Alcohols
Classification
• General Formula: CnH2n+1OH
• Functional Group: -OH
Isomerism
• Position isomers have the –OH group attached at different positions in the carbon chain.
• Results in different classes of alcohols (1°, 2° & 3°) depending on the number of carbon atoms attached to the
carbon bound to –OH.
Nomenclature
• Suffix: -ol
• If an alcohol contains multiple –OH groups, you use the suffix –diol, -triol, etc.
• Keep the e in the alkane parent in the name, e.g. propane-1,2,3-triol.
Classes of Alcohol
Elimination Reaction – Dehydration of Alcohols
• Ethanol can be dehydrated to give ethane by heating with an excess of concentrated sulfuric acid at 170°C.
• This reaction allows you to produce alkenes from renewable resources (without using oil).
Lone pair on oxygen donates
electron to H+ ion, forming a bond.
Oxygen forms 3 bonds, so has 1+
charge.
Forms an alkene, water and H+ is
regenerated.
Dehydration of more complex alcohols can give more than one possible product, as the double bond can form either
side of the carbon atom with the –OH group attached.
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Classification
• General Formula: CnH2n+1OH
• Functional Group: -OH
Isomerism
• Position isomers have the –OH group attached at different positions in the carbon chain.
• Results in different classes of alcohols (1°, 2° & 3°) depending on the number of carbon atoms attached to the
carbon bound to –OH.
Nomenclature
• Suffix: -ol
• If an alcohol contains multiple –OH groups, you use the suffix –diol, -triol, etc.
• Keep the e in the alkane parent in the name, e.g. propane-1,2,3-triol.
Classes of Alcohol
Elimination Reaction – Dehydration of Alcohols
• Ethanol can be dehydrated to give ethane by heating with an excess of concentrated sulfuric acid at 170°C.
• This reaction allows you to produce alkenes from renewable resources (without using oil).
Lone pair on oxygen donates
electron to H+ ion, forming a bond.
Oxygen forms 3 bonds, so has 1+
charge.
Forms an alkene, water and H+ is
regenerated.
Dehydration of more complex alcohols can give more than one possible product, as the double bond can form either
side of the carbon atom with the –OH group attached.
19
