- Selective dimerization of cyclohexene over a Re2O7-B2O3/Al2O3 catalyst under mild conditions
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A Re2O7-B2O3/Al2O3 catalyst was demonstrated to reveal significant activity in cyclohexene dimerization into 1-cyclohexenylcyclohexane with a total yield of 95 % and a selectivity close to
- Greish, Alexander A.,Barkova, Alexandra P.,Finashina, Elena D.,Salmi, Tapio O.,Kustov, Leonid M.
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Read Online
- Kinetic study of the hydrodenitrogenation of carbazole over bulk molybdenum carbide
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Hydrodenitrogenation (HDN) of N-containing compounds (carbazole in this paper) in the presence of a small amount of sulfur (50 ppm) requires a strong catalytic hydrogenating function. Bulk molybdenum carbide, Mo2C, behaves like a noble metal and has strong hydrogenating properties and can catalyse deep HDN if the S content is not too high. A kinetic investigation monitored both the hydrogenating function through carbazole consumption and the HDN of carbazole through two kinetically coupled cycles. Biphenyl was not observed. Kinetic coupling occurs by means of adsorbed orthocyclohexylaniline. The first route is the direct HDN reaction, leading to cyclohexylbenzene, while the second hydrogenation route leads to bicyclohexyl. At 633 K, a zero-order reaction is observed with respect to carbazole; total HDN is observed for 0.4 s, and the selectivity ratio of bicyclohexyl to cyclohexylbenzene is equal to 9.
- Szymanska, Agnieszka,Lewandowski, Marek,Sayag, Celine,Djega-Mariadassou, Gerald
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- Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
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The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
- Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
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supporting information
p. 5611 - 5615
(2019/08/01)
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- Promising Ni/Al-SBA-15 catalysts for hydrodeoxygenation of dibenzofuran into fuel grade hydrocarbons: Synergetic effect of Ni and Al-SBA-15 support
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This work has been undertaken with the aim of designing promising noble-metal-free catalysts for efficient hydrodeoxygenation (HDO) of dibenzofuran (DBF) into fuel grade hydrocarbons. For this, various Ni/Al-SBA-15 catalysts with different Si/Al (50, 60, 70 and 80) mole ratios were synthesized and their catalytic performance was tested for HDO of DBF in a batch reactor. The catalysts were systematically characterized using XRD, N2-adsorption-desorption, Raman, H2-TPR, NH3-TPD, XRF, and FESEM techniques. The activity results showed that the HDO of DBF proceeds via hydrogenation of benzene on the Ni sites followed by cleavage of C-O bonds on the acidic sites of the catalyst to yield unsaturated hydrocarbons. Further hydrogenation of unsaturated hydrocarbons on the Ni sites gives bicyclohexane as the major product. Remarkably, a 100% DBF conversion was found for all the catalysts except for Ni/SBA-15 and Ni/Al-SBA-15(80) (Si/Al mole ratio = 80) catalysts, which showed 97.97 and 99.31%, respectively. A significant observation noticed in this study is that the incorporation of Al into Ni/SBA-15 results in an outstanding improvement in the selectivity of the bicyclohexane product. Among the catalysts tested, the Ni/Al-SBA-15(50) (Si/Al mole ratio = 50) catalyst showed the highest efficiency, with superior selectivity of ~87% for bicyclohexane and ~96% degree of deoxygenation at 10 MPa, 260 °C and 5 h. The obtained structure-activity results reveal the synergetic effect of Ni and support in HDO of DBF reaction: the concentration of acidic sites has a significant effect on the selectivity of the desired products.
