Journal articles: 'Mechanism of 2-methyl-1,3-dioxolane'

1

Schweitzer, L., J. Noblet, E. Ruth, and I. H. Suffet. "The Formation, Stability, and Odor Characterization of 2-ethyl-4-methyl-1,3-dioxolane (2-EMD)." Water Science and Technology 40, no. 6 (September 1, 1999): 293–98. http://dx.doi.org/10.2166/wst.1999.0312.

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A class of compounds which are byproducts of the resin manufacturing process, has been responsible for three different taste and odor episodes in drinking water around the world. One such episode which occurred on the Ohio River, Pennsylvania, USA in 1989 was linked to the chemical, 2-ethyl-4-methyl-1,3-dioxolane (2-EMD). In this study, the mechanism and kinetics of formation of 2-EMD were examined specifically under the conditions which were present in the waste water of a resin manufacturer during the Ohio River event. The stability (fate) of 2-EMD was studied at aqueous pHs of 3, 5, 7, and 9. Hydrolysis occurred on the order of hours at pH 3 and its stability was questionable even at pH 7, but appeared to be stable at pH 9. 2-EMD was synthesized and purified in order to determine odor characteristics and odor thresholds using the method of flavor profile analysis (FPA). The distinctive sweet odor described as “sickening sweet” or “medicinal sweet” was found to have an odor threshold concentration of between 5 and 10 ng/l. The levels of 2-EMD found in drinking water samples from the taste and odor event of the Ohio River were above this odor threshold.

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Kaválek, Jaromír, Vladimír Macháček, Miloš Sedlák, and Vojeslav Štěrba. "Study of Cyclization of 1-Benzoyl-3-methyl-3-(2-methoxycarbonylphenyl)thiourea to 1-Methyl-2-thioxo-4-quinazolone." Collection of Czechoslovak Chemical Communications 58, no. 5 (1993): 1122–32. http://dx.doi.org/10.1135/cccc19931122.

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The reaction mechanism of the title reaction was proposed on the bases of the kinetic study. The reaction takes place in two stages considerably differing in rates. In the first, faster stage, the anion of initial substance cyclizes to 1-methyl-3-benzoyl-2-thioxo-4-quinazolone. The reaction is reversible, the concentration of 1-methyl-3-benzoyl-2-thioxo-4-quinazolone decreases with increasing concentration of methanolate. In the second stage, the benzoyl group rearrangement in the given substance from nitrogen to sulfur and subsequent methanolysis to 1-methyl-2-thioxo-4-quinazolone take place. The rate-determining step is the methanolysis for [CH3O(-)] < 4 . 10-3 mol l-1 and the benzoyl group rearrangement for higher methanolate concentrations.

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Arnold, Donald R., Laurie J. Lamont, and Allyson L. Perrott. "1,n-Radical ions. Photosensitized (electron transfer) carbon–carbon bond cleavage. Formation of 1,6-radical cations." Canadian Journal of Chemistry 69, no. 2 (February 1, 1991): 225–33. http://dx.doi.org/10.1139/v91-036.

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The reactivity of the radical cations of methyl 2,2-diphenylcyclohexyl ether (7), 6,6-diphenyl-1,4-dioxaspiro[4.5]decane (8), methyl cis- and trans-2-phenylcyclohexyl ether (9cis and trans), and 6-phenyl-1,4-dioxaspiro[4.5]decane (10), generated by photosensitized (electron transfer) irradiation, has been studied. Solutions of the ethers and acetals in acetonitrile–methanol (3:1), with 1,4-dicyanobenzene (2) serving as the electron acceptor, were irradiated with a medium-pressure mercury vapour lamp through Pyrex. The diphenyl derivatives 7 and 8 were reactive; 7 gave 6,6-diphenylhexanal dimethyl acetal (11) and 8 gave 2-methoxy-2-(5,5-diphenylpentyl)-1,3-dioxolane (12). These are the products expected from the intermediate 1,6-radical cation, formed upon carbon–carbon bond cleavage of the cyclic radical cation. The monophenyl derivatives 9cis and trans and 10 were stable under these irradiation conditions. The mechanism for the carbon–carbon bond cleavage and for the cis–trans isomerization is discussed. An explanation, based upon conformation, is offered for the lack of reactivity of 9 and 10. Molecular mechanics (MM2) calculations were used to determine the preferred conformation of 9cis and trans, and 10. Key words: photosensitization, electron transfer, radical cation, carbon–carbon bond cleavage, conformation.

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Calmanti, Roberto, Emanuele Amadio, Alvise Perosa, and Maurizio Selva. "Reaction of Glycerol with Trimethyl Orthoformate: Towards the Synthesis of New Glycerol Derivatives." Catalysts 9, no. 6 (June 14, 2019): 534. http://dx.doi.org/10.3390/catal9060534.

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The reactivity of glycerol with trimethyl orthoformate is here described with an emphasis on developing a reliable synthetic approach for glycerol valorization. The glycerol based orthoester 4-(dimethoxymethoxy)methyl)-2-methoxy-1,3-dioxolane (3) was synthesized, under catalytic as well as catalyst-free conditions, by taking advantage of the thermodynamically controlled equilibrium between intermediates. Both Brønsted and Lewis acid catalysts accelerated the attainment of such an equilibrium, particularly Brønsted acidic ionic liquids BSMImHSO4 and BSMImBr were the most effective compounds for this reaction. The kinetic profiles allowed the proposal of a mechanism that accounts for the selectivity of the reaction.

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Popsavin, Velimir, Ljubica Radic, Mirjana Popsavin, and Vera Cirin-Novta. "Unexpected cycloreversion of a tosylated sugar oxetane under E2 conditions: The facile formation of 2-(2-furanyl)-1, 3-dioxolane from a novel 2, 5:4, 6-dianhydro-L-idose derivative (Preliminary commun." Journal of the Serbian Chemical Society 69, no. 2 (2004): 117–22. http://dx.doi.org/10.2298/jsc0402117p.

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2,5:4,6-Dianhydro-3-O-p-toluenesulfonyl-L-idose ethylene acetal (4) was synthesized with the aim of studying its chemical behaviour in the presence of several basic agents (Bu4NF/MeCN, NaOMe/MeOH, KOBut/ButOH/THF, and NaH/DMSO). Treatment of 4 with sodium hydride in dimethyl sulphoxide at room temperature unexpectedly gave the 2-(2-furanyl)-1,3-dioxolane. The mechanism of the process presumably involved the initial conversion of 4 to the corresponding 2,3-unsaturated derivative 5, followed by a facile oxetane ring cycloreversion by the elimination of formaldehyde.

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Rejňák, Michal, Jiří Klíma, Jiří Svoboda, and Jiří Ludvík. "Synthesis and Electrochemical Reduction of Methyl 3-Halo-1-benzothiophene-2-carboxylates." Collection of Czechoslovak Chemical Communications 69, no. 1 (2004): 242–60. http://dx.doi.org/10.1135/cccc20040242.

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A preparative method of synthesis of the new methyl 3-iodo-1-benzothiophene-2-carboxylate was elaborated. Electrochemical behavior of methyl 3-chloro-, bromo- and iodo-1-benzothiophene-2-carboxylates 1-3, and of their reduction and dimer products 4, 5 in anhydrous dimethylformamide has been investigated at mercury and platinum electrodes using polarography, cyclic voltammetry and voltammetry on a rotating platinum disk electrode. The reduction in divided cells follows the ECE mechanism (electron - chemical step - electron), where the primary radical anion is split into a halide anion and neutral heterocyclic radical, which is immediately reduced by the second electron and protonated. The only reduction product is the methyl 1-benzothiophene-2-carboxylate (5); whereas the EDim mechanism (electron - dimer formation) leading to the dimeric species 4 was not observed under the above conditions. Reduction of 1-3 on platinum causes formation of a blocking film on the electrode. Sonication during electrolysis successfully reactivates the electrode.

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Kaválek, Jaromír, Josef Jirman, and Vojeslav Štěrba. "Kinetics and mechanism of rearrangement and methanolysis of acylphenylthioureas." Collection of Czechoslovak Chemical Communications 50, no. 3 (1985): 766–78. http://dx.doi.org/10.1135/cccc19850766.

