Functional group analysis preliminary reaction

Preliminary reactions are widely used in GC for protecting functional groups [17,18] in order to obtain stable, more volatile and less polar derivatives. Owing to these reactions, the range of compounds that can be analysed becomes fairly large. At the same time, preliminary reactions can be considered as methods of functional group analysis. 

Gas chromatography has become widely used for the determination of these substances. Their conversion into derivatives prior to the analysis proper is often unavoidable as only a few of them can be analysed by GC as such. Selection of the derivatization procedure follows general rules depending on the type of functional groups present, and it includes the application of almost all of the reactions that are commonly used. Various substances active as medicaments or drugs differ much from the viewpoint of chemistry and several functional groups often occur in one molecule. In many instances individual procedures for particular substances differ only in the technique of preliminary isolation. Therefore, of numerous publications, the number of which has been rapidly increasing recently, this section will report only representative examples. Further details and information can be found in several reviews [504-506] and a book [507]. 

Preliminary experiments for the analogous functionalization of PILi with N-trimethylsilyldiphenylcarbimide were consistent with only the expected addition to 1,1-diphenylmethylene carbon (path (a) in Scheme 7). Only one spot was observed by TLC analysis and only one trimethylsilyl group resonance was observed by NMR analysis. These results are consistent with both the decreased steric requirements of PILi compared to PSLi and the sensitivity of this functionalization reaction to the steric requirements of the organolithium reagent. 

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