Хроматографическое разделение продуктов взаимодействия 1,1-диметилгидразина с изотиоцианатами

1,1-Dimethylhydrazine is a toxic component of a widely used rocket fuel. Chromatographic determination of polar 1,1-dimethylhydrazine in aqueous solutions is carried out as the analysis of its non-polar derivatives usually. The 1,1-dimethylthiosemicarbazides were synthesized as the reaction products of 1,1-dimethylhydrazine and ethyl-, allyl-, and phenyl- isothiocyanates. The purpose of this work was to investigate the possibility of the chromatographic separation of the reagents and the reaction products as well as to create the grounds of the quantity analysis of 1,1-dimethylhydrazine in aqueous solutions as its S,N-derivatives. Theoretical and experimental studies of the chromatographic behavior and adsorption characteristics of different thiosemicarbazides were carried out. It was shown that allyl- and ethyl-isothiocyanates, and corresponding derivatives of 1,1-dimethylhydrazine (1,1-dimethylthiosemicarbazides) can be separated effectively by gas chromatography–mass spectrometry technique using a capillary column with polydimetylsiloxane. Mass-spectra of ethylandallyl- thiosemicarbazides were obtained and investigated. Retention characteristics of isothiocyanates and thiosemicarbazides were calculated by two different methods. The molecular statistical calculations of their adsorption characteristics on the ideal carbon surface were performed as well as their retention characteristics were calculated using the increments of the functional groups of isothiocyanates and thiosemicarbazides. The simplified models of molecules with rigid and non-rigid bond lengths were used. The different approaches to taking into account of internal rotation of the molecule were used A satisfactory correlation has been obtained between the experimental and theoretically calculated retention characteristics of thiosemicarbazides and isothiocyanates on the non-polar stationary phase. The derivative of 1,1-dimethylhydrazine with phenylisothiocyanate is too thermallyunstable to be analyzed by gas chromatography. The recommendations on gas chromatographic analysis of such mixtures are given.