A Mechanistic Study of Protonated Aniline to Protonated Phenol Substitution Considering Tautomerization by Ion Mobility
- PDF / 1,724,217 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 19 Downloads / 121 Views
J. Am. Soc. Mass Spectrom. (2019) DOI: 10.1007/s13361-019-02321-4
RESEARCH ARTICLE
A Mechanistic Study of Protonated Aniline to Protonated Phenol Substitution Considering Tautomerization by Ion Mobility Mass Spectrometry and Tandem Mass Spectrometry Christopher Kune,1 Cédric Delvaux,1 Jean R. N. Haler,1,2 Loïc Quinton,1 Gauthier Eppe,1 Edwin De Pauw,1 Johann Far1 1
MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
2
Abstract. We report the use of ion mobility mass spectrometry (IMMS) and energy-resolved collisional activation to investigate gas-phase reactions of protonated aniline and protonated phenol. Protonated aniline prototropic tautomerization and nucleophilic substitution (SN1) to produce phenol with traces of water in the IMMS cell are reported. Tautomerization of protonated phenol and its ability to form protonated aniline in presence of ammonia in the gas phase are also observed. These results are supported by energy landscapes obtained from computational chemistry. These structure modifications in the IMMS cell affected the measured collision cross section (CCS). A thorough understanding of the gas-phase reactions occurring in IMMS appears mandatory before using the experimental CCS as a robust descriptor which is stated by the recent literature. Keywords: Ion mobility, Mass spectrometry, Tautomerism, Nucleophilic substitution, Aniline, Phenol, Gas-phase reaction, Computational chemistry Received: 30 May 2019/Revised: 1 August 2019/Accepted: 11 August 2019
Introduction
A
collision cross section (CCS) is usually experimentally obtained from ion mobility spectrometry (IMS). Ion mobility coupled to mass spectrometry (IMMS) provides both CCS values and mass spectra (m/z) in a single experiment. Analytical chemistry applications recently found interest in the use of IMMS to increase peak capacity, thus resulting not only in a better signal-to-noise ratio in mass spectra [1, 2], but also in the use of the CCS as a new ion descriptor for the identification of Electronic supplementary material The online version of this article (https:// doi.org/10.1007/s13361-019-02321-4) contains supplementary material, which is available to authorized users. Correspondence to: Christopher Kune; e-mail: [email protected]
compounds such as pesticides or metabolites [3–6]. To play that role, IMMS must provide a unique and reproducible CCS value. Nonetheless, several authors already suggested that the observed arrival time distribution (ATD) or equivalent quantities (e.g., ramping voltage profile) leading to the CCS could be affected by ion diffusion and gas-phase reactions occurring in-source or during the separation of ions in the mobility devices [7–10]. Understanding gas-phase reactions and their effects on ion mobility profiles is then pivotal to enhance confidence in the CCS values as a unique ion descriptor. Most of the gas-phase reactions reported i
Data Loading...
