Answer to Question #57705 in Organic Chemistry for reena

Question

How can I explain and Write a structural equation of to ethanol when
warmed with potassium dichromate (VI) ?? I can not get the right answer when i try to write it out myself

Answer 1

Primary alcohols are oxidized with dichromates to aldehydes:
3C2H5OH + K2Cr2O7 + 8HCl → 3CH3CHO + 2CrCl3 + 7H2O
Ethanol is reducing agent in the presence of Cr6+ therefore it is easily oxidized to acetaldehyde.
During the oxidation it loses 2 electrons at the same time Cr6+ gets 3 elecrons:
C2H5OH – 2 e → CH3CHO + 2H+
Cr2O7
2- + 6 e + 14H+ → 2Cr3+ + 7H2O
However, if we use the excess of dichromate, formed acetaldehyde is oxidized to acetic acid:
3 CH3CHO + K2Cr2O7 + 8HCl → 3CH3COOH + 2CrCl3 + 4H2O
Thus, the overall equation is:
3C2H5OH + 2K2Cr2O7 + 16HCl → 3CH3CHO + 4CrCl3 + 11H2O