Transcript TYPES OF HYBRIDIZATION AND GEOMETRY OF MOLECULES

1
Learning Objectives
Chapter six concerns alcohols and phenols and by the end of this chapter the student
will:
 know the difference in structure between alcohols and phenols
Know the different classes of alcohols
 Know how to name alcohols and phenols
 Know the physical properties (solubility, boiling and melting points)
 Know how hydrogen bonds are formed and its effect on boiling points of
alcohols
Know the acidic properties of alcohols and phenols
know the different methods that can be used to prepare alcohols and
phenols.
 Know the chemical reactions of these compounds ( some reactions are
review, others are extensions of the chemistry that will be discussed on
chapters 8, 9 & 10
145 Chem.
King Saud University
Chemistry Department
Structure Of Alcohols and Phenols
 Alcohols and phenols may be viewed as organic derivatives of water.
H-O-H
Water
R-O-H or PhCH2OH
Alcohol
Ph-O-H
Phenol
 Alcohols and phenols have a common functional group, the hydroxyl group,
—OH.
- In alcohols the hydroxyl group is attached to an alkyl group, —R.
- In phenols the hydroxyl function is directly attached to benzene ring
OH
OH
OH
145 Chem.
Phenol
Benzyl alcohol
Cyclohexanol
3
King Saud University
Chemistry Department
Classification and Nomenclature of Alcohols
Alcohols are classified according to the type of the carbon
atom connected to the hydroxyl group (carbinol carbon) into:
145 Chem.
4
King Saud University
Chemistry Department
NOMENCLATURE OF ALCOHOLS
IUPAC Nomenclature Of Alcohols
Alcohols are named according to the following rules:
1.
Select the longest continuous carbon chain that contains the -OH group. Replace
the ending e of the alkane by the suffix –ol
2. If a molecule contains both an -OH group and a C=C or cΞc bond;



Choose the chain that include both of them even if this is not the longest chain.
The name should include suffixes indicate presence of both the OH group and the
unsaturated groups.
The OH group takes precedence over the double or triple bonds in getting the
lower number.
3. The suffix diol is added to the name of the parent hydrocarbon when there are two OH
groups.
4. The suffix triol is added when there are three OH groups.
145 Chem.
5
King Saud University
Chemistry Department
Common Nomenclature Of Alcohols
 List the names of alkyl substituents attached to the hydroxyl group, followed by the
word alcohol.
If two OH groups present on two adjacent carbons these known as glycols
Primary alcohols
CH3OH
CH3CH2OH
Common
Methyl alcohol
Ethyl alcohol
IUPAC
Methanol
Ethanol
145 Chem.
CH2=CHCH2OH
Allyl alcohol
2-Propen-1-ol
6
King Saud University
Chemistry Department
Secondary and tertiary alcohols
OH
OH
CH3
OH
Common Isopropyl alcohol
IUPAC
145 Chem.
2-Propanol
Cyclopentyl alcohol
Cyclopentanol
Methylcyclohexyl alcohol
1-Methyl-1-cyclohexanol
7
King Saud University
Chemistry Department
OH
Examples
OH
OH
1-Phenylmethanol
Benzyl alcohol (common name)
2-Phenylethanol
OH
Cl
4-Methyl-2-cyclohexen-1-ol
OH
OH
Ethan-1,2-diol
Ethelene glycol (common name)
4-Chloro-2-methyl-1-penten-3-ol
5
4
3
2
1
(CH3)2C=CHCH(OH)CH3
4- Methyl-3-penten-2-ol
145 Chem.
8
King Saud University
Chemistry Department
Examples
OH
OH
OH
But-3-en-2-ol
5-Ethyl-hex-5-en-3-ol
Pent-4-yn-1-ol
OH
OH
CH3
HO
145 Chem.
OH
OH
IUPAC
Ethane-1,2-diol
Propane-1,2-diol
or 1,2-Propanediol
Common
Ethylene glycol
Propylene glycol
OH
OH
Propane-1,2,3-triol
or 1,2,3,-Propantriol
Glycerol or Glycerin
King Saud University
Chemistry Department
Physical Properties of Alcohols
1) Solubility Of Alcohols and Phenols
 Diols and triols are more soluble in water than monohydroxyalcohols.
 As the number of carbons in the alcohol increases, the solubility in water decreases.
2) Boiling Points of Alcohols
The boiling points increase with increase in molecular weights.
