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Journal articles on the topic 'Ethoxide'

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Published: 1 April 2023

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1

Balakrishnan, Vimal K., Julian M. Dust, Gary W. vanLoon, and Erwin Buncel. "Catalytic pathways in the ethanolysis of fenitrothion, an organophosphorothioate pesticide. A dichotomy in the behaviour of crown/cryptand cation complexing agents." Canadian Journal of Chemistry 79, no. 2 (February 1, 2001): 157–73. http://dx.doi.org/10.1139/v01-006.

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The rates of displacement of 3-methyl-4-nitrophenoxide ion from the pesticide, fenitrothion, by alkali metal ethoxides in anhydrous ethanol were followed spectrophotometrically. Through product analysis experiments, which included 31P NMR and GC-MS, as well as spectrophotometric analysis, three reaction pathways were identified: nucleophilic attack at the phosphorus centre, attack at the aliphatic carbon, and a minor SNAr route ([Formula: see text]7%). Furthermore, a consecutive process was found to occur on the product of attack at the phosphorus centre. For purposes of kinetic treatment, the processes at the aliphatic and aromatic carbon were combined (i.e., the minor SNAr pathway was neglected), and the observed reaction rate constants were dissected into rate coefficients for nucleophilic attack at phosphorus and at aliphatic carbon. Attack at phosphorus was found to be catalyzed by the alkali metal ethoxides in the order KOEt > NaOEt > LiOEt. Catalysis arises from alkali metal ethoxide aggregates in the base solutions used (0–1.8 M); treatment of the system as a mixture of free ethoxide, ion-paired metal ethoxide, and metal ethoxide dimers resulted in a good fit with the kinetic data. An unexpected dichotomy in the kinetic behaviour of complexing agents (e.g., DC-18-crown-6, [2.2.2]cryptand) indicated that the dimers are more reactive than free ethoxide anions, which are in turn more reactive than ion-paired metal ethoxide. The observed relative order of reactivity is explained in the context of the Eisenman theory in which the free energy of association of the metal ion with the rate-determining transition state is largely determined by the solvent reorganization parameter. In contrast with displacement at the phosphorus centre, attack at the aliphatic carbon was not found to be catalyzed by alkali metals. In this case, the free ethoxide anion was more reactive than either the ion-paired metal ethoxide or the dimeric aggregate. The differing effects of alkali metals on the two pathways is ascribed largely to the leaving group pKa. For carbon attack, the pKa value estimated for demethyl fenitrothion, 2.15, is sufficiently low that metal ions are not required to stabilize the rate-determining transition state. In contrast, for phosphorus attack, 3-methyl-4-nitrophenoxide, with a pKa of 7.15, requires stabilization by metal ion interactions. Hence, alkali metal ions catalyze attack at phosphorus, but not attack at the carbon centres.Key words: organophosphorothioate, pesticide, fenitrothion, ethanolysis, alkali metal ethoxide, ion-pair reactivity, dimers, catalysis, competitive pathways.
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2

Pregel, Marko J., Edward J. Dunn, and Erwin Buncel. "Metal ion catalysis in nucleophilic displacement reactions at carbon, phosphorus, and sulfur centers. III. Catalysis vs. inhibition by metal ions in the reaction of p-nitrophenyl benzenesulfonate with ethoxide." Canadian Journal of Chemistry 68, no. 10 (October 1, 1990): 1846–58. http://dx.doi.org/10.1139/v90-287.

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The rate of the nucleophilic displacement reaction of p-nitrophenyl benzenesulfonate (1) with alkali metal ethoxides in ethanol at 25 °C has been studied by spectrophotometric techniques. For lithium ethoxide, sodium ethoxide, potassium ethoxide, and cesium ethoxide, the observed rate constants increase in the order LiOEt < NaOEt < CsOEt < KOEt. The effect of added crown ether and cryptand complexing agents was also investigated. Addition of complexing agent to the reaction of KOEt results in the rate decreasing to a minimum value corresponding to the reaction of free ethoxide. Conversely, addition of complexing agent to the reaction of LiOEt results in the rate increasing to a maximum value that is identical to the minimum value seen in the reaction of KOEt in the presence of excess complexing agent. In complementary experiments, alkali metal ions were added in the form of unreactive salts. Addition of a K+ salt to the reaction of KOEt increases the reaction rate, while addition of a Li+ salt to the reaction of LiOEt decreases the rate. The involvement of metal ions in the reaction of 1 is proposed to occur via reactive alkali metal – ethoxide ion pairs. The kinetic data are analyzed in terms of an ion pairing treatment that allows the calculation of second-order rate constants for free ethoxide and metal–ethoxide ion pairs; the rate constants increase in the order LiOEt < EtO−< NaOEt < CsOEt < KOEt. Thus, Li+isaninhibitorofthereactionofethoxidewith1, whiletheothermetalsionsstudiedareallcatalysts. Equilibrium constants for the association of the various metal ions with the transition state are calculated using a thermodynamic cycle, and are compared to association constants in the ground state. Consistent with the observed kinetic results, Li+ is found to stabilize the ground state more than the transition state, while Na+, K+, and Cs+ all stabilize the transition state more than the ground state. The trend in the magnitude of the transition state stabilization is interpreted in terms of interactions of the transition state with bare or solvated metal ions. It is concluded that the transition state for the reaction of 1 with ethoxide forms solvent separated ion pairs with alkali metal ions. Analogous data were available for the reaction of p-nitrophenyl diphenylphosphinate (2) with ethoxides, where Li+, Na+, K+, and Cs+ all function as catalysts, and the results are analyzed as above. In contrast to the sulfonate system, it is proposed that the phosphinate transition state forms contact ion pairs with alkali metal ions. The difference is attributed to a greater localization of negative charge in the phosphinate transition state, leading to stronger interactions with metal ions, which overcome metal ion – solvent interactions. Keywords: nucleophilic substitution at sulfur, alkali metal ion catalysis.
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3

