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1.
The thermal decomposition of piperidine hydrothiocyanate, piperazine hydrothiocyanate, and the dihydrothiocyanates of ethylenediamine and 1,3-diaminopropane has been studied using TG. Piperidine hydrothiocyanate decomposes in a single step while the dihydrothiocyanates follow more complicated decomposition patterns yielding H2S and half of the organic moiety first. The second step involves the loss of H2S and the remainder of the organic moiety. In each case, complex polymeric materials result. Piperazine hydrothiocyanate also decomposes in two steps, the first involving the loss of half of the piperazine and the second involving the loss of piperazine and H2S. Kinetic parameters have been determined for all these reactions. 相似文献
2.
Robert Glaser Menachem Twaik Shimona Geresh Jeanine Blumenfeld 《Tetrahedron letters》1977,18(52):4635-4638
Z--acetamidocinnamic acid was hydrogenated with neutral diphosphine-rhodium(I) complexes containing trans-1,2-bis(diphenylphosphinomethyl) cycloalkanes to give N-acetylphenylalanine: 86 % e.e.-(R) [(1R,2R)-cyclobutane]; 63 % e.e.-(R) [(1R,2R)-cyclopentane]; 35 % e.e.-(S) [(1S,2S)-cyclohexane]; and 82 % e.e.-(R) [(2R,3R)-DIOP]. Similarly, -acetamidoacrylic acid was hydrogenated to give N-acetylalanine: 72 % e.e.-(R) [(1R,2R)-cyclobutane]; 72 % e.e.-(R) [(1R,2R)-cyclopentane]; 40 % e.e.-(S) [(1S,2S)-cyclohexane]; and 73 % e.e.-(R) [(2R,3R)-DIOP]. 相似文献
3.
The densities and volumetric specific heats of aqueous solutions of Bu3NHBr, Pent3NHCl, and three diazonium salts, HN?Oct3?NHBr2, HN?Dec3?NHCl2, and Bu3N?Oct?NBu3Br2, have been measured at 25°C. From these data, the apparent molal volumes φ v and apparent molal heat capacities φ c have been calculated and are reported here. In the series of compounds chosen, the diazonium (higher homologs) can be regarded as dimers of the alkyl-substituted ammonium ions (lower homologs), and these systems are examined as chemical models for the hydrophobic interaction. With the three homologous pairs studied here, the chemical model predicts that the strong interaction (limitingly, chemical binding) of two hydrocarbon chains in water leads to a major decrease in both φ v and φ c of the interacting solutes, ca.?22 cm3-mole?1 and ?200 J-oK?1-mole?1. These predictions constitute limiting behavior — useful, but not sufficient, to explain the observed concentration dependence of φ v and φ c in aqueous solutions of the lower homologs Bu3NHBr, Pent3NHCl, and Bu4NBr. An explanation for the concentration dependence of φ c is suggested with reference to ultrasonic relaxation data. 相似文献
4.
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6.
The half-life period (6.6 mm.) for the hydrogenation of Z-methyl-a-acetamidocinnamate (catalyzed by a neutral DIOPRh complex) was found to be the same when the Me ester reduction was performed in the presence of equimolar quantities of the corresponding i-Pr or t-Bu ester unsaturated stbstrates. Neither the Me nor the i-Pr or t-Bu esters underwent appreciable Z,E-isomerization. The formation of N-acetylphenylalanine methyl ester product suffered inhibition when the hydrogenation reaction was performed in the presence of the corresponding bornyl or 1-adamantyl unsaturated esters (half-life period of the Me ester: 27 ~ 40 mm., respectively. The greater the inhibition of the Me ester unsaturated substrate, the more the bulky inhibitor itself underwent Z,E-isomerization. In the presence of inhibitors, the Me unsaturated substrate did not undergo appreciable Z,E-isomerization. 相似文献
7.
The reactivity of [rac-(C2H4(1-indenyl)2)Zr(n-butyl)][MeB(C6F5)3] (4), [rac-(C2H4(1-indenyl)2)Zr(sec-butyl)][MeB(C6F5)3] (5), and [rac-(C2H4(1-indenyl)2)Zr(polypropenyl)][MeB(C6F5)3] with propene, ethene, and hydrogen was studied by low-temperature (<-40 degrees C) 1H and 13C NMR spectroscopy in toluene solutions. In contrast with previous suggestions that 2 degrees zirconium alkyl species such as 5 are dormant sites, these measurements demonstrate reactivity of 2 degrees zirconium alkyls with propene and ethene comparable to the 1 degrees zirconium alkyl species 4 and [rac-(C2H4(1-indenyl)2)Zr(polypropenyl)][MeB(C6F5)3]. Because 2,1-insertion of propene is an infrequent event, these results preclude significant accumulation of catalyst in the form of 2 degrees zirconium alkyls for this metallocene and counterion. The reactivity of 5 with hydrogen is at least 2 orders of magnitude faster than other 1 degrees zirconium alkyls. Such high reactivity accounts for the puzzlingly high fraction of butyl end groups in prior hydrooligomerization studies and implies that catalyst responsivity to H2 as a molecular weight control agent correlates with the regioselectivity of the catalyst. 相似文献
8.
