[ceity]

Write a balanced equation for the reduction of 9-fluorenone to 9-hydroxyfluorene by sodium borohydride.

C13H8O + BH4- ==> C13H9O- + BH3

BH3 + CH3CH2OH ==> CH3CH2OHBH3

C13H9O- + CH3CH2OHBH3 ==> C13H9OH + CH3CH2OBH3-

4C13H8O + BH4- + 4CH3CH2OH ==> 4C13H9OH + B(OCH2CH3)4-

Is this correct?

[orgopete]

I'd prefer to write it differently, though with the same stoichiometry. Since borohydride decomposes in acid, I'd prefer to use the bases already present. Either add the hydroxyfluorene anion to BH3 or exchange with solvent to make ethoxide. Add ethoxide to BH3 to make a new borohydride. Repeat until (EtO)4B- forms.