Features of trialkyl phosphites revealing in reaction mixtures and their gc-ms characterization
T15N2
I.G. Zenkevich, V.E. Nosova
The interaction of aliphatic alcohols ROH with phosphorous trichloride at the absence of bases leads to the exclusive formation of dialkyl phosphonates (RO)2PHO. The same reaction can be used for synthesis of trialkyl phosphites (RO)3Р with controlling the pH of reaction mixtures by adding of N,N-dimethyl aniline (рКа 5.1 ± 0.1). The identification of trialkyl phosphites directly in mixtures without preliminary isolation is possible, but it implies the joint considering their mass spectra and gas chromatographic retention indices at the condition of identification of all constituents of these mixtures. The necessity for compliance with this condition has led to the identification of few homologues of previously not-characterized series of 2-alkoxy-1,3,2-dioxaphospholanes, which formed from the ethylene glycol as random impurity in N,N-dimethyl aniline. Using such joint GC/MS analytical parameters as homologous increments of retention indices allows distinguishing trialkyl phosphites from isobaric dialkyl phosphonates [both series belong to the same homologous group у = 12, y ≡ M(mod14)]. The absence of the signals of molecular ions in EI mass spectra of trialkyl phosphites does not preclude the evaluation of their molecular weights. Besides that, the comparison of homologous increments explains the less polarity of trialkyl phosphites comparing with dialkyl phosphonates.
Хроматографическая «составляющая» хроматомасс-спектрометрической идентификации
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