Gas-Chromatographic Retention Indices in GC/MS Identification of Alkyl Dichlorophosphates, Dialkyl Chlorophosphates, and Their Thio Analogues

Abstract

The determination of a series of analytical parameters for the gas-chromatographic/mass-spectrometric identification of reactive intermediate products of phosphoryl chloride (POCl₃) and thiophosphoryl chrolide (PSCl₃) interaction with aliphatic alcohols, O-alkyl dichlorophosphates (I), O,O-dialkyl chlorophosphates (II), O-alkyl dichlorothiophosphates (III), and O,O-dialkyl chlorothiophosphates (IV) is considered. The members of these series are not sufficiently presented in contemporary databases; an exception is provided by series (I) and (II), which are characterized with EI mass spectra (NIST MS Database, 2017) for 8 and 19 homologues, respectively. The data set includes EI mass spectra and gas-chromatographic retention indices (RI) on standard nonpolar polydimethylsiloxane stationary phases. Strong differences in the mass spectra of homologues of series (I) depending on the conditions of their registration are revealed. A comparison of RI values for alkyl chlorophosphates and thiophosphates allows the evaluation of increments for the hypothetic substitution of the oxygen atom in the P=O fragment with the sulfur atom (P=S), namely 59 ± 4 and 30 ± 4 for O-alkyl dichloro- and O,O-dialkyl chloroderivatives. The statistical processing of the so-called homologous increments of retention indices leads to average values attributed to a homologous series rather than to individual homologues. Using these values permitted us to evaluate the molecular weights of homologues for which no reliably detected signals of molecular ions are present in EI mass spectra.