Synthesis and structural characterization of CO(2)-soluble oxidizers [Bu(4)N]BrO(3) and [Bu(4)N]ClO(3) and their dissolution in cosolvent-modified CO(2) for reservoir applications

CO(2) utilization in upsteam oil and gas applications requires CO(2)-soluble additives such as polymers, surfactants, and other components. Here we report the facile synthesis of CO(2)-soluble oxidizers composed of judiciously selected organic cations paired with oxidizing anions. [Bu(4)N]BrO(3) and [Bu(4)N]ClO(3) are prepared using a double displacement synthetic strategy, whereby the crystalline product is readily obtained in high yield and structurally characterized using single-crystal X-ray diffraction. The facility of the approach is demonstrated through the preparation of several additional alkylammonium bromate compounds. Static solubility studies using a high-pressure cell with viewing windows showed that tetrabutylammonium compounds could be solubilized using cosolvent-modified CO(2). Using 4 mol% ethanol as cosolvent, >3 mM [Bu(4)N]BrO(3) could be dissolved in CO(2), while ∼0.75 mM [Bu(4)N]ClO(3) could be dissolved in the same solvent system. The solubility properties of [Bu(4)N]BrO(3) along with its thermal stability up to ∼200 °C suggest that it is a promising oilfield oxidizer that can be utilized in subterranean CO(2) applications.