Alcohols
- Created by: micheal yewman
- Created on: 05-10-10 20:25
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Alcohols - Revision Notes
1. General
- Functional group is -OH
- General formula is CnH2n+1OH
- The –OH group means that alcohols hydrogen bond with each other. Alcohols have low volatility (high boiling points) for their size because the hydrogen bonds have to be broken
- Alcohols are highly soluble in water because hydrogen bonding occurs between –OH of alcohols and water molecules
2. Classifying Alcohols
- Classified according to the number of carbons attached to C-OH
- Primary alcohols have 1 carbon attached e.g. ethanol
- Secondary alcohols have 2 carbons attached e.g. propan-2-ol
- Tertiary alcohols have 3 carbons attached e.g. 2-methylpropan-2-ol
Primary 1° Secondary 2° Tertiary 3°
3. Reactions of Alcohols
- Reagents = the other chemicals needed
- Conditions = required temperature, pressure, catalyst etc
a) Combustion
- Example C2H5OH + 3O2 ® 2CO2 + 3H2O
- Balance C’s then H’s then O’s
- Don’t forget the O in the OH when balancing
b) Dehydration to form an alkene
- Example C2H5OH ® CH2=CH2 + H2O
- Needs heat and a strong acid catalyst (concentrated sulphuric acid or concentrated phosphoric acid)
c) Reaction with a carboxylic acid to form an ester (esterification)
- Carboxylic acids contain the functional group –COOH, esters have the form RCOOR’
- Example C2H5OH + CH3COOH ® CH3COOC2H5 + H2O
Ethanoic acid ethyl ethanoate
- Conditions catalyst of concentrated H2SO4
d) Oxidation of primary alcohol to aldehyde
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