title: Fragmentation of deprotonated diacylhydrazine derivatives in electrospray ionization tandem mass spectrometry: generation of acid anions via intramolecular rearrangement.
abstract: The gas-phase fragmentation pathways of deprotonated diacylhydrazine derivatives (R1(C = O)-N(t-Bu)NH(C = O)R2, Compounds 1-6) were investigated by the combination of electrospray ionization tandem mass spectrometry (ESI-MS/MS) and theoretical calculations. Upon collisional activation, the deprotonated molecular ions [M - H](-) dissociate in two reaction channels, both of which involve intramolecular rearrangement. The main product ion is confirmed to be an anionic acid species, [R1-CO2](-), generated through intramolecular rearrangement of [M - H](-) initiated by the nucleophilic attack of the amide O6 on the carbonyl C2 (Path-1). The minor fragment channel (Path-2) involves methylpropene elimination of the precursor ion, followed by a similar nucleophilic displacement reaction to produce another acid anion [R2-CO2](-). Density functional theory calculations at the B3LYP/6-31+G(d,p) level indicate that Path-1 is more favorable than Path-2 for dissociation of the deprotonated halofenozide.
authors.affiliation: Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, Zhejiang, China.
authors.forename: Kezhi
authors.initials: K
authors.lastname: Jiang
authors.forename: Hu
authors.initials: H
authors.lastname: Zhang
authors.forename: Jianmei
authors.initials: J
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Mingrong
authors.initials: M
authors.lastname: Qian
mesh_terms: D000143:Acids / Q000737:chemistry*; D000838:Anions / Q000737:chemistry*; D001565:Benzoates / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D008970:Molecular Weight; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics
chemical_list: D000143:Acids; D000838:Anions; D001565:Benzoates; D006834:Hydrazines; D011522:Protons; C437546:N-4-chlorobenzoyl-N'-benzoyl-N'-tert-butylhydrazine