Manufacture of 1,6-hexanediol from butadiene

A process for the manufacture of 1,6-hexanediol by hydroformylation of 1,3-butadiene, wherein, in a first hydroformylation stage, 1,3-butadiene is reacted with carbon monoxide and hydrogen at from 70.degree. to 130.degree.C and from 50 to 600 atmospheres in the presence of a rhodium complex which contains carbon monoxide and a tertiary organic phosphine or tertiary organic phosphite and a halogen atom as ligands, and with an alkanol or alkanediol of 1 to 4 carbon atoms, the rhodium compound is removed, the pent-3-en-1-al-acetal thus obtained is subjected to a second hydroformylation stage, either in the hydroformylation mixture from the first stage after the rhodium compound is removed or after isolation therefrom, with carbon monoxide and hydrogen at from 120.degree. to 220.degree.C and from 20 to 120 atmospheres in the presence of a cobalt carbonyl complex modified with a tertiary organic phosphine, the hydroformylation product thus obtained is hydrogenated by conventional methods in the presence of a hydrogenation catalyst at elevated temperature and superatmospheric pressure, and the 1,6-hexanediol produced is isolated, also by conventional methods.