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S-Acyl-1-phenylthioureas and their 3-methyl derivatives are rearranged to 1-acyl derivatives of thiourea in methanolic solution. The rearrangement of the 1-acyl-1-phenyl derivative to the thermodynamically more stable 3-acyl derivative is subject to specific base catalysis. The rearrangement of acetyl group is about 2 orders of magnitude slower than that of benzoyl group. 1-Acetyl-l-phenylthiourea undergoes base-catalyzed methanolysis (giving phenylthiourea and methyl acetate) instead of the rearrangement. The methanolysis rates of l-acyl-3-phenylthioureas and their N-methyl derivatives have been measured. The acetylthioureas react at most 3x faster than the benzoyl derivatives. The methyl group at the nitrogen adjacent to acyl group accelerates the solvolysis by almost 2 orders of magnitude; the methyl group at the other nitrogen atom retards the solvolysis by almost 1 order of magnitude. Replacement of hydrogen atom by methyl group at the phenyl-substituted nitrogen increases acidity of the phenylacetylthiourea by 2 orders of magnitude. The same replacement at the benzoyl-substituted nitrogen increases the acidity by 3 orders of magnitude, the increase in the case of the acetyl derivative being as large as 4 orders of magnitude.

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Gu, Zhengxian, Mark A. Wainberg, Nghe Nguyen-Ba, Lucille L’Heureux, Jean-Marc de Muys, Terry L. Bowlin, and Robert F. Rando. "Mechanism of Action and In Vitro Activity of 1′,3′-Dioxolanylpurine Nucleoside Analogues against Sensitive and Drug-Resistant Human Immunodeficiency Virus Type 1 Variants." Antimicrobial Agents and Chemotherapy 43, no. 10 (October 1, 1999): 2376–82. http://dx.doi.org/10.1128/aac.43.10.2376.

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ABSTRACT (−)-β-d-1′,3′-Dioxolane guanosine (DXG) and 2,6-diaminopurine (DAPD) dioxolanyl nucleoside analogues have been reported to be potent inhibitors of human immunodeficiency virus type 1 (HIV-1). We have recently conducted experiments to more fully characterize their in vitro anti-HIV-1 profiles. Antiviral assays performed in cell culture systems determined that DXG had 50% effective concentrations of 0.046 and 0.085 μM when evaluated against HIV-1IIIB in cord blood mononuclear cells and MT-2 cells, respectively. These values indicate that DXG is approximately equipotent to 2′,3′-dideoxy-3′-thiacytidine (3TC) but 5- to 10-fold less potent than 3′-azido-2′,3′-dideoxythymidine (AZT) in the two cell systems tested. At the same time, DAPD was approximately 5- to 20-fold less active than DXG in the anti-HIV-1 assays. When recombinant or clinical variants of HIV-1 were used to assess the efficacy of the purine nucleoside analogues against drug-resistant HIV-1, it was observed that AZT-resistant virus remained sensitive to DXG and DAPD. Virus harboring a mutation(s) which conferred decreased sensitivity to 3TC, 2′,3′-dideoxyinosine, and 2′,3′-dideoxycytidine, such as a 65R, 74V, or 184V mutation in the viral reverse transcriptase (RT), exhibited a two- to fivefold-decreased susceptibility to DXG or DAPD. When nonnucleoside RT inhibitor-resistant and protease inhibitor-resistant viruses were tested, no change in virus sensitivity to DXG or DAPD was observed. In vitro drug combination assays indicated that DXG had synergistic antiviral effects when used in combination with AZT, 3TC, or nevirapine. In cellular toxicity analyses, DXG and DAPD had 50% cytotoxic concentrations of greater than 500 μM when tested in peripheral blood mononuclear cells and a variety of human tumor and normal cell lines. The triphosphate form of DXG competed with the natural nucleotide substrates and acted as a chain terminator of the nascent DNA. These data suggest that DXG triphosphate may be the active intracellular metabolite, consistent with the mechanism by which other nucleoside analogues inhibit HIV-1 replication. Our results suggest that the use of DXG and DAPD as therapeutic agents for HIV-1 infection should be explored.

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9

Abell, AD, and RA Massy-Westropp. "Mechanism of Acetal Cleavage with Methylmagnesium Iodide." Australian Journal of Chemistry 38, no. 7 (1985): 1031. http://dx.doi.org/10.1071/ch9851031.

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The reaction of methylmagnesium iodide with methyl (1R,3S,5R)-1-(furan- 3′-yl)-5-methyl-2,8-dioxabicyclo[3.2.1]octane-3-carboxylate (2) gives products arising from regioselective carbon-oxygen bond fission and intermolecular transfer of the methyl group of the Grignard reagent to the intermediate oxocarbonium ion, in addition to the usual tertiary alcohol.

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10

Brown, D. Sean, Jason V. Jollimore, Marcus P. Merrin, Keith Vaughan, and Donald L. Hooper. "Formation of methyl 2-arylhydrazono-3-oxobutanoates and 2-arylhydrazono-3-oxobutanenitriles during the coupling reaction of arenediazonium ions with methyl 3-aminocrotonate and 3-aminocrotononitrile." Canadian Journal of Chemistry 73, no. 2 (February 1, 1995): 169–75. http://dx.doi.org/10.1139/v95-025.

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Reaction of aryldiazonium salts with methyl 3-aminocrotonate (1) affords high yields of the methyl 2-arylhydrazono-3-oxobutanoates (4); analogous diazonium coupling with 3-aminocrotononitrile (2) gives the 2-arylhydrazono-3-oxobutanenitriles (5). The hydrazones are the product of diazonium coupling at the C2-vinylic carbon, concomitant with hydrolysis of the 3-amino substituent to the 3-oxo derivative; there is no evidence for the formation of a triazene (6), which would be the product of N-coupling. All hydrazones (4a–e and 5a–d) have been fully characterized by IR and 1H and 13C NMR spectroscopy; the NMR spectra of the methyl 2-arylhydrazono-3-oxobutanoates (4) suggest the presence of two isomeric intramolecularly H-bonded forms in solution. Selected compounds were further characterized by elemental analysis and mass spectrometry. A mechanism is proposed for the conversion of 1 or 2 into 4 or 5, and these observations are compared with previously reported observations of diazonium coupling reactions with unsaturated systems. Keywords: hydrazone, diazonium, aminocrotonate, aminocrotononitrile, hydrogen bonding.

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11

Granell-Ortiz, Laura B., and Syun Ru Yeh. "Indoleamine 2, 3- Dioxygenases 2: The Missing Link For The 1-methyl-D-trp Mechanism Of Action?" Biophysical Journal 96, no. 3 (February 2009): 435a. http://dx.doi.org/10.1016/j.bpj.2008.12.2232.

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12

Polat, Kamran, Mustafa Uçar, M. Levent Aksu, and Hüseyin Ünver. "Electrochemical behaviour of 1-{[(3-halophenyl)imino]methyl}-2-naphthol Schiff bases on graphite electrodes." Canadian Journal of Chemistry 82, no. 7 (July 1, 2004): 1150–56. http://dx.doi.org/10.1139/v04-021.

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An electrochemical study of the reduction of 1-{[(3-halophenyl)imino]methyl}-2-naphthol compounds on graphite electrodes was carried out. All the compounds were dissolved in a 1:4 (volume fraction) mixture of tetrahydrofuran (THF) and methanol. NaClO4 (0.1 mol L1) was used as the supporting electrolyte. Cyclic voltammetry, chronoamperometry, constant-potential coulometry (bulk electrolysis), and constant-potential preparative electrolysis were employed. The cyclic voltammetric data revealed that the reduction on graphite was irreversible and followed an EC mechanism. The diffusion coefficients and the number of electrons transferred were determined using the chronoamperometric Cottrell slope and the ultramicro electrode steady-state current. The number of electrons was also determined by bulk electrolysis. The products of the electroreduction were synthesized in milligram quantities by the use of constant-potential preparative electrolysis. These products were purified and characterized by spectroscopic methods. Based on these findings, a mechanism for the electroreduction process is proposed.Key words: electrochemical reduction, hydroxynaphthylideneaniline Schiff bases, cyclic voltammetry, ultramicro electrode.

