- THERMAL DEGRADATION OF GLUCOSINOLATES
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Three glucosinolates (allyl-, benzyl- and 2-phenethyl-) were shown to degrade thermally in a GC column to yield products identical with those obtained conventionally on enzymic decomposition, namely nitriles and isothiocyanates.Nitriles were formed more readily at 125 deg but the facility for isothiocyanate production varied slightly with the glucosinolate; 2-phenethylglucosinolate was the most labile of those studied yielding isothiocyanate at a column temperature of 150 deg.Temperature was confirmed as the cause of degradation by isolated heated-tube experiments.The results have significance both with regard to analytical methodology for glucosinolates and their products, and with regard to furthering understanding of the mechanisms of glucosinolate degradation.Key Word Index- Criciferae; glucosinolates; nitriles; isothiocyanates; thermal degradation.
- Macleod, Alexander J.,Panesar, Satwinder S.,Gil, Victor
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- Overtone-induced isomerization of allyl isocyanide
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The rate of isomerization of allyl isocyanide to allyl cyanide is monitored using Stern-Volmer kinetics when various features of the 5-O and 6-O C-H overtone stretch region are excited.Previously, Reddy and Berry found that the isomerization rates varied from band to band and that the variations were not monotonic with excitation energy.They attributed this behavior to nonstatistical effects.It is found in this study that the isomerization rates vary within an overtone band by up to a factor of 1.8, in addition to the variations from band to band seen previously.This observation rules out the possibility that the overtone bands are purely lifetime broadened.In addition, the photoisomerization rate increases with increasing temperature.An increase of 60 K increases the photolysis yield in the 5-O C-H region by a factor of 3-4, while increases in the 6-O C-H region are smaller, 25percent-60percent.These effects can be qualitatively explained if the overtone spectrum of allyl isocyanide is inhomogeneously broadened because of the presence of vibrational "hot bands." In this case, molecules excited by the photolysis laser will have varying amounts of initial thermal energy depending on where the laser is tuned within a band.A simple model for the effects of hot bands on the isomerization rate is in good agreement with experimental results.It is not necessary to invoke nonstatistical effects in order to explain the observed overtone-pumped isomerization rates of allyl isocyanide.
- Segall, Jeffrey,Zare, Richard N.
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- A method for the cyanation of alkenes using nitromethane as a source of cyano group mediated by proton-exchanged montmorillonite
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A novel method for the cyanation of alkenes using nitromethane as a source of the cyano group is described. H+-montmorillonite mediates the cyanation through the in situ formation of trimethylsilanecarbonitrile oxide from nitromethane and allylsilane, followed by 1,3-dipolar cycloaddition and subsequent rearrangement to afford the corresponding nitriles.
- Motokura, Ken,Matsunaga, Kenta,Miyaji, Akimitsu,Yamaguchi, Sho,Baba, Toshihide
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- Copper-Catalyzed Carbonylative Synthesis of β-Homoprolines from N-Fluoro-sulfonamides
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A new methodology for the carbonylative transformation of N-fluoro-sulfonamides into N-sulfonyl-β-homoproline esters has been described. In the presence of a catalytic amount of Cu(OTf)2, a range of β-homoproline derivatives were prepared in moderate to good yield. The reaction proceeds via the intramolecular cyclization and intermolecular carbonylation of a free carbon radical. Notably, this procedure offers the possibility to build potential functionalized bioactive molecules.
- Wu, Xiao-Feng,Yin, Zhiping,Zhang, Youcan
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supporting information
p. 1889 - 1893
(2020/03/24)
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- 2 - ((4R, 6R) - 6-aminomethyl-ethyl -2,2-dimethyl -1,3-dioxane-4-yl) acetate simple method for preparing
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The invention relates to a simple preparation method of 2-((4R,6R)-6-aminoethyl-2,2-dimethyl-1,3-dioxyhexacyclo-4-yl)acetate (I). The method comprises the following steps: reacting 3-cyanopropylene (II) and 3,3-dialkoxypropionate (III) or 3-alkoxyacrylate (IV) under the catalytic action of Lewis acid to prepare 2-((4R,6R)-6-cyanomethyl-2-ester-methyl-1,3-dioxyhexacyclo-4-yl)acetate (V), removing the solvent, directly carrying out blocking group conversion to prepare 2-((4R,6R)-6-cyanomethyl-2,2-dimethyl-1,3-dioxyhexacyclo-4-yl)acetate (VI), and carrying out Raney nickel catalytic hydrogenation two-step reaction to prepare (I). The stable form of the hexatomic ring chair-structure equatorial bond is utilized to construct the chiral center without using any additional chiral assistant. The method has the advantages of accessible raw materials, short reaction procedure and low cost, avoids carbonyl asymmetric reduction, is simple and environment-friendly, and is industrial production.
