Online ESI-MS analysis of reactions under high pressure.

A new approach for real-time mass spectrometric analysis and identification of intermediates in confined, pressurized vessels is presented. The high-pressure reaction media is depressurized, mixed with a solvent, and fed directly to the atmospheric pressure electrospray ionization source of a tandem mass spectrometer. The method was applied to track product evolution for the dehydration of hydroxenin monoacetate, a commercially, important vitamin A precursor, and for the hydrogenation of 5-norbornene-2-carbonitrile with Pd/CaCO(3) as catalyst.

Dehydration reaction of hydroxenin monoacetate in carbon tetrachloride and an aliphatic alcohol under ultrasound irradiation.

A new method for the preparation of an E/Z mixture of vitamin A acetate from hydroxenin monoacetate is described. This two-step reaction was studied by changing the reaction parameters (reaction temperature, ultrasound power, and reaction time) and the alcohol used. This approach consists of the dehydration reaction of hydroxenin monoacetate under ultrasound irradiation in CCl4 and an aliphatic alcohol under an inert atmosphere.