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13

Hu, Qi-Shan, Lai-Cai Li, and Xin Wang. "Theoretical study on the mechanism of reaction between 3-hydroxy-3-methyl-2-butanone and malononitrile catalyzed by lithium ethoxide." Open Chemistry 6, no. 2 (June 1, 2008): 304–9. http://dx.doi.org/10.2478/s11532-008-0004-9.

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AbstractThe The mechanism of reaction between 3-hydroxy-3-methyl-2-butanone and malononitrile for the synthesis of 2-dicyanomethylene-4, 5, 5-trimethyl-2,5-dihydrofuran-3-carbonitrile catalyzed by lithium ethoxide was investigated by density functional theory (DFT). The geometries and the frequencies of reactants, intermediates, transition states and products were calculated at the B3LYP/6-31G(d) level. The vibration analysis and the IRC analysis verified the authenticity of transition states. The reaction processes were confirmed by the changes of charge density at the bond-forming critical point. The results indicated that lithium ethoxide is an effective catalyst in the synthesis of 2-dicyanomethylene-4, 5, 5-trimethyl-2, 5-dihydrofuran-3-carbonitrile from malononi-trile and 3-hydroxy-3-methyl-2-butanone. The activation energy of the reaction with lithium ethoxide was 115.86 kJ·mol−1 less than the uncatalyzed reaction. The mechanism of the lithium ethoxide catalyzed reaction differed from the mechanism of the uncatalyzed reaction.

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14

Begum, Saheen Shehnaz, Nand Kishor Gour, Satyajit Dey Baruah, and Ramesh Chandra Deka. "Kinetics and mechanism of 3-chloro-2-methyl-1-propene(3-ClMP) initiated by OH radical: an insight from DFT calculations[1]." Molecular Physics 117, no. 3 (August 13, 2018): 280–88. http://dx.doi.org/10.1080/00268976.2018.1509146.

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15

Schuster, David I., Jie-Min Yang, Jan Woning, Timothy A. Rhodes, and Anton W. Jensen. "Mechanism of acid-catalyzed photoaddition of methanol to 3-alkyl2-cyclohexenones." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2004–10. http://dx.doi.org/10.1139/v95-247.

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Contrary to a previous report, it is concluded that formation of methanol adducts to 3-methyl-2-cyclohexenones and of deconjugated enones on irradiation of the enones in acidified solutions proceeds via protonation of the intermediate enone π,π* triplet excited state and not by protonation of a relatively long-lived ground state trans-cyclohexenone. A rate constant for protonation of the triplet state of 3-methyl-2-cyclohexenone by sulfuric acid of 1.7 × 109 M−1 s−1 was determined by laser flash photolysis in ethyl acetate. Based on quantum efficiencies of product formation, a rate constant of ca. 108 M−1 s−1 was estimated for protonation of the enone triplet by acetic acid, which is too small to cause measurable reduction in the triplet state lifetime in the mM concentration range used in the preparative studies. The intermediate carbocation can be trapped by methanol, or revert to starting enone or the exocyclic deconjugated enone by loss of a proton. Since products revert to starting materials in an acid-catalyzed process, there is an acid concentration at which the yields of products are optimal. This concentration is ca. 6 mM for acetic acid, but is only 0.1 mM for p-toluenesulfonic or sulfuric acids. Product formation could be quenched using 1-methylnaphthalene and cyclopentene as triplet quenchers; in the latter case, formation of [2 + 2] photoadducts was observed to compete with formation of methanol adducts. Quenching rate constants were determined by laser flash studies. Keywords: laser flash photolysis, kinetic absorption spectroscopy (KAS), photoacoustic calorimetry (PAC), protonation of triplet states, trans-cyclohexenones.

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Smith, Martyn T., Gunilla Ekström, Martha S. Sandy, and Donato Di Monte. "VI. Studies on the mechanism of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine cytotoxicity in isolated hepatocytes." Life Sciences 40, no. 8 (February 1987): 741–48. http://dx.doi.org/10.1016/0024-3205(87)90301-8.

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17

Illmann, Niklas, Rodrigo Gastón Gibilisco, Iustinian Gabriel Bejan, Iulia Patroescu-Klotz, and Peter Wiesen. "Atmospheric oxidation of <i>α</i>,<i>β</i>-unsaturated ketones: kinetics and mechanism of the OH radical reaction." Atmospheric Chemistry and Physics 21, no. 17 (September 14, 2021): 13667–86. http://dx.doi.org/10.5194/acp-21-13667-2021.

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Abstract. The OH-radical-initiated oxidation of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one was investigated in two atmospheric simulation chambers at 298±3 K and 990±15 mbar using long-path FTIR spectroscopy. The rate coefficients of the reactions of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one with OH radicals were determined to be (6.5±1.2)×10-11 and (8.1±1.3)×10-11 cm3molecule-1s-1, respectively. To enlarge the kinetics data pool the rate coefficients of the target species with Cl atoms were determined to be (2.8±0.4)×10-10 and (3.1±0.4)×10-10 cm3molecule-1s-1, respectively. The mechanistic investigation of the OH-initiated oxidation focuses on the RO2+NO reaction. The quantified products were acetoin, acetaldehyde, biacetyl, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 3-methyl-3-penten-2-one with OH radicals and acetone, methyl glyoxal, 2-hydroxy-2-methylpropanal, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 4-methyl-3-penten-2-one with OH, respectively. Based on the calculated product yields an upper limit of 0.15 was determined for the yield of RONO2 derived from the OH reaction of 4-methyl-3-penten-2-one. By contrast, no RONO2 formation was observed for the OH reaction of 3-methyl-3-penten-2-one. Additionally, a simple model is presented to correct product yields for secondary processes.

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Musgrave, RP, NW Jacobsen, G. Bourne, CHL Kennard, G. Smith, and TCW Mak. "Cycloaddition Reactions of 3-Dimethylamino-1-methyl-1,2,4-triazinium-5-olates With Dimethyl Acetylenedicarboxylate." Australian Journal of Chemistry 48, no. 6 (1995): 1175. http://dx.doi.org/10.1071/ch9951175.

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The cycloaddition reactions of some 3-dimethylamino-1-methyl-1,2,4-triazinium-5-olates (1) with dimethyl acetylenedicarboxylate ( dmad ) were studied. The products in all cases were found tobe dimethyl 4-dimethylamino-1-methyl-6-oxo-1,3a,6,6a-tetrahydropyrrolo[3,4-c]pyrazole-3,3a-dicarboxylate derivatives (2). The structure determinations were carried out by 1H and 13C n.m.r. and mass spectrometry, and for one derivative by single-crystal X-ray diffractometry. The mechanism of the reaction is also discussed.

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Wang, Wenjing, Ming Zhao, Yuji Wang, Jiawang Liu, Jianhui Wu, Guifeng Kang, and Shiqi Peng. "{2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic acid methyl ester (MIAM): Its anti-cancer efficacy and intercalation mechanism identified via multi-model systems." Mol. BioSyst. 7, no. 3 (2011): 766–72. http://dx.doi.org/10.1039/c0mb00049c.

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Lesnov, Andrey E., Peter T. Pavlov, Larisa V. Pustovik, and Irina А. Sarana. "1-ALKYL-3-METHYL-4-HYDROXYIMINO-2-PYRAZOLINE-5-ONES AS EXTRACTION REAGENTS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 5 (June 23, 2017): 30. http://dx.doi.org/10.6060/tcct.2017605.5527.

