oxidation, combustion, dehydration

1. REACTIONS OF
ALCOHOLS

2. ALCOHOLS
 Alcohols: Organic compounds containing
hydroxyl (-OH) functional groups.
R OH

3.  Combustion
 Reaction with sodium
 Oxidation
 Esterification
 Dehydration
REACTIONS OF ALCOHOLS

4. COMBUSTION
• Ethanol burns with oxygen to produce carbon dioxide
and water.
• The reaction is exothermic, with large amounts of heat
energy being produced
• Ethanol burns with a clear blue flame
• This is due to the ration of carbon on to hydrogen atoms
being low. All is carbon is converted to carbon dioxide.
• No unreacted carbon is left to produce soot.

5. REACTION WITH SODIUM
 Alcohols reacts with Na at room temperature to
form salts (sodium alkoxides) and hydrogen.
2R-O-H + 2Na → 2R-ONa + H2
+ H2
 For example:
CH3CH2OH + Na → CH3CH2ONa
alcohol sodium ethoxide

6. OXIDATION
CH₃ C OH
H
KMnO4/H+
or K2Cr2O7/H+
O
CH₃-C-OH
carboxylic acid
H
 When ethanol is heated with acidified potassium manganate (VII)
solution or acidified potassium dichromate (VI), powerful oxidizing
agents, ethanol is oxidized to ethanoic acid
 Ethanol is the reducing agent
 When heated with potassium manganate (VII) solution the purple
colour is decolorized
 The ethanol reduces the purple manganate (VII) ion (MnO4⁻) to
colourless manganese (II) ion (Mn²⁺)
 When heated with acidified potassium dichromate (VI), the ethanol
reduces the orange dichromate (VI),Cr2O7²⁻, to the green
chrominium (III) ion, Cr³⁺.

7.  Esterification:
- the reaction between an alcohol and a carboxylic acid to
form an ester and H2O.
ESTERIFICATION
O
R C O H H O R'
H+
CH3CH2-O-H
O
CH3 C O H
H+
R
O
CH3 C OCH2CH3
O
C O R' H2O
H2O
carboxylic acid alcohol ester
EXAMPLES
ethanol ethanoic acid ethyl ethanoate

8.  Dehydration of alcohols will formed alkenes
DEHYDRATION
conc. H2SO4
R-CH2-CH2-OH R-CH=CH2 + H2O
170⁰C

9. REFERENCES
 https://easychem.com.au/production-of-materials/renewable-
ethanol/dehydration-of-ethanol/
 Miza Kamaruzzaman, 2013 Chaper 1 alcohols,
https://www.slideshare.net/mizakamaruzzaman/chapter-1-
alcohols?from_action=save
 Tindale, Ritchie et al, 2014, Chemistry for CSEC 2nd Edition,
Nelson Thornes. Chapter 15, p256-258
 https://www.youtube.com/watch?v=-aLRcr5QZNU