Cobalt-catalyzed process for preparing alkanediols using a rhodium promoter

A process for preparing an alkanediol comprising the steps of:

• (a) contacting, at a temperature within the range of about 50.degree. to about 100.degree. C. and a pressure within the range of about 500 to about 5000 psig, an ethylene oxide with carbon monoxide and hydrogen in an essentially non-water miscible solvent in the presence of an effective amount of a non-phosphine-ligated cobalt catalyst and an effective amount of a rhodium promoter under reaction conditions effective to produce an intermediate product mixture comprising less than 15 wt % hydroxyaldehyde;
• (b) adding an aqueous liquid to said intermediate product mixture and extracting into said aqueous liquid a major portion of the hydroxyaldehyde at a temperature less than about 100.degree. so as to provide an aqueous phase comprising the hydroxyaldehyde in greater concentration than the concentration of hydroxyaldehyde in the intermediate product mixture, and an organic phase comprising at least a portion of the cobalt catalyst or a cobalt-containing derivative thereof and at least a portion of the rhodium promoter or a rhodium-containing derivative thereof;
• (c) separating the aqueous phase from the organic phase;
• (d) contacting the aqueous phase comprising the hydroxyaldehyde with hydrogen in the presence of a hydrogenation catalyst at a pressure of at least about 100 psig and a temperature during at least a portion of the hydrogenation step of at least about 40.degree. C. to provide a hydrogenation product mixture comprising an alkanediol;
• and
• (e) recovering the alkanediol from the hydrogenation product mixture.