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With nitrosation of the corresponding 1-R-3-methylpyrazole-5-one (R = C4H9, C5H11, C6H13, C7H15, C8H17, C6H5) in acidic aqueous methanolic medium at 0-5 °C a series of 1-alkyl-3-methyl-4-hydroxyimino-2-pyrazolin-5-ones with a yield of 72-85% were synthesized. The compounds are soluble in CHCl3, C2H4Cl2, C6H5CH3, i-C4H9OH, CCl4, C2H5OH, slightly soluble in C6H14, H2O. They can be recrystallized from a mixture of C6H14: C6H5CH3 = 5: 1 or isooctane. The structure of the compounds was confirmed by the data of ECR, IR, Raman spectroscopy and TLC data. The interphase distribution of oxyiminopyrazolones between chloroform and aqueous solutions was studied as a function of pH. In alkaline media, the reagents completely transferred into the aqueous phase. In acidic solutions, up to 1 mol/l HCl, the compounds are in the organic phase. The maximum values of the partition coefficient are observed for the reagents with the maximum length of the aliphatic radical. The effect of the length of aliphatic radical at the first position of the pyrazoline ring on their extraction properties were studied by example of extraction of nickel and copper (II) ions. The length of the radical does not affect the composition of the recoverable complexes of nickel and copper (II). In all cases the ratio is close to 1:2. Extraction proceeds through a cation-exchange mechanism. Replacement of the phenyl radical in the first position of the pyrazoline ring by an aliphatic resulted to the increase in partition constants of the reagents between chloroform and aqueous solutions. The range of pH values of the maximum extraction of elements was widened. The capacity of the extractant for metals also increased. At the same time, the pH50 extraction values remained practically unchanged. In the case of 0.05 mol/l solution of 1-phenyl-3-methyl-4-oxyimino-2-pyrazolin-5-one in chloroform, when the extract was saturated with the metal ion, precipitation of the complex was observed.For citation:Lesnov A.E., Pavlov P.T., Pustovik L.V., Sarana I.A. 1-Alkyl-3-methyl-4-hydroxyimino-2-pyrazoline-5-ones as extraction reagents. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 5. P. 30-36.

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Gottschling, Stephen E., Michael C. Jennings, and Kim M. Baines. "The addition of alkynes to a tetrasilyldisilene Evidence for a biradical intermediate." Canadian Journal of Chemistry 83, no. 9 (September 1, 2005): 1568–76. http://dx.doi.org/10.1139/v05-169.

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The addition of two newly developed mechanistic probes, (trans,trans-2-methoxy-3-phenylcyclopropyl)ethyne (1) and (trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)ethyne (2), to tetrakis(tert-butyldimethylsilyl)disilene (3) has been investigated. The addition of 1 to 3 gave 1-[2-(cis-2-methoxy-3-phenylcyclopropylidene)vinyl]-1,1,2,2-tetrakis(tert-butyldimethylsilyl)disilane (5) as the major product; whereas addition of alkyne 2 to the disilene gave three stereoisomers of 1,1,2,2-tetrakis(tert-butyldimethylsilyl)-6-methoxy-5-methyl-7-phenyl-1,2-disilacyclohepta-3,4-diene (79) and 1,1,2,2- tetrakis(tert-butyldimethylsilyl)-3-(trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)-1,2-disilacy-clobut-3-ene (10) as the major products. The formation of cycloheptaallenes 79 provides convincing evidence that the addition of alkynes to tetrasilyldisilenes involves the formation of a biradical intermediate. Key words: disilene, alkyne, cycloaddition, reaction mechanism, mechanistic probe.

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Janovec, Ladislav, Stanislav Böhm, Ivan Danihel, Ján Imrich, Pavol Kristian, and Karel D. Klika. "Theoretical Confirmation of the Reaction Mechanism Leading to Regioselective Formation of Thiazolidin-4-one from Bromoacetic Acid Derivatives." Collection of Czechoslovak Chemical Communications 72, no. 10 (2007): 1435–45. http://dx.doi.org/10.1135/cccc20071435.

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A regioselective synthesis of 3-alkyl-2-[(anthracen-9-yl)imino]thiazolidin-4-ones 2a-2e and 2-(alkylimino)-3-(anthracen-9-yl)thiazolidin-4-ones 3a-3e from appropriate thioureas using methyl bromoacetate or bromoacetyl bromide, respectively, has been rationalized by DFT calculations of model thiourea and its phenyl derivative. The proposed mechanism indicates that the regioselective formation of the target thiazolidinones is a consequence of a different reactivity of the reagents and a varying stability of the intermediates, 1-alkyl-3-(anthracen-9-yl)-2-[(methoxycarbonyl)methyl]isothioureas 4a-4e and 1-alkyl-3-(anthracen-9-yl)-2-(bromoacetyl)isothioureas 6a-6e.

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23

Ryabova, R. S., G. F. Osipova, and M. I. Vinnik. "Kinetics and mechanism of the hydration of the equilibrium mixture of 3-methyl-1-buten-3-ol and 3-methyl-2-buten-1-ol with isoprene in aqueous solutions of sulfuric acid." Bulletin of the Russian Academy of Sciences Division of Chemical Science 41, no. 6 (June 1992): 1021–24. http://dx.doi.org/10.1007/bf00866577.

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24

Park, Gunhyuk, Young-Joon Park, Hyun Ok Yang, and Myung Sook Oh. "Ropinirole protects against 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced neurotoxicity in mice via anti-apoptotic mechanism." Pharmacology Biochemistry and Behavior 104 (March 2013): 163–68. http://dx.doi.org/10.1016/j.pbb.2013.01.017.

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25

Pragliola, Stefania, Antonio Botta, and Pasquale Longo. "Polymerization mechanism study of poly(4-methyl-1,3-pentadiene) and poly(4-methyl-1-pentene) prepared by using rac-[CH 2 (3- tert -butyl-1-indenyl) 2 ]ZrCl 2 / 13 C enriched methylaluminoxane." European Polymer Journal 94 (September 2017): 332–39. http://dx.doi.org/10.1016/j.eurpolymj.2017.07.024.

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26

Wang, Xingyu, Yan Zhang, Yongsheng Yang, and Ying Xue. "The mechanism and diastereoselectivity in the formation of trifluoromethyl-containing spiro[pyrrolidin-3,2′-oxindole] by a catalyst-free and mutually activated [3+2]-cycloaddition reaction: a theoretical study." New Journal of Chemistry 44, no. 40 (2020): 17465–76. http://dx.doi.org/10.1039/d0nj04063k.

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The mechanism and diastereoselectivity of the [3+2] cycloaddition reaction between (Z)-1-methyl-3-imino-indolin-2-one and 5-nitro-2-vinylpyridine with no catalyst in acetonitrile have been investigated by the DFT method and SMD solvation model.

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27

McCallum, Peter B. W., M. Ross Grimmett, Allan G. Blackman, and Rex T. Weavers. "Reaction of Imidazoles with Cyanogen Bromide: Cyanation at N 1 or Bromination at C 2?" Australian Journal of Chemistry 52, no. 3 (1999): 159. http://dx.doi.org/10.1071/c98105.

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The reaction in acetonitrile solution of a number of imidazoles(1H-, 1-methyl-, 2-methyl-, 4-methyl-, 1,2-, 1,4- and1,5-dimethyl-, 1-ethyl-, 1-benzyl- and 1-butyl-imidazole) and imidazolecomplexes([Co(NH3)5(imH)](ClO4)3,[Co(NH3)5(im)](ClO4)2 and[Co(NH3)5(1-Meim)](ClO4)3) with BrCN has beenstudied. Those imidazoles bearing an N-alkyl substituent and having a hydrogenat C2 react to give the 2-bromo products, while the N-H imidazoles react togive N-cyano derivatives. The product(s) from thereaction of 1,2-dimethylimidazole with BrCN could not be characterized. Of thecomplexes, only[Co(NH3)5(im)](ClO4)2 reacts, giving the 2-bromoproduct. Our observations suggest a lone pair on a ring nitrogen atom isnecessary for an imidazole to react with BrCN, and a possible mechanism issuggested. The X-ray structure of 2-methylimidazole-1-carbonitrile isreported. Crystal data (–143°C) forC5H5N3:monoclinic, P21/c, a10·201(5), b 7·110(3),c 7·227(3) Å, β 100·47(2)°,V 515·4(4) Å 3 , Z 4,dcalcd 1·380 gcm¯3 . Refinement of the structure converged withR1 0·0444 for 1183reflections with Fo >4F(Fo) andwR2 0·1259 for all 1278data.