OH
>
OH
>
OH
 Alcohols have higher boiling points(b .p.) than alkanes of similar weight this is
due to the presence of hydrogen bonds between molecules of alcohols.
hydrogen bond
145 Chem.
10
King Saud University
Chemistry Department
OH
>
OH
>
OH
>
Br
>
Melting & boiling points
Increases in this direction
H2C
H
C
CH2
OH
OH
Homework
IUPAC
Nomenclature
OH
Commen
3) Acidic Properties of Alcohols
 Alcohols are very weak acids
145 Chem.
11
King Saud University
Chemistry Department
Synthesis (Preparation) of Alcohols
1- From Alkenes
H3O+
OH
major
+
minor
OH
OH
KMnO4
OH-/H2O
OH
cis glycol
2- From alkyl halide
alcohol,KOH
heat
H3C C CH2
H
(elimination of HX using
base gives alkene)
CH3CH2CH2Cl
dil OH-
145 Chem.
CH3CH2CH2OH nucleophilic substitution
12
King Saud University
Chemistry Department
3- Reduction of aldehydes, ketones and carboxylic acids
O
H
LiAlH4
H
C
C CH3
3
CH3CCH3 or NaBH
4
OH
or H2/Pt
O CH MgBr
H
3
H3C C CH3
CH3CH
OMgBr
O
LiAlH4
CH3COH
145 Chem.
H3O+
H
H3C C CH3
OH
H2
H3C C OH
13
King Saud University
Chemistry Department
4Addition
ketones
MgCl
O
CH3CCH3 +
of
Grignard compounds to aldehydes &
OH
H3C C CH3
OMgBr
H3C C CH3
H3O+
Tertiary alcohol
Ketone
Secondary alcohol
Primary alcohol
Methanal
formaldehyde
145 Chem.
14
King Saud University
Chemistry Department
Reaction of Alcohols
1. Dissociation of O-H Bond
Reaction as acids (Breaking of oxygen- Hydrogen bond CO ‫ـــــ‬H)
A. Formation of Salt
CH3CH2OH
Na
H2
H3C C ONa
Sodium ethoxide
B.
Formation of Esters
H+
H+/ H2O
145 Chem.
15
King Saud University
Chemistry Department
2. Dissociation of C-O Bond
Reaction with C‫ــــ‬OH bond cleavage
A. Elimination Reactions
CH3CH2OH
conc.H2SO4
H2C CH2
B. Substitution Reaction
CH3CH2OH
HCl/ ZnCl2
H3C CH2Cl
or SOCl2
or PCl3
or PCl5
145 Chem.
16
King Saud University
Chemistry Department
C. Oxidation Reactions
CH3CH2OH
OH
CH3CHCH3
Cu/
or CrO3
Cu/
or CrO3
KMnO4
O
H3C CH
O
H3C C-CH3
or PCC
, CrO3. HCl
PCC =
Pridinium Chloro chromate
N
145 Chem
17
King Saud University
Chemistry Department
Nomenclature and acidity of Phenols
Phenols (compounds having hydroxyl group directly attached to a
benzene ring ) are generally named as derivatives of the simplest
member of the family, phenol
Acidity :
Alcohols and phenols have weak acidic properties.
Phenols are much stronger acids than alcohols.
Introduction of electron-withdrawing groups, such as NO2 or CN,
on the ring increases the acidity of phenols.
145 Chem.
18
King Saud University
Chemistry Department
145 Chem.
19
King Saud University
Chemistry Department
Synthesis of Phenols
145 Chem.
20
King Saud University
Chemistry Department
Reactions Phenols
Ethers formation
O
OH
CrO3 / H+
OH
Hydroquinone
145 Chem.
O
p-Benzoquinone
21
King Saud University
Chemistry Department
2. Electrophilic Substitution Reactions
145 Chem.
22
King Saud University
Chemistry Department
Home Work
KMnO4
OH-/H2O
MgCl
O
HCH +
O
145 Chem.
H3O+
H2C MgBr
H3O+
+
23
King Saud University
Chemistry Department
4) The IUPAC name of
A) 4-Ethyl-5-heptyn-3-ol
B) 4-Ethyl-5-heptan-3-ol
C) 4-Ethyl-5-hepten-3-ol
D) 4-Etyl-2-hepten-5-ol
5) The IUPAC name of
is:
OH
is:
A) 3-Methyl-1-bromocyclohexanol
B) 2-Bromo-3-methylcyclohexanol
C) 4-Bromo-2-methylcyclohexanol
D) 3-Bromo-1-methylcyclohxanol
6) The most acidic compound is:
145 Chem.
24
King Saud University
Chemistry Department
7) The common name of 2-methyl-2-propanol is:
A) Allyl alcohol
B) Isopropyl alcohol
C) tert-Butyl alcohol
D) Benzyl alcohol
8) The following reaction gives
A) 4-Ethylphenol
B) 2-Ethylphenol
C) Ethylphenyl ether
D) Ethylphenyl ketone
145 Chem.
25
King Saud University
Chemistry Department
9) The major product for the following reaction is
10) The product of the reaction shown below is
11) Which of the following compounds has the highest boiling point?
Questions?