Reaction gas chromatography/mass spectrometry. Part IX: Post‐column hydrodesulfurization in capillary GC/MS as an aid in structure elucidation of cyclic sulfides within mixtures

Abstract

SummaryThis article describes a method that assists in structure determination of cyclicsulfides mixtures by GC/MS. The method involves the use of a gas-phase hydrodesulfurization microreactor (AP-56 catalyst, reaction temperature 300-315OC, hydrogen as a carrier and reagent gas) located between the capillary column (OV-17) and the mass spectrometer. The presence of a microreactor in such a position does not essentially affect the chromatographic separation achieved by using the capillary column. Combined analysis of the mass spectra registered for theoriginal sulfidesand the hydrodesulfurization products permits the structure determination of each effluent to be made more reliably. This is illustrated by the investigation of a reaction mixture containing the structural and geometric isomers of methyl-su bstituted thia bicyclononanes.

Derivatization in Mass Spectrometry—7. On-Line Derivatization/Degradation

“…For instance, post-column hydrodesulfurization (commercial AP-56 catalyst, 300-325°C, carrier and reagent gas hydrogen) was -325°C, carrier and reagent gas hydrogen) was 325°C, carrier and reagent gas hydrogen) was°C, carrier and reagent gas hydrogen) was C, carrier and reagent gas hydrogen) was used for structure elucidation of substituted thiabicyclononanes within a synthetic mixture. 69 As a result, for each eluted stereoisomeric 8-methyl-7-thiabicyclo�4.2.1�nonane (A), identical mass spectra of ethylcycloheptane were recorded. At the same time, the mass spectra registered for separated 8-methyl-7-thiabicyclo�4.3.0�nonanes (B) and 7-methyl-6-thiabicyclo�3.3.1�nonanes (C) corresponded to a mixture of n-propylcyclohexane and n-propylbenzene (the product of additional dehydrogenation): It should be noted that, because only six-membered carbocycles undergo aromatization, cyclohexane and cyclopentane or cycloheptane rings can be distinguished.…”

Derivatization in Mass Spectrometry—5. Specific Derivatization of Monofunctional Compounds

“…The extension of this methodology is the insertion of a vaporphase hydrodesulfurization microreactor (Pd / Al 2 O 3 or Raney nickel; carrier gas-hydrogen) into the GC/MS system. 161,162 This approach enables operation with submicrogram amounts of sample and provides rapid analysis. The microreactor may be located before or after chromatographic column.…”