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Paragraph 0050-0052
(2017/02/28)
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- PHOTOLABILE COMPOUNDS
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The present invention describes Photolabile Compounds methods for use of the compounds. The Photolabile Compounds have a photoreleasable ligand, which can be biologically active, and which is photoreleased from the compound upon exposure to light. In some embodiments, the Photolabile Compounds comprise a light antenna, such as a labeling molecule or an active derivative thereof. In one embodiment, the light is visible light, which is not detrimental to the viability of biological samples, such as cells and tissues, in which the released organic molecule is bioactive and can have a therapeutic effect. In another embodiment, the photoreleasable ligand can be a labeling molecule, such as a fluorescent molecule.
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Page/Page column 71-72
(2011/01/12)
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- Looking for heteroaromatic rings and related isomers as interstellar candidates
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Finding complex organic molecules in the interstellar medium (ISM) is a major concern for understanding the possible role of interstellar organic chemistry in the synthesis of prebiotic species. The present interdisciplinary report is a prospective study aimed at helping detection of heteroaromatic compounds or at least of some of their isomers in the ISM. The thermodynamic stabilities of the C4H5N, C4H4O, C4H4S families were calculated using density functional theory (DFT). It was found that pyrrole, furan and thiophene are unambiguously the most stable isomers at the 10-50 K temperatures of the ISM. Several of the less stable isomers were synthesized and flash vacuum thermolysis experiments were performed on these species. Although the detection of pyrrole in the pyrolysis of many compounds has been reported in the literature, we observed that none of its isomers led to pyrrole in these conditions, which suggests that other formation routes are to be considered. On the other hand, these three aromatic compounds present a very high stability, few % been decomposed at 1500 K by flash vacuum thermolysis; these experiments also show a great stability of crotonitrile that is the most stable compound that can be formed in these conditions. The rotational constants, dipole moments and IR frequencies of the low-lying isomers are given to encourage laboratory experiments on these prototype molecules.
- Lattelais,Ellinger,Matrane,Guillemin
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experimental part
p. 4165 - 4171
(2011/08/02)
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- An efficient and convenient KF/Al2O3 mediated synthesis of nitriles from aldehydes
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KF/Al2O3 brings about a facile one-pot and economical conversion of various aryl and alkyl aldehydes into the corresponding nitriles in high yields by reaction with hydroxylamine hydrochloride.
- Movassagh, Barahman,Shokri, Salman
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p. 6923 - 6925
(2007/10/03)
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- Potassium, fluoride doped on alumina: An efficient catalyst for conversion of aldoximes into nitriles
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Potassium fluoride loaded on alumina catalyzed the dehydration of alkyl and aryl aldoximes into nitriles in good to high yields.
- Movassagh, Barahman,Shokri, Salman
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p. 887 - 890
(2007/10/03)
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- The thermal decomposition of 5-membered rings: A laser pyrolysis study
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The mechanisms of pyrolysis of cyclopentadiene, furan, pyrrole and thiophene have been investigated using a combination of IR laser powered homogeneous pyrolysis, chemical and physical trapping of radical intermediates, and use of precursors specifically designed to generate selected radical intermediates. The results confirm the central role played by free radicals in the cases of cyclopentadiene and thiophene, and the dominant step of 1,2-H shifts in the cases of furan and pyrrole. The experimental results may be interpreted according to the high level ab initio calculations recently reported in the literature.
- Hore, Nathan R.,Russell, Douglas K.
