The mass spectra of some guanidines

Abstract

Abstract-%mass spectra of guanidme and ten of its derivatives have been studied under both high and low resolution conditions. Evidence was detected for themigrationofmethyl groups, the formation of intermediate threemembered ring structures and decompositions involving expulsion of N with release of kinetic energy. INTRODUCTION THERE are no published spectra of guanidine or its derivatives although Loudon, Maccoll and Webb1 have examined the methyl guanidines, measured their ionization potentials, and discussed some of the prominent fragment ions, meta-stable ion transitions and rearrangement mechanisms involved in their fragmentation under electron impact.A detailed study of meta-stable transitions has previously been shown to assist greatly in determining thedissociation processes involved in aromatic nitro compounds8 and cyclic amines., In this present work, therefore, the spectra of guanidine and 10 substituted guanidines were recorded in a double-focusing instrument in such a way that the sensitivity to meta-stable ions was higher than is usually the case. In the mass spectrometer used, the resolving power was adjusted to about 1 part in 800 by using comparatively wide source and collector slits and the gain of the electron multiplier was increased. The composition of each ion species involved in a meta-stable transition was then determined by examination at a resolving power of 1 in 10, OOO and by accurate mass measurement using the peak matching technique.The large numbers of meta-stable transitions detected in this investigation have shown that the fragmentation processes involved proceed along many competing paths. When there is no meta-stable transition linking a prominent fragment ion with any ion of higher mass it is assumed that this ion is produced by very fast processes occurring before the field free region preceding the magnetic analyser, and probably in the ionisation chamber itself.

Activated Peroxide for Enzymatic Control of Wool Shrinkage Part I: Elucidation

“…As expected, detection of peroxide proposed in the reaction pathway was not detected by HPLC. Factors such as concentration, stability and volatility of the peroxide product might have impeded its detection [34].…”

Synthetic Strategies Towards O6-Substituted Guanine Derivatives and their Application in Medicine

“…Their synthetic strategy for the introduction of the 15 N-label involved the application of 15 NH 3 and progress in synthesis was confirmed by EI/MS spectrometry by comparing specific fragmentation patterns (Fig. (6)) [47].…”

Unexpected ring closure reaction of α,β‐unsaturated ketones with aminoguanidine. entry into 1,3,5‐trisubstituted pyrazoles

“…Peak matching with perfluorokerosene as the reference was utilized for accurate mass measurements by hrms. The nmr spectra were measured on a Bruker AC-400 spectrometer with a dual 1 H/ 13 ,c and 10b,c.…”

“…The mass spectrum of the product furnished a significant proof of the amidine structure 5a. The prominent peaks at m/z 201, 176 and 175 were produced by loss of neutral molecules of NH 3 and HN=C=NH and the HN=C-NH 2 radical from the molecular ion (m/z 218), the primary cleavage modes being typical of N-substituted guanidines [13]. In addition, the second most abundant peak at m/z 83, (C 4 H 7 N 2 ) + , was a clue that indicated a 3-methylpyrazolinium species.…”