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Articles de revues sur le sujet « Lithium alkyls »

Auteur : Grafiati
Publié le 9 mars 2023

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1

Charrier, Claude, Nicole Maigrot, Francois Mathey, Francis Robert et Yves Jeannin. « Reactions of 1,2-diphosphetenes with lithium and lithium alkyls ». Organometallics 5, no 4 (avril 1986) : 623–30. http://dx.doi.org/10.1021/om00135a002.

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Jutzi, Peter, et Bernd Hielscher. « Reaction of decamethylstannocene with lithium alkyls ». Organometallics 5, no 12 (décembre 1986) : 2511–14. http://dx.doi.org/10.1021/om00143a018.

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3

Martínez-Martínez, Antonio J., Alan R. Kennedy, Valerie Paprocki, Felipe Fantuzzi, Rian D. Dewhurst, Charles T. O’Hara, Holger Braunschweig et Robert E. Mulvey. « Selective mono- and dimetallation of a group 3 sandwich complex ». Chemical Communications 55, no 65 (2019) : 9677–80. http://dx.doi.org/10.1039/c9cc03825f.

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While lithium alkyls and lithium amides do not metallate the scandium compound [(η5-C5H5)Sc(η8-C8H8)], a synergistic lithium–aluminium base-trap partnership cannot resist taking a bite with one C–H bond selectively cleaved from both Cp and COT rings.
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4

Ballard, D. G. H., R. J. Bowles, D. M. Haddleton, S. N. Richards, R. Sellens et D. L. Twose. « Controlled polymerization of methyl methacrylate using lithium aluminum alkyls ». Macromolecules 25, no 22 (octobre 1992) : 5907–13. http://dx.doi.org/10.1021/ma00048a008.

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Sirsch, P., W. Scherer, M. Gardiner, S. A. Mason et G. S. McGrady. « Electron delocalization in lithium alkyls : negative hyperconjugation and agostic bonding ». Acta Crystallographica Section A Foundations of Crystallography 58, s1 (6 août 2002) : c352. http://dx.doi.org/10.1107/s0108767302099063.

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Schumann, Herbert, et Gerald Jeske. « Metallorganische Verbindungen der Lanthanoide, XXXIII [1] Dicyclopentadienyllanthanoid-alkyle und -hydride von Neodym, Samarium und Lutetium [2] / Organometallic Compounds of the Lanthanides, XXXIII [1] Dicyclopentadienyllanthanide Alkyls and Hydrides of Neodymium, Samarium and Lutetium [2] ». Zeitschrift für Naturforschung B 40, no 11 (1 novembre 1985) : 1490–94. http://dx.doi.org/10.1515/znb-1985-1112.

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Tricyclopentadienylneodymium and -lutetium react with sec-butyl lithium and terf-butyl lithium to form sec-butyl- and tert-butyl(dicyclopentadienyl)neodymium and -lutetium, which decompose to the corresponding dicyclopentadienyllanthanide hydride complexes. Dicyclopentadienyl-bis-(trimethylsilyl)methylsamarium and -lutetium are made from dicyclopentadienylsamarium or -lutetium chloride and bis(trimethylsilyl)methyl lithium. They react with hydrogen to form the corresponding dicyclopentadienyllanthanide hydride complexes.
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Seyam, Afif M. « Observations on the reaction of uranium tetrachloride and dichlorodioxouranium(VI) with lithium alkyls ». Inorganica Chimica Acta 110, no 2 (septembre 1985) : 123–26. http://dx.doi.org/10.1016/s0020-1693(00)84567-3.

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8

Galliani, Guido, Bruno Rindone, Ricardo Suarez-Bertoa, Francesco Saliu et Alberto Terraneo. « Stereoselective Addition of Grignard Reagents and Lithium Alkyls onto 3,5-Disubstituted-1,3-oxazolidine-2,4-diones ». Synthetic Communications 43, no 5 (13 novembre 2012) : 749–57. http://dx.doi.org/10.1080/00397911.2011.609301.

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Kershenbaum, I. L., I. A. Oreshkin et B. A. Dolgoplosk. « Formation of carbene species in the reaction of lithium alkyls with molybdenum, tungsten, and cobalt chlorides ». Bulletin of the Russian Academy of Sciences Division of Chemical Science 41, no 1 (janvier 1992) : 172–74. http://dx.doi.org/10.1007/bf00863939.

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Galliani, Guido, Bruno Rindone, Ricardo Suarez-Bertoa, Francesco Saliu et Alberto Terraneo. « ChemInform Abstract : Stereoselective Addition of Grignard Reagents and Lithium Alkyls onto 3,5-Disubstituted-1,3-oxazolidine-2,4-diones. » ChemInform 44, no 24 (23 mai 2013) : no. http://dx.doi.org/10.1002/chin.201324114.

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Büschen, Thomas, Wibke Dietz, Uwe Klingebiel, Mathias Noltemeyer et Yvonne Schwerdtfeger. « Synthese von Fluorsilylenolaten, Aminosilylenolaten, -ethern und Aldolkondensaten/Synthesis of Fluorosilylenolates, Aminosilylenolates, -ethers, and Aldol Condensates ». Zeitschrift für Naturforschung B 62, no 11 (1 novembre 2007) : 1358–70. http://dx.doi.org/10.1515/znb-2007-1103.

