as 1.

• Locate and name any groups attached to the chain.

• Combine the name and location for other groups, and the longest

chain into the final name; phenol

Classification of Alcohols

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°)

Physical Properties of Alcohols: Solubility

• Low molecular weight alcohols are soluble in water in all proportions.

• As the size of the alkyl group in an alcohol increases, the physical

properties become less water-like and more alkane-like.

Reactions of Alcohols: Acid-Base

• Alcohols are neither strongly acidic nor strongly basic.

• Their behavior in acid–base reactions greatly depends upon what other

species are in solution.

• They are best described as being amphoteric, meaning they can be either

acidic or basic.

• When reacting with a strong acid, the oxygen in an alcohol becomes

protonated.

Reactions of Alcohols: Acid-Base

• For an alcohol to be deprotonated, the base must be stronger than

hydroxide.

• Phenols typically act as weak acids.

Reactions of Alcohols: Acid-Base

• Alcohols are neither strongly acidic nor strongly basic.

• Their behavior in acid–base reactions greatly depends upon what other

species are in solution.

• They are best described as being amphoteric, meaning they can be either

acidic or basic.

• When reacting with a strong acid, the oxygen in an alcohol becomes

protonated.

Reactions of Alcohols: Acid-Base

For an alcohol to be deprotonated, the base must be stronger than

hydroxide.

• Phenols typically act as weak acids.

Combustion

-make C02, water, and energy

2CH3—CH2—OH(g) + 6O2(g) ------> 4CO2(g) + 6H2O(g) +energy

Dehydration reaction:

A reaction in which water is chemically removed from a

compound.

• This reaction can occur in two different ways, depending on the reaction

temperature. At 180 °C, alkenes are the predominant products; alkenes

Reactions of Alcohols:

Dehydration (140 °C)

At 140°C, the major product of alcohol dehydration is an ether

Oxidation of 1° Alcohols

An oxidation reaction occurs when a molecule gains oxygen atoms or loses hydrogen atoms.

• Primary alcohols usually generate carboxylic acids through an intermediate aldehyde

Secondary alcohols

generate ketones as final products.

Tertiary alcohols

do not react under oxidizing conditions

Fermentation

A reaction of sugars, starch, or cellulose to produce ethanol and carbon dioxide.

• Some phenol derivatives are used in mouth washes.

Applications of Alcohols

• Some phenol derivatives are used as

antiseptics, or disinfectants

• Other phenol derivatives are used as

antioxidants (BHA).

Antioxidants

A substance that

prevents another substance from

being oxidized.

Ether

A compound that contains the functional group.

Heterocyclic ring:

A ring containing at least one atom of

an element other than carbon.

• Ethers can hydrogen bond with water, but they cannot hydrogen

bond with themselves.

Naming Ethers

put in alphabetical order and put the name ether at the end

Amine

An organic compound derived by replacing one or more of the hydrogen

atoms of ammonia with alkyl or aromatic groups, as in RNH2, R2NH, and R3N.

Primary amine:

An amine having one alkyl or aromatic group bonded to

nitrogen, as in R–NH2.

Secondary amine:

An amine having two alkyl or aromatic groups bonded to

nitrogen, as in R2NH

Tertiary amine:

An amine having three alkyl or aromatic groups bonded to

nitrogen, as in R3N

Properties of Amines;

Hydrogen Bonding of Amines

• Like alcohols, primary and secondary amines form hydrogen bonds among

themselves.

• Because nitrogen is less electronegative than oxygen, the hydrogen bonds formed

by amines are weaker than those formed by alcohols.

• Amines with fewer than six carbon atoms are generally soluble in water as a result

of hydrogen bond formation between amine functional groups and water

molecules.

Properties of Amines; Amine Salts

Amine salts have physical properties characteristic of other ionic

compounds. They are white crystalline solids with high melting points.

• Amine drugs are often given in the form of salts so that they will dissolve in

body fluids as they are more water soluble because they are ionic.

Neurotransmitter:

A substance that acts

as a chemical bridge in nerve impulse

transmission between nerve cells.

Alkaloids

are a class of nitrogenous organic compounds of plant origin which

have pronounced physiological actions on humans.

• A number of alkaloids are also used medicinally, including as pain relievers.