Dunn, Edward J., and Erwin Buncel. "Metal ion catalysis in nucleophilic displacement reactions at carbon, phosphorus, and sulfur centers. I. Catalysis by metal ions in the reaction of p-nitrophenyl diphenylphosphinate with ethoxide." Canadian Journal of Chemistry 67, no. 9 (September 1, 1989): 1440–48. http://dx.doi.org/10.1139/v89-220.

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The effect of macrocyclic crown ether and cryptand complexing agents on the rate of the nucleophilic displacement reaction of p-nitrophenyl diphenylphosphinate by alkali metal ethoxides in ethanol at 25 °C has been studied by spectrophotometric techniques. For the reactions of potassium ethoxide, sodium ethoxide, and lithium ethoxide, the observed rate constant increased in the order KOEt < NaOEt < LiOEt. Crown ether and cryptand cation-complexing agents have a retarding effect on the rate. Increasing the ratio of complexing agent to base results in a decrease in kobs to a minimum value corresponding to the rate of reaction of free ethoxide ion. In complementary experiments, alkali metal ions were added to these reaction systems in the form of unreactive salts, causing an increase in reaction rate. The kinetic data were analysed in terms of ion-pairing treatments, which allowed evaluation of rate coefficients due to free ethoxide ions and metal ion – ethoxide ion pairs. Possible roles of the metal cations are discussed in terms of ground state and transition state stabilization. Evaluation of the equilibrium constants for association of the metal ion with ground state (Ka) and the transition state (K′a) shows that catalysis occurs as a result of enhanced association between the metal ion and the transition state, with (K′a) values increasing in the order K+ < Na+ < Li+. A model is proposed in which transition state stabilization arises largely from chelation of the solvated metal ion to two charged oxygen centers. This appears to be the first reported instance of catalysis by alkali metal cations in nucleophilic displacement at phosphoryl centers. Keywords: nucleophilic displacement at phosphorus, alkali-metal-ion catalysis.
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4

Joshi, Vikram, and Martha L. Mecartney. "The influence of water of hydrolysis on microstructural development in sol-gel derived LiNbO3 thin films." Journal of Materials Research 8, no. 10 (October 1993): 2668–78. http://dx.doi.org/10.1557/jmr.1993.2668.

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The effect of water of hydrolysis on nucleation, crystallization, and microstructural development of sol-gel derived single phase LiNbO3 thin films has been studied using transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray diffraction (XRD), and differential scanning calorimetry (DSC). A precursor solution of double ethoxides of lithium and niobium in ethanol was used for the preparation of sol. DSC results indicated that adding water to the solution for hydrolysis of the double ethoxides lowered the crystallization temperature from 500 °C (no water) to 390 °C (2 moles water per mole ethoxide). The amount of water had no effect on the short-range order in amorphous LiNbO3 gels but rendered significant microstructural variations for the crystallized films. AFM studies indicated that surface roughness of dip-coated films increased with increasing water of hydrolysis. Films on glass, heat-treated for 1 h at 400 °C, were polycrystalline and randomly oriented. Those made with a low water-to-ethoxide ratio had smaller grains and smaller pores than films prepared from sols with higher water-to-ethoxide ratios. Annealing films with a low water concentration for longer times or at higher temperatures resulted in grain growth. Higher temperatures (600 °C) resulted in grain faceting along close-packed planes. Films deposited on c-cut sapphire made with a 1:1 ethoxide-to-water ratio and heat-treated at 400 °C were epitactic with the c-axis perpendicular to the film-substrate interface. Films with higher concentrations of water of hydrolysis on sapphire had a preferred orientation but were polycrystalline. It is postulated that a high amount of water increases the concentration of amorphous LiNbO3 building blocks in the sol through hydrolysis, which subsequently promotes crystallization during heat treatment.
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5

Brorson, Sverre-Henning. "How to Examine the Antigen-damaging Effect of Sodium Ethoxide on Deplasticized Epoxy Sections." Journal of Histochemistry & Cytochemistry 45, no. 1 (January 1997): 143–46. http://dx.doi.org/10.1177/002215549704500117.

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The purpose of this investigation was to develop a method that could be used to estimate how damaging sodium ethoxide is to different antigens with respect to immunolabeling when epoxy sections are deplasticized. If we obtain weak labeling for an antigen on deplasticized epoxy sections, this might be caused by the damaging effect of the ethoxide solution. It is therefore interesting to develop a method to check if this really is the reason. Fibrin clots and tissues of human kidney and thyroid were embedded in LR White resin. Some thin sections from these specimen blocks were exposed to sodium ethoxide in the same way as epoxy sections are when being deplasticized. Other sections from the same blocks were not exposed to sodium ethoxide. Both categories of sections were immunogold-labeled with anti-fibrinogen, anti-thyroglobulin, anti-IgA, anti-IgG, or anti-IgM. The intensity of immunolabeling of sections treated with ethoxide was compared with the immunolabeling of corresponding sections that were not treated with ethoxide. No significant differences were found in immunolabeling for fibrinogen, IgA, IgG, and IgM. For thyroglobulin, the intensity was approximately 30% less in tissues that were exposed to sodium ethoxide. The practical significance of this method is that we easily can examine the degree to which a given antigen is affected by sodium ethoxide, which is the agent used for deplasticizing epoxy sections.
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6

Stirling, J. W., and P. S. Graff. "Antigen unmasking for immunoelectron microscopy: labeling is improved by treating with sodium ethoxide or sodium metaperiodate, then heating on retrieval medium." Journal of Histochemistry & Cytochemistry 43, no. 2 (February 1995): 115–23. http://dx.doi.org/10.1177/43.2.7529784.

