alcohols and phenols 145 chem1 king saud university chemistry department
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145 Chem 1
Alcohols and Phenols
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145 Chem 2
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- Alcohols and phenols may be viewed as organic derivatives of water.
- 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 attached to an aromatic ring, Ar.
Alcohols and Phenols
H-O-H R-O-H Ar-O-H
Water Alcohol Phenol
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Alcohols are classified into:
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Classification and Nomenclature of Alcohols
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In the IUPAC system, 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 C-C triple bond, - The name should include both the hydroxyl and the unsaturated groups.-The -OH group takes preference before the double or triple bonds in getting the lower number.- If a compound contains both OH and a double or triple bond, choose the chain that include them both even if this is not the longest chain.
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IUPAC Name:
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3. In the IUPAC system - The suffix diol is added to the name of the parent
hydrocarbon when there are two OH groups.- The suffix triol is added when there are three OH groups.
- listing the alkyl substitutents attached to the hydroxyl group, followed by the word alcohol.
- Two OH groups on adjacent carbons are known as 1,2-glycols.
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Common name
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- Primary alcohol
CH3OH CH3CH2OH CH2=CHCH2OH
Common
Methyl alcohol Ethyl alcohol Allyl alcohol
IUPAC Methanol Ethanol 2-Propen-1-ol
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- Secondary and tertiary alcohol
Common
Isopropyl alcohol
Cyclopentyl alcohol
Methylcyclohexyl alcohol
IUPAC 2-Propanol Cyclopentanol1-Methyl-1-cyclohexanol
CH3
OH
OHOH
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OH
OH OHOH
OH
OH
4-Methyl-2-cyclohexen-1-ol
Phenol1-Phenylmethanol
Benzyl alcohol (common name)
2-Phenylethanol
Ethan-1,2-diolEthelene glycol (common name)
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Diols and triols are more soluble in water than monohydroxyalcohols.
As the number of carbons in the alcohol increases, the solubility in
water decreases.
The boiling points increase with increase in molecular weights.
Physical Properties of Alcohols
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The presence of the hydrogen bonding between alcohol molecules as a result of the high b.p. of alcohol.
Alcohols are week acids.
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H2C
OH OH
HC
OH
CH2
Nomenclature
IUPAC
Commen
Homework
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1. From alkene
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Synthesis (Preparation) of Alcohols
H3O+ OH+
OHmajor minor
KMnO4
OH-/H2O
OH
OHcis glycol
alcohol,KOH
CH3CH2CH2Cl
heat
dil OH-
CH3CH2CH2OH
H3C CH
CH2
2. From – alkyl halid
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3. Reduction of aldehyde, ketone and carboxylic acid.
4. Addition of Grignard compounds to aldehyde and ketone.
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LiAlH4CH3CCH3 or NaBH4
or H2/Pt
H3CHC CH3
O
OH
LiAlH4CH3COH H3C
H2C OH
O
LiAlH4
or NaBH4or H2/Pt
H3CHC H
OH
CH3CH
O
CH3 MgBrCH3CH H3C
HC CH3
O
OMgBr
H3O+
H3CHC CH3
OH
CH3 MgBrH
HC CH3
OMgBr
H3O+
HHC CH3
OHH H
O
Tertiary alcohol
Secondary alcohol
Primary alcohol
CH3CCH3
O
OMgBr
H3O+
+
MgBr C CH3H3C
OH
C CH3H3C
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B. Ester Formation
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Reactions of Alcohols 1. Reaction as acids (Breaking of oxygen- Hydrogen bond CO ـــــH)
NaCH3CH2OH H3C
H2C ONa
Sodium ethoxide
2. Reaction with CــــOH bond cleavage
A. Elimination Reactions
conc.H2SO4CH3CH2OH H2C CH2
B. Substitution Reaction HCl
CH3CH2OH H3C CH2Clor SOCl2or PCl3or PCl5
R OH
O
+ R- OHR OR
O
A. Salt Formation
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3. Oxidation Reactions
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Cu/CH3CH2OH H3C CH
or CrO3
O
CH3CH2OH H3C C-OH
OKMnO4
Cu/CH3CHCH3 H3C C-CH3
or CrO3KMnO4
OOH
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Phenols are generally named as derivatives of the simplest member of the family, phenol (hydroxyl group attached directly to a benzene ring are called phenols).
Nomenclature and acidity of Phenols
OH OH OH OH OH
OCH3NO2 NO2
O2N O2N NO2
NO2
4-nitrophenol 2,4-dinitrophenol picric acid2,4,6-trinitrophenol
phenol
4-methoxyphenolp-Cresol (Common)
pKa 10 pKa = 10 pKa = 7 pKa = 4 pKa= 0.25
OH
CHO
OH
COOH
OH
Cl NH2
3-Amino-5-chlorophenol2-Hydroxybenzoic acido-Hydroxybenzoic acid
Salicylic acid
2-Hydroxybenzaldehydeo-Hydroxybenzaldehyde
Salicylaldehyde
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- Introduction of electron-withdrawing groups, such as NO2 or CN,
on the ring increases the acidity of phenols.
- Alcohols and phenols have weak acidic properties.
- Phenols are much stronger acids than alcohols.
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Synthesis of Phenols
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Reactions of Phenols
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Electrophilic Substitution Reaction
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Home Work
KMnO4
OH-/H2O
HCH
OH3O+
+
MgCl
MgBr
H3O+
+
O H2C
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4) The IUPAC name of
is:A) 4-Ethyl-5-heptyn-3-ol B) 4-Ethyl-5-heptan-3-olC) 4-Ethyl-5-hepten-3-olD) 4-Etyl-2-hepten-5-ol
OH
5) The IUPAC name of
is:A) 3-Methyl-1-bromocyclohexanolB) 2-Bromo-3-methylcyclohexanolC) 4-Bromo-2-methylcyclohexanolD) 3-Bromo-1-methylcyclohxanol
HO
H3C Br
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6) The common name of 2-methyl-2-propanol is:A) Allyl alcoholB) Isopropyl alcoholC) tert-Butyl alcoholD) Benzyl alcohol
7) The following reaction gives
A) 4-EthylphenolB) 2-EthylphenolC) Ethylphenyl etherD) Ethylphenyl ketone
NaOHOH
1)
CH3-CH2-Br2)
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