4- reaction with rhenium

By combining the methods reported above, Cook and Andrews in 1996 discovered the first catalytic process based on the stoichiometric reactions with rhenium (V) diolate complexes reported in the 10 years before. The use of a reductant in the form of a triarylphosphine was found to be critical to close the deoxydehydration... 

Heating the solution (to not higher than 60°C, since volatile acetone is present) also increases the reaction rate. The optimum acidity in the medium corresponds to 0.8-1 M HCl. The reaction with rhenium requires a considerable excess of a-furildioxime, the quality of which affects the absorbance [34]. The minimum amount of stannous chloride necessary is 2.5 ml of 10% SnCb solution per 25 ml of the final solution. 

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