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To optimize the ultrastructural localization of immunoglobulin G in corneal crystalloid deposits, we compared a range of antigen unmasking techniques. A human corneal biopsy specimen was fixed in formalin, post-osmicated, and embedded in epoxy resin for electron microscopy. Thin sections were immunogold-labeled for IgG after treatment with sodium ethoxide or sodium metaperiodate. Sections were also treated by heating them at 95 degrees C while they floated on water, 0.01 M citrate buffer (pH 6.0), or sodium metaperiodate. The treatments were applied separately and combined. After labeling, crystalloids in untreated sections had a probe density of 5 particles/microns2. Crystalloids in sections treated only with sodium ethoxide or sodium metaperiodate had probe densities of 15-20 particles/microns2. Sodium ethoxide combined with heating on water, or citrate buffer, gave probe densities of 140-160 particles/microns2. Sodium metaperiodate combined with heating on citrate buffer gave the highest probe density (195 particles/microns2). Although sodium ethoxide coupled with heating increased probe density, the ethoxide etched the sections and caused unacceptable damage. Treatment with sodium metaperiodate followed by heating on citrate buffer is recommended for antigen unmasking. This combination gave a high probe density and sections remained intact, with good ultrastructural detail.
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7

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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8

YANG, Haiping, Shenghai YANG, Motang TANG, and Bihui LI. "The Electrosynthesis of Tantalum Ethoxide." Electrochemistry 82, no. 9 (2014): 743–48. http://dx.doi.org/10.5796/electrochemistry.82.743.

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9

Rincón-Ortiz, Sergio A., Jhonatan Rodriguez-Pereira, and Rogelio Ospina. "Niobium ethoxide analyzed by XPS." Surface Science Spectra 27, no. 2 (December 2020): 024014. http://dx.doi.org/10.1116/6.0000472.

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10

Chammingkwan, Patchanee, Mingkwan Wannaborworn, Le Thi Tuyet Mai, Minoru Terano, Toshiaki Taniike, and Phairat Phiriyawirut. "Particle engineering of magnesium ethoxide-based Ziegler-Natta catalyst through post-modification of magnesium ethoxide." Applied Catalysis A: General 626 (September 2021): 118337. http://dx.doi.org/10.1016/j.apcata.2021.118337.

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11

Dohner, Brent R., and William H. Saunders Jr. "Mechanisms of elimination reactions. 40. Attempted study of stereochemistry of elimination from 2-(p-nitrophenyl)ethyltrimethylammonium ion. Base-promoted cis–trans isomerization of p-nitrostyrene-β-d." Canadian Journal of Chemistry 64, no. 6 (June 1, 1986): 1026–30. http://dx.doi.org/10.1139/v86-172.

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Stereospecifically deuterated ArCHDCHDNMe3+ I − and ArCHDCHDNMe2O have been prepared, where Ar=C6H5 and p-NO2C6H4. When Ar=C6H5, the elimination reaction of the quaternary salt with ethoxide in ethanol goes with >98% anti stereochemistry, and the Cope elimination of the amine oxide with >98% syn stereochemistry. When Ar=p-No2C6H4, however, both reactions lead to apparent 50:50 anti/syn product. Subjection of (E)-p-nitrostyrene-β-d to the conditions of both the ethoxide-promoted and Cope eliminations results in complete cis–trans equilibration. No loss of deuterium from p-nitrosryrene-α-d occurs under either set of conditions, excluding isomerization via an α-arylvinyl carbanion. The most likely mechanism for isomerization is reversible addition of ethoxide under E2 conditions and ArCHDCHDNMe2O under Cope conditions to the β-carbon of p-nitrostyrene. The cis–trans isomerization of the p-nitrosryrene is sufficiently rapid to preclude determination of the stereochemistry of base-promoted eliminations leading to it.
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12

Weng, Wenjian, Zishang Ding, Yiming Mao, and Feipeng Zhang. "The gelation behaviour of copper ethoxide." Journal of Non-Crystalline Solids 147-148 (January 1992): 102–5. http://dx.doi.org/10.1016/s0022-3093(05)80601-5.

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13

Hachfeld, Edward A., Young-Joo Kim, and Lorraine Falter Francis. "Dip coating of titanium ethoxide solutions." Materials Letters 18, no. 3 (December 1993): 141–47. http://dx.doi.org/10.1016/0167-577x(93)90114-d.

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14

Van Bommel, M. J., and T. N. M. Bernards. "Spin coating of titanium ethoxide solutions." Journal of Sol-Gel Science and Technology 8, no. 1-3 (February 1997): 459–63. http://dx.doi.org/10.1007/bf02436882.

