ome homologues of diethyl ketals of aliphatic carbonyl compounds were synthesized from the corresponding carbonyl compounds and ethyl orthoformate with the presence of catalytic amounts of sulfuric acid or magnesium hydrosulfate on the silica gel. All products were characterized with mass spectra (electron ionization) and GC retention indices (RI) on the standard non-polar polydimethyl siloxane stationary phases. As the parameters attributed not to the individual compounds, but to the homologous series, the retention indices differences between products and initial substrates were determined; they were 266 ± 26 and 99 ± 20 index units for diethyl ketals and ethyl (1-alkenyl) ethers respectively. These parameters allow predicting the positions of the chromatographic peaks of previously non-characterized compounds of these series using the RI values for the initial carbonyl compounds. Another variable for the homologues that unites the mass spectrometric and chromatographic parameters were the homologous increments of the retention indices: i RI = RI - 100 x , where x = int( M /14), and the function “int” means the integer part of the quotient from the division of the molecular mass number by 14, which is equivalent to M = 14 x + y , where y is the number of homologous group of the compound, y M º M (mod14). Such increments allow evaluating the molecular masses (for the compounds with low intensities of peaks of molecular ions) using chromatographic retention parameters, as well as controlling the identification results in order to prevent errors.
|Number of pages||15|
|Journal||Analitika i Kontrol|
|Publication status||Published - Aug 2019|