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Functional Class Nomenclature of Alcohols( Common Names)
Name the alkyl group and add "alcohol" as aseparate word.
4
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
Ethyl alcoholEthyl alcohol
1-Methylpentyl alcohol1-Methylpentyl alcohol
1,1-Dimethylbutyl1,1-Dimethylbutylalcoholalcohol
IUPAC Nomenclature of Alcohols•Name as "alkanols." Replace –e ending of alkanename by -ol.•Number chain in direction that gives lowest numberto the carbon that bears the —OH group.
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
EthanolEthanol
2-Hexanol2-Hexanol
2-Methyl-2-pentanol2-Methyl-2-pentanol
Name these:
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CH3 CH
CH3
CH2OH
CH3 C
CH3
CH3
OH
CH3 CH
OH
CH2CH32-methyl-1-propanol
2-methyl-2-propanol
2-butanol
OH
Br CH3
3-bromo-3-methylcyclohexanol =>
Unsaturated Alcohols
Number the chain in thedirection that gives the lowest number to the carbon that bears the OH group
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4-penten-2-ol (old)
pent-4-ene-2-ol =>
CH2 CHCH2CHCH3
OH
Naming Priority
• Acids• Esters• Aldehydes• Ketones• Alcohols• Amines
• Alkenes• Alkynes• Alkanes• Ethers• Halides
=>
Chapter 10 8
Hydroxy Substituent
• When -OH is part of a higher priority class of compound, it is named as hydroxy.
• Example:
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CH2CH2CH2COOH
OH
4-hydroxybutanoic acid =>
Classes of Alcohols
• Primary: carbon with –OH is bonded to one other carbon. -CH2OH
• Secondary: carbon with –OH is bonded to two other carbons. -CHOH
• Tertiary: carbon with –OH is bonded to three other carbons. -COH =>
10
Diols
• Two numbers are needed to locate the two -OH groups.
• Use -diol as suffix instead of -ol.
Chapter 10 13
HO OH
1,6-hexanediol
=>
Glycols
• 1, 2 diols (vicinal diols) are called glycols.• Common names for glycols use the name of the
alkene from which they were made.
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CH2CH2
OH OH
CH2CH2CH3
OH OH
1,2-ethanediol
ethylene glycol
1,2-propanediol
propylene glycol =>
Thiols
• Contains an –SH (sulfhydryl) group.
• Is named by selecting the longest carbon chain that contain the -SH. We add -thiol to the name of the parent alkane.
• Parent chain is numbered from the end nearest tothe -SH group.
Methanethiol Ethanethiol
CH3─S─H CH3─CH2─S─H
Physical Properties of Alcohols
1. Alcohols are polar molecules (because of O-H and C-O).
2. Have higher boiling point than Alkanes, Alkenes & Alkynes due to Hydrogen bonding involves oxygen of one molecule and hydrogen of another in alcohol molecules.
3. As the molecular weight increase, boiling point decrease.
4. As the molecular weight increase, solubility in water decrease .
5. The solubility of alcohols in water is due to hydrogen bonding between alcohol and water molecules.
6. They are weak acids (weaker than Phenol).
PHYSICAL PROPERTIES OF ALCOHOLS, cont.• The –OH group can hydrogen bond between alcohol molecules
leading to relatively high boiling points.• Hydrogen bonding in pure ethanol:
PHYSICAL PROPERTIES OF ALCOHOLS• The –OH group is polar and capable of hydrogen bonding.• This makes low molecular weight alcohols highly soluble in
water.• Hydrogen bonding in a water-methanol solution:
Acidity of Alcohols
pKa range: 15.5-18.0 (water: 15.7)Acidity decreases as alkyl group
increases.Halogens increase the acidity.Phenol is 100 million times more acidic
than cyclohexanol!
=>
Chapter 10 21
Preparation of Alcohols by Hydration of Alkenes
Water molecule add to double bond in accordance with Markovnikov’s rule
Preparation of Alcohols by Grignard ReagentsBy reaction of grignard reagents with aldehydes and
ketones to form Primary, Secondary and Tertialy Alcohols.
CH3CH2MgBr + C
H
H
O CH3CH2CH2OH
primary alcohol
CH3CH2MgBr + C
H
H3C
O CH3CH2CHOH
Secondry alcohol
CH3
CH3CH2MgBr + C
H3C
H3C
O CH3CH2COH
Tertiary alcohol
Ether
H3O+
Ether
H3O+
Ether
H3O+
CH3
CH3
Preparation of Diols
Diols formed by reduction of dialdehyde by catalytic hydrogenation as the following reaction.
4- Conversion of Alcohols to Ethers
By Heating primary alcohols in the presence of Sulfuric acid (Condensation reaction)
PCC : Pyridinium Chlorochromate
Primary alcohol is oxidized under strong or mild oxidizing agents to give acid or aldehyde
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