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Depending on the reaction conditions, ketones react with n-BuLi, tert-BuLi or lithium diisopropylamide to give enolates or alcoholates. In the reaction of tert-butylmethylketone with n-BuLi followed by fluorosilanes, the fluorosilyl-enolates H2C=C(O-SiFRR′)CMe3 (1 - 4) and fluorosilylethers Me3C(CH3)(n-C4H9)C-O-SiFRR′ (5 - 8) [R,R′ = Me (1, 5); F, CMe3 (2, 6); F, C6H5 (3, 7); F, CHMe2 (4, 8)] are formed. Using tert-butylmethylketone, n-BuLi and (Me3C)2SiF2, isobutene and the fluorosilyl-enolate of acetaldehyde H2C=CH-O-SiF(CMe3)2 (9) are obtained. Diisopropylketone reacts with Me3CLi and fluorosilanes to give the fluorosilyl-enolates Me2C=C(O-SiFRR′)CHMe2 (10, 11) and -ethers,Me3C(Me2HC)2C-O-SiFRR′ (12, 13) [R,R′ = Me (10, 11); F, CMe3 (12, 13)] whereas only the silylethers R(Me)(C6H5)C-O-SiFRR′ [R, R′, R′′ = n-C4H9, Me, Me (14); C6H5, F, Me (15)] are generated in the reaction of H3C(C6H5)C=O with lithium-alkyls and fluorosilanes. 1- Di(tert-butyl)fluorosiloxy-1-cyclohexene (16) is the product of the reaction of lithiated cyclohexanone and (Me3C)2SiF2. A side reaction of the enolate formation is often a condensation releasing water. For that reason, acyclic and cyclic siloxanes may appear as by-products, e. g. disiloxane (17) using (Me3C)2SiF2, cyclotrisiloxane (Me3C(C6H5)Si-O)3 (18) using Me3(C6H5)SiF2, or cyclotetrasiloxane (Me3CSiF-O)4 (19) using Me3CSiF3 in these reactions. Attempts to prepare the enolate of cyclopentanone in the reaction with lithium diisopropylamide lead to the formation of 2,5-dicyclopentylidenepentanone (20). The 3,5,7-triphenyl-3-methyl-4,6-hexadienephenone (21) is an aldol condensate of Me(C6H5)CO. Lithium-tert-butylmethylenolate reacts with fluorosilyl-enolates 1 - 3 or SiF4 to give bis(enolato)silanes, (H2C=C(CMe3)O-)2SiRR′ [R, R′ = Me (22); F, CMe3 (23); F, C6H5 (24);] and the tris(enolato)silanes (H2C=C(CMe3)O-)3SiR [R = C6H5 (25); F (26)]. Aminosilyl-enolates H2C=C(O-SiR′R′′-NHR)CMe3 are obtained in reactions of fluorosilyl-enolates with lithium amide [27: R= CMe3, R′= Me, R′′= Me; 28: R= C6H5, R′= F, R′′= CMe3;]. Results of the crystal structure determinations of 17, the cis-isomer of 18, one trans-isomer of 19, the pentanone 20, and the hexadienephenone 21 are reported.
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12

Parfenova, Lyudmila V., Tatyana V. Berestova, Irina V. Molchankina, Leonard M. Khalilov, Richard J. Whitby et Usein M. Dzhemilev. « Stereocontrolled monoalkylation of mixed-ring complex CpCp′ZrCl2 (Cp′ = 1-neomenthyl-4,5,6,7-tetrahydroindenyl) by lithium, magnesium and aluminum alkyls ». Journal of Organometallic Chemistry 726 (février 2013) : 37–45. http://dx.doi.org/10.1016/j.jorganchem.2012.12.004.

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13

Duhamel, Lucette, et Jean-Christophe Plaquevent. « 4-Phenylbenzylidene benzylamine : A new and convenient reagent for the titration of solutions of lithium alkyls and metal amides ». Journal of Organometallic Chemistry 448, no 1-2 (avril 1993) : 1–3. http://dx.doi.org/10.1016/0022-328x(93)80058-j.

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14

Hitchcock, Peter B., Michael F. Lappert, Marcus Layh, Dian-Sheng Liu, Rafael Sablong et Tian Shun. « Reactions of LiCHR2 and related lithium alkyls with α-H free nitriles and the crystal structures of eleven representative lithium 1,3-diazaallyls, 1-azaallyls and β-diketiminates ». Journal of the Chemical Society, Dalton Transactions, no 14 (2000) : 2301–12. http://dx.doi.org/10.1039/b002376k.

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15

Robertson, Stuart D., Alan R. Kennedy, John J. Liggat et Robert E. Mulvey. « Facile synthesis of a genuinely alkane-soluble but isolable lithium hydride transfer reagent ». Chemical Communications 51, no 25 (2015) : 5452–55. http://dx.doi.org/10.1039/c4cc06421f.

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1-Lithio-2-alkyl-1,2-dihydropyridines, easily formed from addition of (n- or t-)BuLi to pyridine, have been compared; the steric bulk of the branched alkyl substituent enforces lesser oligomerization, thus enhancing alkane solubility making it an amenable, convenient lithium hydride transfer reagent in non-polar, aliphatic media.
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16

Bade, Otto Morten, Richard Blom et Martin Ystenes. « A study of the catalyst formed when reacting lithium-alkyls with Cr(II)/SiO2 : ethylene polymerisation, diffuse reflectance infrared fourier transform spectroscopy and gas chromatography results ». Journal of Molecular Catalysis A : Chemical 135, no 2 (octobre 1998) : 163–79. http://dx.doi.org/10.1016/s1381-1169(97)00301-4.

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17

Zapała-Sławeta, Justyna. « Combined Influence of Lithium Nitrate and Metakaolin on the Reaction of Aggregate with Alkalis ». Materials 16, no 1 (30 décembre 2022) : 382. http://dx.doi.org/10.3390/ma16010382.