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15

Anhede, Bo, Nils-Åke Bergman, and A. Jerry Kresge. "An MNDO SCF-MO study of proton transfer from fluoroethanols." Canadian Journal of Chemistry 64, no. 6 (June 1, 1986): 1173–78. http://dx.doi.org/10.1139/v86-194.

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Proton exchange between β-fluorinated ethanols and ethoxide ions has been studied using the MNDO SCF-MO method. Calculations were performed on reactions of ethoxide ion with ethanols substituted in the β-position with 0, 1, 2, and 3 fluorine atoms as well as on reactions where both the ethanol and the ethoxide ion were substituted with the same number (1, 2, 3) of fluorine atoms in the β-position. The energies obtained for the ion–molecule reactant complexes and the transition states from these reactions have been analyzed using the Marcus equation. Through the calculated force-constant matrices of reactants and transition states we also calculated the kinetic isotope effects for the proton-transfer reactions. The semiclassical isotopic rate constant ratios (kH/kD)s were found to be of rather normal magnitude and showed a variation with the energy of reaction. The calculated ratios of tunnel correction factors, QtH/QtD, proved to be unrealistically high. These factors were also calculated with the frequencies scaled down by 10% and this was found to reduce the QtH/QtD ratios to more realistic values.
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16

Kulkarni, Naveen V., Animesh Das, Shawn G. Ridlen, Erin Maxfield, Venkata A. K. Adiraju, Muhammed Yousufuddin, and H. V. Rasika Dias. "Fluorinated triazapentadienyl ligand supported ethyl zinc(ii) complexes: reaction with dioxygen and catalytic applications in the Tishchenko reaction." Dalton Transactions 45, no. 11 (2016): 4896–906. http://dx.doi.org/10.1039/c6dt00257a.

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17

Mercado-Marin, Eduardo V., Pratik Rajesh Chheda, Andrea Faulkner, and Diane Carrera. "Magnesium ethoxide mediated lactone aminolysis with aminoheterocycles." Tetrahedron Letters 61, no. 9 (February 2020): 151552. http://dx.doi.org/10.1016/j.tetlet.2019.151552.

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18

Brar, Loveleen K., Gourav Singla, and O. P. Pandey. "Evolution of structural and thermal properties of carbon-coated TaC nanopowder synthesized by single step reduction of Ta-ethoxide." RSC Advances 5, no. 2 (2015): 1406–16. http://dx.doi.org/10.1039/c4ra12105h.

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19

Svoboda, Jiří, Miloslav Nič, and Jaroslav Paleček. "Application of Magnesium Alkoxides to Syntheses of Benzoheterocyclic Compounds." Collection of Czechoslovak Chemical Communications 58, no. 3 (1993): 592–99. http://dx.doi.org/10.1135/cccc19930592.

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The Dieckmann condensation of methyl [(2-methoxycarbonyl)phenyl]-X-acetates Ia-Ih (X = O, S, SO2, NH, NCH3) initiated by action of magnesium methoxide, ethoxide, isopropoxide and other basic reagents have been studied under various conditions. Whereas magnesium methoxide has comparable efficiency as sodium methoxide and potassium tert-butoxide in syntheses of benzoheterocyclic compounds IIa-IIh, magnesium ethoxide gives the ethyl ester IIb in medium yield, and magnesium isopropoxide is quite inefficient in the condensation reaction. The alkylation of the esters IIa, IId, and IIg with methyl chloroacetate in the presence of sodium hydride in dimethylformamide gives the diesters IIi - IIk which on action by potassium tert-butoxide undergo the cyclization reaction to give esters III.
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20

Lari, G. M., K. Desai, C. Mondelli, and J. Pérez-Ramírez. "Selective dehydrogenation of bioethanol to acetaldehyde over basic USY zeolites." Catalysis Science & Technology 6, no. 8 (2016): 2706–14. http://dx.doi.org/10.1039/c5cy02020d.

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Alkali-activated zeolites are active, selective and stable catalysts for ethanol dehydrogenation to acetaldehyde. Molecular oxygen eases hydrogen abstraction from the adsorbed ethoxide intermediate boosting the catalytic performance.
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21

Yogo, Toshinobu, Kouichi Banno, Wataru Sakamoto, and Shin-ichi Hirano. "Synthesis of a KNbO3 particle/polymer hybrid from metalorganics." Journal of Materials Research 18, no. 7 (July 2003): 1679–85. http://dx.doi.org/10.1557/jmr.2003.0230.

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A nanocrystalline KNbO3 particle/polymer hybrid was synthesized through controlled hydrolysis and polymerization of metalorganics below 100 °C. A KNbO3 precursor was synthesized from potassium ethoxide, niobium ethoxide, and acetoacetoxyethyl methacrylate. The K–Nb alkoxide precursor was hydrolyzed and polymerized yielding KNbO3 particle/polymer hybrid. The organic matrix included nanometer-sized crystalline particles depending upon the hydrolysis conditions. The nanocrystalline particles were identified to be potassium niobate by electron diffraction and energy dispersive x-ray analysis. The suspension of the hybrid in silicone oil revealed a yield stress dependent upon various conditions, such as concentration and applied field. The hybridization was found to have a pronounced effect on the electrorheological properties of the fluid, including the KNbO3 particle/polymer hybrid.
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22

Nakagawa, Keizo, Tiantian Jia, Weiran Zheng, Simon Michael Fairclough, Masahiro Katoh, Shigeru Sugiyama, and Shik Chi Edman Tsang. "Enhanced photocatalytic hydrogen evolution from water by niobate single molecular sheets and ensembles." Chem. Commun. 50, no. 89 (2014): 13702–5. http://dx.doi.org/10.1039/c4cc04726e.

