Desorption electrospray ionization mass spectrometry for monitoring the kinetics of Baeyer-Villiger solid-state organic reactions

Abstract

Desorption electrospray ionization mass spectrometry (DESI-MS) has been used for monitoring solid-state organic reaction in ambient air, specifically the Baeyer-Villiger (BV) type reaction involving the oxidation of ketones (benzophenone or deoxybenzoin) by m-chloroperbenzoic acid (m-CPBA) in solid-state. The DESI mass spectra obtained at regular intervals during the BV reaction processes are featured, with the amount of ester products increasing as those of ketone reactants decrease. Quantitative analyses of relative intensities of the product, made to quantify the reaction degree of typical solid-state organic reaction (SSOR), show a precision with RSDs of around 5% to 12%, though the RSDs for direct analysis of intensities of the reactant or the product in the solid-state are obviously larger. [20,21]. To our knowledge, however, effort focusing on MS monitoring of SSOR has never been discussed heretofore. Here we reported the first application using DESI-MS for direct characterization of kinetics of two representative SSORs, i.e., the BaeyerVilliger (BV) [22,23] type reactions of m-chloroperbenzoic acid (m-CPBA) with benzophenone (PhCOPh, 1) or deoxybenzoin (PhCOCH 2 Ph, 2). Unexpected kinetics of the BV reactions in solid-state, including reaction rate, kinetic curve, and concentration dependence, have been revealed to be different from those of the same reactions in solution. Experimental Materials and ChemicalsBenzophenone (98%) and chloroform (99%) were purchased from Sinopharm Chemical Reagent Co. Monitoring the BV Reaction by DESI-MSThe experiments were conducted at the temperature around 22°C. About 0.2 g of ketone (1 or 2) was mixed together with 2 mol equiv of m-CPBA to afford the reactant mixture. For the concentration-dependent experiments, the reactants "concentration" (60 and 80 wt%) of 2 and m-CPBA were changed depending on the Address reprint requests to Dr.

Electrospray Ionization Mass Spectrometry: A Technique to Access the Information beyond the Molecular Weight of the Analyte

“…For example, catalytic intermediate of the Suzuki coupling reaction [289] and the Heck reaction mechanism [291] has been studied by ESI-MS. Raney nickel-catalyzed coupling reaction of 2-bromo-6-methylpyridine was studied, and a reactive dimer of the intermediate Ni[II] complex of 6,6′-dimethyl-2,2′-bipyridine was detected [293]. Desorption electrospray ionization mass spectrometry (DESI-MS) has been used for monitoring solid-state organic reaction in ambient air, specifically the Bayer-Villiger type reactions involving the oxidation of ketones by m-chloroperbenzoic acid in solid state [294]. The 1-adamantyl radicals have been identified as a reactive intermediate in several organic syntheses.…”

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Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices

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