Mass spectrometric synthesis. 1—the reaction of catechol with 2,4-dimethyl-2,3-pentadiene

The reaction of catechol with 2,4-dimethyl-2,3-pentadiene, carried out in the chemical ionization chamber of a VG ZAB2F mass spectrometer, has been studied with respect to the partial pressure of the reacting species. The structure of the reaction product, 2,2-diisopropyl-1,3-benzodioxole, has been proved by exact mass measurements, B/E linked scans, labelling experiments and collisionally activated dissociation mass analysed ion kinetic energy spectra.     

The reaction of thiophosphoryl dichloride with catechol

Phenyl thiophosphonyl dichloride reacted with catechol n the presence of triethylamine to yield a pentacoordinated phosphorus compound 3. The reactions of a number of phosphorodi-chloridothioates with catechol gave a hexacoordinated phosphorus compound 8. The mechanism of these reactions are discussed.     

Mass spectrometric synthesis. V. The gas-phase ion-molecule dimerization of some sulfur containing heterocycles

The gas-phase, ion-molecule reactions occurring in the ion source of a mass spectrometer between differently substituted thiazoles, employed as starting compounds for synthesis of polymers exhibiting semiconducting properties, have been studied in detail. The structural characterization of the dimeric moieties so obtained has been carried out by exact mass measurements, linked scans for metastable analysis and collisional spectroscopy.     

Mass spectrometric studies—II: Mass spectrometric studies of maleimides and benzaldazine adducts. Identification of solid mixtues

It has been found by mass spectrometric studies that the so-called ‘1:1-adduct’ formed by N-( nbutyl)maleimide and benzaldazine, is in fact a solid mixture of one part bis-imide L and one part benzaldazine. Bis-imide L is one of the three stereoisomeric products obtained by the addition of two mole of N-( n-butyl)malemide and one mole of benzaldazine. The three stereoisomeric bis-imides gave identical mass spectra. Mass spectra of bis-imide M and bis-imide M- d2 are discussed, and confirm the proposed structures of perhydroprazolo-pyrazole derivatives for these 1:2-adducts.     

Mass spectrometric detection of the Gibbs reaction for phenol analysis

This paper describes a new method for detecting phenols, by reaction with Gibbs reagent to form indophenols, followed by mass spectrometric detection. Unlike the standard Gibbs reaction, which uses a colorometric approach, the use of mass spectrometry allows for simultaneous detection of differently substituted phenols. The procedure is demonstrated to work for a large variety of phenols without para‐substitution. With para‐substituted phenols, Gibbs products are still often observed, but the specific product depends on the substituent. For para groups with high electronegativity, such as methoxy or halogens, the reaction proceeds by displacement of the substituent. For groups with lower electronegativity, such as amino or alkyl groups, Gibbs products are observed that retain the substituent, indicating that the reaction occurs at the ortho or meta position. In mixtures of phenols, the relative intensities of the Gibbs products are proportional to the relative concentrations, and concentrations as low as 1 μmol/L can be detected. The method is applied to the qualitative analysis of commercial liquid smoke, and it is found that hickory and mesquite flavors have significantly different phenolic composition.     

Tunneling in the reaction of acetone with OH

Based on recent detailed quantum mechanical computations of the mechanism of the title reaction and, this paper presents kinetics analysis of the overall rate constant and its temperature dependence, for which ample experimental data are available for comparison. The analysis confirms that the principal channel is the formation of acetonyl radical + H(2)O, while the channel leading to acetic acid is of negligible importance. It is shown that the unusual temperature dependence of the overall rate constant, as observed experimentally, is well accounted for by standard RRKM treatment that includes tunneling. This treatment is applied at the microcanonical level, with chemically activated distribution of entrance species, i.e. using a stationary rather than a thermal distribution that incorporates collisional energy transfer and competition between the redissociation and exit channel. A similar procedure is applied to the isotopic reaction acetone-d6 + OH with equally satisfying results, so that the experimental temperature dependence of the KIE (kinetic isotope effect) is perfectly reproduced. This very good agreement between calculation and experiment is obtained without any fitting to experimental values and without any adjustment of the parameters of calculation.     

Trichloroethylene in organic synthesis: II. reaction of trichloroethylene with secondary amines

In a novel reaction, trichloroethylene reacts with secondary aliphatic amines in the presence of aqueous solution of NaOH and catalytic quantity of benzyltriethylammonium chloride to give the corresponding N,N,N,'N'-tetraalkylsubstituted glycinamides. The following glycinamides were obtained with high yield: /N-morpholine/acetic acid morpholide, N-/piperidineacetyl/piperidine, N,N,N,'N'-tetra-n-butylglycinamide and N,N,N,'N'-tetraethlyglycinamide. Mechanism of the reaction is discussed.     

Mass spectrometric determination of cadmium in i.a.e.a. fish solubles

The cadmium content of the I.A.E.A Fish Solubles [A-6 (1975)] was determined by the isotope dilution method. After dry-ashing and dissolution of the specimen, the cadmium was equilibrated with a known amount of ¹⁰³Cd spike, isolated by ion exchange, purified by dithizone extraction, and converted to the sulfide form in 1% H₃PO₄ solution. The CdS precipitate was loaded onto a baked single rhenium filament for mass spectrometric analysis. The ¹⁰³Cd/¹¹⁰Cd ratio was measured to compute the cadmium content of 0.278 ± 0.032 ppm (dry weight basis) in the Fish Solubles.     