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23

Seisenbaeva, Gulaim A., Suresh Gohil, Evgeniya V. Suslova, Tatiana V. Rogova, Nataliya Ya Turova, and Vadim G. Kessler. "The synthesis of iron (III) ethoxide revisited: Characterization of the metathesis products of iron (III) halides and sodium ethoxide." Inorganica Chimica Acta 358, no. 12 (August 2005): 3506–12. http://dx.doi.org/10.1016/j.ica.2005.03.048.

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24

James, Joanne H., Michael E. Peach, and Charles R. Williams. "Reactions of some fluoroaromatics with the ethoxide anion." Journal of Fluorine Chemistry 27, no. 1 (January 1985): 91–104. http://dx.doi.org/10.1016/s0022-1139(00)80901-x.

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25

Yoo, Seung-Joon, Ho-Sung Yoon, Hee Dong Jang, Seung-Tae Hong, Hyung-Sang Park, Sang-Ug Park, Dong-Heui Kwak, and Se-Il Lee. "Synthesis of aluminum ethoxide from used aluminum cans." Korean Journal of Chemical Engineering 24, no. 5 (September 2007): 872–76. http://dx.doi.org/10.1007/s11814-007-0057-z.

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26

Yang, Sheng Hai, Guo Feng Huo, Jiao Yun Xia, and Hai Ping Yang. "Electrochemical Synthesis of Zirconium Ethoxide and the Electrochemical Behaviors of Zirconium in the Process." Advanced Materials Research 266 (June 2011): 275–79. http://dx.doi.org/10.4028/www.scientific.net/amr.266.275.

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Zirconium ethoxide was synthesized by direct electrochemical reaction of anhydrous ethanol with sacrificial zirconium anode in the presence of tetraethylammonium chlorides (Et4NCl) as a conductive agent. The samples of products were characterized by Fourier transform infrared spectra (FT-IR) and Proton nuclear magnetic resonance spectroscopy (1H-NMR). The experiment results show that direct electrochemical synthesis of zirconium ethoxide has high current efficiency and abundant synthetic product compared with the conventional chemical methods. The behaviors of Zr in Et4NCl ethanol solutions were measured through potentiodynamic polarization, cyclic voltammetry, and potentiostatic current-time transient techniques. Effects of the temperature, scanning rate and the Et4NCl concentration were investigated. The results indicate that the electrochemical dissolution of the metal in anhydrous ethanol is a process of corrosive pitting. The rate of pit nucleation and pit growth increases with increasing of temperature and the Et4NCl concentration.
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27

Satchell, Derek P. N., Rosemary S. Satchell, and Wasfy N. Wassef. "The Kinetics and Mechanism of Addition of Water and Alcohols to p-Nitrophenyl Isothiocyanate. The Effects of Added Dimethyl Sulphoxide." Zeitschrift für Naturforschung B 45, no. 7 (July 1, 1990): 1032–36. http://dx.doi.org/10.1515/znb-1990-0721.

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The second order-rate constants for the addition of water and ethanol to p-nitrophenyl isothiocyanate are larger in dimethyl sulphoxide solution than in pure water or ethanol. The detailed behaviour over a wide composition range suggests that H-bonding by the hydroxylic reactant to the solvent favours reaction, whereas H-bonding to this reactant retards reaction. The behaviour and relative reactivities of isocyanates and isothiocyanates suggest that protontransfer concurrent with nucleophilic attack at carbon, is less important in additions of hydroxylic compounds to isothiocyanates than to isocyanates. Branched-chain alcohols react more slowly with isothiocyanates than do primary alcohols. An excess of ethoxide ions reacts relatively rapidly with p-nitrophenyl isothiocyanate in ethanol to give the ionized thiourethane. The kinetics of this process, and the equilibrium constant for proton transfer between thiourethane and ethoxide ions, have been determined.
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28

Ferber, PH, GE Gream, and TI Stoneman. "The 9-Decalyl and Related cations VII. Solvolysis of 3-(Cyclohex-1′-enyloxy)propyl p-Nitrobenzenesulfonate." Australian Journal of Chemistry 38, no. 5 (1985): 699. http://dx.doi.org/10.1071/ch9850699.

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The solvolysis of 3-(cyclohex-1′-enyloxy) propyl p- nitrobenzenesulfonate (5) in ethanol buffered separately with sodium ethoxide and triethylamine and 2,2,2-trifluoroethanol buffered with triethylamine has been investigated. Kinetic determinations and product studies have been carried out. In ethanol buffered with sodium ethoxide , π-bond participation in the above ester occurs to the extent of 30%; this is raised to 84% when triethylamine is used as the buffering agent. With buffered trifluoroethanol as solvent, π-bond participation in the ester is complete; kunsat/ksat = 920 and a quantitative yield of cyclized products is obtained. Kinetic evidence indicates a lack of significant involvement of a lone pair on oxygen (enol ether system) in the solvolysis of the sulfonate ester; in trifluoroethanol , the compound solvolyses only 1.15 times more rapidly than does 4-(cyclohex-1′-enyl)butyl p-nitrobenzenesulfonate (2), its carbon analogue.
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29

Phulé, Pradeep P., Thomas A. Deis, and David G. Dindiger. "Low temperature synthesis of ultrafine LiTaO3 powders." Journal of Materials Research 6, no. 7 (July 1991): 1567–73. http://dx.doi.org/10.1557/jmr.1991.1567.

