Mass spectroscopy aldehydes

Polyester composition can be determined by hydrolytic depolymerization followed by gas chromatography (28) to analyze for monomers, comonomers, oligomers, and other components including side-reaction products (ie, DEG, vinyl groups, aldehydes), plasticizers, and finishes. Mass spectroscopy and infrared spectroscopy can provide valuable composition information, including end group analysis (47,101,102). X-ray fluorescence is commonly used to determine metals content of polymers, from sources including catalysts, delusterants, or tracer materials added for fiber identification purposes (28,102,103). 

Aldehydes and ketones generally give moderately intense signals due to their molecular ions, M+. Thus the determination of the molecular weight of a ketone by mass spectroscopy usually is not difficult. Furthermore, there are some characteristic fragmentation patterns that aid in structural identification. These are ... 

Girard T or Girard P derivatives of cigarette MSS aldehydes and ketones were characterized my mass spectroscopy. 4-Nitrophenylhydrazine (4-NPH)... 

Procedures for etherification and esterification of carbohydrates for GLC analysis, advantages and disadvantages of the different methods of hydroxyl and aldehyde group derivatization, columns used for the separation of the various derivatives, detection methods for GLC, mass spectroscopy and fast atom bombardment (FAB) as well as outlines of some strategies for structural analysis of carbohydrates are described, discussed and reviewed in an excellent book on the analyses of carbohydrates by GLC (35). 

Latter on, de Souza and colleagues studied the mechanism of Bigjnelli reaction with mass spectrometry by direct infusion electrospray (electron-spray ionization mass spectroscopy, ESl-MS) [8]. In their studies, they found that reacting benz-aldehyde and urea leads to the formation of ions of m/z 209,167, and 149 (Figure 4). When the reaction was carried out with the three components (xuea, acetoacetate, and benzaldehyde), existences of the same intermediates were also detected. 

In addition, we should note that data of H, NMR spectroscopy, mass-spectra, and elemental analysis given in [138] did not contradict the structure of compound 98, being regioisomer of 97. The similar situation had already been shown in the synthesis of 3-aminoimidazo[l,2-a]pyrimidines [139]. Mandair et al. carried out the model MCRs of 2-aminopyrimidine with several aldehydes and isonitrile components in the methanol under the ambient temperamre with the various catalysts. As a result, 3-aminoimidazo[l,2-a]pyrimidine and position isomeric 2-aminoimidazo[l,2-a]pyrimidines were isolated from the reaction mixture in different ratio (Scheme 45). The stmctures of the isomers obtained in this case were confirmed by the X-ray diffraction analysis, as well as the structures of the side-products isolated. 

Reactions of 5f/-2-methyl-l,2,4-triazepino[2,3- ]benzimidazol-4-one 71, prepared by reaction of 1,2-diaminobenz-imidazole 72 with acetoacetic ester 73, with different reagents was described, in the search of new heterocycles with biological activity <2002CHE598>. When lactam 71 was treated with aromatic aldehydes in boiling 1-BuOH with addition of piperidine 74, 577-3-arylidene-2-methyl-l,2,4-triazepino[2,3- ]benzimidazol-4-ones 75a-c were obtained (Scheme 7). Coupling lactam 71 with phenyldiazonium chloride 76 in dioxane afforded the 3-phenylazo-substituted tricycle 77. When 71 was treated with phosphorus pentasulfide 78 in boiling dioxane or pyridine, its thio analog 79 was obtained. The reaction proceeded most efficiently when lactam 71 was refluxed with twofold excess of 78 in dry dioxane. These thiones 79 react with ammonia and amines by nucleophilic substitution. When 79 was refluxed with ammonia, benzylamine, piperidine, or morpholine, the 4-amino-substituted tricycles 80a-d were obtained. All the described compounds were identified by NMR, mass spectrometry, and IR spectroscopy. 

Regarding ozonation processes, the treatment with ozone leads to halogen-free oxygenated compounds (except when bromide is present), mostly aldehydes, carboxylic acids, ketoacids, ketones, etc. [189]. The evolution of analytical techniques and their combined use have allowed some researchers to identify new ozone by-products. This is the case of the work of Richardson et al. [189,190] who combined mass spectrometry and infrared spectroscopy together with derivatization methods. These authors found numerous aldehydes, ketones, dicarbonyl compounds, carboxylic acids, aldo and keto acids, and nitriles from the ozonation of Mississippi River water with 2.7-3 mg L 1 of TOC and pH about 7.5. They also identified by-products from ozonated-chlorinated (with chlorine and chloramine) water. In these cases, they found haloalkanes, haloalkenes, halo aldehydes, haloketones, haloacids, brominated compounds due to the presence of bromide ion, etc. They observed a lower formation of halocompounds formed after ozone-chlorine or chloramine oxidations than after single chlorination or chlorami-nation, showing the beneficial effect of preozonation. 

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