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Mass spectra of some 1‐substituted‐4‐acetoacetyl‐3‐methylpyrazol‐5‐ols
Author(s) -
Singh S. P.,
Vaid R. K.,
Dinakar P.,
Singh Lukhvinder
Publication year - 1988
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210230213
Subject(s) - ketene , mass spectrum , chemistry , intramolecular force , fragmentation (computing) , ion , molecule , moiety , polyatomic ion , hydrogen cyanide , cyanide , electron ionization , acetone , medicinal chemistry , stereochemistry , organic chemistry , computer science , ionization , operating system
The fragmentation of 1‐phenyl‐, l‐(2′‐pyridyl)‐ and 1‐(4′‐methyl‐2′‐quinolyl)‐4‐acetoacetyI‐3‐methyIpyrazol‐5‐ols (compounds 1, 2 and 3, respectively) on electron impact has been studied and the major processes interpreted. The common feature in the mass spectra of these compounds is the loss of ketene, acetonyl radical, acetone and two molecules of ketene from the molecular ion. Whereas the ion generated after the last process, which corresponds to 1‐substituted‐3‐methyIpyrazol‐5‐ols, loses methyl cyanide in the case of 1, similar ions in the case of 2 and 3 lose Ċ 2 HO moiety, necessitating an intramolecular hydrogen transfer followed by ring fission and subsequent loss of methyl cyanide. All these and other related processes have been substantiated with the help of accurate mass measurements of the fragment ions and B/E linked‐scan spectra.