Mass spectrometric and theoretical studies on dissociation of the CS bond in the benzenesulfonic acid and benzenesulfinic acid anion series: Homolytic cleavage vs heterolytic cleavage

Zhang, Xiang

doi:10.1016/j.molstruc.2012.06.029

Cited by 7 publications

(12 citation statements)

References 38 publications

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“…Thus, the anion at m / z 186 ( 1k ) corresponded to 2‐nitrobenzenesulfinate (Ns – ). The losses of SO and SO 2 from 1k after CID were consistent with documented fragmentations of sulfinate ions and the loss of SO 2 from 2‐hydroxybenzenesulfinate [ 1d , Fig. (D) and Fig.…”

Section: Resultssupporting

confidence: 79%

“…After loss of SO 2 from 2-hydroxysulfinate (1d), additional energy was required to reach the transition structure TS 1e-1e′ for the isomerization of 2-hydroxyphenide (1e) to the more stable phenoxide ion 1e′ (m/z 93). The energetics of these steps were similar to values computed for the loss of SO 2 from 4-hydroxybenzenesulfinate, [47] and hydroxyphenide isomerization by 1,3-proton transfer. [51,52] Consistent with the route presented in Fig.…”

Section: S Fromsupporting

confidence: 65%

“…5(B)]. Both, however, were significantly lower than barriers computed for analogous reactions of benzenesulfinate [47] and 2-hydroxybenzenesulfinate [ Fig. 3(B)], consistent with the electronwithdrawing effect of the 2-nitro substituent.…”

Section: (B) Dual Bond Cleavagementioning

confidence: 54%

“…After deprotonation of the sulfonamide group in the nonaromatic rings of hydrochlorothiazide and hydroflumethiazide (Supporting Information, Scheme S1), a reaction sequence of ring opening and proton abstraction, followed by heterolytic N–S and C–S bond cleavage, was proposed to account for the sequential formation of HCN and SO 2 . The last step was supported by the more recently documented loss of SO 2 from benzenesulfinate and toluenesulfinate ions . In the fragmentation pathway of deprotonated NsGly ( 1a ), analogous mechanistic steps would be expected, if cyclization accompanied the loss of HONO.…”

Section: Resultsmentioning

confidence: 95%

“…[19] The last step was supported by the more recently documented loss of SO 2 from benzenesulfinate and toluenesulfinate ions. [47] In the fragmentation pathway of deprotonated NsGly (1a), analogous mechanistic steps would be expected, if cyclization accompanied the loss of HONO. Consistent with 18 O labeling (Table 1), seven-membered ring formation by a favorable 7-endo-trig ring closing reaction [48] would connect an oxygen atom of the carboxyl group to the aryl ring ortho to the sulfonamide group.…”

Section: S Frommentioning

confidence: 86%

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Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

et al. 2014

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The correlation of anion structure with the fragmentation behavior of deprotonated nitrobenzenesulfonylamino acids was investigated using tandem mass spectrometry, isotopic labeling and computational methods. Four distinct fragmentation pathways resulting from the collision-induced dissociation (CID) of deprotonated 2-nitrobenzenesulfonylglycine (NsGly) were characterized. The unusual loss of the aryl nitro substituent as HONO was the lowest energy process. Subsequent successive losses of CO, HCN and SO2 indicated that an ortho cyclization reaction had accompanied loss of HONO. Other pathways involving rearrangement of the ionized sulfonamide group, dual bond cleavage and intramolecular nucleophilic displacement were proposed to account for the formation of phenoxide, arylsulfinate and arylsulfonamide product ions at higher collision energies. The four distinct fragmentation pathways were consistent with precursor-product relationships established by CID experiments, isotopic labeling results and the formation of analogous product ions from 2,4-dinitrobenzenesulfonylglycine and the Ns derivatives of alanine and 2-aminoisobutyric acid. The computations confirmed a low barrier for ortho cyclization with loss of HONO and feasible energetics for each reaction step in the four pathways. Computations also indicated that three of the fragmentation pathways started from NsGly ionized at the carboxyl group. Overall, the pathways identified for the fragmentation of the NsGly anion differed from processes reported for anions containing a single functional group, demonstrating the importance of functional group interactions in the fragmentation pathways of multifunctional anions.

