Nature of the cobalt compound

Nature of the cohait eompound. With unpromoted cobalt catalysts generally, Co2(CO), is thouglit to be the main active catalyst precursor 1]. This compound can be formed from a variety of cobalt salts under CO pressure. 

Three major reactions of Coz(CO) have to be anticipated under homoloiga-tion conditions, thus, hydrogenation yields hydrocoball tetracarbonyl. a compound which acts as an acid in polar solvents Or as a hydride in unpolar ones (Equation (S . 

The disproportionation reaction (6) takes place in the presence of a base such as methanol and leads to a axfold coordinated and Co(CO)4. It has to be noted that tltis reaction is reversible under pressure of CO. niosphine ligands give a similar disproportiemation reaction (7). 

Infrared measurements under homologation conditions have shown a correlation between the concentration of Co(CO)4 and the rate of methanol hydro carbonybtion [25]. Investigations by Deluzarche er af. established the following order of reactivity (c.f. Table III) Co(OAc 2 Coj(CO) Cofacac) Co4(CO)i3. This order may reflect the ability of the cobalt compounds to form Co(CO)4 . Interestingly, there is a remarkable dilTerence in reactivity between Co2(CO) andCo4(CO),2 [26.  

Conditions 300 bai II2/CO (2 1) IStTC catalyst cone. 3 X 10 mote/inole McOH. 

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