Boric acid catalysed hydrolysis of peroxyacids

Area of Science:

• Chemical Kinetics
• Catalysis
• Oxidative Chemistry

Background:

• Peroxyacids like peracetic acid (PAA) and 3-chloroperbenzoic acid (MCPBA) are vital in oxidation, bleaching, and disinfection.
• Understanding the hydrolysis mechanisms of peroxyacids is essential due to their widespread industrial and laboratory applications.
• Previous studies have not fully elucidated the catalytic pathways influencing peroxyacid decomposition rates.

Purpose of the Study:

• To investigate the catalytic effect of boric acid on the hydrolysis of peroxyacids.
• To determine the optimal pH conditions for boric acid-catalyzed peroxyacid hydrolysis.
• To elucidate the catalytic mechanism involving boric acid species.

Main Methods:

• Hydrolysis rates of PAA and MCPBA were measured in the presence of boric acid.
• Hydrogen peroxide formation was quantified using a specific Ti(iv) complexation method.
• Reactions were conducted across a wide pH range (3-13), with metal ion chelation using EDTA and EDTMP.

Main Results:

• Boric acid increased peroxyacid hydrolysis rates approximately 12-fold.
• Maximum hydrolysis rates were observed at pH 9 for PAA and pH 8.4 for MCPBA.
• Catalysis involves boric acid acting as a Lewis acid, with contributions from single molecules, pairs, or polyborate species.

Conclusions:

• Boric acid effectively catalyzes peroxyacid hydrolysis, impacting their stability and application.
• The catalytic mechanism is complex, involving multiple boric acid species.
• This finding provides critical insights into the chemical behavior of peroxyacids in various environments.