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The best known and effective methods for the reduction of the negative effects of an alkali–silica reaction in concrete include the application of mineral additives with an increased aluminium content and reduced share of calcium, as well as chemical admixtures in the form of lithium compounds. Because both aluminium and lithium ions increase the stability of reactive silica in the system with alkalis, it is possible to presume that the application of both corrosion inhibitors together will provide a synergistic effect in the ASR limitation. The paper presents the results of studies on the influence of combined application of metakaolin and lithium nitrate on the course of corrosion caused by the reaction of opal aggregate with alkalis. The potential synergistic effect was studied for the recommended amount of lithium nitrate, i.e., the Li/(Na + K) = 0.74 molar ratio and 5%, 10%, 15%, and 20% of cement mass replacements with metakaolin. The effectiveness of the applied solution was studied by measurements of mortars expansion in an accelerated test, by microstructure observations, and by determination of the ASR gels composition by means of SEM-EDS. The influence of metakaolin and the chemical admixture on the compressive and flexural strengths of mortars after 28 and 90 days of hardening were also analysed. The results of the studies revealed a synergistic effect for mixtures containing metakaolin at 15% and 20% cement replacement and lithium nitrate admixture in alkali–silica reaction expansion tests. It was found that corrosion processes in mortars with 5 and 10% levels of metakaolin became more severe after adding a lithium admixture to mortars with metakaolin only. The obtained results were confirmed by observations of the mortars’ microstructures. There was no synergistic impact of lithium nitrate and metakaolin on compressive strength characteristics. The compressive strength of mortars containing a combination of metakaolin and lithium nitrate decreased both after 28 and after 90 days, compared to mortars with metakaolin alone.
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18

Cai, Xiaoping, Barbara Gehrhus, Peter B. Hitchcock, Michael F. Lappert et J. Chris Slootweg. « The stable silylene Si[(NCH2tBu)2C6H4-1,2] : insertion into LiC or LiSi bonds of lithium alkyls LiR or [LiSi(SiMe3)3(THF)3] [R=Me, tBu or CH(SiMe3)2] ». Journal of Organometallic Chemistry 643-644 (février 2002) : 272–77. http://dx.doi.org/10.1016/s0022-328x(01)01273-6.

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19

Brooks, P., MJ Gallagher et A. Sarroff. « Organophosphorus Intermediates. IX. The Cleavage of α,ω-Bisdiphenylphosphinoalkanes With Lithium. A 13P N.M.R. Study ». Australian Journal of Chemistry 40, no 8 (1987) : 1341. http://dx.doi.org/10.1071/ch9871341.

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The title phosphines, Ph2P(CH2).PPh2 (n = 2-5), react with lithium in tetrahydrofuran to give the corresponding 1, n-dilithio-1, n-di(phenylphosphines) directly with little or no intermediacy of the 1-lithio- 1-phenyl- n- diphenylphosphinoalkanes which can, however, be obtained by arylation of the diphosphides. Methylenebisdiphenylphosphine and 1,4-diphenyl-1,4-diphosphinane undergo exclusive phosphorus-alkyl carbon cleavage. The chemistry and 31P n.m.r. spectroscopy of the diphosphides are described and the mechanism of the cleavage reaction is discussed. Some cleavage reactions in liquid ammonia are described.
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20

Dayaker, Gandrath, William Erb, Madani Hedidi, Floris Chevallier, Marielle Blot, Philippe C. Gros, Göran Hilmersson et al. « Enantioselective deprotometalation of alkyl ferrocenecarboxylates using bimetallic bases ». New Journal of Chemistry 45, no 48 (2021) : 22579–90. http://dx.doi.org/10.1039/d1nj04526a.

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21

Cai, Xiaoping, Barbara Gehrhus, Peter B. Hitchcock, Michael F. Lappert et J. Chris Slootweg. « The stable silylene Si[(NCH2Bu)2C6H4-1,2] : insertion into LiC or LiSi bonds of lithium alkyls LiR or [Li{Si(SiMe3)3}(THF)3] [R=Me, Bu or CH(SiMe3)2] ». Journal of Organometallic Chemistry 651, no 1-2 (mai 2002) : 150–56. http://dx.doi.org/10.1016/s0022-328x(02)01315-3.

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22

Pasynkiewicz, Stanisław, Antoni Pietrzykowski, Lidia Trojanowska, Piotr Sobota et Lucjan Jerzykiewicz. « Reactions of nickelocene with lithium and magnesium alkyls containing β-hydrogen atoms1Dedicated to Professor Ken Wade on the occasion of his 65th birthday in recognition of his outstanding contributions to organometallic chemistry.1 ». Journal of Organometallic Chemistry 550, no 1-2 (janvier 1998) : 111–18. http://dx.doi.org/10.1016/s0022-328x(97)00179-4.

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Xu, Mengqing, Liu Zhou, Yingnan Dong, Yanjing Chen, Julien Demeaux, Alex D. MacIntosh, Arnd Garsuch et Brett L. Lucht. « Development of novel lithium borate additives for designed surface modification of high voltage LiNi0.5Mn1.5O4 cathodes ». Energy & ; Environmental Science 9, no 4 (2016) : 1308–19. http://dx.doi.org/10.1039/c5ee03360h.

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24

Bass, Shekinah, Dynasty Parker, Tania Bellinger, Aireal Eaton, Angelica Dibble, Kaata Koroma, Sylvia Sekyi, David Pollard et Fenghai Guo. « Development of Conjugate Addition of Lithium Dialkylcuprates to Thiochromones : Synthesis of 2-Alkylthiochroman-4-ones and Additional Synthetic Applications ». Molecules 23, no 7 (15 juillet 2018) : 1728. http://dx.doi.org/10.3390/molecules23071728.