Mass spectrometric study of isatins II. N-propyl(allyl,propargyl)isatins

The mass spectra of N-propyl- (I), N-allyl- (IV), and N-propargylisatin (VII) and their 5-methyl (II, V, VIII) and 7-methyl (III, VI, and IX) derivatives were recorded. It is shown that a portion of the [M-2CO]⁺ ions in the mass spectra of N-propargylisatins undergo rearrangement to give ions with a quinoline structure. A scheme for the fragmentation of the investigated compounds is presented. The mass spectra of the 5- and 7-methyl derivatives are compared.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 639–641, May, 1977.     

Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. II

Nine polysulfides, previously unknown as environmental organic pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to low- and high-resolution mass spectrometers. The structure of the polysulfides was elucidated by determination of isotopic composition of abundant molecular and fragment ions by high-resolution mass spectrometry (HRMS), the interpretation of ion structures in low-resolution mass spectra (LMRS) using the thermochemical approach, the application of fragmentation rules and performing the ICLU simulation of abundance of ions in isotope clusters. Seven compounds were known in literature, but mass spectra were reported for only two of them, both recorded from mixture. Struture evaluation was successful for other substances, but not for the substance(s) in first eluting GC peak, where HRMS date were not obtained. Suggested structures of the cyclic compounds were (in the order of GC retention) 3,4-dithiacyclohexene, 1,2,3-trithiacyclohexane, 3,4,5- trithiacyclohexene, 1,2,4-trithiacyclohexane, cyclopropyl hydrodisulfide, 1,2-dithiole-3-thione and 1,2,3,4,5-penta- thiacyclo-octane. One acyclic congener identified was dimethyl tetrasulfide.     

Mass spectrometric analysis of carbohydrates labeled with a biotinylated tag

A derivatization method for mass spectrometric analysis of oligosaccharides is presented. Small saccharides, complex, high‐mannose‐type oligosaccharides and oligosaccharides released from hen ovalbumin were converted into their biotin derivatives by incubating them with biotinamidocaproyl hydrazide (BACH). Improved sensitivity of mass spectrometric analysis of labeled glycans in comparison with their natural counterparts was achieved after derivatization. The labeling reagent contains a biotin handle at one end and a hydrazide group at the other. Hence, the key feature of biotinylated sugars is that in addition to their usefulness in functional studies (e.g. analysis of the interaction between lectins and biotin‐derivatized oligosaccharides) they might be utilized also for structural analysis of oligosaccharides. Mass spectrometric studies were performed by matrix‐assisted laser desorption/ionization time‐of‐flight and electrospray ionization mass spectrometry. Copyright © 2009 John Wiley & Sons, Ltd.     

Radiation-induced synthesis of low molecular weight of PTFE and their crosslinking in acetone medium

Polytetrafluoroethylene was obtained by radiation-induced polymerization of tetrafluoroethylene in acetone at 195 K. An average diameter of the products was very small compared with the commercial one; it was about 0.2 μm. The yield was reached to 100% with a dose of 4 kGy. The crystallinity of the products is decreasing with increasing dose. The crystallinity becomes low, for higher irradiation doses. It was found that PTFE obtained by irradiation of TFE in acetone at 195 K has Y-type crosslinking structure. This was demonstrated by means of ¹⁹F MAS NMR.     

The reaction of chromate with diphenylcarbazide. II

Job's method was employed for ascertaining the detailed mechanism of the chromato-carbazide reaction. Three different systems (1) chromatc-carbaxidc, (2) chromate-carbastone and (3) chromous-earbazone, leading to the formation of the same coloured complex were investigated. From studies in cquimolecular solutions, the maximum composition values for the reactions were found to be 2:3, 1:3 and 1:1, respectively. Proceeding from the assumption that the reaction (3) is a case of simple displacement, the stoichiometry of all the three systems has been formulated. The role of chromate in the chromatc-carbay.ide reaction, has been found to be primarily that of an oxidising agent followed by complex formation. The tentative formulation for the three systems is given below. (1) 2Cr⁺⁶ + 3 carbazide ? 2 [Cr⁺² carbazone^-2 complex ] + carbacliazone + 4 H⁺ (2) Cr⁺⁶ + 3 carbazone ? [Cr⁺² carbazone^-2 complex] + 2 carbadiazone + 2 H⁺ (3) Cr⁺² + carbazone ? [Cr⁺² carbazone^-2 complex] + 2 H⁺ The proposed mechanism seems to explain the relevant facts observed in the course of investigation of the three Systems, particularly the rapid discharge of the colour produced when excess of chromium was added and the greater sensitivity of carbaxide as compared to carbaxonc were accounted for, The determination of K values from studies in non-equimolccular solutions of the three reactions also corroborates the aforesaid mechanism. The apparent dissociation constant of the Cr⁺²-carbazonc complex was found to be 2.7.10^-6 and the equilibrium constants of (1) and (2) were calculated as 5.7.10^-12 and 2.3.10^-7, respectively. The existence of bivalent Cr⁺² ion in the complex molecule has also been independently confirmed from magnetochemical measurements. The molar susceptibility value of 4.6 Bohr magnetons calculated on the basis of 1:1 chromous-carbastonc ratio, indicates ionic bonding in the complex.