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p. 606 - 613
(2007/10/03)
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- Main products and kinetics of the thermal degradation of polyamides
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The thermal degradation of the polyamides (PA) 6, 12, 66 and 612 was investigated by means of thermal analysis/ mass spectrometry (TA-MS) and pyrolysis in a german standard oven. Sample masses were about 20 and 40 mg. The heating rates used in the dynamic studies were 1, 5 and 10 K min-1. Both air and nitrogen atmospheres were utilized. The kinetic parameters were calculated from the TA-MS measurements and the main decomposition products were registered online. The evolved products from the pyrolysis oven were captured and analyzed off-line by GC/ MS.
- Herrera,Matuschek,Kettrup
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p. 601 - 607
(2007/10/03)
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- Cyanidation of halogen compounds and esters catalyzed by PEG400 without solvent
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Primary aliphatic and aromatic nitriles were synthesized in excellent yields (84-96%) and purity by the cyanidation of halogen compounds and esters with dry powdered sodium cyanide catalysed by phase transfer catalyst PEG400 under solvent-free conditions.
- Cao,Chen,Pei
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p. 2203 - 2207
(2007/10/03)
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- Kinetics of Pyrolysis of the Isomeric Butenenitriles and Kinetic Modeling
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Kinetics of pyrolysis of the butenenitrile isomers, cis- and trans-crotonitrile and allyl cyanide, have been studied dilute in argon in a single-pulse shock tube over the temperature range of 1200-1500 K at uniform gas residence times behind the reflected shock of between 650 and 750 μs and at pressures between 18 and 20 atm.Thermal decomposition was preceded by isomerization of the butenenitriles whose rates are coupled with the rates of thermal decomposition.The decomposition was found to follow a free-radical mechanism, with the major chain involving propagation reactions of the cyanomethyl radical to produce acetonitrile and acetylene.Other routes important to the mechanism involve hydrogen atom addition to the butenenitriles.HCN principally arises from this route.A detailed kinetic reaction model is presented to model the experimental reactants and products profiles as a function of temperature.From the modeling and experiment, the following initiation rate constants have been obtained: trans-CH3CH=CHCN -> CH3 + HC=CHCN (k-11 = 1017.45 exp(-96.5/RT) s-1), cis-CH3CH=CHCN -> CH3 + HC=CHCN (k-12 = 1017.53 exp(-98.5/RT) s-1), CH2=CHCH2CN -> H2C=CH + CH2CN (k-13 = 1015.53 exp(-82.6/RT) s-1), where the activation energies are in kcal mol-1.
- Doughty, Alan,Mackie, John C.
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p. 272 - 281
(2007/10/02)
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- Eine neue Methode zur Herstellung von Nitrilen aus Aldoximen
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Aldoximes are dehydrated to nitriles in good yields by reaction with methyl or ethyl cyanoformates.The method can also be used for the synthesis of tert-butyl cyanoformate from tert-butyl oximinoacetate.
- Thomas, H. G.,Greyn, H. D.
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p. 129 - 130
(2007/10/02)
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- Assessment of the Cyano Substituent Effect in the Inhibited Pyrolysis Kinetics of ω-Bromonitriles in the Gas Phase
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The kinetics of the gas-phase pyrolysis of several bromonitriles were determined in a static system over the temperature range of 389.7-470.1 deg C and the pressure range of 38.5-139 Torr.The reactions in seasoned vessels, and in the presence of at least a 4-fold excess of the free-radical inhibitor propene and/or toluene, are homogeneous and unimolecular and follow a first-order rate law.The rate coefficients are given by the following Arrhenius equations: for 3-bromopropionitrile, log k1(s-1) = (13.56+/-0.44)-(231.9+/-6.0)kJmol-1 (2.303RT)-1; for 4-bromobutyronitrile, log k1(s-1) = (14.12*/-0.33) -(233.5+/-4.5)kJmol-1 (2.303RT)-1; for 5-bromovaleronitrile, log k1(s-1) = (13.79+/-0.19)-(225.7+/-2.6)kJmol-1(2.303RT)-1.The electron-withdrawing effect of the CN group along the carbon chain deactivates the HBr elimination during pyrolysis.A plot of the log krel of the cyano substituents in ω-bromonitriles against ?* values gives a good straight line with ρ* = -0.24, correlation coefficient r = 0.988, and intercept = -0.054 at 400 deg C.This slope inflects at ?*(CH3) = 0.00 with another good straight line derived by plotting the log krel vs ?* values of alkyl β-substituted ethyl bromides (? = -1.87, r = 0.991, and intercept = 0.056 at 400 deg C).The present result is explained in terms of slight alteration in the polarity of the transition state due to changes of electronic transmission at the carbon reaction center.