- Gbadamasi, Sharafadeen,Ali, Tammar Hussein,Voon, Lee Hwei,Atta, Abdulazeez Yusuf,Sudarsanam, Putla,Bhargava, Suresh K.,Abd Hamid, Sharifah Bee
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p. 25992 - 26002
(2016/03/25)
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- Effective hydrodeoxygenation of dibenzofuran by a bimetallic catalyst in water
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Effective hydrodeoxygenation (HDO) of dibenzofuran (DBF) catalyzed by a bimetallic nickel/platinum (Ni/Pt) catalyst in water was demonstrated at 200 °C and 1.2 MPa hydrogen (H2) pressure. The bimetallic catalysts prepared by a wet chemical method exhibit prominent activity that overcomes the limitations of use of a single Ni or Pt metal catalyst. The yield of HDO products can be up to 90%. Reaction results indicate that the conversion of DBF was affected by the reaction temperature and H2 pressure. The deoxygenation selectivity was strongly dependent on reaction temperature. The reaction pathway is also proposed.
- Dong, Peng,Lu, Guo-Ping,Cai, Chun
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p. 1605 - 1609
(2016/02/19)
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- Following solid-acid-catalyzed reactions by MAS NMR spectroscopy in liquid phase - Zeolite-catalyzed conversion of cyclohexanol in water
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A microautoclave magic angle spinning NMR rotor is developed enabling insitu monitoring of solid-liquid-gas reactions at high temperatures and pressures. It is used in a kinetic and mechanistic study of the reactions of cyclohexanol on zeolite HBEA in 130 °C water. The 13Cspectra show that dehydration of 1-13C-cyclohexanol occurs with significant migration of the hydroxy group in cyclohexanol and the double bond in cyclohexene with respect to the 13C label. A simplified kinetic model shows the E1-type elimination fully accounts for the initial rates of 1- 13C-cyclohexanol disappearance and the appearance of the differently labeled products, thus suggesting that the cyclohexyl cation undergoes a 1,2-hydride shift competitive with rehydration and deprotonation. Concurrent with the dehydration, trace amounts of dicyclohexyl ether are observed, and in approaching equilibrium, a secondary product, cyclohexyl-1-cyclohexene is formed. Compared to phosphoric acid, HBEA is shown to be a more active catalyst exhibiting a dehydration rate that is 100-fold faster per proton. Hot analysis: The catalytic conversion of cyclohexanol on zeolite HBEA in hot liquid water leads to dehydration as well as alkylation products. A novel microautoclave suitable for application in magic angle spinning (MAS) NMR at high temperatures has been successfully applied to obtain new insight into the mechanistic pathway leading to an understanding of the reactions under selected experimental conditions.
- Vjunov, Aleksei,Hu, Mary Y.,Feng, Ju,Camaioni, Donald M.,Mei, Donghai,Hu, Jian Z.,Zhao, Chen,Lercher, Johannes A.
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supporting information
p. 479 - 482
(2014/01/23)
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- Selective dimerization of higher cycloolefins in the presence of micro- and micromesoporous zeolite catalysts
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Selective synthesis of dimers of cycloolefins C6-C8 was carried out in the presence of highly dispersed zeolite catalysts HY, HBeta, and HZSM-12 and granulated zeolite HY-WB, which differ in acidic properties and pore structure. The high selectivity of microporous zeolite HZSM-12 in cyclohexene dimerization (100%) and micromesoporous zeolite HY-WB in cycloheptene and cyclooctene dimerization (90-95%) was established.
- Grigor'Eva,Bubennov,Khazipova,Khalilov,Kutepov
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p. 444 - 449
(2014/01/17)
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- Fluorinated metal oxide-assisted oligomerization of olefins
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Fluorinated alumina is an efficient catalyst for hex-1-ene, cyclohexene and isobutene oligomerization, whereas fluorinated titania and zirconia are inactive.
- Lermontov, Sergey A.,Malkova, Alena N.,Yurkova, Lyudmila L.,Ivanov, Vladimir K.,Baranchikov, Alexander E.,Vasilyeva, Larisa P.
