Organic Chemistry Alcohols And Phenols
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1
2Organic Chemistry
Lecture Outline
Chapter 17: Alcohols & Phenols
I.
DEFINITION, STRUCTURE & PHYSICAL PROPERTIES OF ALCOHOLS (17.2)
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A. Alcohols are compounds which contain a hydroxy group bonded to an sp
hybridized carbon atom.
B. Alcohols can be classified as primary, secondary or tertiary
C. The physical properties of alcohols differ from their corresponding alkanes
(i.e., polarity, solubility, boiling point, etc..).
D. Alcohols have two properties which make them different from alkanes and alkyl halides.
1. Non-Covalent Interactions
a.
HYDROGEN BONDING: Hydrogen bonds are weak bonds that form between the "positive" H end of the -OH
bond and the "negative" O end of the -OH bond of different alcohol molecules.
b. Dipole-Dipole Interactions
c.
Ion-Dipole Interactions
2. Amphoteric Nature of Alcohols
a.
Alcohols are acidic compounds because they can donate a proton to a base. When an alcohol becomes deprotonated
the resulting species is called an alkoxide.
b. Alcohols can also behave as bases and accept a proton to form an oxonium ion.
II. NOMENCLATURE OF ALCOHOLS (17.1)
A. The parent of an alcohol is the longest continuous carbon chain which contains the carbon atom bonded to the -OH group of
the alcohol.
B. Alcohols are named by using an "-OL" suffix with a hydrocarbon parent
C. The parent chain is numbered so as to give the carbon atom bonded to the -OH group the lowest possible number. A number
corresponding to the position of the OH group on the parent chain is included in the name as a prefix.
D. There are a number of alcohols with common names.
III. DEFINITION & TYPES OF DIOLS
A. Diols are organic compounds which contain two hydroxyl groups.
B. Diols with the two -OH groups bonded to the same carbon atom are referred to as "geminal diols"
C. Diols with the two -OH groups situated in a 1,2-position on the molecule are referred to as "vicinal diols".
IV. DEFINITION, STRUCTURE & PHYSICAL PROPERTIES OF PHENOLS
A. Phenols are compounds which contain a hydroxy group bonded to an sp 2 hybridized carbon atom of a benzene ring.
B. Phenols are acidic, never basic. pKa values of phenols range from ~8-10.
C. Phenols can form H-bonds.
D. NOMENCLATURE OF PHENOLS
1. The parent of a phenol includes the benzene ring and the hydroxyl group
2. Phenols are named by using the term “phenol” as parent
V. REACTIONS OF ALCOHOLS
A. OXIDATION AND OXIDATIVE CLEAVAGE: Overview
(also see handout on Oxidation Summary)
B.
Oxidation of alcohols (17.7)
(also see handout on Oxidation Summary)
1. Primary alcohols can be oxidized to aldehydes or carboxylic acids.
a.
Treatment of a primary alcohol with PCC results in an aldehyde.
b. Treatment of a primary alcohol with Jones reagent results in a carboxylic acid.
2. Secondary alcohols can be oxidized to ketones.
a.
Treatment of a secondary alcohol with Na
Cr
0
in acetic acid, PCC or Jones reagent results in a ketone.
2
2
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3. Tertiary alcohols generally cannot be oxidized.
C. DEHYDRATION: Dehydration of alcohols to give alkenes can occur through two types of mechanisms
1. Dehydration with acid (CH
CO
H, H
PO
or H
SO
) occurs through an E
type mechanism with tertiary, secondary,
3
2
3
4
2
4
1
allylic or benzylic alcohols.
,
2. Dehydration of 1
2
, or 3
alcohols with a combination of tosyl chloride (to make the tosylate) followed by treatment
with base or phosphorous oxychloride (POCl
, base) occurs through an E
type mechanism.
3
2
D. CONVERSION OF ALCOHOLS TO ETHERS (See Chapter 18)
1. SN
to Form Symmetrical Ethers
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2. SN
: Williamson Ether Synthesis
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