- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- Taylor, Nicholas P.,Gonzalez, Jorge A.,Nichol, Gary S.,García-Domínguez, Andrés,Leach, Andrew G.,Lloyd-Jones, Guy C.
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supporting information
p. 721 - 729
(2022/01/04)
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- Reduction of Amides to Amines with Pinacolborane Catalyzed by Heterogeneous Lanthanum Catalyst La(CH2C6H4NMe2- o)3@SBA-15
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Hydroboration of amides is a useful synthetic strategy to access the corresponding amines. In this contribution, it was found that the supported lanthanum benzyl material La(CH2C6H4NMe2-o)3@SBA-15 was highly active for the hydroboration of primary, secondary, and tertiary amides to amines with pinacolborane. These reactions selectively produced target amines and showed good tolerance for functional groups such as -NO2, -halogen, and -CN, as well as heteroatoms such as S and O. This reduction procedure exhibited the recyclable and reusable property of heterogeneous catalysts and was applicable to gram-scale synthesis. The reaction mechanisms were proposed based on some control experiments and the previous literature. This is the first example of hydroborative reduction of amides to amines mediated by heterogeneous catalysts.
- Guo, Chenjun,Zhang, Fangcao,Yu, Chong,Luo, Yunjie
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supporting information
p. 13122 - 13135
(2021/08/31)
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- Electrochemical Reductive N-Methylation with CO2Enabled by a Molecular Catalyst
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The development of benign methylation reactions utilizing CO2 as a one-carbon building block would enable a more sustainable chemical industry. Electrochemical CO2 reduction has been extensively studied, but its application for reductive methylation reactions remains out of the scope of current electrocatalysis. Here, we report the first electrochemical reductive N-methylation reaction with CO2 and demonstrate its compatibility with amines, hydroxylamines, and hydrazine. Catalyzed by cobalt phthalocyanine molecules supported on carbon nanotubes, the N-methylation reaction proceeds in aqueous media via the chemical condensation of an electrophilic carbon intermediate, proposed to be adsorbed or near-electrode formaldehyde formed from the four-electron reduction of CO2, with nucleophilic nitrogenous reactants and subsequent reduction. By comparing various amines, we discover that the nucleophilicity of the amine reactant is a descriptor for the C-N coupling efficacy. We extend the scope of the reaction to be compatible with cheap and abundant nitro-compounds by developing a cascade reduction process in which CO2 and nitro-compounds are reduced concurrently to yield N-methylamines with high monomethylation selectivity via the overall transfer of 12 electrons and 12 protons.
- Rooney, Conor L.,Wu, Yueshen,Tao, Zixu,Wang, Hailiang
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supporting information
p. 19983 - 19991
(2021/12/01)
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- Germyliumylidene: A Versatile Low Valent Group 14 Catalyst
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Bis-NHC stabilized germyliumylidenes [RGe(NHC)2]+ are typically Lewis basic (LB) in nature, owing to their lone pair and coordination of two NHCs to the vacant p-orbitals of the germanium center. However, they can also show Lewis acidity (LA) via Ge?CNHC σ* orbital. Utilizing this unique electronic feature, we report the first example of bis-NHC-stabilized germyliumylidene [MesTerGe(NHC)2]Cl (1), (MesTer=2,6-(2,4,6-Me3C6H2)2C6H3; NHC= IMe4=1,3,4,5-tetramethylimidazol-2-ylidene) catalyzed reduction of CO2 with amines and arylsilane, which proceeds via its Lewis basic nature. In contrast, the Lewis acid nature of 1 is utilized in the catalyzed hydroboration and cyanosilylation of carbonyls, thus highlighting the versatile ambiphilic nature of bis-NHC stabilized germyliumylidenes.