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Lithium dialkylcuprates undergo conjugate addition to thiochromones to afford 2-alkylthiochroman-4-ones in good yields. This approach provide an efficient and general synthetic approach to privileged sulfur-containing structural motifs and valuable precursors for many pharmaceuticals, starting from common substrates-thiochromones. Good yields of 2-alkyl-substituted thiochroman-4-ones are attained with lithium dialkylcuprates, lithium alkylcyanocuprates or substoichiometric amount of copper salts. The use of commercially available inexpensive alkyllithium reagents will expedite the synthesis of a large library of 2-alkyl substituted thiochroman-4-ones for additional synthetic applications.
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Cai, Xiaoping, Barbara Gehrhus, Peter B. Hitchcock, Michael F. Lappert et J. Chris Slootweg. « Erratum to “The stable silylene Si[(NCH2Bu)2C6H4-1,2] : insertion into LiC or LiSi bonds of lithium alkyls LiR or [LiSi(SiMe3)3(THF)3] [R=Me, Bu or CH(SiMe3)2]” ». Journal of Organometallic Chemistry 651, no 1-2 (mai 2002) : 149. http://dx.doi.org/10.1016/s0022-328x(02)01314-1.

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26

Sellmann, Dieter, Wolfgang Kern et Matthias Moll. « Transition metal complexes with sulphur ligands. Part 67. A novel type of reaction : nucleophilic alkylation of thiolato ligands by carbanions via intramolecular electron transfer. Alkylation and reduction of [W(S2C6H4)3] by lithium alkyls ». Journal of the Chemical Society, Dalton Transactions, no 7 (1991) : 1733. http://dx.doi.org/10.1039/dt9910001733.

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27

Luo, Yan-Long, Yu-Feng Liu et Bing-Tao Guan. « Alkyl lithium-catalyzed benzylic C–H bond addition of alkyl pyridines to α-alkenes ». Organic & ; Biomolecular Chemistry 18, no 34 (2020) : 6622–26. http://dx.doi.org/10.1039/d0ob01499k.

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28

Qi, Wen Bin, Chun Yan Tian et Xiao Xin Feng. « Alkali-Silica Reaction in Concrete Engineering Suppression Measures of Inquiry ». Applied Mechanics and Materials 529 (juin 2014) : 26–31. http://dx.doi.org/10.4028/www.scientific.net/amm.529.26.

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Local materials was used as raw materials in the test. Test methods are standard test methods. It compared the use of fly ash alone or lithium hydroxide used alone inhibited the effect of alkali-silica reaction, and to a certain percentage of fly ash and lithium hydroxide complex joint effect of inhibiting alkali-silica reaction in the test. The results showed that compound admixtures overcome the shortcomings of the use of fly ash alone or lithium hydroxide inhibition of alkali-silica reaction. It can achieve the goal of complementary advantages.
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Sharma, Hayden A., Jake Z. Essman et Eric N. Jacobsen. « Enantioselective catalytic 1,2-boronate rearrangements ». Science 374, no 6568 (5 novembre 2021) : 752–57. http://dx.doi.org/10.1126/science.abm0386.

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Asymmetric carbon coupling at boron The Matteson reaction produces carbon–carbon bonds by coupling halocarbons such as widely available dichloromethane with an alkyl substituent on boron. Sharma et al . report asymmetric catalysis of this reaction. Their catalyst, derived from a chiral thiourea, a boronic ester, and an alkyl lithium base, appears to accelerate a chloride abstraction step through its lithium center. The product, still bearing a chloride, can be further modified through stereospecific displacement to generate a wide variety of trisubstituted chiral centers. —JSY
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He, Ping, et Keith E. Johnson. « Electrochemical and 1H NMR studies of proton behavior of ImCl and LiCl solution in acetonitrile ». Canadian Journal of Chemistry 75, no 11 (1 novembre 1997) : 1730–35. http://dx.doi.org/10.1139/v97-606.

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The role of the proton in extending the electrochemical window and promoting the stripping efficiency of alkali metals has been studied in acetonitrile solution. The platinum hydride surface generated in the hydrogen evolution was considered responsible for the potential shift of 1-ethyl-3-methyl-1H-imidazolium (Im+) reduction in the absence of lithium. In lithium chloride solution, the lithium layer deposited on the electrode may be the main cause for the stretch of the solvent electrochemical window because of the high overpotential of Im+ reduction on that surface. The proton may affect the properties of the passive layer on newly deposited alkali metal surfaces and then improve the performance of the alkali metal anodes. Keywords: 1-ethyl-3-methyl-1H-imidazolium chloride, protons, acetonitrile, lithium reduction.
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31

Leung, Wing-Por, Hung-Kay Lee, Zhong-Yuan Zhou et Thomas C. W. Mak. « Reactions of pyridine-functionalized lithium alkyls with nickelocenes and nickel(II) chloride : respective formation of cyclopentadienyl-nickelalkyls and coupled organic products. X-Ray crystal structures of [(η5-C5H5)-2}] and {CH(SiMe 3)C5H4N-2}2 ». Journal of Organometallic Chemistry 462, no 1-2 (décembre 1993) : 7–12. http://dx.doi.org/10.1016/0022-328x(93)83335-s.

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32

Majewski, Marek, D. Mark Gleave et Pawel Nowak. « 1,3-Dioxan-5-ones : synthesis, deprotonation, and reactions of their lithium enolates ». Canadian Journal of Chemistry 73, no 10 (1 octobre 1995) : 1616–26. http://dx.doi.org/10.1139/v95-201.