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Section: Resultssupporting

confidence: 79%

Section: S Fromsupporting

confidence: 65%

Section: (B) Dual Bond Cleavagementioning

confidence: 54%

Section: Resultsmentioning

confidence: 95%

Section: S Frommentioning

confidence: 86%

See 3 more Smart Citations

Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

et al. 2014

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Structural Characterization of Acidic Compounds in Pyrolysis Liquids Using Collision-Induced Dissociation and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

2018

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In this study, a novel approach to characterize and identify acidic oil compounds utilizing the fragmentational behavior of their corresponding precursor ions is presented. Precursor ions of seven analyzed pyrolysis oils that were generated from pyrolysis educts of different origins and degrees of coalification were produced by electrospray ionization in the negative ion mode (ESI(−)). Following a fragmentation of all ions in the ion cloud by collision-induced dissociation (CID), the precursor and product ions were subsequently detected by ultrahigh resolving Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The ESI(−)-CID data sets were evaluated by applying either a targeted classification or untargeted clustering approach. In the case of the targeted classification, 10% of the ionized precursor ions of the analyzed pyrolysis liquid samples could be classified into one of 11 compound classes utilizing theoretical fragmentation pathways of these classes. In contrast, theoretical fragmentation pathways were not necessary for the untargeted clustering approach, making it the more transmittable method. Results from both approaches were verified by analyzing standard compounds of known structure. The analysis and data evaluation methods presented in this work can be used to characterize complex organic mixtures, such as pyrolysis oils, and their compounds in-depth on a structural level.

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Electrochemical versus Enzymatic in Vitro Oxidations of 6-propyl-2-thiouracil: Identification, Detection, and Characterization of Metabolites

Chipiso

Simoyi

2017

J. Phys. Chem. B

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6-Propylthiouracil, PTU, is a well-known antithyroid drug that has been the mainstay of treatment of Graves' disease. It is, however, also associated with liver toxicity and idiosyncratic toxicity. These toxicities are generally associated with metabolites derived from its bioactivation. In this manuscript, bioactivation of PTU was studied via two separate techniques: electrochemical oxidation and through the use of human liver microsomes. The aim of this work was to compare the bioactivation products of these two techniques. The electrochemical technique was studied online with a mass spectrometer, EC/ESI/MS. The microsomal oxidations were studied in tandem with liquid chromatography. The EC/ESI/MS technique was devoid of the normal reducing biological matrix prevalent in microsomal incubations. The predominant product at 400 mV was the dimeric PTU species with negligible formation of other metabolites. At higher potentials, complete desulfurization of PTU was observed with formation of sulfate. No sulfonic acid was observed, suggesting that the cleavage of the C-S bond was effected at the sulfinic acid stage, releasing a highly reducing sulfur species which is known to give rise to genotoxicity. The microsomal oxidations, surprisingly, showed formation of the unstable sulfenic acid, the S-oxide. Further incubation showed both the sulfinic and sulfonic acids. None of the systems showed any adducts with nucleophiles such as glutathione, showing that none of the reactive metabolites were stable enough to be adducted to nucleophiles in both the biological matrix and the electrochemical oxidizing environment.

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Mass spectrometric and theoretical studies on dissociation of the CS bond in the benzenesulfonic acid and benzenesulfinic acid anion series: Homolytic cleavage vs heterolytic cleavage

Cited by 7 publications

References 38 publications

Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

Structural Characterization of Acidic Compounds in Pyrolysis Liquids Using Collision-Induced Dissociation and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Electrochemical versus Enzymatic in Vitro Oxidations of 6-propyl-2-thiouracil: Identification, Detection, and Characterization of Metabolites

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