- Sarkar, Debotra,Dutta, Sayan,Weetman, Catherine,Schubert, Emeric,Koley, Debasis,Inoue, Shigeyoshi
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supporting information
p. 13072 - 13078
(2021/08/09)
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- N-Heterocyclic Carbene-Stabilized Germa-acylium Ion: Reactivity and Utility in Catalytic CO2Functionalizations
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The first acceptor-free heavier germanium analogue of an acylium ion, [RGe(O)(NHC)2]X (R = MesTer = 2,6-(2,4,6-Me3C6H2)2C6H3; NHC = IMe4 = 1,3,4,5-tetramethylimidazol-2-ylidene; X = (Cl or BArF = {(3,5-(CF3)2C6H5)4B}), was isolated by reacting [RGe(NHC)2]X with N2O. Conversion of the germa-acylium ion to the first solely donor-stabilized germanium ester [(NHC)RGe(O)(OSiPh3)] and corresponding heavier analogues ([RGe(S)(NHC)2]X and [RGe(Se)(NHC)2]X) demonstrated its classical acylium-like behavior. The polarized terminal GeO bond in the germa-acylium ion was utilized to activate CO2 and silane, with the former found to be an example of reversible activation of CO2, thus mimicking the behavior of transition metal oxides. Furthermore, its transition-metal-like nature is demonstrated as it was found to be an active catalyst in both CO2 hydrosilylation and reductive N-functionalization of amines using CO2 as the C1 source. Mechanistic studies were undertaken both experimentally and computationally, which revealed that the reaction proceeds via an N-heterocyclic carbene (NHC) siloxygermylene [(NHC)RGe(OSiHPh2)].
- Sarkar, Debotra,Weetman, Catherine,Dutta, Sayan,Schubert, Emeric,Jandl, Christian,Koley, Debasis,Inoue, Shigeyoshi
-
supporting information
p. 15403 - 15411
(2020/10/20)
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- DBU-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO2 and Polymethylhydrosiloxane
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We describe herein an efficient organocatalytic system for the selective N-methylation and N-formylation of amines with carbon dioxide (CO2) as a sustainable C1 feedstock and polymethylhydrosiloxane (PMHS) as a cost-effectvie reducing reagent. High-yielding N-methylation products are obtained with low catalyst loading (1%) of DBU. Selective N-formylation of amines is achieved using the same catalytic system at a lower reaction temperature. (Figure presented.).
- Li, Gang,Chen, Jie,Zhu, Dao-Yong,Chen, Ye,Xia, Ji-Bao
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supporting information
p. 2364 - 2369
(2018/05/07)
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- Ruthenium-Catalyzed Methylation of Amines with Paraformaldehyde in Water under Mild Conditions
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Methylated amines are highly important for a variety of pharmaceutical and agrochemical applications. Existing routes for their formation result in the production of large amounts of waste or require high reaction temperatures, both of which impact the ecological and economical footprint of the methodologies. Herein, we report the ruthenium-catalyzed reductive methylation of a range of aliphatic amines, using paraformaldehyde as both substrate and hydrogen source, in combination with water. This reaction proceeds under mild aqueous reaction conditions. Additionally the use of a secondary phase for catalyst retention and recycling has been investigated with promising results.
- van der Waals, Dominic,Heim, Leo. E.,Gedig, Christian,Herbrik, Fabian,Vallazza, Simona,Prechtl, Martin H. G.
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p. 2343 - 2347
(2016/10/24)
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- Method For Preparing Methylated Amines
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The present invention relates to a method for preparing methylated amines using carbon dioxide and to the use of the method for manufacturing vitamins, pharmaceutical products, glues, acrylic fibres and synthetic leathers, pesticides and fertilizers. The invention also relates to a method for manufacturing vitamins, pharmaceutical products, glues, acrylic fibres, synthetic leathers, pesticides and fertilizers, including a step of preparing methylated amines by the method according to the invention. The present invention also relates to a method for preparing marked methylated amines and to the uses thereof.
- -
-
Paragraph 0161-0172
(2015/06/10)
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- Carbon Dioxide Reduction to Methylamines under Metal-Free Conditions
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The first metal-free catalysts are reported for the methylation of amines with carbon dioxide. Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new methodology enables the methylation of N-H bonds in a wide variety of amines, including secondary amines, with increased chemoselectivity. Organocatalysis: Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new method makes possible the methylation of N-H bonds in a wide variety of amines, including secondary amines (see picture), with increased chemoselectivity.
