How is the mechanism of reduction of benzophenone to diphenylmethanol?

1 Answer
anor277
Dec 13, 2017

Hydride anion adds to the carbonyl....

Explanation:

#H_5C_6C(=O)-C_6H_5 + H^(-) rarr H_5C_6CH(-O^-)C_6H_5 #

Of course work up gives the alcohol.

Benzophenone itself is often used as an indicator in solvent stills....along with gram quantities of sodium or potassium metal. The alkali metal can reduce the benzophenone....

#H_5C_6C(=O)-C_6H_5 + Na rarr underbrace(H_5C_6stackrel(*)C(-O^-)C_6H_5)_"blue" +Na^+#

And when you get the solvent really dry, the benzophenone anion will accept another electron to give a deep-purple coloured ion...

#{underbrace(H_5C_6stackrel(ddot)C^(-)(-O^-)C_6H_5)_"purple"}#

The radical species conveniently react with dioxygen to give oxygen-free solvents....

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