Structural Characterization of Methylenedianiline Regioisomers by Ion Mobility-Mass Spectrometry and Tandem Mass Spectrometry. 4. 3-Ring and 4-Ring Isomers

Abstract

Matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) is used to characterize methylenedianiline (MDA) 3-ring and 4-ring species. Building on our previous MALDI-MS 2-ring MDA isomer study, here we compare 3-ring and 4-ring electrospray ionization (ESI) and MALDI results. In ESI, 3-ring and 4-ring MDAs each form one single [M+H]+ parent ion. Whereas in MALDI, each MDA multimer forms three unique precursor ions: [M+H]+, [M.]+, and [M-H]+. In this study, 3-ring and 4-ring MDA precursors are characterized to identify the unique fragment ions formed and their respective fragmentation pathways. In addition to the three possible precursors, the 3-ring and 4-ring species are higher-order oligomer precursors in polyurethane (PUR) production and thus provides additional insight into the polymeric behavior of these PUR hard block precursors. The combination of ion mobility-mass spectrometry (IM-MS) and tandem mass spectrometry (MS/MS) allow the structural characterization of these larger MDA multimers.

Differentiation of regioisomers of sulfobenzoic acid by traveling‐wave ion mobility mass spectrometry

“…20 From 2014 to 2018, Forsythe et al published four papers in Analytical Chemistry reporting the structural characterization of methylenedianiline (MDA) regioisomers by IM-MS, tandem mass spectrometry (MS/MS), and computational strategies. [21][22][23][24] They studied both electrospray and matrix assisted laser desorption/ionization spectra of 2-ring, 3-ring, and 4-ring MDA isomers. Their work demonstrates the utility of a multifaceted approach for the study of isobaric or isomeric species.…”

“…IM‐MS provides an additional dimension of separation on the basis of the size and shape of gas‐phase ions, allowing predictive structural elucidation 20 . From 2014 to 2018, Forsythe et al published four papers in Analytical Chemistry reporting the structural characterization of methylenedianiline (MDA) regioisomers by IM‐MS, tandem mass spectrometry (MS/MS), and computational strategies 21–24 . They studied both electrospray and matrix assisted laser desorption/ionization spectra of 2‐ring, 3‐ring, and 4‐ring MDA isomers.…”

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“…On the other hand, 4,4-Methylenedianiline has a wide range of applications, including polyurethane spume, cell strengthening in lubricating oils, azo dye manufacturing, iron corrosion protection, and epoxy resin curing agent [1][2][3][4]. MDA (4,4-Methylenedianiline) has the potential to damage human and animal health because it causes eye irritation and damages the kidneys, liver, and skin; yet, it has been used to create several Schiff bases and azo ligands with important medical and therapeutic properties [5].…”