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A general synthetic route to 2-alkyl- and 2,2-dialkyl-1,3-dioxan-5-ones, using tris(hydroxymethyl)-nitromethane as the starting material, is described. Deprotonation of these compounds was studied. It was established that these dioxanones could be deprotonated with LDA; however, the reduction of the carbonyl group via a hydride transfer from LDA, giving the corresponding dioxanols, often competed with deprotonation. The reduction could be minimized by using Corey's internal quench procedure to form silyl enol ethers and was less pronounced in 2,2-dialkyldioxanones (ketals) than in 2-alkyldioxanones (acetals). Self-aldol products were observed when dioxanone lithium enolates were quenched with H2O. Addition reactions of lithium enolates of dioxanones to aldehydes were threo-selective as predicted by the Zimmerman–Traxler model. Dioxanones having two different alkyl groups at the 2-position were deprotonated enantioselectively by chiral lithium amide bases with enantiomeric excess (ee) of up to 70%. Keywords: 1,3-dioxan-5-ones, enantioselective deprotonation, chiral lithium amides.
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33

Kojima, Seiji. « Mixed-Alkali Effect in Borate Glasses : Thermal, Elastic, and Vibrational Properties ». Solids 1, no 1 (19 novembre 2020) : 16–30. http://dx.doi.org/10.3390/solids1010003.

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When oxide glasses are modified by dissimilar alkali ions, a maximum in the electric resistivity or the expansion coefficient appears, called the mixed-alkali effect (MAE). This paper reviews the MAE on the thermal, elastic, and vibrational properties of the mixed-cesium lithium borate glasses, x{(1−y)Cs2O-yLi2O}-(1−x)B2O3. For the single-alkali borate glasses, xM2O(1−x)-B2O3 (M = Li, Na, K, Rb, and Cs), the glass transition temperature, Tg = 270 °C, of a borate glass monotonically increases as the alkali content x increases. However, for the mixed-cesium lithium borate glasses the Tg shows the minimum against the lithium fraction y. The dependences of the elastic properties on the lithium fraction y were discussed regarding the longitudinal modulus, Poisson’s ratio, and Cauchy-type relation. The internal vibrational bands related to the boron-oxide structural groups and the splitting of a boson peak were discussed based on Raman scattering spectroscopy. The MAE on various physical properties are discussed on the basis of the changes in the coordination number of the borons and the nonbridging oxygens caused by the dissimilar alkali ions.
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Min, Xin, Xiaodong Fan et Jie Liu. « Utilization of steric hindrance of alkyl lithium-based initiator to synthesize high 1,4 unit-containing hydroxyl- terminated polybutadiene ». Royal Society Open Science 5, no 5 (mai 2018) : 180156. http://dx.doi.org/10.1098/rsos.180156.

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A novel alkyl lithium-based initiator with relatively large steric hindrance, tert -butyldimethylsiloxydimethylpropyl lithium (TBDMSODPrLi), was designed and synthesized. By using TBDMSODPrLi, hydroxyl-terminated polybutadiene (HTPB) was prepared via anionic polymerization. The macromolecular structure of HTPB was characterized and verified by FTIR and 1 H-NMR. It was found that 1,4 unit content in HTPB initiated by TBDMSODPrLi was significantly higher (over 90%) compared to a HTPB (1,4 unit content of 70%) initiated with another initiator possessing smaller steric hindrance. The possible mechanism, which was based on initiator steric hindrance affecting monomer chain addition behaviour, was deduced. It was that the initiator's larger steric hindrance blocked lithium's intermolecular association during anionic polymerization; as a result, it could effectively increase the 1,4 unit content in HTPB. To further study how to obtain higher and stable 1,4 unit content, the optimal anionic polymerization technique for HTPB was explored including polymerization temperature, time and the amount of initiator used. The study concluded that utilization of an initiator with larger steric hindrance and reducing the polymerization temperature were two important factors to raise the 1,4 unit content in HTPB.
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Zhang, Lan Fang, et Rui Yan Wang. « Experimental Study on Alkali-Activated Slag-Lithium Slag-Fly Ash Environmental Concrete ». Advanced Materials Research 287-290 (juillet 2011) : 1237–40. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1237.

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The aim of this paper is to study the influence of lithium-slag and fly ash on the workability , setting time and compressive strength of alkali-activated slag concrete. The results indicate that lithium-slag and fly-ash can ameliorate the workability, setting time and improve the compressive strength of alkali-activated slag concrete，and when 40% or 60% slag was replaced by lithium-slag or fly-ash, above 10 percent increase in 28-day compressive strength of concrete were obtained.
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36

Piers, Edward, Timothy Wong et Keith A. Ellis. « Use of lithium (trimethylstannyl)(cyano)cuprate for the conversion of alkyl 2-alkynoates into alkyl (Z)- and (E)-3-trimethylstannyl-2-alkenoates ». Canadian Journal of Chemistry 70, no 7 (1 juillet 1992) : 2058–64. http://dx.doi.org/10.1139/v92-260.

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Reaction of functionalized alkyl 2-alkynoates (e.g., 13–19) with lithium (trimethylstannyl)(cyano)cuprate (3) under two sets of carefully defined experimental conditions provides, efficiently and stereoselectively, either alkyl (Z)- or (E)-3-trimethylstannyl-2-alkenoates (e.g., 23, 26–31 and 24, 32–37, respectively).
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37

You, Cai, et Armido Studer. « Three-component 1,2-carboamination of vinyl boronic esters via amidyl radical induced 1,2-migration ». Chemical Science 12, no 47 (2021) : 15765–69. http://dx.doi.org/10.1039/d1sc05811h.

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Zhang, Jiaxiang, Junwen Yang, Limin Yang, Hai Lu, Huan Liu et Bin Zheng. « Exploring the redox decomposition of ethylene carbonate–propylene carbonate in Li-ion batteries ». Materials Advances 2, no 5 (2021) : 1747–51. http://dx.doi.org/10.1039/d0ma00847h.