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p. 110 - 112
(2013/05/21)
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- Comparison of the catalytic activity of [(η5-C 5H5)Ru(2,2′-bipyridine)(L)]OTf versus [(η5-C5H5)Ru(6,6′-diamino-2,2′- bipyridine)(L)]OTf (L = labile ligand) in the hydrogenation of cyclohexanone. Evidence for the presence of a metal-ligand bifunctional mechanism under acidic conditions
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The two title complexes as well as the dimeric complex [Ru(II) (η5-C5H5)(6,6′-diamino-2,2′- bipyridine)]2(OTf)2 have been synthesized and characterized by NMR and single-crystal X-ray crystallography. The direct structural comparison of the 2,2′-bipyridine and 6,6′-diamino-2, 2′-bipyridine complexes suggests that the electronic and steric environments of the ruthenium centers in both complexes are essentially equivalent, providing for a unique opportunity to probe the influence of the noncoordinated amine substituent on the relative reactivity and catalytic activity of the complexes. Opposite to what would be anticipated on the basis of steric effects, the bulkier amine-substituted ligand results in a catalyst showing substantially higher activity in the hydrogenation of cyclohexanone in acidic medium, which is attributed to the operation of a metal-ligand bifunctional hydrogenation mechanism mediated by the amine substituents in their protonated form acting as proton shuttles.
- Dimondo, Domenico,Thibault, Michelle E.,Britten, James,Schlaf, Marcel
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p. 6541 - 6554
(2013/12/04)
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- Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
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Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
- Yurkova, L. L.,Lermontov, S. A.,Kazachenko, V. P.,Ivanov, V. K.,Lermontov, A. S.,Baranchikov, A. E.,Vasil'Eva, L. P.
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p. 1012 - 1019,8
(2012/12/11)
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- Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
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Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
- Yurkova,Lermontov,Kazachenko,Ivanov,Lermontov,Baranchikov,Vasil'Eva
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p. 1012 - 1019
(2013/01/15)
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- Organic-inorganic hybrid saponites obtained by intercalation of titano-silsesquioxane
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The synthesis and characterization of two bifunctional composite materials based on synthetic saponite clays is here presented. These materials were prepared by intercalation of a Ti-containing aminopropylisobutyl polyhedral oligomeric silsesquioxane (Ti-NH2POSS) in synthetic saponite samples containing interlayer sodium (Na-SAP) or protons (H-SAP). Hybrid organic-inorganic materials, Ti-NHM-1 and Ti-NHM-2, were obtained upon ion exchange. Structural, spectroscopic, and thermal properties of both hybrid materials were investigated in detail along with their catalytic activity in cyclohexene oxidation. In questo lavoro sono descritte la sintesi e la caratterizzazione di due materiali compositi bifunzionali a base di saponiti sintetiche. Tali materiali sono stati preparati tramite intercalazione di Ti-aminopropilisobutilPOSS (Ti-NH2POSS) in saponiti sintetiche contenenti nello spazio interlamellare ioni sodio (Na-SAP) o protoni (H-SAP). Tali materiali compositi ibridi organici/inorganici, denominati rispettivamente Ti-NHM-1 e Ti-NHM-2, sono stati sintetizzati tramite reazioni di scambio ionico. Sono state studiate in dettaglio sia le proprieta strutturali, spettroscopiche e termiche di tali ibridi, che la loro attivita catalitica per l'ossidazione del cicloesene. Two hybrid materials, Ti-NHM-1 and Ti-NHM-2, were prepared by the intercalation of a bifunctional titanium-containing silsesquioxane Ti-NH3POSS in the interlayer spaces of synthetic sodium and protonic saponites, respectively. The bifunctional character (acid and redox) of Ti-NHM-2 was also investigated in detail.
- Carniato, Fabio,Bisio, Chiara,Gatti, Giorgio,Guidotti, Matteo,Sordelli, Laura,Marchese, Leonardo
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experimental part
p. 914 - 921
(2011/10/03)
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- ω-Ethylenic allylic substrates as alternatives to cyclic substrates in copper- and iridium-catalyzed asymmetric allylic alkylation
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"Chemical Equation Presented" A new strategy to access highly enantioenriched cyclic compounds (up to 98%) Is proposed using ω-ethylenic allylic substrates through a one-pot asymmetric allylic alkylation and ring-closing metathesis. Such starting compounds can be seen as synthetic equivalents of cyclic allylic substrates.
