Mass spectral studies of a series of N,N‐dialkyl aminoethyl‐2‐chlorides and trimethyl silyl ethers of N,N‐dialkyl aminoethane‐2‐ols under electron impact conditions

Abstract

The electron impact (EI) mass spectra of a series of N,N-dialkyl-aminoethyl-2-chlorides, N(R(1))(R(2))-CH(2)-CH(2)Cl and trimethylsilyl ethers of N,N-dialkyl aminoethane-2-ols, N(R(1))(R(2))-CH(2)-CH(2)-O-Si(CH(3))(3), where R(1) and R(2) = methyl, ethyl, propyl and isopropyl, which are precursors of VX type of compounds, are studied. All the compounds (1-20) show abundant molecular ions, in addition to a weak [M - H](+) ion, except the N,N-diisopropyl group containing compounds (8 and 18). A general EI fragmentation pattern for the above two series of compounds is discussed. The observed fragment ions are due to simple homolytic cleavages, and they are distinct to allow the identification of the compounds unequivocally including those of isomeric compounds. The primary fragmentation of compounds 1-20 is beta-cleavage, i.e. homolytic cleavage of C-C bond, which is linked to the nitrogen atom. Three types of beta-cleavages are possible for these compounds, in which the abundance of beta-cleavage product ions is found to depend on the size and structure of the alkyl group attached to nitrogen. The alpha-cleavage fragment ions are found only for N,N-dialkyl aminoethyl-2-chlorides but are absent in the corresponding trimethylsilyl ethers of N,N-dialkyl aminoethane-2-ols. The retention indices are calculated for all the studied compounds (1-20) and are in the ranges of 750.38-1079.24 for 1-10 and 905.23-1190.25 for 11-20.

Mass spectral characterization of the CWC‐related isomeric dialkyl alkylphosphonothiolates/alkylphosphonothionates under gas chromatography/mass spectrometry conditions

“…A series of isomeric dialkyl alkylphosphonothiolates (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) and dialkyl alkylphosphonothionates (19)(20)(21)(22)(23)(24)(25)(26)(27), which belong to schedule 2.B.4 of the CWC, was synthesized in-house and then analyzed by GC/MS under EI and CI conditions. The study mainly emphasizes the differentiation of phosphonothiolates and phosphonothionates (connectivity between P and S) and also the identification of the alkyl group attached to the sulfur, oxygen and phosphorus atoms.…”

“…In such a case, the presence of the [M-OR] + ion is expected in the EI spectra of dialkyl phosphonothiolates in addition to the expected [M-SR] + ion. Among the studied dialkyl alkylphosphonothiolates (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), the [M-OR] + ion appeared only in compounds where a propyl or a butyl group was attached to sulfur (3-4, 8-10, 13-14). This reveals that the dialkyl phosphonothiolates undergo a 'thiolo-thiono' rearrangement, especially when a higher alkyl group is attached to sulfur.…”

“…Compounds of polar nature can be analyzed directly by liquid chromatography (LC)/MS or by GC/MS after derivatization . GC/MS analysis is typically performed under electron ionization (EI) or chemical ionization (CI) conditions . EI is more routinely used than CI, because it provides extensive details about a compound through its characteristic fragmentations.…”

Mass spectral analysis of N‐oxides of Chemical Weapons Convention related aminoethanols under electrospray ionization conditions

“…Their detection in suspect matrices confirms the presence of either of these two classes of toxic chemicals. Sample preparation, detection and identification methods have been established for aminoethanethiols, aminoethanechlorides, aminoethanols, and aminoethylsulfonic acids (degradation product) 9–17. These compounds are expected to undergo N‐oxidation during the decontamination process or upon aerial oxidation 18, 19.…”

Electrospray ionization mass spectral studies of N,N‐dialkylaminoethane‐2‐sulphonic acids

“…Although the [R 1 R 2 NC 2 H 4 ] + ion is characteristic for this class of compounds, it appears only in 3 – 6 and 8 . The product ions found in the CID spectra of the [M+H] + ions of 1 – 10 are also commonly observed in the EI fragmentation of N,N ‐dialkylaminoethanols and N,N ‐dialkylaminoethyl chlorides 34, 35. The product ions characteristic of the sulphonate part are not observed.…”