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39

Demyan, V., V. Mikhailenko et I. Zhukova. « Electrochemical method of obtaining copper (II) oxide powders in alkaline electrolyte ». Journal of Physics : Conference Series 2131, no 4 (1 décembre 2021) : 042021. http://dx.doi.org/10.1088/1742-6596/2131/4/042021.

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Abstract Within the framework of these studies, an electrochemical method for the synthesis of highly dispersed powders of copper compounds in aqueous solutions of alkalis is presented. The factors influencing the rate of production of nanoscale copper (II) oxide particles are determined. It is shown that during the anodic oxidation of copper by direct current, the speed of highly dispersed powders formation depends on current density, the nature of alkali cation, and the concentration of electrolyte solution. The mass loss of copper electrodes in NaOH solution is higher than in solutions of potassium hydroxide and lithium hydroxide by 10% and 12%, respectively. This experiment suggests that the studied alkalis act similarly on the anodic behavior of copper and the nature of cation does not significantly affect the speed of anodes destruction. The change in the concentration of alkali solution practically does not affect the mass loss of copper electrodes. The speed of copper oxidation remains almost constant over time, but noticeable weight loss and, accordingly, the speed of copper dissolution is achieved within 15 minutes. The speed of copper oxidation does not depend on current density. It is determined by the amount of electricity that has passed. The current density of 1 A/cm2 can be considered optimal.
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Lin, Ye Ting, Chang Jiang Yu, Li Zhu, Xue Qiong Yin, Bang Sheng Lao et Qiang Lin. « Synthesis and Characterization of Alkyl Bacterial Cellulose through Etherification with Alkyl Bromide in DMAc/LiCl ». Applied Mechanics and Materials 320 (mai 2013) : 478–82. http://dx.doi.org/10.4028/www.scientific.net/amm.320.478.

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Four types of alkyl (ethyl, propyl, isopropyl, n-butyl) bacterial cellulose with the degree of substitution 0.14-2.64 were prepared through etherification of bacterial cellulose with alkyl bromide in dimethyl acetamide/lithium chloride solution under ambient pressure at 50°C, with sodium hydride as the acid binding agent. The products were characterized through FTIR, NMR, and elemental analysis. The solubility of the derivatives in chloroform, ethanol, DMSO, and toluene/ethanol (V/V 3/7) was tested. Key words: alkyl bacterial cellulose, alkyl bromide, synthesis, characterization
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41

Abeysooriya, Shanika, Minjae Lee, Luke A. O’Dell et Jennifer M. Pringle. « Plastic crystal-based electrolytes using novel dicationic salts ». Physical Chemistry Chemical Physics 24, no 8 (2022) : 4899–909. http://dx.doi.org/10.1039/d1cp04314e.

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Khan, Md Sharif, Ambroise Van Roekeghem, Stefano Mossa, Flavien Ivol, Laurent Bernard, Lionel Picard et Natalio Mingo. « Ionic Liquid Crystals As Solid Organic Electrolytes for Li-Ion Batteries : Experiments and Modeling ». ECS Meeting Abstracts MA2022-01, no 2 (7 juillet 2022) : 183. http://dx.doi.org/10.1149/ma2022-012183mtgabs.

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The development of the new electrolytes is essential to increase the energy density of the Li-ion batteries (LIBs)1. Solid electrolytes have attracted the interest of researchers as a next-generation electrolyte for LIBs due to their superior physical and chemical stability, large working potential windows, high transference number, and intrinsic safety2 3. In this study, we have designed and synthesized novel organic electrolytes for LIBs with a naphthalene mesogenic moiety bearing a lithium sulfonate group connected to two flexible long-alkyl chains. Starting from the lithium 4-aminonaphthalene-1-sulphonate building block, alkyl-tails were successfully doubly grafted on the amine function with N, N-di-isopropylethylamine in N, N-di-methylformamide. Once the reaction was completed, a washing, purification and neutralization step was carried out to obtain the desired product. Those electrolytes have been synthesized with 95 % purity as suggested from the NMR and mass spectrum. The chains length were differ by the number of alkyl groups in the chains from 8, 12, and 16, namely lithium 4 - (dioctylamino) naphthalene – 1 – sulfonate (BS-Li-8), lithium 4 - (didodecylamino) naphthalene – 1 - sulfonate (BS-Li-12), and lithium 4 - (dihexadecylamino) naphthalene – 1 – sulfonate (BS-Li-16). We have employed molecular dynamics simulations and various experimental techniques for a comprehensive understanding of the bulk structure and transport mechanism of those electrolytes. Simulated static structural factor, radial distribution functions, and experimental small angle x-ray scattering spectrum suggest that degree of aggregation, ionic correlations, and structural properties of materials at the nanoscale of the electrolyte molecules varies with the length of the alkyl chains. The Li+ ion mobility calculated from experimental Electrochemical Impedance Spectra, using a symmetrical cell with blocking electrodes and molecular dynamics simulations reveal that BS-Li-12 is the most conductive (approximately 10-3 S / cm at 1400 C) owing to the weaker cation-anion correlation than others. It was observed that the conductivity of the Li+ ions is directly related to the coordination number between Li+ and anionic centers, since, in BS-Li-12, Li+ coordinates with two anionic centers while for others, it is three. During the conduction, Li+ move from one anionic site to another by changing their coordination number with anion. We successfully synthesized next-generation organic electrolytes with well-organized Li+ conduction channels. The comprehensive study of the influence of the nonpolar alkyl chain on the bulk structural arrangement and conductivity of such electrolytes will contribute significantly to the development of future LIBs electrolytes. References: (1) Armand, M.; Tarascon, J.-M. Building Better Batteries. Nature 2008, 451 (7179), 652–657. https://doi.org/10.1038/451652a. (2) Manthiram, A.; Yu, X.; Wang, S. Lithium Battery Chemistries Enabled by Solid-State Electrolytes. Nature Reviews Materials 2017, 2 (4), 16103. https://doi.org/10.1038/natrevmats.2016.103. (3) Quartarone, E.; Mustarelli, P. Electrolytes for Solid-State Lithium Rechargeable Batteries: Recent Advances and Perspectives. Chem. Soc. Rev. 2011, 40 (5), 2525–2540. https://doi.org/10.1039/C0CS00081G. Figure 1
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43