- Blondiaux, Enguerrand,Pouessel, Jacky,Cantat, Thibault
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p. 12186 - 12190
(2016/02/23)
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- A practical regioselective synthesis of alkylthio- or arylthioindoles without the use of smelly compounds such as thiols
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A convenient method for the synthesis of 3-methylthioindoles has been established which does not use smelly compounds such as thiol derivatives. The method, which introduces an alkyl- or arylthio-group into the C3-position of the indole skeleton, was extended to the direct introduction of a methylthio or bromo group at the C2-position using 3-methylthioindoles. No dimerization occurred, and the reaction mechanism was confirmed. The products have the partial structure of potent anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) bromomethylthioindoles (MC 5-8) isolated from marine algae. Furthermore, this reaction could be applied to the synthesis of 3,3-diindolyl thioether which is a core structure of Echinosulfone A.
- Hamashima, Toshihiko,Mori, Yoshiaki,Sawada, Kazunori,Kasahara, Yuko,Murayama, Daisuke,Kamei, Yuto,Okuno, Hiroaki,Yokoyama, Yuusaku,Suzuki, Hideharu
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p. 292 - 303
(2013/05/08)
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- Catalytic hydrogenation of amides to amines under mild conditions
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Under (not so much) pressure: A general method for the hydrogenation of tertiary and secondary amides to amines with excellent selectivity using a bimetallic Pd-Re catalyst has been developed. The reaction proceeds under low pressure and comparatively low temperature. This method provides organic chemists with a simple and reliable tool for the synthesis of amines. Copyright
- Stein, Mario,Breit, Bernhard
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supporting information
p. 2231 - 2234
(2013/03/28)
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- CO2 as a C1-building block for the catalytic methylation of amines
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A novel catalytic reaction has been designed to utilize, for the first time, CO2 as a C1 feedstock in the synthesis of N-methylamines. Simple zinc catalysts, based on commercially available zinc salts and ligands, prove highly efficient in promoting both a 6 electron reduction of carbon dioxide and the formation of a C-N bond, using hydrosilanes and amines.
- Jacquet, Olivier,Frogneux, Xavier,Das Neves Gomes, Christophe,Cantat, Thibault
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p. 2127 - 2131
(2013/05/21)
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- High-Purity N-Ethylmethylamine and Process for Preparing Same
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The present invention relates to N-ethylmethylamine having a very high degree of purity, that is to say very low contents of impurities commonly encountered in conventional industrial processes, and also to the process for preparing, on an industrial scale, high-purity N-ethylmethylamine.
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Page/Page column 3-4
(2011/07/29)
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- Dialkylamino and nitrogen heterocyclic analogues of hexadecylphosphocholine and cetyltrimetylammonium bromide: Effect of phosphate group and environment of the ammonium cation on their biological activity
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A series of dialkylamino and nitrogen heterocyclic analogues of hexadecylphosphocholine and cetyltrimethylammonium bromide have been synthesized. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds. However, quaternary ammonium compounds exhibit significant higher activity against human tumor cells and Acanthamoeba lugdunensis compared to alkylphosphocholines. In addition, their haemolytic toxicity has been investigated. The relationship between structure and biological activity of the tested compounds is discussed.
- Lukac, Milos,Mojzis, Jan,Mojzisova, Gabriela,Mrva, Martin,Ondriska, Frantisek,Valentova, Jindra,Lacko, Ivan,Bukovsky, Marian,Devinsky, Ferdinand,Karlovska, Janka
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scheme or table
p. 4970 - 4977
(2010/02/27)
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- Reductive methylation of primary and secondary amines and amino acids by aqueous formaldehyde and zinc
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Amines can be methylated when treated with formaldehyde and zinc in aqueous medium. Selective mono- or dimethylation can be achieved by proper choice of pH, stoichiometry and reaction time. This method can also be applied for amino acids.
- da Silva, Renato A.,Estevam, Idália H.S.,Bieber, Lothar W.
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p. 7680 - 7682
(2008/03/30)
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- Process for obtaining amines by reduction of amides
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Disclosed is a process for the preparation of primary, secondary and tertiary amines via a catalytic hydrogenation of unsubstituted, N-substituted, and N,N-disubstituted amides. The amide is led, together with an auxiliary amine, in vaporised form in a hydrogen containing gas flow over the catalyst. The process can be carried out at relatively low pressures, between 2 and 50 bars, using typical hydrogenation catalysts like CuCr-type catalysts. The amine is obtained with high yield and high selectivity. The process can be carried out in a continuous fixed bed reactor.