- Giacomina, Francesca,Riat, David,Alexakis, Alexandre
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supporting information; experimental part
p. 1156 - 1159
(2010/05/18)
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- Palladium supported on an acidic resin: A unique bifunctional catalyst for the continuous catalytic hydrogenation of organic compounds in supercritical carbon dioxide
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1% Palladium-doped acidic resin (Amberlyst 15; styrene-divinylbenzene matrix with sulfonic acid groups) is shown to be a highly active catalyst for the continuous catalytic hydrogenation of C=C bonds in supercritical carbon dioxide (scCO2) without affecting C=O bonds. This 1% Pd/Amberlyst-15 catalyst promotes the industrially important selective formation of 2-ethylhexanal from crotonaldehyde in a one-pot pathway involving hydrogenation and aldol condensation witha number of merits. The selectivity behavior of 1% Pd/Amberlyst-15 is strikingly different compared to that of 1% Pd/C and 1% Pd/Al2O3 due to its prominent bifunctional nature based on sulfonic acid groups adjacent to metallic Pd sites. Hybrid [Pdn-H]+ sites are suggested to act as bothmet al and acid sites promoting the bifunctional catalysis.
- Seki, Tsunetake,Grunwaldt, Jan-Dierk,Van Vegten, Niels,Baiker, Alfons
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body text
p. 691 - 705
(2009/04/12)
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- Hydroamination and hydroalkoxylation catalyzed by triflic acid. Parallels to reactions initiated with metal triflates
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(Chemical Equation Presented) Intermolecular additions of the O-H bonds of phenols and alcohols and the N-H bonds of sulfonamides and benzamide to olefins catalyzed by 1 mol % of triflic acid and studies to define the relationship between these reactions and those catalyzed by metal triflates are reported. Cyclization of an alcohol containing pendant monosubstituted and trisubstituted olefins catalyzed by either triflic acid or metal triflates form products from addition to the more substituted olefin, and additions of tosylamide catalyzed by triflic acid or metal triflates form indistinguishable ratios of the two N-alkyl sulfonamides.
- Rosenfeld, Devon C.,Shekhar, Shashank,Takemiya, Akihiro,Utsunomiya, Masaru,Hartwig, John F.
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p. 4179 - 4182
(2007/10/03)
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- High selectivity of MCM-22 for cyclopentanol formation in liquid-phase cyclopentene hydration
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Highly effective formation of cyclopentanol through the liquid-phase hydration of cyclopentene has been attempted on various zeolites catalysts. MCM-22 zeolite was the most selective catalyst, which actively converted cyclopentene to cyclopentanol with a selectivity up to 99%. The effects on the hydration of catalyst preparation method, reaction atmosphere and temperature have been investigated for the MCM-22 catalysts. On the basis of the effect of reaction atmosphere, the mechanism of liquid-phase cyclopentene hydration was proposed. The thermodynamic equilibrium between cyclopentene and cyclopentanol was suggested to control greatly the cyclopentene conversion. The cyclopentene conversion was increased to 10% by increasing the water/cyclopentene ratio. Poisoning using organic amines with different molecular sizes revealed that the hydration occurred mainly in the 10-membered ring channels of MWW structure, which had an elliptic aperture smaller than that of MFI structure, exhibiting a significant shape selectivity by suppressing the etherification cyclopentanol.