French, R. J., et J. J. Shoukimas. « An ion's view of the potassium channel. The structure of the permeation pathway as sensed by a variety of blocking ions. » Journal of General Physiology 85, no 5 (1 mai 1985) : 669–98. http://dx.doi.org/10.1085/jgp.85.5.669.

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We have studied the block of potassium channels in voltage-clamped squid giant axons by nine organic and alkali cations, in order to learn how the channel selects among entering ions. When added to the internal solution, all of the ions blocked the channels, with inside-positive voltages enhancing the block. Cesium blocked the channels from the outside as well, with inside-negative voltages favoring block. We compared the depths to which different ions entered the channel by estimating the "apparent electrical distance" to the blocking site. Simulations with a three-barrier, double-occupancy model showed that the "apparent electrical distance," expressed as a fraction of the total transmembrane voltage, appears to be less than the actual value if the blocking ion can pass completely through the channel. These calculations strengthen our conclusion that sodium and cesium block at sites further into the channel than those occupied by lithium and the organic blockers. Our results, considered together with earlier work, demonstrate that the depth to which an ion can readily penetrate into the potassium channel depends both on its size and on the specific chemical groups on its molecular surface. The addition of hydroxyl groups to alkyl chains on a quaternary ammonium ion can both decrease the strength of binding and allow deeper penetration into the channel. For alkali cations, the degree of hydration is probably crucial in determining how far an ion penetrates. Lithium, the most strongly hydrated, appeared not to penetrate as far as sodium and cesium. Our data suggest that there are, minimally, four ion binding sites in the permeation pathway of the potassium channel, with simultaneous occupancy of at least two.
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44

Zirzow, Karl-Heinz, et Alfred Schmidpeter. « Dialkylamino-phenyldi- und -triphosphide aus dem (PhP)5-Abbau mit Alkaliamiden / Dialkylamino-phenyldi- and -triphosphides from the Degradation of (PhP)5 by Alkali Amides ». Zeitschrift für Naturforschung B 42, no 9 (1 septembre 1987) : 1083–87. http://dx.doi.org/10.1515/znb-1987-0905.

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(PhP)5 and lithium dialkylamides in tetrahydrofuran form equilibrium mixtures of lithium aminophenylphosphides (PhP)nNR- with n = 3 and (mainly) 2. The monophosphides (n = 1) are not formed; it is concluded that they are generally unstable, decomposing to aminodiphosphides and cyclophosphines. Alkylation of an equilibrium mixture gives 1-alkyl-2-dialkylamino-diphenyl- diphosphines which, however, are thermally unstable. (PhP)5 degradation equilibria using differ­ent anionic nucleophiles are compared.
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45

de Jong, B. H. W. S., H. T. J. Supèr, A. L. Spek, N. Veldman, W. van Wezel et V. van der Mee. « Structure of KLiSi2O5 and the hygroscopicity of glassy mixed alkali disilicates ». Acta Crystallographica Section B Structural Science 52, no 5 (1 octobre 1996) : 770–76. http://dx.doi.org/10.1107/s0108768196001656.

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KLiSi2O5, Mr = 182.21, λ(Mo Kα) = 0.71073 Å, 150 K, monoclinic, P21, a = 5.9803 (6), b = 4.7996 (6), c = 8.1599 (11) Å, β = 93.477 (10)°, V = 233.78 (5) Å3, μ(MoKα) = 15.7 cm−1, Z = 2, F(000) = 180, Dx = 2.5885 (6) Mg m−3, R 1 = 0.0331 for 1023 reflections with I > 2.0σ(I), wR 2 = 0.0864 for all 1064 reflections. The crystal structure of potassium lithium phyllosilicate has been determined and the hygroscopicity of glassy single and mixed alkali disilicates has been measured. The potassium lithium phyllosilicate sheet topology is the same as that of lithium phyllosilicate, consisting of six-membered silica rings in a chair configuration. Li is fourfold oxygen coordinated by three non-bridging O and one bridging O, while K is sixfold oxygen coordinated by five non-bridging O and one bridging O. The K atoms are sandwiched between the LiSi2O5 layer. Crystalline and glassy lithium disilicate are not hygroscopic. Crystalline and glassy potassium disilicate are the most hygroscopic alkali disilicates known to date, whereas the mixed system, crystalline and glassy lithium potassium disilicate, is again not hygroscopic. Calculated valences for lithium potassium phyllosilicate do not provide a rationale for these observations.
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46

Bekker, R. A., et Yu V. Bykov. « Lithium Preparations in Psychiatry, Addiction Medicine and Neurology. Part II. Biochemical Mechanisms of Its Action ». Acta Biomedica Scientifica 4, no 2 (25 mai 2019) : 80–100. http://dx.doi.org/10.29413/abs.2019-4.2.13.

