Mass spectrometry as an aid in the detection and identification of piperidyl benzilates and related glycolates.
On the basis of the data presented above the following conclusions may be drawn. 1. The molecular ion peaks of most of the compounds examined are relatively weak but usually easily discernible to permit molecular weight determination. 2. The mass spectra of benzilate esters exhibit a relatively intense peak at m/e 183, and monitoring of this ion can serve as a means for preliminary screening for the presence of this type of a system. 3. Related esters exhibit a similar type of fragmentation resulting in a fragment ion analogous to m/e 183 but shifted by the appropriate number of mass units according to the substituents present. 4. Cleavage of the piperidine ring-ester oxygen bond in 3 and 4-substituted isomers is followed by selective losses of hydrogen radicals to produce ions of type e, f, and g as indicated above. It is significant that in a related piperidine ring system (methylphenidate) substituted in the 2 position, the same type of cleavage results in no further hydrogen losses [16] because of charge stabilization from the ring nitrogen (ion j, Fig. 17) [17]. In other words, the tendency to form a conjugated ion following initial bond cleavage can serve as a means for identifying the position of substitution on the ring and for distinguishing positional isomers.
D001561:Benzilates / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D006016:Glycolates / Q000302:isolation & purification*; D013058:Mass Spectrometry; D008722:Methods; D010880:Piperidines / Q000302:isolation & purification
D001561:Benzilates; D006016:Glycolates; D010880:Piperidines