Alcohols
Read our general notes on Risk Assessment
Why cannot methanol be reduced?
Igloo writes ...
All alcohols, including methanol, can be reduced with powerful enough reducing agents to give alkanes, e.g.
CH3CH2OH + 2[H] -> CH3CH3 + H2O
CH3OH + 2[H] -> CH4 + H2O
The type of reducing agents used are somewhat obscure – which is why I haven’t listed any examples here – but the main thing to realise is that it is the presence of a hydroxyl group (OH) which is all important, rather than the length of the carbon chain.
I think that your question refers to dehydration, rather than reduction.
Most alcohols can be dehydrated to alkenes, using a suitable dehydrating agent:
e.g. CH3CH2OH - H2O -> CH2=CH2
Suitable dehydrating agents include aluminium oxide and concentrated sulphuric acid.
However, in this sort of reaction it is the presence of a hydroxyl group on one carbon atom, and a hydrogen atom on a neighbouring carbon atom, which are both needed for the elimination reaction to take place, resulting in the creation of a carbon/carbon double bond.
Methanol only has one carbon atom, so no double bond can be formed, therefore methanol cannot be dehydrated in the same way.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
Rate this page or react
Share your views on this page, 7 ratings so far
, rated at 
updated: 24 February 2006