- Chuchani, Gabriel,Dominguez, Rosa M.
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p. 203 - 205
(2007/10/02)
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- CYANATION OF HALO DERIVATIVES BY ACETONE CYANOHYDRIN
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A preparative method is proposed for the synthesis of substituted acetonitriles by the cyanation of halo derivatives by acetone cyanohydrin in the presence of base and phase transfer catalysts.
- Shapiro, E. A.,Pereverzeva, Yu. O.,Nefedov, A. O.,Eismont, M. Yu.
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p. 2432 - 2433
(2007/10/02)
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- Chemie der α-Aminonitrile. 1. Mitteilung. Einleitung und Wege zu Uroporphyrinogen-octanitrilen
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Chemistry of α-Aminonitriles I: Introduction and Pathways to Uroporphyrinogen-octanitriles.An introduction to experimental studies on the chemistry of α-aminonitriles potentially relevant to the problems of prebiotic chemistry is presented.The framework of conditions wherein the investigations is chosen to be carried out implies both molecular oxygen and - whenever feasible - water to be excluded from reaction conditions.This study focusses on 2-amino-2-propenenitrile (3) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5).Schemes 13, 16, 23 as well as 25, and 26 summarize reaction sequences by which 3 is tranformed within the definied framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroporphyrinogen-octanitriles 57-60.HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one present in all biological porphinoids.Preparative procedures for the synthesis of 3 (Scheme 9), the β,β-disubstututed pyrrol-nitriles 30, 53, and 54 (Scheme 19) as well as the porphyrinogen-octakis(propionitrile) and -octakis(acetonitrile) 65 and 66, respectively (Scheme 24) are given.
- Ksander, Gary,Bold, Guido,Lattmann, Rene,Lehmann, Christian,Frueh, Thomas,et al.
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p. 1115 - 1172
(2007/10/02)
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- CATALYTIC AND STOICHIOMETRIC TRANSFORMATIONS WITH TRIPHENYL(P,P,P-TRIPHENYLPHOSPHINE IMIDATO-N) PHOSPHORUS CYANIDE,
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Reactions involving anhydrous +CN-, 1, are described for a series of nucleophilic displacements.The reagent may be used stoichiometrically with moisture sensitive substrates, and also acts as an efficient phase transfer catalyst.
- Dillon, Keith B.,Hodgson, Martin,Parker, David
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p. 849 - 854
(2007/10/02)
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- ACCELERATION OF SOLID-LIQUID TWO-PHASE REACTION BY MEANS OF ALUMINA-WATER-ULTRASOUND. A SUBSTITUTE FOR A PHASE TRANSFER CATALYST
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Combined use of alumina, a trace of water, and ultrasound greatly accelerated a solid-liquid two-phase nucleophilic substitution by cyanide ion in nonpolar organic solvents.The efficiency under the optimum conditions were compared with that of phase transfer catalysts such as 18-crown-6.
- Ando, Takashi,Kawate, Takehiko,Ichihara, Junko (nee Yamawaki),Hanafusa, Terukiyo
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p. 725 - 728
(2007/10/02)
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- Chloraminometric Reactions: Kinetics and Mechanisms of Oxidations of Amino-acids by Sodium N-Chlorotoluene-p-sulphonamide in Acid and Alkaline Media
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Available data on the kinetics of oxidations of amino-acids by sodium N-chloro toluene-p-sulphonamide (chloramine T) in acid and alkaline media have been critically examined.General mechanisms have been proposed for both acid and alkaline medium oxidations.The oxidation process in acid media has been shown to proceed via two paths, one involving the direct interaction of N-chlorotoluene-p-sulphonamide (RNHCl) with the neutral amino-acid in a slow step leading to the formation of the monochloroamino-acid which subsequently interacts with another molecule of RNHCl, in a fast step, to give the NN-dichloroamino-acid which in turn undergoes molecular rearrangement and elimination to yield the products, and the other involving the interaction of Cl2 or H2OCl(1+), produced from the disproportionation of RNHCl in the presence or absence of Cl(1-), with the substrate to give the products.In the alkaline medium mechanisms involving the interaction of RNHCl, HOCl, RNCl(1-), and OCl(1-) with the substrate are proposed.The mechanisms proposed and the derived rate lows are consistent with the observed kinetics.The rate constants predicted by the derived rate laws, as the concentrations of substrate and Cl(1-) ion change, are in excellent agreement with the observed rate constants thus further verifying the rate laws and hence the proposed mechanisms.