Giovanni Sorba Giuseppe Ermondi Roberta Fruttero Ubaldina Galli Alberto Gasco 《Journal of heterocyclic chemistry》1996,33(2):327-334
The use of benzenesulfonyl substituted furoxans as flexible intermediates for the synthesis of new functionalized furoxans interesting for their potential biological properties is discussed. Reaction of benzenesul-fonylphenylsulfonylfuroxan isomers 7a and 7b with ethanol and ethanethiol in basic medium affords the expected ethers and sulphides respectively. Reaction of bis(benzenesulfonyl)furoxan ( 1 ) with ethanol in basic medium gives 3-benzenesulfonyl-4-ethoxyfuroxan ( 2 ) or diethoxyfuroxan (3), according to the experimental procedure. In contrast the reaction of 1 with ethanethiol gives a mixture of substitution compounds and the 4-benzenesulfonyl-3-ethylthiofurazan ( 11 ). The structure of the compounds has been assigned by nmr spectroscopy and, in the case of 3-benzenesulfonyl-4-ethylthiofuroxan ( 9b ), confirmed by X-ray analysis. 相似文献
9.
Latifa Latrous Jeanine Tortajada Violette Haldys Emmanuelle Léon Catarina Correia Jean‐Yves Salpin 《Journal of mass spectrometry : JMS》2013,48(7):795-806
Gas‐phase interactions of organotins with glycine have been studied by combining mass spectrometry experiments and quantum calculations. Positive‐ion electrospray spectra show that the interaction of di‐ and tri‐organotins with glycine results in the formation of [(R)2Sn(Gly)‐H]+and [(R)3Sn(Gly)]+ ions, respectively. Di‐organotin complexes appear much more reactive than those involving tri‐organotins. (MS/MS) spectra of the [(R)3Sn(Gly)]+ ions are indeed simple and only show elimination of intact glycine, generating the [(R)3Sn]+ carbocation. On the other hand, MS/MS spectra of [(R)2Sn(Gly)‐H]+complexes are characterized by numerous fragmentation processes. Six of them, associated with elimination of H2O, CO, H2O + CO and formation of [(R)2SnOH]+ (?57 u),[(R)2SnNH2]+( ?58 u) and [(R)2SnH]+ (?73 u), are systematically observed. Use of labeled glycines notably concludes that the hydrogen atoms eliminated in water and H2O + CO are labile hydrogens. A similar conclusion can be made for hydrogens of [(R2)SnOH]+and [(R2)SnNH2]+ions. Interestingly, formation [(R)2SnH]+ ions is characterized by a migration of one the α hydrogen of glycine onto the metallic center. Finally, several dissociation routes are observed and are characteristic of a given organic substituent. Calculations indicated that the interaction between organotins and glycine is mostly electrostatic. For [(R)2Sn(Gly)‐H]+complexes, a preferable bidentate interaction of the type η2‐O,NH2 is observed, similar to that encountered for other metal ions. [(R)3Sn]+ ions strongly stabilize the zwitterionic form of glycine, which is practically degenerate with respect to neutral glycine. In addition, the interconversion between both forms is almost barrierless. Suitable mechanisms are proposed in order to account for the most relevant fragmentation processes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
R. Coquereaux L. Frappat E. Ragoucy P. Sorba 《Communications in Mathematical Physics》1990,133(1):1-35
We study theN-extended super-Ka-Moody algebras, i.e. extensions of the Lie algebra of the loop group over the super-circleA
N
. The extensions are characterized by 2-cocycles which are computed in terms of the cyclic cohomology of the Grassmann algebra withN generators. The graded algebra of super-derivations compatible with each extension is determined. The casesN=1,2,3 are examined in detail and their relation with the Ademollo et al. superconformal algebras is discussed. We examine the possibility of defining new superconformal algebras which, forN>1, generalize theN=1 Ramond-Neveu-Schwarz algebra. 相似文献