Chemistry 121 Winter 2016
Introduction to Organic Chemistry and Biochemistry
Instructor Dr. Upali Siriwardane (Ph.D. Ohio State)
E-mail: upali@latech.edu
Office: 311 Carson Taylor Hall ; Phone: 318-257-4941;
Office Hours: MTW 8:00 - 10:00 am;
ThF 9:00 - 10:00 am 1:00 - 2:00 pm.
December 18, 2015: Test 1 (Chapters 12-13)
January 25 , 2016: Test 2 (Chapters 14-16)
February 17, 2016: Test 3 (Chapters 17-19)
February 29, 2016: Test 4 (Chapters 20-22)
March 1 , 2016:
Make Up Exam: Chapters 12-22)
Bring Scantron Sheet 882-E
1
Chapter 14 and GHW#4
Questions
Introduction Alcohols, Phenols, and
Ethers:
Chapter 14. Alcohols, Phenols, and Ethers
14.1 Bonding Characteristics of Oxygen Atoms in Organic Compounds, 423
14.2 Structural Characteristics of Alcohols, 424
14.3 Nomenclature for Alcohols, 425
14.4 Isomerism for Alcohols, 427
14.5 Important Commonly Encountered Alcohols, 427
14.6 Physical Properties of Alcohols, 431
14.7 Preparation of Alcohols, 433
14.8 Classification of Alcohols, 434
14.9 Chemical Reactions of Alcohols, 435
14.10 Polymeric Alcohols, 443
14.11 Structural Characteristics of Phenols, 443
14.12 Nomenclature for Phenols, 443
14.13 Physical and Chemical Properties of Phenols, 444
14.14 Occurrence of and Uses for Phenols, 445
14.15 Structural Characteristics of Ethers, 447
14.16 Nomenclature for Ethers, 449
14.17 Isomerism for Ethers, 452
14.18 Physical and Chemical Properties of Ethers, 453
14.19 Cyclic Ethers, 454
14.20 Sulfur Analogs of Alcohols, 454
14.21 Sulfur Analogs of Ethers, 457
Alcohols, Phenols, and Ethers
•
•
•
•
•
Functional groups:
alcohol: R-O-H
phenols: Ar-OH
ether: R-O-R'
thiol: R-S-H
Alkyl, R = CH3 Mehtyl etc.
Phenyl, Ar = C6H5
1. Bonding Characteristics of Oxygen Atoms
in Organic Compounds
Structural Characteristics of Alcohols
Alcohols - Nomenclature
• IUPAC names
– the parent chain is the longest chain that contains
the -OH group
– number the parent chain in the direction that
gives the -OH group the lower number
– change the suffix -e to -ol
• Common names
– name the alkyl group bonded to oxygen followed
by the word alcohol
Nomenclature of compounds containing
functional groups
• The IUPAC system deals with functional groups two different
ways.
• Modification of the hydrocarbon name to indicate the
presence of a functional group.
• alcohol, -OH
use -ol ending.
• ether: CH3CH2-O-CH3 use methoxy
methoxy ethane
• thiol: R-S-H
use -thiol ending.
Alcohols - Nomenclature
Problem: Write the IUPAC name of each alcohol
(a) CH3 ( CH2 ) 6 CH2 OH
OH
(b)
OH
(c)
Alcohols - Nomenclature
Compounds containing
– two -OH groups are named as diols,
– three -OH groups are named as triols, etc.
CH2 CH2
OH OH
1,2-Eth anediol
(Eth ylen e glycol)
CH3 CHCH2
HO OH
1,2-Propan ediol
(Propylene glycol)
CH2 CHCH2
HO HO OH
1,2,3-Propan etriol
(Glycerol, Glycerin)
Alcohols - Nomenclature
Examples:
OH
Eth anol
(Ethyl alcoh ol)
OH
OH
1-Propan ol
(Propyl alcohol)
2-Prop anol
(Is op ropyl alcohol)
OH
OH
1-Butanol
(Butyl alcohol)
OH
2-Bu tan ol
(s ec-Bu tyl alcohol)
OH
2-Methyl-1-propanol
(Is ob utyl alcoh ol)
OH
Cyclohexanol
2-Methyl-2-prop anol
(t ert-Butyl alcohol) (Cyclohexyl alcohol)
1. Identify the Alcohols, Phenols, and Ethers from the
following and give their common and/or IUPAC names.
1. Identify the Alcohols, Phenols, and Ethers from the
following and give their common and/or IUPAC names.
2. Circle the constitutional isomers of 1-
hexanol among following alcohols.
Classification of alcohols
• Primary
• Secondary
• Tertiary.