- Gowda, Basavalinganadoddy Thimme,Mahadevappa, Darndinasivara S.
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p. 323 - 334
(2007/10/02)
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- Mechanism of Gas Phase Cyanation of Alkenes and Aromatics
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ICN was photolyzed at 254 nm in the gas phase in the presence of 15-20 torr of certain alkenes or aromatics.The products were analyzed by GC-MS.Ethene gave acrylonitrile; propene gave acrylonitrile, allyl cyanide and cis- and trans-1-cyanopropene; 2-methylpropene gave 2 cyanopropene; benzene gave benzonitrile; toluene gave benzonitrile and 2-, 3-, and 4-cyanotoluene.These products are explained by a mechanism involving attack of CN on the organic to give vibrationally excited radicals.These radicals rapidly fragment, producing the major products, or react more slowly in bimolecular processes.The relevance of these results to RF discharge chemistry is discussed.
- Henis, Neil B. H.,Miller, Larry L.
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p. 2820 - 2823
(2007/10/02)
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- Olefin complexes of nickel(0). 4. Equilibria in solutions containing P(O-o-tolyl)3 and cyanoolefins
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31P and 1H NMR and IR spectroscopy and spectrophotometry are used to demonstrate the presence of both olefin and nitrile complexes in solutions containing cyanoolefins, P(O-o-tol)3 (tol = tolyl), and nickel(0). Coordination of the olefinic double bond is favored by a terminal location and by conjugation with the nitrile group. Coordination of the nitrile nitrogen is favored by conjugation and by increased concentrations of free P(O-o-tol)3. A number of equilibrium constants and electronic spectra in benzene at 25 °C are reported and discussed in terms of the structures of the cyanoolefins.
- Tolman, Chadwick A.
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p. 614 - 621
(2008/10/08)
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- Production of Acrylonitrile and Other Unsaturated Nitriles from Alkenes and Alkynes
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Passage of unsaturated organic molecules trough a 13.56-MHz radio-frequency discharge, in the presence of cyanogen, results in the formation of unsaturated nitriles.Acrylonitrile was the major product from ethylene, propylene, acrolein, methyl vinyl ketone, or 1,1,1-trifluoropropylene. 1-Butene, 2-butene, and isobutylene gave mixtures of nitrile products with the CN situated at vinylic or allylic positions. 2-Butyne gave 1-cyanopropyne.Other compounds gave only low yields of nitriles and considerable polymer.The effects of power, pressure, flow rate, and ratios of reactants on the yields of acrylonitrile from propylene and cyanogen were studied.A typical power yield of acrylonitrile was 30 g kW-1 h-1.Maximum material yields of nitrile products were obtained at intermediate powers and pressures.The products are consistent with a reaction scheme involving attack of initially formed cyano radicals on the organic substrate.This step forms activated radical intermediates, which decay through elimination of an atom or group.The atom or group which is most weakly bound is preferentially lost.
- Henis, Neil B.,Miller, Larry L.
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p. 2526 - 2529
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of Proline by Chloramine-T
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The title reaction has been suggested to proceed through two pathways. (i) Interaction of N-chloro-p-toluene-sulphonamide molecule, produced in a fast step from CAT, with proline in a slow step resulting in the formation of an intermediate, N-chloroproline, which which in a subsequent fast step interacts with another molecule of N-chloro-p-toluenesulphonamide yielding the products (allyl cyanide, HCl and carbone dioxide). (ii) In this pathway hypochlorite ion replaces N-chloro-p-toluenesulphonamide in the above steps.Both the mechanisms satisfy the observed stoichiometry, negligible influence of ionic strength and a positive dielectric effect.
- Sharma, Janardhan,Pandey, Lalji,Mushran, S. P.
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p. 475 - 476
(2007/10/02)
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