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Page/Page column 5
(2008/06/13)
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- PROCESS FOR OBTAINING AMINES BY REDUCTION OF AMIDES
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Disclosed is a process for the preparation of primary, secondary and tertiary amines via a catalytic hydrogenation of unsubstituted, N- substituted, and N,N- disubstituted amides. The amide is led, together with an auxiliary amine, in vaporised form in a hydrogen containing gas flow over the catalyst. The process can be carried out at relatively low pressures, between 2 and 50 bars, using typical hydrogenation catalysts like CuCr-type catalysts. The amine is obtained with high yield and high selectivity. The process can be carried out in a continuous fixed bed reactor.
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Page/Page column 13
(2008/06/13)
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- Process for the synthesis of N-methyl-dialkylamines from secundary amines and formaldehyde
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Production of N-methyldialkylamines comprises reacting a dialkylamine with 1.5-3 molar equivalents of formaldehyde at 100-200[deg]C; degassing the reaction product; separating the aqueous phase; and distilling the organic phase.
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Page column 4
(2008/06/13)
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- Soluble polymer-supported synthesis of tertiary amines
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The synthesis of tertiary amines on a modified soluble polymer, poly(ethylene glycol) (PEG), is described. The PEG-bound quaternary intermediates were assembled via Michael addition reaction, followed by alkylation. Cleavage from the soluble polymer support was induced by insoluble weak basic resin, to afford the target tertiary amines in excellent purity.
- Chen, Zuxing,Yang, Guichun,Zhang, Zhaojun
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p. 729 - 734
(2007/10/03)
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- Electronic Structure and Gas-Phase Thermolysis of 2-Tetrazenes with Acyclic or Cyclic Amino Groups Studied by Photoelectron Spectroscopy
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The electronic structures and the gas-phase thermolysis of the 2-tetrazenes 2-13 have been studied by He(I) photoelectron spectroscopy.The compounds are characterized by at least three ionization potentials with energies less than 10 eV which are assigned to the molecular orbitals ?3 (HOMO), n(+), ?2, and n(-).In the thermolyses either the formal disproportionation products (amine and imine) of the respective aminyl radical are found, or the latter is stabilized by loss of an alkyl radical affording also an imine.Further products which can be explained by radical reactions are detected in flash vacuum pyrolyses.The tricyclic cis-2-tetrazene 13 is cleaved by cycloreversion.The methoxymethylsubstituted compound 8 exhibit a more complex cleavage pattern. - Key Words: Electronic structure / PE spectroscopy / Thermolysis, gas-phase / Imines / Radicals
- Rademacher, Paul,Heymanns, Peter,Muenzenberg, Ralf,Woell, Heike,Kowski, Klaus,Poppek, Rainer
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p. 2073 - 2080
(2007/10/02)
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- The effect of the nature of the amine leaving group on the nature of the E2 transition state for the reaction of 1-phenylethylammonium ions with sodium ethoxide in ethanol
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To investigate the effect of the leaving group on the elimination reaction of 1-phenylethylammonium ions with sodium ethoxide in ethanol at 60 deg C, the reaction of seven different quaternary ammonium salts and their β-deuterated analogues with trimethylamine, N-methylpiperidine, N-methyldiethylamine, triethylamine, N,N-dimethylbenzylamine, tripropylamine, and N,N-diethylbenzylamine as leaving groups has been studied.In all cases the elimination, which was shown to proceed via the concerted E2 process, was accompained by competing substitution reactions.Although a significant depedence of the rate of the elimination process on the nature of the leaving group was noted, there was not any linear correlation with the basicity of the amine leaving group.The primary hydrogen-deuterium kinetic isotope effect for the elimination process, (kH/kD)E, was found to increase initially with an increase of reaction rate, kHE, for substrates containing the leaving groups trimethylamine, N-methylpiperidine, N-methyldiethylamine, triethylamine, and N,N-dimethylbenzylamine; i.e., (kH/kD)E=5.03, 5.26, 5.40, 5.83, and 5.85, respectively.A further increase in rate, using substrates with tripropylamine and N,N-diethylbenzylamine as leaving groups resulted in a decrease of the magnitude of the hydrogen-deuterium isotope effect; i.e., (kH/kD)E= 5.42 and 4.67, respectively.It is concluded that steric effects mainly determine leaving group ability.As well, it is concluded that the leaving group ability of the amine determines the structure of the E2 transition state.For the reaction of the poorer leaving groups, trimethylamine, N-methylpiperidine, and N-methyldiethylamine, the proton is more than one-half transferred at the transition state while for reaction involving the two best leaving groups, tripropylamine and N,N-diethylbenzylamine, the Cβ-H bond is less than one-half broken at the transition state.The conclusions are considered in the light of the More O'Ferrall-Jencks potential energy surface diagram.Key words: elimination mechanism, transition state, isotope effects, leaving group, quaternary salts.