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Lithium is the first and the lightest in the series of alkali metals, to which, in addition to lithium, two very biologically important elements – sodium and potassium, as well as trace elements rubidium and cesium, belong. Despite its formal affiliation to the group of alkali metals, lithium, like many other chemical elements of the «atypical» second period of the periodic table (for example, boron), is more similar in its chemical properties not to its counterparts in the group, but to its «diagonal brother» – magnesium. As we will show in this article, the diagonal chemical similarity between lithium and magnesium is of great importance for understanding the mechanisms of its intracellular biochemical action. At the same time, the intragroup chemical similarity of lithium with sodium and potassium is more important for understanding the mechanisms of its absorption, its distribution in the body and its excretion. Despite the 70 years that have passed since John Cade’s discovery of the antimanic effect of lithium, the mechanisms of its therapeutic action are still not completely understood. In the end, it turns out that the mechanism of the therapeutic action of lithium is extremely complex, multicomponent, unique and not imitable. Certain aspects of the mechanism of its action may be compatible with the mechanisms of action of other mood stabilizers, or with the mechanisms of action of so-called «lithium-mimetics», such as ebselen. However, no other drug to date failed to fully reproduce the biochemical effect of lithium on the body.
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47

Lochmann, Lubomír, et Jiří Trekoval. « Lithium - Heavier alkali metal exchange in organolithium compounds induced by alkoxides of heavier alkali metals and reactions occurring in this system ». Collection of Czechoslovak Chemical Communications 53, no 1 (1988) : 76–96. http://dx.doi.org/10.1135/cccc19880076.

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Organolithium compounds of various types undergo an exchange reaction lithium-heavier alkali metal when treated with heavier alkali metal alkoxides. In the presence of a third reactive compound the exchange reaction gives rise to a compound of the third component substituted with the heavier alkali metal. Using this exchange reaction, organic derivatives of heavier alkali metals in the individual state can be easily prepared. The mechanism of such reactions is discussed, and the formation of lithium alkoxide is assumed to contribute significantly to the driving force of the reaction. Organic compounds of heavier alkali metals possess a considerably higher reactivity than organolithium compounds, and are therefore used as reactive intermediates in preparative chemistry, or as polymerization initiators in macromolecular chemistry. This review provides information about the scope and possibilities of this exchange reaction, which has been increasingly widely used in the recent years.
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48

Halcovitch, Nathan R., et Michael D. Fryzuk. « Iminoacyl Alkyl Complexes of Zirconium Supported by a Ferrocene-Linked Diphosphinoamide Ligand Scaffold ». Australian Journal of Chemistry 69, no 5 (2016) : 555. http://dx.doi.org/10.1071/ch15763.

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Zirconium dialkyl complexes of the general formula fc(NPiPr2)2ZrR2 (where fc = 1,1′-ferrocenyl, R = CH3, CH2Ph, CH2tBu, tBu) have been synthesized and characterized via the addition of alkyl lithium or potassium benzyl derivatives to the dichloride complex fc(NPiPr2)2ZrCl2(THF). Addition of 2,6-dimethylphenylisocyanide to these alkyl derivatives generates the corresponding mono iminoacyl alkyl zirconium complexes. On thermolysis, the iminoacyl moiety containing a benzyl substituent undergoes rearrangement to yield a new complex that contains an alkene-amido fragment. Mechanistic studies point to a 1,2 hydrogen shift as the rate-determining step.
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49

Deng, Yu Hai, Chang Qing Zhang, Hai Qiang Shao, Han Wu et Nie Qiang Xie. « Effects of Different Lithium Admixtures on Ordinary Portland Cement Paste Properties ». Advanced Materials Research 919-921 (avril 2014) : 1780–89. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1780.

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Lithium-based chemicals are known to their signal effect on restraining alkali-silica reaction but uncertain influence on workability and mechanical property in the concrete. The aim of this research is to analyze the effects of three lithium additiveslithium nitrate (LiNO3), lithium hydroxide (LiOH) and lithium carbonate (Li2CO3) at various dosages, with an extensive comparison on fluidities, setting times and compressive strength of cement pastes. The experimental study shows that test results vary with the type of admixture. In general, three conclusions can be made: 1) lithium nitrate and lithium hydroxide can enhance the fluidity of cement paste, but lithium carbonate has opposite effects; 2) all three lithium salts shorten setting time as well as decrease the strength at suitable dosages; 3) the variations in lithium additives dosages have different influence on the cement pastes setting time and compressive strength development.
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Lochmann, Lubomír, et Miroslav Janata. « 50 years of superbases made from organolithium compounds and heavier alkali metal alkoxides ». Open Chemistry 12, no 5 (1 mai 2014) : 537–48. http://dx.doi.org/10.2478/s11532-014-0528-0.

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AbstractA review of reactions of organolithium compounds (RLi) with alkali metal alkoxides is presented. On the one hand, simple lithium alkoxides form adducts with RLi the reactivity of which differs only slightly from that of RLi. On the other hand, after mixing heavier alkali metal alkoxides (R’OM, M = Na, K, Rb, Cs) with RLi, a new system is formed, which has reactivity that dramatically exceeds that of the parent RLi. A metal interchange, according to the equation RLi + R’OM = RM + R’OLi, occurs in this system, giving rise to a superbase. This reaction is frequently used for the preparation of heavier alkali metal organometallic compounds. Similar metal interchange takes place between R’OM and compounds such as lithium amides and lithium enolates of ketones or esters, thus demonstrating the general nature of this procedure. Superbases react easily with many types of organic compounds (substrates), resulting in the formation of a heavier alkali metal derivative of the substrate (metalation). The metalated substrate can react in situ with an electrophile to yield the substituted substrate, a procedure that is frequently used in synthetic and polymer chemistry. An improved mechanism of metal interchange and reaction of superbases with substrates is proposed.
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