3. Classify each of the following as
1', 2', or 3' alcohols.
a)
d)
b)
c)
Physical Properties of Alcohols
• Alcohols are polar compounds
– both the C-O and O-H bonds are polar covalent
H
+
C
H
H
O
+
H
Hydrogen Bonding
• Alcohols associate in the liquid state by hydrogen
bonding
• Hydrogen bonding: the attractive force between a
partial positive charge on hydrogen and a partial
negative charge on a nearby oxygen, nitrogen, or
fluorine atom
– the strength of hydrogen bonding in alcohols is
approximately 2 to 5 kcal/mol
– hydrogen bonds are considerably weaker than
covalent bonds (for example, 110 kcal/mol for an
O-H bond)
– nonetheless, hydrogen bonding can have a
significant effect on physical properties
Hydrogen Bonding
– Figure shows the association of ethanol molecules
in the liquid state (only two of the three possible
hydrogen bonds to the upper oxygen are shown
here).
Boiling Points
– alcohols have higher boiling points and are more
soluble in water than hydrocarbons
Molecu lar Boilin g
Weight
Poin t Solub ility
(g/mol)
(°C) in Water
Structural Formu la
N ame
CH3 OH
CH3 CH3
methanol
ethan e
32
30
65
-89
infinite
ins olu ble
CH3 CH2 OH
CH3 CH2 CH3
ethan ol
propane
46
44
78
-42
infinite
ins olu ble
CH3 CH2 CH2 OH
CH3 CH2 CH2 CH3
1-propanol
bu tane
60
58
97
0
infinite
ins olu ble
CH3 CH2 CH2 CH2 CH2 OH 1-pen tanol
88
138
2.3 g/100 g
HOCH2 CH2 CH2 CH2 OH 1,4-bu tanediol
CH3 CH2 CH2 CH2 CH2 CH3 hexan e
90
86
230
69
infinite
ins olu ble
Chemical Reactions of Alcohols
1) Combustion: Alcohol are very flammable and the combustion
products are carbon dioxide and water.
2) Substitution Reactions: OH group is replaced by a another
group such as halogen.
3) Elimination Reactions:
Intarmolecular dehydration : Water is removed from a alcohol
molecule and a alkene is produced. ( H2SO4 at 180)
Intermolecular dehydration : Water is removed from two alcohol
molecules and an ether is produced. ( H2SO4 at 140) Williamson Ether
synthesis.
4) Oxidation Reactions:
Oxygen is added to 1ry and 2ry alcohols
Dehydration of Alcohols
An alcohol can be converted to an alkene by
elimination of H and OH from adjacent carbons
(a -elimination)
– 1° alcohols must be heated at high temperature in
the presence of an acid catalyst, such as H2SO4
with K2CrO4
– 2° alcohols undergo dehydration at somewhat
lower temperatures
– 3° alcohols often require temperatures only at or
slightly above room temperature
Zaitsev’s rule (or the opposite of
Markovnikov’s rule)
Dehydration of an alcohol can result in more than
one alkene product, because hydrogen loss can occur
from either of the neighboring carbon atoms.
Hydrogen is removed from the carbon with lowest
hydrogen atoms ( poor get poorer)
Dehydration of Alcohols
– examples:
CH3 CH 2 OH
OH
H2 SO 4
o
180 C
CH 2 =CH 2 + H 2 O
H2 SO 4
+ H 2O
140o C
Cyclohexanol
CH3
CH3 COH
CH3
Cyclohexene
H2 SO 4
50o C
CH3
CH3 C= CH2
+
2-Methylpropene
(Is obutylene)
H2 O
4a. Complete the following reactions of alcohol.
a) Dehydration:
4b) What is Zaitsev Rule?
5) Complete the following reactions of
alcohol oxidation:
(Cr+6)
(Cr+4)
Green
6) Draw condensed formula of each of the
following:
a. 3-Hexanol
b. 1,2,3-Pentanetriol
c. 2-Methyl-2-pentanol
d. Cyclohexanol
e. 3,4-dimethyl-3-heptanol
7) Draw the alkene products of the dehydration
of the following alcohols:
a)2-Pentanol:
b)3-Methyl-1-pentanol:
c) 2-Butanol:
d)4-Chloro-2-pentanol:
e)1-Propanol:
Oxidation of Alcohols
• Oxidation of a 1° alcohol gives an aldehyde or
a carboxylic acid, depending on the oxidizing
agent and experimental conditions
– the most common oxidizing agent is chromic acid
CrO3
+ H2 O
Chromium(VI)
oxide
H2 SO4
H2 CrO4
Chromic acid
– chromic acid oxidation of 1-octanol gives octanoic
acid
O
O
CrO3
CH3 (CH2 ) 6 CH2 OH
CH3 (CH2 ) 6 CH
H2 SO4 , H2 O
1-Octan ol
Octan al
(not isolated)
CH3 (CH2 ) 6 COH
Octan oic acid
Oxidation of Alcohols
– to oxidize a 1° alcohol to an aldehyde, use PCC
CrO3 Cl-
CrO3 + HCl +
N
Pyridine
N+
H
Pyridiniu m chloroch romate
(PCC)
– PCC oxidation of geraniol gives geranial
O
Geraniol
PCC
OH CH Cl
2
2
H
Geranial
• Tertiary alcohols are not oxidized by either of these reagents;
they are resistant to oxidation
8) Give the oxidation products of the following
alcohols. If no reaction occurs, write N.R.