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28

Vaughan, Keith, Shasta Lee Moser, Reid Tingley, M. Brad Peori, and Valerio Bertolasi. "Triazene derivatives of (1,x-)diazacycloalkanes. Part VI. 3-({5,5-Dimethyl-3-[2-aryl-1-diazenyl]-1-imidazolidinyl}methyl)-4,4-dimethyl-1-[2-aryl-1-diazenyl]imidazolidines — Synthesis, characterization, and X-ray crystal structure." Canadian Journal of Chemistry 84, no. 10 (October 1, 2006): 1294–300. http://dx.doi.org/10.1139/v06-091.

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Reaction of a series of diazonium salts with a mixture of formaldehyde and 1,2-diamino-2-methylpropane affords the 3-({5,5-dimethyl-3-[2-aryl-1-diazenyl]-1-imidazolidinyl}methyl)-4,4-dimethyl-1-[2-aryl-1-diazenyl]imidazolidines (1a–1f) in excellent yield. The products have been characterized by IR and NMR spectroscopic analysis, elemental analysis, and X-ray crystallography. The X-ray crystal structure of the p-methoxycarbonyl derivative (1c) establishes without question the connectivity of these novel molecules, which can be described as linear bicyclic oligomers with two imidazolidinyl groups linked together by a one-carbon spacer. This is indeed a rare molecular building block. The molecular structure is corroborated by 1H and 13C NMR data, which correlates with the previously published data of compounds of types 5 and 6 derived from 1,3-propanediamine. The triazene moieties in the crystal of 1c display significant π conjugation, which gives the N—N bond a significant degree of double-bond character. This in turn causes restricted rotation around the N—N bond, which leads to considerable broadening of signals in both the 1H and 13C NMR spectra. The molecular ion of the p-cyanophenyl derivative (1b) was observed using electrospray mass spectrometry (ES + Na). The mechanism of formation of molecules of type 1 is proposed to involve diazonium ion trapping of the previously unreported bisimidazolidinyl methane (13).Key words: triazene, bistriazene, imidazolidine, synthesis, X-ray crystallography, NMR spectroscopy.

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29

Jing, Yaru, Zhe Han, Chengbu Liu, and Dongju Zhang. "Theoretical investigation on the mechanism of glucose-to-fructose isomerization synergistically catalyzed by MnCl2 and [C4SO3HMIM][CH3SO3] in [BMIM]Cl." New Journal of Chemistry 43, no. 10 (2019): 4022–28. http://dx.doi.org/10.1039/c8nj05988h.

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The mechanism of glucose-to-fructose isomerization catalyzed by manganese chloride (MnCl₂) and 1-methyl-3-(3-sulfobutyl)-imidazolium methylsulfonate ([C₄SO₃HMIM][CH₃SO₃]) in a 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid (IL) was investigated computationally.

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30

Lotulung, Puspa Dewi Narrij, Tjandrawati Mozef, Chandra Risdian, and Akhmad Darmawan. "In Vitro Antidiabetic Activities of Extract and Isolated Flavonoid Compounds from Artocarpus altilis (Parkinson) Fosberg." Indonesian Journal of Chemistry 14, no. 1 (March 1, 2014): 7–11. http://dx.doi.org/10.22146/ijc.21261.

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The antidiabetic activity test through a mechanism of inhibition of α-glucosidase enzyme was studied against ethanol, n-hexane, ethyl acetate and n-butanol fractions of ethanol extract of Artocarpus altilis (Parkinson) Fosberg (Moraceae) leaves and four flavonoid compounds isolated from ethyl acetate extracts of A. altilis. Ethyl acetate fraction has strongest antidiabetic activity compared to ethanol, n-hexane, and n-butanol fractions with IC50values5.98,6.79, 440.18and14.42μg/mL, respectively. Four flavonoid compounds (1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (AC-31), 2-geranyl-2',3,4,4'-tetrahydroxy dihydrochalcone (AC-51), 8-geranyl-4',5,7-trihydroxyflavone (AC-33) andcyclocommunol (AA-3), have been isolated from ethylacetate fraction. AC-31 was the strongest antidiabetic compound compared to AC-51, AC-33 and cyclocommunolwithIC50values are 15.73, 24.41,49.49,and72.20μg/mL. Kineticstudies of AC-31 using Lineweaver-Burk method showed that inhibition mechanism of enzymeα-glucosidase was anon-competitivetype.

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31

Kubík, Richard, Stanislav Böhm, Jan Čejka, Vladimír Havlíček, Tomáš Strnad, Bohumil Kratochvíl, and Josef Kuthan. "Sterically Crowded Heterocycles. VIII. Preparative Photoisomerization of Some Imidazo[1,2-a]pyridines." Collection of Czechoslovak Chemical Communications 61, no. 10 (1996): 1473–88. http://dx.doi.org/10.1135/cccc19961473.

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UV-Illumination of (Z)-3-(2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one (1a) or its 6-methyl and 6-iodo derivatives 1c and 1g resulted in minor (E)-isomers 2a, 2c, and 2g and prevailing (E,Z)-mixtures of N-(pyridin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amines 3a, 3c, and 3g while only corresponding furanoic derivatives 3b and 3d-3f were obtained from 5-methyl (1b), 7-methyl (1d), 8-methyl (1e), and 5-phenyl (1f) derivatives of the (Z)-ketone 1a. VIS-Illumination of (Z)-1,3-diphenyl-3-(2-phenylimidazo[1,2-a]benzo[I]quinolin-3-yl)prop-2-en-1-one (4) led to N-(benzo[h]quinolin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amine (5). Photoisomers 2a, 2c, 2g, 3a-3g, and 5 were isolated and the molecular structure of 3c was X-ray determined. Mechanism of the photoisomerization is discussed using semiempirical quantum chemical calculations and compared with mass spectra of compounds 1a, 2a, 3a, 1g, 2g, and 3g.

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32

Danish, Isravel A., and Karnam J. R. Prasad. "Reduction of 1-Hydroxyimino-1,2,3,4-tetrahydrocarbazoles by Metal and Baker’s Yeast – Syntheses of Aminocarbazole Derivatives." Zeitschrift für Naturforschung B 59, no. 9 (September 1, 2004): 1054–58. http://dx.doi.org/10.1515/znb-2004-0918.

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1-Hydroxyimino-1,2,3,4-tetrahydrocarbazoles (1) were reduced with zinc in acetic acid and acetic anhydride and with bakers’ yeast in an aim to synthesize 1-aminocarbazoles, but interestingly the reaction gave hitherto unknown compounds, 2-acetoxy-1-(acetylamino)carbazoles (2) and 6- [acetoxy(hydroxy)methyl]-1-hydroxylaminocarbazoles (3), respectively. A plausible mechanism for the formation of compounds 2 and 3 is proposed. All new compounds were characterised by IR, NMR, mass spectral methods and elemental analysis.

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33

Lesnov, Andrey E., Larisa V. Pustovik, and Irina A. Sarana. "EXTRACTION OF METAL IONS BY 4-BENZOYL- OR 4-(3-NYTROBENZOYL-1-HEXYL- 3-METHYL-2-PYRAZOLINE-5-ONES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 9 (August 5, 2020): 63–69. http://dx.doi.org/10.6060/ivkkt.20206309.6216.

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The extraction properties of solutions of 4-benzoyl- and 4- (3-nitrobenzoyl) -1-hexyl-3-methyl-2-pyrazolin-5-ones in chloroform were studied. The pH dependence of the degree of extraction is S-shaped. Ions Cu2+, Pb2+, Zn2+, Ni2+, Co2+, Mn2+, Cd2+, Ca2+, Mg2+ are extracted in the form of complexes with the ratio M (II): reagent determined by the equilibrium shift method equals to 1: 2. A lower equilibrium pH than the initial value indicates a cation-exchange extraction mechanism. The introduction of an electronegative nitro group into the benzoyl fragment of the reagent led to a shift in the pH50 values of the extraction of metal ions in a more acidic region. The presence of a correlation between the values of the Klopman hardness parameters of the above metal cations and extraction pH50 values was shown. The influence of the nature of the solvent on the extraction of zinc ions was studied. The addition of polar isopentanol to the extractant shifts the pH of the metal extraction to a more acidic region. In order to increase the pH50 value of zinc extraction, the solvents are arranged in a row: 30% isopentanol in CHCl3 < benzene < xylene < toluene < chloroform < dichloroethane. The introduction of additional neutral electron-donating hydrophobic organic compounds into the extract: 1-hexyl-3-methyl-2-pyrazolin-5-one, triisobutyl phosphate, trioctylphosphine oxide significantly increases the values of the partition coefficients of zinc. The observed synergistic effect is explained by the formation of a coordinatively unsaturated intracomplex compound of zinc with aroylpyrazolone, in which the free coordination sites are filled with neutral reagent molecules. In this case, water is replaced and due to the increased hydrophobicity of the complex, an increase in extraction occurs. Confirmation of the formation of a coordination-unsaturated zinc complex is a close to unity value of the slope of the decimal logarithm of the metal distribution constant for pH.

