Application of nicotinate derivatives to the structural determination of glycerol ethers

Abstract Nicotinate derivatives were prepared from reference samples of 1‐ O ‐alkyl‐glycerols, 1‐ O ‐acyl‐glycerols and from 1‐ O ‐alkyl‐gylcerols containing branched chains obtained from extracts of rabbit and guinea pig Harderian glands. A modification of the earlier method for preparation of these esters from monohydric alcohols, in which acetonitrile was substituted for pyridine as solvent, gave superior results. Fragmentation of these derivatives was analogous to that of the corresponding derivatives of mono‐ and dihydric alcohols in that the chain was induced to fragment by radical‐induced cleavage following hydrogen abstraction. This gave a series of ions formed by cleavage at each carbon‐carbon bond from which the structure of the chain (straight or branched) could easily be determined. One complicating factor, however, was the presence of a relatively abundant ion at [M − 43] + which distorted the pattern of ions expected from the compounds containing anteiso chains. This ion was not present in the corresponding spectra of monoacyl glycerol derivatives, but its origin was not determined. The diagnostic alkyl‐cleavage ions were comparatively weak compared with their counterparts in the spectra of nicotinate derivatives of monohydric alcohols and were supplemented by ions at [M − 106] + , [M − 122] + and [M − 123] +. produced by loss of PyCO and PyCOO, respectively, not seen in the corresponding spectra of the monohydric alcohol derivatives. These were useful in confirming the mass of the rather weak molecular ions. In addition, a weak series of ions, similar to the major diagnostic series, was seen to arise from the [M − 122] + , [M − 123] + group of peaks. Spectra were dominated by the ion at m / z 106 which differentiated them from those of monohydric alcohols which produced base peaks at m / z 124.