The use of carbon monoxide under pressure with the highly poisonous cobalt carbonyls is not without danger. The ill effect of breathing carbon
monoxide is sufficiently well known so that a warning is perhaps not necessary. According to Gilmont and Blanchard "the odor of cobalt
tetracarbonyl hydride is so intolerable that the danger from inhaling it is much less than from nickel tetracarbonyl. However, it is probably equally
poisonous, and the same precautions should be taken as with nickel tetracarbonyl."
The hydride decomposes even at room temperature, so that it will disappear rapidly from reaction mixtures held at atmospheric pressure, with the
formation of dicobalt octacarbonyl. Fortunately this latter compound has a low vapor pressure and so may be handled with much less hazard than nickel
tetracarbonyl. The dicobalt octacarbonyl also decomposes slowly in an open vessel to give carbon monoxide at room temperature. However, in an ether
solution in a closed Pyrex bottle there is no development of pressure or appreciable decomposition at room temperature. |