Reactions of organometallic complexes with carbon monoxide. Part III. Carbonylation of neopentyl and other alkyl complexes of mercury(II)

Abstract

The reactions of carbon monoxide with nitrato(alkyl)mercury complexes HgRNO₃(R = Buⁿ, Me₃C·CH₂, and MeO·CH₂·CH₂) have been investigated in methanol. At low pressures (25 atm.) the main products were the esters RCO₂Me and the nitro-compounds, RNO₂. At higher pressures (200–300 atm.)α-oxo-esters, RCO·CO₂Me, are also found. Nitrato(neopentyl)mercury was studied to allow a search to be made for rearranged products derived from the t-pentyl (1,1-dimethylpropyl) group. None was found and it is concluded that the mechanism of carbonylation does not involve carbonium ion formation as does the solvolysis of these complexes. The formation of an intermediate carbonyl complex is suggested. Nitrato-(n-butyl)mercury reacts with carbon monoxide in water, yielding n-pentanoic acid while in benzene solution nitroalkanes and alkyl nitrates are formed together with alcohols, acids, and esters (ROH, RCO₂H, and RCO₂R) that probably arise from traces of water.