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Controlled chemical polymerization of tantalum ethoxide in the presence of glacial acetic acid (HOAc/Alk. = 16) and solubilized lithium acetate (Li/Ta = 1.00, H2O/Alk. = 55.55) was used for the preparation of an amorphous gel precursor to LiTaO3. Although additional investigations are required, the results suggest that successful formation of amorphous gel network, as opposed to that of colloidal tantalum (hydrous) oxide, may be due to the generation of a new organotantalum precursor via a structural modification reaction between the tantalum ethoxide and glacial acetic acid. The evolution of LiTaO3 ceramics from pre-ceramic gels was investigated using thermal analysis, electron microscopy, and x-ray diffraction. The results indicate that after the completion of gel pyrolysis (200–400 °C) and crystallization (Tc = 590 °C), ultrafine (average particle size 100–300 nm), single phase, crystalline (a = 5.243, c = 13.812 Å) LiTaO3 powders can be prepared at low processing temperatures.
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Mohd Hizam, Sara Maira, and Mohamed Shuaib Mohamed Saheed. "Facile Electrochemical Approach Based on Hydrogen-Bonded MOFs-Derived Tungsten Ethoxide/Polypyrrole-Reduced GO Nanocrystal for ppb Level Ammonium Ions Detection." Chemosensors 11, no. 3 (March 21, 2023): 201. http://dx.doi.org/10.3390/chemosensors11030201.

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Ammonium (NH4+) ions are a primary contaminant in the river and along the waterside near an agricultural area, therefore, necessitating sensitive detection of pollutants before irreversibly damaging environment. Herein, a new approach of metal-organic framework-derived tungsten ethoxide/polypyrrole-reduced graphene oxide (MOFs-W(OCH2CH3)6/Ppy-rGO) electrochemical sensors are introduced. Through a simple hydrothermal process, Ppy-rGO is linked to tungsten ethoxide as an organic linker. This creates the MOFs-W(OCH2CH3)6/Ppy-rGO nanocrystal through hydrogen bonding. The synergistic combination of tungsten ethoxide and Ppy-rGO provides three-fold advantages: stabilization of Ppy-rGO for extended usage, enabling detection of analytes at ambient temperature, and availability of multiple pathways for effective detection of analytes. This is demonstrated through excellent detection of NH4+ ions over a dynamic concentration range of 0.85 to 3.35 µM with a ppb level detection limit of 0.278 µM (9.74 ppb) and a quantitation limit of 0.843 µM (29.54 ppb). The increment in the concentration of NH4+ ions contributes to the increment in proton (H+) concentration. The increment in proton concentration in the solution will increase the bonding activity and thus increase the conductivity. The cyclic voltammetry curves of all concentrations of NH4+ analytes at the operating potential window between −1.5 and 1.5 V exhibit a quasi-rectangular shape, indicating consistent electronic and ionic transport. The distinctive resistance changes of the MOFs-W(OCH2CH3)6/Ppy-rGO to various NH4+ ion concentrations and ultrasensitive detection provide an extraordinary platform for its application in the agriculture industry.
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31

Feng, Guo, Wei Hui Jiang, Jian Min Liu, Quan Zhang, Zi Hu, Li Feng Miao, and Qian Wu. "Low-Temperature Synthesis of Magnesium-Stabilized Aluminum Titanate Powder via Non-Hydrolytic Sol-Gel Method." Materials Science Forum 848 (March 2016): 319–23. http://dx.doi.org/10.4028/www.scientific.net/msf.848.319.

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Magnesium-stabilized aluminum titanate powder was prepared via non-hydrolytic sol-gel method using titanium tetrachloride and anhydrous aluminium chloride as precursors, anhydrous ethanol as the oxygen donor, magnesium powder, magnesium fluoride, magnesium ethoxide and anhydrous magnesium acetate as stabilizers. The effect of magnesium stabilizers on low temperature synthesis of aluminum titanate was investigated, and their role and mechanism in stabilizing aluminum titanate were also studied by XRD, FT-IR and thermal expansion dilatometer. The results show that introducing magnesium powder or magnesium fluoride can’t stabilize aluminum titanate, they also lead to the failure of aluminum titanate low-temperature synthesis at 750 °C due to its promotion of non-hydrolytic homogeneous condensation. Anhydrous magnesium acetate and magnesium ethoxide can react with aluminum alkoxide and titanium alkoxide in the precursor mixture to form heterogeneous condensation bonds, which promotes magnesium ion to dope into aluminum titanate lattice at 750 °C, and hence to improve its thermal stability.
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32

Nakano, Hiromi, and Yoko Suyama. "In Situ TEM Observation of Crystallization Process for LiNbO3 and NaNbO3." Advances in Science and Technology 63 (October 2010): 47–51. http://dx.doi.org/10.4028/www.scientific.net/ast.63.47.

