Transcript Dihydric alcohols Glycols

Dihydric alcohols
Glycols
Dihydric alcohols (Glycols)
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They are saturated hydrocarbons in which 2
hydrogen atoms are replaced by 2(OH)
groups.
They are classified into α, β, γ according to
the relative position of the OH groups in the
molecule.
Dihydric alcohols (Glycols)
Dihydric alcohols (Glycols)
Dihydric alcohols (Glycols)

Preparation:
1. Mild oxidation
Dihydric alcohols (Glycols)
Preparation:
2. Reduction of glyoxal:
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Dihydric alcohols (Glycols)
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Preparation:
Dihydric alcohols (Glycols)
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Chemical reactions:
Dihydric alcohols (Glycols)

Chemical reactions:
2- When treated with a dehydrating agent, it is dehydrated
and cyclised to a heterocyclic compound called dioxane.
Dihydric alcohols (Glycols)

Chemical reactions:
3- Oxidation:
Dihydric alcohols (Glycols)
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Chemical reactions:
4- Ether formation
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The ethyl ether is named Cellosolve because it is a good
Solvent to cellulose nitrate (it has two function groups - O
- & OH) it is also used in manufacture of lacquers.
Ethers
Ethers
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General formula R – O – R´
Ethers are considered as water molecules in which the
two hydrogen atoms are replaced by two organic
radicals.
Also they are regarded as the anhydrides of the
alcohols
Ethers
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1.
Ethers are divided into two groups:
Simple ethers: R – O – R
Ethers
2. Mixed ethers: R – O - R´
Ethers
Preparation:
1- By continuous etherification process, heating excess
ethyl alcohol with cone. H2SO4.
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Ethers
Preparation:
2- William Son's synthesis:
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Ethers
Chemical Reactions:
1- Formation of oxonuim salt:
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The formation of salts shows that ethers are basic in
character (i.e. electron doner).
Ethers
Chemical Reactions:
2- When treated with chlorine or bromine,
ethers undergo substitution reactions. In the
dark, diethyl ether reacts with chlorine to
form α-chlorodiethylether, further chlorination
yields α,α´-dichlorodiethyl ether.
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Ethers
•In presence of light, total chlorination
occurs and perchlorodiethyl ether is formed.
Ethers
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The most important ethers is diethylether, it is
generally known as sulphuric ether, it is
colorless liquid, boiling point 35°C, difficulty
soluble in water, and highly inflammable, it is
used in surgery as anesthesia.
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