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34

Chen, Xiu, Xin Jin, Yong Bin Lai, Jia Min Hu, Jun Feng Shu, Yu Qi Zhang, Bo Wang, and Meng Hong Yuan. "Nucleation Mechanism of Biodiesel Derived from Palm Oil at Low Temperatures." Advanced Materials Research 953-954 (June 2014): 183–86. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.183.

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The compositions and crystallization process at low temperature of palm-based biodiesel (PME) are investigated. In this work, we show that PME is mainly composed of fatty acid methyl esters of 14-24 even-numbered C atoms: C14:0-C24:0, C16:1-C22:1, C18:2, and C18:3. Palm-based biodiesel crystallization comprises three steps, viz., forming supersaturated solution, nucleation and ester crystal growth; the driving force for saturated fatty acid methyl esters nucleation is the degree of supersaturation. The rate equation of nucleation is put forward. The objective of this research is to provide theoretical support for hindering the ester crystal nucleation and growth, and improving the cold flow properties of PME.

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Cui, Yong, Yin Nan Yuan, Xiu Chen, and Yong Bin Lai. "Mechanism of Flow Properties for Biodiesel Blends at Low Temperature." Advanced Materials Research 662 (February 2013): 490–97. http://dx.doi.org/10.4028/www.scientific.net/amr.662.490.

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The chemical composition of biodiesel was analyzed by gas chromatography-mass spectrometry. The cold filter plugging point of biodiesel was measured according to GB/T 20828-2007. The cold flow properties of biodiesel were investigated on the basis of the crystallization theory, including chemical composition and molecular structure. Biodiesel might be considered a pseudobinary mixture, namely, high-melting-point saturated fatty acid methyl esters and low–melting-point unsaturated ones. Bilayer crystal structure of biodiesel was founded. Bilayer structure with headgroups aligned next to each other inside the crystal and away from nonpolar bulk liquid was large platelet lamellae. The results showed that biodiesel was mainly composed of saturated fatty acid methyl esters (C14:0～C24:0 ) and unsaturated ones(C16:1～C22:1、C18:2 and C18:3 ). The cold flow properties for biodiesel were determined mainly by the amount and molecular structure of saturated fatty acid methyl esters. The long-straight-chain saturated fatty acid methyl esters tend to have relatively poor cold flow properties. The cold flow properties worsen with increasing the amount and carbon chain length of straight-chain saturated fatty acid methyl esters. The ways of adjusting biodiesel composition and treating with depression of cold filter plugging point were given; they could improve cold flow properties.

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36

Zhang, Xian Yun, Xue Feng Song, Jin Tao Li, and Wen Cheng Yin. "Preparation of Modified Silica Sol, the Mechanism Analysis and the Applied Research." Applied Mechanics and Materials 687-691 (November 2014): 4319–22. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4319.

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Using the methyl trimethoxy silane (MTMS) and methyl triethoxy siliance (MTES) each modified the surface of nanosilica sol.Through measuring the percent conversion of silance coupling agent and the water absorption of the cement paste.the optimal technical processes of the modified silica sol were obtained:: Mcoupling agent = 3:1,pH = 2,the synthesis temperature of 40 °C,the Synthetic time for 40 min. MTMS hydrophobic effect of modified silica sol significantly better than MTES, the higher the stability of the solution and the infrared spectrum analysis of the grafting mechanism of silane coupling agent.

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37

Vu, B. Christie, Paul L. Boyer, Maqbool A. Siddiqui, Victor E. Marquez, and Stephen H. Hughes. "4′-C-Methyl-2′-Deoxyadenosine and 4′-C-Ethyl-2′-Deoxyadenosine Inhibit HIV-1 Replication." Antimicrobial Agents and Chemotherapy 55, no. 5 (February 22, 2011): 2379–89. http://dx.doi.org/10.1128/aac.01290-10.

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ABSTRACTIt is important to develop new anti-HIV drugs that are effective against the existing drug-resistant mutants. Because the excision mechanism is an important pathway for resistance to nucleoside analogs, we are preparing analogs that retain a 3′-OH and can be extended after they are incorporated by the viral reverse transcriptase. We show that 4′-C-alkyl-deoxyadenosine (4′-C-alkyl-dA) compounds can be phosphorylated in cultured cells and can inhibit the replication of HIV-1 vectors: 4′-C-methyl- and 4′-C-ethyl-dA show both efficacy and selectivity against HIV-1. The compounds are also effective against viruses that replicate using reverse transcriptases (RTs) that carry nucleoside reverse transcriptase inhibitor resistance mutations, with the exception of the M184V mutant. Analysis of viral DNA synthesis in infected cells showed that viral DNA synthesis is blocked by the incorporation of either 4′-C-methyl- or 4′-C-ethyl-2′-deoxyadenosine.In vitroexperiments with purified HIV-1 RT showed that 4′-C-methyl-2′-dATP can compete with dATP and that incorporation of the analog causes pausing in DNA synthesis. The 4′-C-ethyl compound also competes with dATP and shows a differential ability to block DNA synthesis on RNA and DNA templates. Experiments that measure the ability of the compounds to block DNA synthesis in infected cells suggest that this differential block to DNA synthesis also occurs in infected cells.

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38

Csongradi, Eva, Megan V. Storm, and David E. Stec. "Renal Inhibition of Heme Oxygenase-1 Increases Blood Pressure in Angiotensin II-Dependent Hypertension." International Journal of Hypertension 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/497213.

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The goal of this study was to test the hypothesis that renal medullary heme oxygenase (HO) acts as a buffer against Ang-II dependent hypertension. To test this hypothesis, renal medullary HO activity was blocked using QC-13, an imidazole-dioxolane HO-1 inhibitor, or SnMP, a classical porphyrin based HO inhibitor. HO inhibitors were infused via IRMI catheters throughout the study starting 3 days prior to implantation of an osmotic minipump which delivered Ang II or saline vehicle. MAP was increased by Ang II infusion and further increased by IRMI infusion of QC-13 or SnMP. MAP averaged113±3,120±7,141±2,153±2, and154±3 mmHg in vehicle, vehicle + IRMI QC-13, Ang II, Ang II + IRMI QC-13, and Ang II + IRMI SnMP treated mice, respectively (n=6). Inhibition of renal medullary HO activity with QC-13 in Ang II infused mice was also associated with a significant increase in superoxide production as well as significant decreases in antioxidant enzymes catalase and MnSOD. These results demonstrate that renal inhibition of HO exacerbates Ang II dependent hypertension through a mechanism which is associated with increases in superoxide production and decreases in antioxidant enzymes.

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Konovalov, V. A. "Mechanism of ring opening of cis- and trans-1-methyl-2-aryl-3-aroylaziridine perchlorates under the influence of alcohols." Chemistry of Heterocyclic Compounds 25, no. 8 (August 1989): 879–83. http://dx.doi.org/10.1007/bf00479605.

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40

Kusrijadi, Mr Ali, Mr Yaya Sonjaya, and Mr Yayan Sunarya. "KAJIAN PROSES EKSTRAKSI ION LOGAM Cu(II) DAN Co(II) DENGAN EKSTRAKTAN 1-fenil-3-metil-4-stearoilpirazol-5-on (HPMSP) (STUDY ON THE EXTRACTION OF Cu(II) AND Co(II) WITH 1-phenyl-3-methyl-4-stearoylpyrazol-5-one (HPMSP)." Jurnal Pengajaran Matematika dan Ilmu Pengetahuan Alam 3, no. 1 (January 13, 2015): 41. http://dx.doi.org/10.18269/jpmipa.v3i1.378.