- Smith, Peter James,Amin, Md.
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p. 1457 - 1467
(2007/10/02)
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- BIS(N,N-DIETHYLCARBAMATO)BIS(DIETHYLAMINE)PALLADIUM(II), THE FIRST HOMOLEPTIC CARBAMATO COMPLEX OF PALLADIUM
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The reaction of NHEt2 and carbon dioxide with (BF4)2 at room temperature and atmospheric pressure produced the N-N-diethylcarbamato complex trans-Pd(O2CNEt2)2(NHEt2)2.Single-crystal X-ray diffractometry showed the monodentate carbamato groups and the amine ligands in a planar arrangement of the donor atoms around palladium.Evidence for the formation of the corresponding isopropyl derivative is presented.
- Anillo, Adela,Dell'Amico, Daniela Belli,Calderazzo, Fausto,Pelizzi, Giancarlo,Rocchi, Lucia
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p. 653 - 656
(2007/10/02)
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- Degradation and disposal of some antineoplastic drugs
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Bulk quantities and pharmaceutical preparations of the antineoplastic drugs carmustine (BCNU), lomustine (CCNU), chlorozotocin, N-[2-chloroethyl]-N'-[2,6-dioxo-3-piperidinyl]-N-nitrosourea (PCNU), methyl CCNU, mechlorethamine, melphalan, chlorambucil, cyclophosphamide, ifosfamide, uracil mustard, and spiromustine may be degraded using nickel-aluminium alloy in KOH solution. The drugs are completely destroyed and only nonmutagenic reaction mixtures are produced. destruction of cyclophosphamide in tablets requires refluxing in HCl before the nickel-aluminium alloy reduction. Streptozotocin, chlorambucil, and mechlorethamine may be degraded using an excess of saturated bicarbonate solution. The nitrosourea drugs BCNU, CCNU, chlorozotocin, PCNU, methyl CCNU, and streptozotocin were also degraded using hydrogen bromide in glacial acetic acid. The drugs were completely destroyed but some of the reaction mixtures were mutagenic and the products were found to be, in some instances, the corresponding mutagenic, denitrosated compounds.
- Lunn,Sansone,Andrews,Hellwig
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p. 652 - 659
(2007/10/02)
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- Novel Amination of Phosphorus Diesters Promoted By Titanium Tetrakis(Diethylamide)
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Reaction of titanium tetrakis(diethylamide) with phosphorus diesters results in a displacement of both ester functions by the diethylamino groups, but phosphoric triesters are inert to the title reagent.
- Vather, S. M.,Modro, T. A.
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p. 383 - 385
(2007/10/02)
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- Oxidation of thiols employing cobalt molybdate/triethylamine catalyst
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A thiol is oxidized to a corresponding disulfide employing a supported cobalt molybdate catalyst in combination with a liquid tertiary amine. 2-propanethiol is converted to diisopropyl disulfide with conversions of the order of 94% and selectivities of the order of 98%.
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- Preparation of esters of phosphorus acids
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Esters of phosphorus acids are prepared by an improved process whereby aromatic alcohols and phosphorus halides are reacted at specified temperatures in the presence of amine catalysts thereby providing high yields of substantially pure esters and allowing preparation of selected halogen-containing mono- and di-esters of phosphorus acids wherein halogen is directly bonded to phosphorus having substantially no side reactant contamination. The phosphorus esters are useful as intermediates in the preparation of plasticizers, oil additives and functional fluids.
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