Download Structure and Synthesis of Alcohols

Structure and Synthesis
of Alcohols
Structure of Alcohols
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Hydroxyl (OH) functional group
Oxygen is sp3 hybridized.
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Classification
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Primary: carbon with –OH is bonded to one
other carbon.
Secondary: carbon with –OH is bonded to
two other carbons.
Tertiary: carbon with –OH is bonded to three
other carbons.
Aromatic (phenol): -OH is bonded to a
benzene ring.
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Classify these:
CH3
CH3
CH3
CH CH2OH
CH3
C OH
CH3
OH
OH
CH3
CH CH2CH3
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IUPAC Nomenclature
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Find the longest carbon chain containing the
carbon with the -OH group.
Drop the -e from the alkane name, add -ol.
Number the chain, starting from the end
closest to the -OH group.
Number and name all substituents. =>
Name these:
CH3
CH3
CH CH2OH
2-methyl-1-propanol
OH
CH3
CH CH2CH3
2-butanol
CH3
CH3
OH
C OH
CH3
2-methyl-2-propanol
Br
CH3
3-bromo-3-methylcyclohexanol
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Unsaturated Alcohols
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Hydroxyl group takes precedence. Assign that
carbon the lowest number.
Use alkene or alkyne name.
OH
CH2
CHCH2CHCH3
4-penten-2-ol (old)
pent-4-ene-2-ol
(1997 revision of IUPAC rules)
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Naming Priority
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Acids
Esters
Aldehydes
Ketones
Alcohols
Amines
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Alkenes
Alkynes
Alkanes
Ethers
Halides
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Hydroxy Substituent
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When -OH is part of a higher priority class of
compound, it is named as hydroxy.
Example:
OH
CH2CH2CH2COOH
also known as GHB
4-hydroxybutanoic acid
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Common Names
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Alcohol can be named as alkyl alcohol.
Useful only for small alkyl groups.
Examples:
CH3
CH3
CH CH2OH
isobutyl alcohol
OH
CH3
CH CH2CH3
sec-butyl alcohol
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Naming Diols
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Two numbers are needed to locate the two
-OH groups.
Use -diol as suffix instead of -ol.
OH
HO
1,6-hexanediol
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Glycols
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1, 2 diols (vicinal diols) are called glycols.
Common names for glycols use the name of the
alkene from which they were made.
CH2CH2
CH2CH2CH3
OH OH
OH OH
1,2-ethanediol
1,2-propanediol
ethylene glycol
propylene glycol
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Naming Phenols
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-OH group is assumed to be on carbon 1.
For common names of disubstituted phenols, use
ortho- for 1,2; meta- for 1,3; and para- for 1,4.
Methyl phenols are cresols.
OH
OH
H3C
Cl
3-chlorophenol
meta-chlorophenol
4-methylphenol
para-cresol
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Physical Properties
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Unusually high boiling points due to hydrogen
bonding between molecules.
Small alcohols are miscible in water, but
solubility decreases as the size of the alkyl
group increases.
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