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The extraction of Cu(II) and Co(II) with 1-phenyl-3-methyl-4-stearoylpyrazol-5-one (HPMSP) as the chelating ligand using chloroform solvent have been studied. The extraction mechanism of Cu(II) and Co(II) and the composition of extracted species has been determined. Cu(II) and Co(II) was extracted as Cu(PMSP)2 and Co(PMSP)2. The effect of concentration HPMSP and pH has also been investigated.

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41

Petrović, Biljana V., and Živadin D. Bugarčić. "Kinetic and Mechanistic Study on the Reactions of [Pd(dien)H2O]2+ and [Pt(dien)H2O]2+ with L-Cysteine and S-Methyl-L-cysteine." Australian Journal of Chemistry 58, no. 7 (2005): 544. http://dx.doi.org/10.1071/ch05033.

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The reactions of [Pd(dien)H2O]2+ and [Pt(dien)H2O]2+ (dien = diethylenetriamine or 1,5-diamino-3-azapentane) with l-cysteine and S-methyl-l-cysteine were studied in an aqueous 0.10 M NaClO4 solution using stopped-flow and conventional UV-vis spectrophotometry. The second-order rate constants for the reactions of [Pd(dien)H2O]2+ at pH 1.0 are k1298 = (9.11 ± 0.11) × 102 M−1 s−1 for l-cysteine, and k1298 = (33.79 ± 0.63) × 102 M−1 s−1 for S-methyl-l-cysteine. The second-order rate constants for the reactions of [Pt(dien)H2O]2+ at pH 1.0 with l-cysteine is k1298 = (1.28 ± 0.08) × 10−2 M−1 s−1 and for S-methyl-l-cysteine is k1298 = (3.87 ± 0.02) × 10−2 M−1 s−1. Activation parameters were determined for all reactions, and the negative values of entropy of activation support an associative complex formation mechanism. Substitution reactions were also studied at pH 0.5, 1.0, and 1.5. The rate constants increase with increase in pH. These results are discussed in terms of protolitic equilibrium.

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42

Silva, D. H. S., F. C. Pereira, M. Yoshida, and M. V. B. Zanoni. "Electrochemical evaluation of lipophilic antioxidants from Iryanthera juruensis fruits (Myristicaceae)." Eclética Química 30, no. 3 (September 2005): 15–21. http://dx.doi.org/10.1590/s0100-46702005000300002.

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TLC autographic assays revealed in the hexane extract of Iryanthera juruensis (Myristicaceae) the presence of two compounds, with antioxidant properties towards beta-carotene. They were isolated and identified as 3-methyl-sargachromenol (1) and sargachromenol (2). Further investigation of the hexane extract led to isolations of 3-methyl-sargaquinoic acid (3) and sargaquinoic acid (4). The electrochemical behaviour of these compounds was studied in CH2Cl2/Bu4NBF4 at glassy carbon electrode. The phenolic group in both tocotrienols 1 and 2 are oxidized at +0.23V and +0.32V and their oxidation potentials are correlated with the observed antioxidant activities and oxidation mechanism of alpha-tocopherol. The reductive voltametric behaviour of quinone function in both plastoquinones 3 and 4 is discussed.

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43

Danish, Isravel A., and Karnam J. R. Prasad. "Synthesis of 5-Methyl-1,2,3,4,5,6-hexahydrocyclopenta[g]carbazole-1,7- diones and Crotonyl-2-isopropyl-1-oxo-1,2,3,4-tetrahydrocarbazoles from 1-Oxo-1,2,3,4-tetrahydrocarbazoles by Friedel-Crafts Reaction." Zeitschrift für Naturforschung B 59, no. 6 (June 1, 2004): 711–15. http://dx.doi.org/10.1515/znb-2004-0613.

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The reaction of 1-oxo-1,2,3,4-tetrahydrocarbazoles (1) with crotonic acid in polyphosporic acid afforded hitherto unknown 5-methyl-1,2,3,4,5,6-hexahydrocyclopenta[g]carbazole-1,7-diones (2) and 6-crotonyl-2-isopropyl-1-oxo-1,2,3,4-tetrahydrocarbazoles (3) in a single step. A plausible mechanism for the formation of the title compounds has been proposed, and all new compounds were characterized by IR, NMR, mass spectral methods and elemental analysis.

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44

Arnold, Donald R., and Shelley A. Mines. "Radical ions in photochemistry. 21. The photosensitized (electron transfer) tautomerization of alkenes; the phenyl alkene system." Canadian Journal of Chemistry 67, no. 4 (April 1, 1989): 689–98. http://dx.doi.org/10.1139/v89-105.

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Alkenes, conjugated with a phenyl group, can be converted to nonconjugated tautomers by sensitized (electron transfer) irradiation. For example, irradiation of an acetonitrile solution of the conjugated alkene 1-phenylpropene, the electron accepting photosensitizer 1,4-dicyanobenzene, the cosensitizer biphenyl, and the base 2,4,6-trimethylpyridine gave the nonconjugated tautomer 3-phenylpropene in good yield. Similarly, 2-methyl-1-phenylpropene gave 2-methyl-3-phenylpropene, and 1-phenyl-1-butene gaveE- and Z-1-phenyl-2-butene. The reaction also works well with cyclic alkenes. For example, 1-phenylcyclohexene gave 3-phenylcyclohexene, and 1-(phenylmethylene)cyclohexane gave 1-(phenylmethyl)cyclohexene. The proposed mechanism involves the initial formation of the alkene radical cation and the sensitizer radical anion, induced by irradiation of the sensitizer and mediated by the cosensitizer. Deprotonation of the radical cation assisted by the base gives the ambident radical, which is then reduced to the anion by the sensitizer radical anion. Protonation of the ambident anion at the benzylic position completes the sequence. Reprotonation at the original position is an energy wasting step. Tautomerization is driven toward the isomer with the higher oxidation potential, which is, in the cases studied, the less thermodynamically stable isomer. The regioselectivity of the deprotonation step is dependent upon the conformation of the allylic carbon–hydrogen bond. The tautomerization of 2-methyl- 1-phenylbutene gave both 2-phenylmethyl-1-butène and 2-methyl-1-phenyl-2-butene (E and Z isomers), while 2,3-dimethyl- 1-phenylbutene gave only 3-methyl-2-phenylmethyl-1 -butene. In the latter case, steric interaction of the methyls on the isopropyl group prevents effective overlap of the tertiary carbon–hydrogen bond with the singly occupied molecular orbital, thus inhibiting deprotonation from this site. Keywords: photosensitized, electron transfer, alkene, tautomerization, radical cation.

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Choudhry, Ghulam Ghaus, Norma Jean Graham, and G. R. Barrie Webster. "Photochemistry of halogenated benzene derivatives. Part VIII. Photoformation of 2-methyl-4,5,6,7-tetrachlorobenzoxazole from pentachlorophenol in water–acetonitrile." Canadian Journal of Chemistry 65, no. 9 (September 1, 1987): 2223–33. http://dx.doi.org/10.1139/v87-371.

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Photolysis of a solution of pentachlorophenol (1) in H2O–CH3CN (2:3 v/v) was conducted on a synthetic scale using wavelengths ≥290 nm. After changing the pH of the photolyzate of 1 to ≥12, the photoproduct 2-methyl-4,5,6,7-tetrachloro-benzoxazole (2) was extracted with n-hexane. The product 2 was crystallized from methanolic solution. Ultraviolet, IR, FT-1H-NMR, proton-decoupled normal FT-13C-NMR, and proton-decoupled DEPT (distortionless enhancement by polarization transfer) sequence FT-13C-NMR spectroscopy were used to identify photoproduct 2 as 2-methyl-4,5,6,7-tetrachlorobenzoxazole. A mechanism for the photoformation of benzoxazole 2 from 1 is proposed. 3,4,5,6-Tetrachlorocyclohexa-3,5-diene-1,2-ketocarbene formed from 2-hydroxy-3,4,5,6-tetrachlorophenyl radical is suggested as key intermediate involved in the generation of oxazole 2 from phenol 1. The chemical yield of 2 on the basis of 1 was ca. 1%. A mechanism is proposed to explain the mass spectral fragmentation of 2 via the losses of Ċl,:C=O, Cl—Ċ=O, CH3—Ċ=O, CH3CN, and C3H3ClNO species from the parent molecular ion.

