Chem 121

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Chapter 14 Lecture Outline
Prepared by Andrea D. Leonard
University of Louisiana at Lafayette

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Organic Compounds that Contain Oxygen, Halogen, or Sulfur
Four families of compounds that contain a C atom singly bonded to O, S, or X (F, Cl, Br, or I) are: 1. Alcohols, which contain an OH (hydroxyl) group

2. Ethers, which have two alkyl groups bonded to an O atom

2

Organic Compounds that Contain Oxygen, Halogen, or Sulfur
3. Alkyl halides, which contain a halogen atom X (X = F, Cl, Br, or I)

4. Thiols, which contain a SH (sulfhydryl) group

3

Structure and Properties of Alcohols
•Alcohols contain a hydroxyl (OH) group.

•Alcohols are classified by the number of C atoms bonded to the C with the OH group.

A primary (1o) alcohol has an OH group on a C bonded only to 1 C atom. 1o
4

Structure and Properties of Alcohols
A secondary (2o) alcohol has an OH group on a C bonded only to 2 C atoms.

2o

3o

A tertiary (3o) alcohol has an OH group on a C bonded only to 3 C atoms. 5

Structure and Properties of Alcohols
•An alcohol contains an O atom with a bent shape like H2O, with a bond angle of 109.5o.

•Alcohols have two polar bonds, C—O and O—H, with a bent shape, therefore it has a net dipole.

6

Structure and Properties of Alcohols
•Alcohols have an H atom bonded to an O atom, making them capable of intermolecular hydrogen bonding.

•All of these properties give alcohols much stronger intermolecular forces than alkanes and alkenes. 7

Structure and Properties of Alcohols
•Therefore, alcohols have higher boiling and melting points than hydrocarbons of comparable size and shape.

stronger intermolecular forces higher boiling and melting point 8

Structure and Properties of Alcohols
•Alcohols are soluble in organic solvents. •Low molecular weight alcohols (6 C’s or less) are soluble in water. •Higher molecular weight alcohols (6 C’s or more) are not soluble in water.

2 C’s in chain water soluble

8 C’s in chain water insoluble
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Nomenclature of Alcohols
HOW TO Name an Alcohol Using the IUPAC System
Example Give the IUPAC name of the following alcohol.

Step [1]

Find the longest carbon chain containing the C bonded to the OH group. •Change the –e ending of the parent alkane to the suffix –ol. 10

6 C’s in longest chain hexane ----> hexanol

Nomenclature of Alcohols
HOW TO Name an Alcohol Using the IUPAC System
Step [2] Number the carbon chain to give the OH group the lower number, and apply all other rules of nomenclature.

3-hexanol

Answer 5-methyl-3-hexanol
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Nomenclature of Alcohols
•When an OH group is bonded to a ring, the OH is automatically on C1. •The “1” is usually omitted from the name. •The ring is then numbered to give the next substituent the lower number.

12

Nomenclature of Alcohols
•Common names are often used for simple alcohols.

•Name all the C atoms of the molecule as a single alkyl group. •Add the word alcohol, separating the words with a space.

13

Nomenclature of Alcohols
•Compounds with two OH groups are called diols or glycols. •Compounds with three OH groups are called triols.

1,2-ethanediol

1,2-cyclopentanediol

14

Interesting Alcohols
Common alcohols
•Methanol (CH3OH) is a useful as a solvent and a starting material for plastics, but it is toxic due to its oxidation in the liver. •Ethanol (CH3CH2OH) is the alcohol present in alcoholic beverages, and it is formed from the fermentation of carbohydrate chains. •2-Propanol [(CH3)2CHOH), isopropyl alcohol] is the major component of rubbing alcohol, which is used to sterilize skin and medical instruments. 15

Interesting Alcohols
Common Diols and Triols
•Ethylene glycol (HOCH2CH2OH), a diol, is the major component of antifreeze; it is sweet tasting but extremely toxic. •Glycerol [(HOCH2)2CHOH], a triol, is used in lotions, liquid...
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