- Nuntasri, Duangamol,Wu, Peng,Tatsumi, Takashi
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p. 272 - 280
(2007/10/03)
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- Highly selective formation of cyclopentanol through liquid-phase cyclopentene hydration over MCM-22 catalysts
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MCM-22 catalyst exhibits an extremely high shape selectivity not observed on other zeolites of MFI, MOR and BEA structures, in that it effectively catalyzes the liquid-phase hydration of cyclopentene at a conversion up to 10% and a cyclopentanol selectivi
- Nuntasri, Duangamol,Wu, Peng,Tatsumi, Takashi
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p. 224 - 225
(2007/10/03)
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- New Low-Valent Titanium Reagents for Dicarbonyl Coupling and Their Use in a General Method of Annulation
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New low-valent titanium reagents have been prepared by reducing TiCl3 (1 mol) with C8K (2 mol) or by reducing TiCl4 (1 mol) with Na-naphthalene (2.75 mol).Ketones carrying a chain that incorporates a suitably placed oxo function (aldehyde or ketone) undergo intramolecular dicarbonyl coupling to produce a bicyclic compound when treated with an excess (16-17 mol of titanium halide per mol of dicarbonyl compound) of one of these reagents.The procedure works well even for highly oxygenated substrates and constitutes a general method of annulation.Other reducing agents besides C8K or Na-naphthalene are suitable, and a brief examination of Na(Hg) and Na-K alloy was made.The C8K/TiCl3 system was also used to convert a cis-1,2-diol into the corresponding olefin.
- Clive, Derrick L. J.,Zhang, Chengzhi,Murthy, K. S. Keshava,Hayward, William D.,Daigneault, Sylvain
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p. 6447 - 6458
(2007/10/02)
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- Addition of methanetrisulfonyl fluoride to unsaturated bonds
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The reactions of methanetrisulfonyl fluoride, HC(SO2F)3 with acrylic acid derivatives lead to addition products containing the tris(fluorosulfonyl)methyl group, while methyl vinyl ketone gives an unstable adduct.The methyl ester of propiolic acid is converted to a mixture of cis- and trans-tris(fluorosulfonyl)crotonic acid esters.The reaction of cyclohexene with methanesulfonyl fluoride leads to dimerization of the olefin and the cyclohexyl derivative is formed in low yield.
- Yagupol'skii, Yu. L.,Gerus, I. I.,Savina, T. I.
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- MECHANISM AND STEREOCHEMISTRY OF OXETANE REACTIONS. IV. REGIO- AND STEREOCHEMISTRY OF THE REACTIONS OF 6-(CYCLOHEXYL)-7-OXABICYCLOOCTANE UNDER ACIDIC CONDITIONS
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Previous work on 2-aryl substituted oxetanes (1a,b) have now been extended to an aliphatic-substituted one, the cyclohexyl derivative 1c, in order to verify the effect of an aliphatic group on the ring opening of the four-membered heterocyclic system.Somewhat surprisingly, the ring opening reactions of 1c were regiospecific but not anti-stereoselective, affording mixtures consisting of minor amounts of the syn (3c) and anti (4c) addition products, together with substantial amounts of the olefin 5c and of the unsaturated alcohol 6c.The results obtained in the reactions of 1c further confirm that the chemical behaviour of oxetanes under acidic conditions differs significantly from that of the corresponding oxiranes.A possible rationalisation of the results is given in term of intermediate structures implying a high degree of carbocationic character on the tertiary carbon.
- Crotti, Paolo,Macchia, Franco,Stoppioni, Annalisa,Turbanti, Luigi
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p. 411 - 418
(2007/10/02)
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- HIGHLY REACTIVE METALS FROM POTASSIUM-GRAPHITE. PREPARATION AND USE OF TITANIUM-GRAPHITE AND TIN-GRAPHITE
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The potassium-graphite route to active forms of metals has been extended to the preparation of titanium-graphite (Ti-Gr) and tin-graphite (Sn-Gr).The Ti-Gr is used to achieve the reductive coupling of ketones to give alkenes, and Sn-Gr is used in the preparation of diallyltin dibromide complexes which react with aldehydes to give homoallylic alcohols.
- Boldrini, Gian Paolo,Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
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p. 307 - 312
(2007/10/02)
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