Universität zu Köln

Zeh, Dennis, Bast, Marcel, Martens, Jonathan ORCID: 0000-0001-9537-4117, Berden, Giel ORCID: 0000-0003-1500-922X, Oomens, Jos ORCID: 0000-0002-2717-1278, Brunken, Sandra, Schlemmer, Stephan, Schaefer, Mathias and Kuck, Dietmar (2022). Unidirectional Double- and Triple-Hydrogen Rearrangement Reactions Probed by Infrared Ion Spectroscopy. J. Am. Soc. Mass Spectrom., 33 (8). S. 1377 - 1393. WASHINGTON: AMER CHEMICAL SOC. ISSN 1879-1123

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Abstract

Unidirectional double-hydrogen (2H) and triple-hydrogen (3H) rearrangement reactions occur upon electron-ionization-induced fragmentation of trans-2-(4-N,N-dimethylaminobenzyl)-1-indanol (1), trans-2-(4-methoxybenzyl)-1-indanol (2), 4-(4-N,N-dimethylaminophenyl)-2-butanol (3), and related compounds, as reported some 35 years ago (Kuck, D.; Filges, U. Org. Mass Spectrom. 1988, 23, 643-653). These unusual intramolecular redox processes were found to dominate the mass spectra of long-lived, metastable ions. The present report provides independent evidence for the structures of the product ions formed by the 2H and 3H rearrangement in an ion trap instrument. The radical cations 1(& BULL;+) and 3(& BULL;+) as well as ionized 1-(4-N,N-dimethylaminophenyl)-5-(4-methoxyphenyl)-3-pentanol, 5(& BULL;+), were generated by electrospray ionization from anhydrous acetonitrile solutions. The 2H and 3H fragment ions were obtained by collision-induced dissociation and characterized by IR ion spectroscopy and density functional theory calculations. Comparison of the experimental and calculated infrared ion spectra enabled the identification of the 2H rearrangement product ion, C9H14N+ (m/z 136), as an N,N-dimethyl-para-toluidinium ion bearing the extra proton ortho to the amino group, a tautomer which was calculated to be 31 kJ/mol less stable than the corresponding N-protonated form. The 3H rearrangement product ion, C8H13N & BULL;+ (m/z 123), formerly assumed to be a distonic ammonium ion bearing a cyclohexadienyl radical, was now identified as a conventional radical cation, ionized N,N-dimethyl-2,3-dihydro-para-toluidine. Thus, the 3H rearrangement represents an intramolecular transfer hydrogenation between a secondary alcohol and an ionized aromatic ring. Based on these structural assignments, more detailed mechanisms for the unidirectional 2H and 3H rearrangement reactions are proposed.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zeh, Dennis UNSPECIFIED UNSPECIFIED UNSPECIFIED Bast, Marcel UNSPECIFIED UNSPECIFIED UNSPECIFIED Martens, Jonathan UNSPECIFIED orcid.org/0000-0001-9537-4117 UNSPECIFIED Berden, Giel UNSPECIFIED orcid.org/0000-0003-1500-922X UNSPECIFIED Oomens, Jos UNSPECIFIED orcid.org/0000-0002-2717-1278 UNSPECIFIED Brunken, Sandra UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlemmer, Stephan UNSPECIFIED UNSPECIFIED UNSPECIFIED Schaefer, Mathias UNSPECIFIED UNSPECIFIED UNSPECIFIED Kuck, Dietmar UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-673180
DOI:	10.1021/jasms.2c00039
Journal or Publication Title:	J. Am. Soc. Mass Spectrom.
Volume:	33
Number:	8
Page Range:	S. 1377 - 1393
Date:	2022
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1879-1123
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GAS-PHASE ION; CORRELATED MOLECULAR CALCULATIONS; 2-BENZYLINDANE RADICAL CATIONS; TANDEM MASS-SPECTROMETRY; GAUSSIAN-BASIS SETS; STEREOCHEMICAL PROBLEMS; PROTON AFFINITIES; NEUTRAL FRAGMENTS; ORGANIC IONS; SPECTRA Multiple languages Biochemical Research Methods; Chemistry, Analytical; Chemistry, Physical; Spectroscopy Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/67318