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Fabrication of advanced electronic components requires high-quality powders. In this work, nano-powders of Li or Na niobates are synthesized from (Li or Na)-Nb ethoxide by a sol-crystal method. A single crystal of (Li or Na)-Nb ethoxide is decomposed to an amorphous matrix below 473 K. Next, small crystals are grown by heating at the appropriate temperature for each specimen. The sol-crystal method provides homogeneous quality and fine grains by heating at lower temperature. Structural analysis of the powders is performed by a transmission electron microscope (TEM) and X-ray diffraction. As a result, LiNbO3 turns to dense-powders, but NaNbO3 forms nano-porous powders. In order to understand this difference, we try to observe in-situ the crystallization and grain growth processes by high-temperature TEM. We successfully observe in-situ this processing and discuss the structural change and formation mechanism of LiNbO3, comparing these features with those of NaNbO3.
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33

YANG, Sheng-hai, Yong-ming CHEN, Hai-ping YANG, Yin-yuan LIU, Mo-tang TANG, and Guan-zhou QIU. "Preparation of high-purity tantalum ethoxide by vacuum distillation." Transactions of Nonferrous Metals Society of China 18, no. 1 (February 2008): 196–201. http://dx.doi.org/10.1016/s1003-6326(08)60035-7.

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34

Kirkwood, D. A., and A. J. Stace. "Infrared and collision-induced fragmentation of iron ethoxide cations." International Journal of Mass Spectrometry and Ion Processes 171, no. 1-3 (December 1997): 39–49. http://dx.doi.org/10.1016/s0168-1176(97)00024-4.

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35

Chandran, K., M. Kamruddin, P. K. Ajikumar, A. Gopalan, and V. Ganesan. "Kinetics of thermal decomposition of sodium methoxide and ethoxide." Journal of Nuclear Materials 358, no. 2-3 (November 2006): 111–28. http://dx.doi.org/10.1016/j.jnucmat.2006.07.003.

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36

Cai, Ya-nan, Sheng-hai Yang, Sheng-ming Jin, Hai-ping Yang, Guo-feng Hou, and Jiao-yun Xia. "Electrochemical synthesis, characterization and thermal properties of niobium ethoxide." Journal of Central South University of Technology 18, no. 1 (February 2011): 73–77. http://dx.doi.org/10.1007/s11771-011-0661-2.

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37

Gupta, V. K., S. Satish, and I. S. Bhardwaj. "Magnesium-Ethoxide-Based Titanium Catalysts for Polymerization of Propylene." Journal of Macromolecular Science, Part A 31, no. 4 (1994): 451–63. http://dx.doi.org/10.1080/10601329408545297.

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38

Gupta, V. K., S. Satish, and I. S. Bhardwaj. "Magnesium-Ethoxide-Based Titanium Catalysts for Polymerization of Propylene." Journal of Macromolecular Science, Part A 31, no. 4 (April 1994): 451–63. http://dx.doi.org/10.1080/10601329409351531.

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39

Rubel, Glenn O. "The dynamics of titanium ethoxide‐doped dodecane droplet microencapsulation." Journal of Applied Physics 64, no. 5 (September 1988): 2742–45. http://dx.doi.org/10.1063/1.341617.

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40

Ramaiah, Manjunatha M., Nanjunda Swamy Shivananju, and Priya Babu Shubha. "A Facile, Efficient and Solvent-Free Titanium (IV) Ethoxide Catalysed Knoevenagel Condensation of Aldehydes and Active Methylenes." Letters in Organic Chemistry 17, no. 2 (January 7, 2020): 107–15. http://dx.doi.org/10.2174/1570178616666190401194641.

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: Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.
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41

Haggam, Reda Ahmed, Mohamed Gomma Assy, Mohamed Hassan Sherif, and Mohamed Mohamed Galahom. "A series of 1,3-imidazoles and triazole-3-thiones based thiophene-2-carboxamides as anticancer agents: Synthesis and anticancer activity." European Journal of Chemistry 9, no. 2 (June 30, 2018): 99–106. http://dx.doi.org/10.5155/eurjchem.9.2.99-106.1701.

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By addition of semicarbazide or phenylhydrazine hydrochloride to thienoylisothiocyanate (1) resulted in building of thiosemicarbazide derivative (2), triazole derivative (4) and thiophene-2-carboxamide (5), respectively. Basic cyclization of compound 2 led to formation of oxadiazine (3). Synthesis of thiadiazine derivative (6) was achieved via reaction of compound 5 and maleic anhydride in triethyl amine. Heating of compound 5 with ethyl chloroacetate or sodium ethoxide produced thiadiazine derivative (7) and triazolethione (8), respectively. Thiosemicarbazide derivative 11 was synthesized by addition of nicotinic hydrazide to compound 1. Refluxing of compound 11 with lead acetate afforded triazole (13). Moreover, acid and base mediated cyclizations of compound 11 gave thiadiazole (12) and 1,2,4-triazolethione (14) throughout thiophene intermediate, respectively. Addition of ethyl 2-aminothiophene-3-carboxylate to compound 1 formed thiourea (15) which was refluxed with ethoxide giving thiophene-3-carboxylic acid (16). Lastly, nucleophilic addition of amino phenol or ethylene diamine to compound 1 yielded oxazine structure (18) and imidazole derivative (19), respectively. The yields of the synthesized compounds were 61-95%. The detailed synthesis and spectroscopic data of the new compounds are reported.
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42

Barou, Odile, Norbert Laroche, Sabine Palle, Christian Alexandre, and Marie-Hélène Lafage–Proust. "Pre-osteoblastic Proliferation Assessed with BrdU in Undecalcified, Epon-embedded Adult Rat Trabecular Bone." Journal of Histochemistry & Cytochemistry 45, no. 9 (September 1997): 1189–95. http://dx.doi.org/10.1177/002215549704500902.