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van Hylckama Vlieg, Johan E. T., Hans Leemhuis, Jeffrey H. Lutje Spelberg, and Dick B. Janssen. "Characterization of the Gene Cluster Involved in Isoprene Metabolism in Rhodococcus sp. Strain AD45." Journal of Bacteriology 182, no. 7 (April 1, 2000): 1956–63. http://dx.doi.org/10.1128/jb.182.7.1956-1963.2000.

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ABSTRACT The genes involved in isoprene (2-methyl-1,3-butadiene) utilization in Rhodococcus sp. strain AD45 were cloned and characterized. Sequence analysis of an 8.5-kb DNA fragment showed the presence of 10 genes of which 2 encoded enzymes which were previously found to be involved in isoprene degradation: a glutathioneS-transferase with activity towards 1,2-epoxy-2-methyl-3-butene (isoI) and a 1-hydroxy-2-glutathionyl-2-methyl-3-butene dehydrogenase (isoH). Furthermore, a gene encoding a second glutathioneS-transferase was identified (isoJ). TheisoJ gene was overexpressed in Escherichia coliand was found to have activity with 1-chloro-2,4-dinitrobenzene and 3,4-dichloro-1-nitrobenzene but not with 1,2-epoxy-2-methyl-3-butene. Downstream of isoJ, six genes (isoABCDEF) were found; these genes encoded a putative alkene monooxygenase that showed high similarity to components of the alkene monooxygenase fromXanthobacter sp. strain Py2 and other multicomponent monooxygenases. The deduced amino acid sequence encoded by an additional gene (isoG) showed significant similarity with that of α-methylacyl-coenzyme A racemase. The results are in agreement with a catabolic route for isoprene involving epoxidation by a monooxygenase, conjugation to glutathione, and oxidation of the hydroxyl group to a carboxylate. Metabolism may proceed by fatty acid oxidation after removal of glutathione by a still-unknown mechanism.

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Fu, Dong-Jun, Victor Pham, Matthew-Alexander Tippin, Liankun Song, Xiaolin Zi, En Zhang, and Hong-Min Liu. "(1R,5S)-6-(4-Methyl-2-oxo-2,5-dihydrofuran-3-yl)-3-phenyl-4-oxa-2,6-diazabicyclo[3.2.0]hept-2-en-7-one." Molbank 2018, no. 3 (August 30, 2018): M1016. http://dx.doi.org/10.3390/m1016.

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Efficient large-scale and feasible industrial synthesis of the 1-oxacephem core structure from 6-aminopenicillanic acid (6-APA) has been reported for several decades. Via the industrial synthesis route, a byproduct (compound 9) containing a butenolide unit was purified and characterized by NMR and HRMS in this work. It is worth noting that compound 9 is an entirely new compound. Additionally, a plausible mechanism and effects on the formation of 9 by different Lewis acids were proposed. The discovery of compound 9 could improve the purity of this feasible industrial synthesis and provide considerable cost savings.

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Biswas, Partha. "Reaction mechanism and kinetic study of the •OH initiated tropospheric oxidation of 3-methyl-2-buten-1-ol: A quantum chemical investigation." Journal of Theoretical and Computational Chemistry 13, no. 06 (September 2014): 1450052. http://dx.doi.org/10.1142/s0219633614500527.

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In this article a theoretical study of mechanism and kinetics of the OH -initiated oxidation reaction of 3-methyl-2-buten-1-ol (MBO-321) is presented. This degradation mechanism of MBO-321 consists of H -abstraction reaction and OH -addition to olefinic bond. In addition, probable product analysis alongwith the mechanism for secondary reactions in presence of O 2 and NO has been investigated. Energetics have been studied at the CCSD(T)/6-311++g(d,p)//MP2 = full/6-31+G(d) level of theory. Thermochemical analysis has been done using CBS-QB3 method starting from the geometry obtained in the MP2 method. All the H -abstraction reactions pass through positive energy barrier except H4 -abstraction channel. OH -addition to the double bond takes place via formation of the pre-reactive complex as these reaction channel pass through negative activation barrier. OH -addition is the predominant reaction pathway for the overall oxidation process. Using TST theory at 1 atm pressure and in the temperature range of 200 K–400 K, the calculated rate constant and lifetime of OH -addition is [Formula: see text] molecule-1 s-1 and 1.88 h, which is consistent with the previous experimental data, [Formula: see text] molecule-1 s-1 and 1.9 h respectively (Imamura et al., Rate coefficients for the gas phase reactions of OH radical with methylbutenols at 298 K, Int J Chem Kinet36:379–385, 2004).

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Meier, Chris, Ulrike Muus, Jürgen Renze, Lieve Naesens, Erik De Clercq, and Jan Balzarini. "Comparative Study of Bis(Benzyl)Phosphate Triesters of 2′,3′-Dideoxy-2′,3′-Didehydrothymidine (d4T) and CycloSal-d4TMP — Hydrolysis, Mechanistic Insights and Anti-HIV Activity." Antiviral Chemistry and Chemotherapy 13, no. 2 (April 2002): 101–14. http://dx.doi.org/10.1177/095632020201300204.

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A comparative study of three cycloSal-d4TMP 1, 2 and 3 and a variety of bis(benzyl) phosphate triester 4–8 of the antivirally active nucleoside analogue 2′,3′-dideoxy-2′,3′-didehydrothymidine (d4T) will be described. This study has been initiated by the observation that the introduction of a simple 7-methyl group in the cycloSal-structure (2) led to a completely different hydrolysis pattern as compared to the prototype cycloSal- d4TMP 1. Instead of the selective formation of d4TMP, a phenyl phosphate diester was formed in the case of the 7-methyl-substituted compound 2. The difference in degradation pathway was caused by a change of the reaction mechanism. The phenyl phosphate diester was chemically and enzymatically inert to further cleavage to yield d4TMP. For comparison bis(benzyl)-d4TMP 4, bis(α-methylbenzyl)-d4TMP 5, bis(α-methoxycarbonylmethyl [MCM]-benzyl)-d4TMP 6 as well as the enzyme-cleavable bis(4-acetoxybenzyl)- d4TMP [bis(AB)-d4TMP(7 and bis(α-methoxycarbonylmethyl-4-acetoxybenzyl)-d4TMP [bis(α-MCM-AB)-d4TMP] 8 were synthesized. Chemical hydrolysis studies proved that all bis(benzyl) triesters hydrolyze to give the intermediate benzyl phosphate diesters. Moreover, the latter two triesters 7,8 and cycloSal-d4TMPs 1 and 3 led finally to the delivery of d4TMP. The chemical hydrolysis studies allowed a detailed mechanistic interpretation of the degradation pathways of triesters 1–8. Cell extract studies of the bis(benzyl) triesters 4–8 confirmed that only triesters 7 and 8 released d4TMP although with a considerable increase of the reaction rate. Anti-HIV evaluation of the compounds showed that cycloSal-d4TMP 1 and the bis(AB) triesters 7,8 were entirely independent of the presence of cellular thymidine kinase (TK).

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KARTASHOV, V. R., E. V. SKOROBOGATOVA, N. V. MALISOVA, YU K. GRISHIN, D. V. BAZHENOV, and N. S. ZEFIROV. "ChemInform Abstract: Stereochemistry, Kinetics and Mechanism in the Mercuration of Methyl Esters of δ2-2-Aryl-3-phenylcyclopropene-1-carboxylic Acids." ChemInform 23, no. 36 (August 21, 2010): no. http://dx.doi.org/10.1002/chin.199236230.

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Journal articles on the topic 'Mechanism of 2-methyl-1,3-dioxolane'

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