The electron-impact and chemical-ionization mass spectra of benzothiazole-2-thione (1), benzimidazole-2-thione (2), and benzoxazole-2-thione (3) have been compared with those of their pyrolysis products and parallels have been found. In each case, the loss of S from the molecular ions and from the ( + H) ions is the lowest energy fragmentation. At 800°, 1 gives a 23% yield of benzothiazole (4) and a 13% yield of cyanobenzene (5).
The electron-impact and chemical-ionization mass spectra of 2-benzoxazolinone (5), 2-benzimidazolinone (6), and 2-benzothiazolinone (7) have been compared with their pyrolysis products and parallels have been found. In each case, loss of CO occurs from M t , followed by loss of C O for 5 and by H C N for 6 and 7. At 950" in a stream of N,, 5 gave 17% of C,H,N isomers, related to the loss of 2C0, along with 5.6% of quinoline. Compound 6gave 14% of C6H,N, isomers, related to the loss of CO. At 950°, 7 gave 2-thiophenecarbonitrile (1 .I%), cyanonaphthalenes (4.5%), sniline (373, cyanobenzene (2.5%), naphthalene (1.5%), and phenylisocyanate (2.5%). From 5-7 20-70% of the starting material was recovered or accounted for by isolation and identification of products in each case. G.c.1m.s. was used t o study pyrolysis mixtures.On rapporte les spectres de masse de la benzoxazolinone-2 (5), de la benzimidazolinone-2 (6) e t de la benzothiazolinone-2 (7). tels qu'obtenus par impact tlectronique et par ionisation chimique en utilisant I'isobutane. On compare ces spectres avec les produits de pyrolyse des coniposCs 5-7. Dans chaque cas, l'ion molCculaire elimine une molecule de CO. Pour les composCs 6 et 7, ce processus est suivi d'une elimination de HCN, alors que pour le compose 5, il est suivi de la perte d'une deuxieme molCcule d e CO.La pyrolyse du compost 5 a 950" dans un courant d'azote conduit a la formation de quinoline (5.6%) et d'isomeres repondant a la formule C5H,N, ces derniers a la suite de I'elimination de deux molecules de CO. Parallelement, le compose 6 donne des isomeres repondant a la formule C5H,N, ces derniers a la suite de I'Climination de deux molCcules de CO. Parallelement, le compose 6 donne des isomeres rdpondant a la formule C6H,N, par elimination d'une molCcule de C O et d'une molecule de HZ. Les produits de la pyrolyse du compose 7 a 950" sont le thiophknecarbonitrile-2 (1.1%), les cyanonaphthalenes (4.5%), I'aniline (373, le cyanobenzene (2.5%), le naphthalene (1.5%) et I'isocyanate de phenyle (2.5%). Les produits form& ainsi que les produits originaux rCcupCrCs representent de 20 a 70% des produits de depart. La combinaison de la chromatographie en phase gazeuse avec la spectrometrie de masse etait employee pour Ctudier les melanges obtenus des pyrolyses.
The potent endectocide 23-(O-methyloximino)-F28249a and related compounds were identified and characterized by mass spectrometry. The fragmentation pathway of 23-(O-methyloximino)-F28249a was identified by its highresolution mass spectrum and the electron impact unit mass spectra of its homologs. This fragmentation pathway is presented and discussed.
Several Finngan-MAT mass spectrometer data systems were networked together to achieve the following two primary objectives: (1) to allow access to mass spectrometry data and data processing functions from remote locations without affecting simultaneous data acquisition at the instruments, and (2) to electronically archive mass spectrometry data at a central location on a high-capacity, fast-access device that allows rapid retrieval of archived data for all data processing operations at all locations. UNIX workstations, IBM PC/AT-compatible computers, and Data General Nova minicomputers were connected via Ethernet interfaces to allow rapid data transfer among all systems as well as X-Windows access to UNIX-based systems. Bridging techniques were used to isolate possible high-traffic areas of the network and to enable security measures for adequate protection of files. Additionally, serial connections were made through a Northern Telecom phone system to provide remote terminal access to the Data General Nova-based systems. Use of these connectivity techniques significantly improved productivity by allowing retrieval, processing, and printing of data from remote locations, such as office areas, without affecting data acquisition, processing, and printing performed simultaneously at the instruments. For archival purposes, data files are electronically stored on high-capacity magneto-optical disks for rapid retrieval. A highcapacity fixed disk is also available for centralized temporary data file storage. A Digital Equipment Corporation DECstation 2100 UNIX workstation was used as the file server for centralized data storage while being simultaneously utilized as the data system computer for one of the mass spectrometers. Utilization of this UNIX-based file server system in conjunction with Ethernet connectivity techniques provides a centralized, rapid-access, high-capacity, cost- and space-efficient method for electronic archival of mass spectrometry raw data recorded at all of the instruments.
Flow injection Thermospray mass spectrometry (TSP‐MS) has been developed and utilized for molecular weight and structural confirmation for thousands of potential new agricultural chemicals. Initially, it was necessary to find TSP conditions which provide an optimal compromise between providing reproducible, informative mass spectra and being sufficiently universal and rugged for a wide variety of compound types. By acquiring both positive‐ and negative‐ion spectra for each sample, the range of compounds that can be analyzed successfully is greatly expanded. The method developed is sufficiently universal that flow injection TSP‐MS now provides the required information in approximately 70% of the mass spectrometric structural confirmations performed at the Agricultural Research Division of American Cyanamid. The success in using flow injection TSP‐MS led to the development of instrumentation to fully automate these analyses. An IBM PC/AT® compatible computer is used to control sample delivery, data acquisition and data output. The PC performs the functions of both terminal and operator for a Finnigan® TSQ 46 triple quadrupole mass spectrometer and its Data General Nova® 4X data system, while simultaneously controlling a Micromeritics® 725 (Alcott®) autosampler and its Reodyne® 8126 pneumatically actuated 6‐port sampling valve. Furthermore, the need to document analyses in a manner that is consistent with Good Laboratory Practices has led to automated documentation for the instrument analysis log, as well as for the headers of the electronic data files and the printed spectral output. The new automated flow injection TSP‐MS system described here was constructed using only commercially available equipment and has notably improved efficiency by reducing the instrument time required to record spectra and by minimizing analyst intervention.
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