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We evaluated bromodeoxyuridine (BrdU) immunohistochemistry in undecal-cified adult rat tibiae to study cell kinetics in various bone compartments: primary and secondary spongiosae, periosteum, and bone marrow. Several regimens of BrdU administration were tested (IP injections and osmotic minipumps). We compared LR White resin, methylmethacrylate, and Epon–araldite embedding, microwave irradiation for antigen retrieval, several concentrations of sodium ethoxide for deplastification, and various DNA de-naturation procedures. Paraffin-embedded decalcified tibiae and Epon-embedded bowel were used as positive controls. The best results were obtained in rats labeled with 40 mg of BrdU for 72 hr using osmotic minipumps. The procedure using a Microprobe system in Epon-embedded bone tissue with a sodium ethoxide concentration of 50% for two intervals of 20 min provided the best staining quality and tissue preservation. Labeled pre-osteoblastic cells and bone marrow cells could be counted. Epon embedding allowed preservation of tetracycline double labeling performed 1 to 5 days before sacrifice. The number of labeled pre-osteoblastic cells was correlated with the double-labeled surface area measured histomorphometrically.
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43

Adlere, I., A. Krauze, and G. Duburs. "Synthesis of 3-Unsubstituted 4-Aryl-4,7-Dihydrothieno[2,3-b]Pyridine-2,5-Dicarboxylates / 3-Neaizvietotu 4-Aril-4,7-Dihidrotiēno[2,3-B]Piridīn-2,5-Dikarbonskābes Esteru Sintēze." Latvian Journal of Chemistry 51, no. 3 (November 1, 2012): 257–63. http://dx.doi.org/10.2478/v10161-012-0009-8.

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Novel 3-unsubstituted 4,7-dihydrothieno[2,3-b]pyridines were prepared by heterocyclization of methyl acetoacetate, an aromatic aldehyde and Meldrum’s acid in the presence of ammonium acetate in glacial acetic acid, followed by treatment of formed intermediates - pyridones with Wilsmeier-Haack reagent and with ethyl mercaptoacetate in the presence of sodium ethoxide in dry ethanol.
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44

Veverka, Miroslav, and Miroslav Marchalín. "Addition-cyclization reactions of ethyl isothiocyanatoacetate with carboxylic acid hydrazides." Collection of Czechoslovak Chemical Communications 52, no. 1 (1987): 113–19. http://dx.doi.org/10.1135/cccc19870113.

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Ethyl (3-substituted 5-thioxo-1,2,4-triazolin-4-yl)acetates were prepared by addition-cyclization reaction of ethyl isothiocyanatoacetate with carboxylic acid hydrazides in the presence of sodium ethoxide. Thermal cyclization of the adduct in dimethylformamide afforded 1-acetamido-2-thiohydantoin. The effect of substituents on the cyclization course and the thione-thiol tautomerism are discussed.
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45

Hayes, RN, JC Sheldon, JH Bowie, and DE Lewis. "Elimination of Molecular Hydrogen and Methane from Collision-Activated Alkoxide Negative Ions in the gas Phase. An ab initio and Isotope Effect Study." Australian Journal of Chemistry 38, no. 8 (1985): 1197. http://dx.doi.org/10.1071/ch9851197.

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Ab initio calculations indicate that the collisional induced losses of molecular hydrogen from the ethoxide negative ion and methane from the t- butoxide negative ion to be stepwise processes in which the key intermediates are [H-… MeCHO ] and [Me-…Me2CO] respectively. Deuterium kinetic isotope effects observed for these and other alkoxide negative ions are in accord with the operation of a stepwise reaction.
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46

Mcfadden, HG, and JL Huppatz. "Synthesis of 4,6-Dialkylpyrimidine-5-carbonitriles." Australian Journal of Chemistry 45, no. 6 (1992): 1045. http://dx.doi.org/10.1071/ch9921045.

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4,6-Dialkylpyrimidine-5-carbonitriles were synthesized from 2-(1-ethoxyalkylidine)-3-oxoalkane-nitriles and bidentate nucleophiles such as thiourea in the presence of sodium ethoxide. The synthesis was found to be limited to dialkylpyrimidines where both alkyl groups contained between one and three carbons. Subsequent derivatization of the 2-thioxo function provides scope for the synthesis of a variety of novel pyrimidines.
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47

NAKANO, Hiromi, Tsuyoshi YANO, and Yoko SUYAMA. "Microstructural Evolution During Crystallization of Ba5Nb4O15 from Ba-Nb Ethoxide." Journal of the Ceramic Society of Japan 113, no. 1313 (2005): 59–63. http://dx.doi.org/10.2109/jcersj.113.59.

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48

Beske, Maurice, Lukas Tapmeyer, and Martin U. Schmidt. "Crystal structure of sodium ethoxide (C2H5ONa), unravelled after 180 years." Chemical Communications 56, no. 24 (2020): 3520–23. http://dx.doi.org/10.1039/c9cc08907a.

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49

Weng, Luqian, and Simon N. B. Hodgson. "Sol-gel processing of tellurite materials from tellurium ethoxide precursor." Materials Science and Engineering: B 87, no. 1 (October 2001): 77–82. http://dx.doi.org/10.1016/s0921-5107(01)00708-5.

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50

Paul, Anam C., Md Asmaul Reza, and Jinjun Liu. "Dispersed-fluorescence spectroscopy of jet-cooled calcium ethoxide radical (CaOC2H5)." Journal of Molecular Spectroscopy 330 (December 2016): 142–46. http://dx.doi.org/10.1016/j.jms.2016.09.001.

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