or more demetalling reactors wherein the cobalt values are converted into cobalt acetate separating the crude hydroformylation into an aqueous phase comprising cobalt acetate and an organic phase comprising the crude hydroformylation product concentrating the aqueous phase comprising cobalt acetate in said evaporator by distilling off a stream comprising water and acetic acid and taking a bottom portion comprising cobalt acetate from said evaporator comprising concentrated cobalt acetate passing said concentrated cobalt acetate to a preforming stage wherein said portion comprising concentrated cobalt acetate values is contacted with synthesis gas in the presence of an organic phase to form cobalt carbonyl passing said cobalt carbonyl from the preformer to said one or more stripper reactors wherein said process further comprises at least one additional step selected from separating said stream comprising water and acetic acid from said evaporator into an acetic acid rich stream and acetic acid depleted water stream and using the acetic acid depleted water stream to wash said aldehyde phase recovered in step e in a wash tower whereby an acetic acid depleted aldehyde phase is obtained and adding an organic alcohol to said preforming stage in an amount and for a time sufficient to convert a substantial portion of formic acid impurities into formate esters of said organic alcohol while avoiding a substantial portion of acetic acid conversion to acetate esters of said organic alcohol and also more preferred embodiments including.