Can we balanced carbon oxidation reactions? For instance could we stoichiometrically represent the oxidation of isopropyl alcohol to give acetone by the action of permanganate ion?

1 Answer
Oct 20, 2017

#"Isopropyl alcohol"stackrel([O])rarr"Acetone"#

Explanation:

Secondary alcohols can be oxidized to ketones. The oxidizing agent is here unspecified, and could be a high-valent metal salt, i.e. #KMnO_4# or #K_2Cr_2O_7#, which are respectively reduced to #Mn^(2+)# or #Cr^(3+)#.

#(H_3stackrel(-III)C)_2stackrel(0)CHOHrarr(H_3C)_2stackrel(+II)C=O+2H^+ + 2e^(-)# #(i)#

It is uncommon to assign oxidation numbers to carbons in organic molecules, however, here the ipso carbon has clearly been oxidized to give the ketone, and I think the given oxidation numbers are correct.

ANd for every oxidation there is a corresponding reduction, for instance....

#MnO_4^(-) +8H^+ + 5e^(-) rarr Mn^(2+) + 4H_2O(l)# #(ii)#

If I wanted to write a stoichiometric reaction, I would simply cross-multiply #(i)# and #(ii)# so that the electrons are eliminated.......

So #5xx(i)+2xx(ii)# gives......

#5(H_3C)_2CHOH+2MnO_4^(-) +cancel(16)11H^+ + cancel(10e^(-))rarr5(H_3C)_2C=O+cancel(5H^+) +2Mn^(2+) + 8H_2O(l)+ cancel(10e^(-))#

to give finally....

#5(H_3C)_2CHOH+2MnO_4^(-) +11H^+ rarr5(H_3C)_2C=O +2Mn^(2+) + 8H_2O(l)#

....which (I think) is balanced with respect to mass and charge.