Mass spectrometry carbonyl compounds

A systematic investigation of the free amino acids of the Leguminosae led to the isolation of a novel ninhydrin-positive compound from the leaves of Derris elliptica Benth. (Papilionidae) (93). This substance was analyzed as C6H,3N04 (microanalysis and high resolution mass spectrometry) and was shown to be an amino alcohol. The absence of a carbonyl in the 1R, the loss of 31 mass units in the mass spectrum, and a positive periodate cleavage reaction were best embodied into a dihydroxydihydroxymethylpyrrolidine structure. The relative simplicity of the NMR spectra (three peaks in the 13C spectrum four spin-system in the H spectrum) pointed out a symmetrical structure. Inasmuch as the material was optically active ([a]D 56.4, c = 7, H20), meso structures were ruled out, and the 2R, 3R, 4R, 5R relative configuration was retained (93). This structure (53) was further confirmed by an X-ray determination (94). 

The existence of the neutral rhenium carbonyl [Re(C0)4] was first claimed in 1965 206 but, although it is easily sublimed, it has not yet been characterized by mass spectrometry and the value of n is still not known. This colourless substance [v (CO) 2055 and 1995 cm-1 in CHC13] has been obtained as a by-product in the synthesis of Re2(CO)i0 starting from Re2S7, copper powder, and carbon monoxide at 85 atm, 200 °C206>. There has also been a report of the compound Re4(CO)10(PPh2Me)6, which can be considered to be a substitution product of the hypothetical species, Re4(CO)i6 it has been obtained by a photochemical reaction between Re2(CO)j0 and PPh2Me194. In both cases, and particularly in the phosphine derivative, a tetrahedral structure seems improbable because of steric constraints. 

A new, fast, sensitive, and solventless extraction technique was developed in order to analyze beer carbonyl compounds. The method was based on solid-phase microextraction with on-fiber derivatization. A derivatization agent, 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBOA), was absorbed onto a divinyl benzene/poly(dimethylsiloxane) 65- xm fiber and exposed to the headspace of a vial with a beer sample. Carbonyl compounds selectively reacted with PFBOA, and the oximes formed were desorbed into a gas chromatograph injection port and quantified by mass spectrometry. This method provided very high reproducibility and linearity When it was used for the analysis of aged beers, nine aldehydes were detected 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal. (107 words)... 

Yu, J., H. E. Jeffries, and R. M. Le Lacheur, Identifying Airborne Carbonyl Compounds in Isoprene Atmospheric Photooxidation Products by Their PFBHA Oximes Using Gas Chromatography/ Ion Trap Mass Spectrometry, Environ. Sci. Technol., 29, 1923-1932 (1995). 

Fischer and co-workers have prepared several novel carbene derivatives of chromium pentacarbonyl and have confirmed the molecular formulas by mass spectrometry (5, 6, 73, 74, 77, 128, 147). The spectra show the expected stepwise loss of the five carbonyl groups giving the ions [Ligand Cr(CO) ]+ (w = 0-5). The compounds for which spectral data have been reported are given in Table III. The selenium derivative (XXIX) shows... 

A CO Sensor Based Upon Self-assembled Ferrocenyl Ferraazetine. Having demonstrated the CO dependent solid-state electrochemistry of ferrocenyl ferraazetine, we synthesized a ferrocenyl ferraazetine molecule with disulfide functionality (Id). Scheme III. The specific aim was to design a CO sensitive molecule that could be confined to the working electrode of a two-terminal device via monolayer self-assembly techniques. Disulfides have been shown to irreversibly adsorb to Au and Pt surfaces (3-10). NMR and mass spectrometry are consistent with the proposed structure for compound Id. The FTIR spectrum of Id in THF exhibits metal carbonyl bands at 2067,2024,1989,1985 cm similar to the spectra for other ferraazetine derivatives la-c (2,5-6). Like derivatives la-c. Id reacts with CO (1 atm) at 298 K in CH2C12 to form a ferrapyrrolinone complex 2d, equation (3). 

---