Reduction of Ethanal (Acetaldehyde) to Ethane or Ethanol
Ethanal is an aldehyde compound found in organic chemistry. Reduction of ethanal (acetaldehyde) to ethane or ethanol can be done by two methods. Clemmensen reagent and Lithium aluminium hydride (LiAlH4) are used to prepare ethane and ethanol respectively. Carbonyl carbon atom in ethanal molecule is reduced to oxidation states of -1 and -3 when ethane and ethanol are prepared respectively.
Chemical formulas for ethanal, ethane and ethanol
Because, here we are going to see some chemical reactions, it's better to understand the structure of each chemical because oxidation numbers of some atoms in these molecules are changed during these reactions. You can see each following compound has only two carbon atoms in their only carbon chain.
- Ethanal (acetaldehyde) : CH3CHO
- Ethane - CH3CH3
- Ethanol - CH3CH2OH
Oxidation state of ethanal
Ethanal is an aldehyde compound. Oxidation number of carbinol carbon of ethanal is +1. Therefore that carbon atom can be reduced to lesser oxidation states such as -1, -3. Ethanal can be reduced to ethane or ethanol easily by one step.
Ethanal to ethane - clemmensen reduction
Clemmensen reduction is used to reduce aldehydes and ketone compounds to hydrocarbons. Using clemmensen reagent ( Zn(Hg) and concentrated HCl), ethanal can be reduced to ethane. Ethane is a hydrocarbon compound (alkane). Oxidation number of carbonyl carbon atom is changed from +1 to -1.
Ethanal reduction to ethanol by reducing agents
Ethanal can be converted to ethanol by using following reagents. Ethanol is an alcohol compound. Oxidation number of carbonyl carbon atom is changed from +1 to -3.
- LiAlH4 / ether
- NaBH4
- H2 and Ni/Pt/Pd
- Na / CH3CH2OH
Questions
What compound has the higher oxidation state after ethanal reduction, ethanol or ethane
In ethanol, one carbon atom has a bond with an oxygen atom. Therefore that carbon atom is oxidized due to higher electronegativity of oxygen atom. But in ethane, there are only hydrogen atoms around the carbon atom and all carbon atoms are reduced.
Can PCC be used to convert ethanol to ethanal?
Yes. you can oxidize ethanol to ethanal using PCC. PCC is not a strong oxidizing agent. PCC is used to oxidize primary alcohols to aldehyde compounds.
Reduction of acetaldehyde to ethyl alcohol
Ethyl alcohol is ethanol and acetaldehyde is ethanal.