- ELECTROCHEMICAL SYNTHESIS OF 2,2,6,6,-TETRAMETHYLPIPERIDINE
-
A preparative method for the production of 2,2,6,6-tetramethylpiperidine based on the electrochemical reduction of 4-oxo-2,2,6,6-tetramethylpiperidine in 30percent sulfuric acid on cadmium or lead electrodes was developed.
- Kagan E. Sh.,Avrutskaya, I. A.,Kondrashov, S. V.,Novikov, V. T.,Fioshin, M. Ya.,Smirnov, V. A.
-
-
Read Online
- Reductive amination of triacetoneamine with n-butylamine over Cu-Cr-La/γ-Al2O3
-
A series of Cu-based catalysts were prepared and examined for the reductive amination of triacetoneamine with n-butylamine, thereinto, Cu-Cr-La/γ- Al2O3 showed excellent results. The catalysts were studied by XRD, XPS, H2-TPR and NH3-TPD. It was found that doped Cr remarkably enhanced the activity of Cu/γ-Al2O3 due to better dispersion of Cu0, which is believed to be the active site for the reductive amination. Additionally, it was obvious that introduction of La to Cu-Cr/γ-Al2O3 led to a higher selectivity and longer lifetime. The reaction parameters were optimized and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine was obtained in a yield of 94%. Graphical Abstract: The addition of Cr does not impact obviously on the total acidity of Cu20/γ-Al2O3. However, the La addition to Cu20Cr5/γ-Al2O3 not only decreases the total acidity but also reduces the strength of acid sites. The introduction of La was found to result in a higher selectivity and longer lifetime. The conversion of TAA and selectivity of TEMPBA remained around 99.7 and 94.5% in 120 h.[Figure not available: see fulltext.][Figure not available: see fulltext.]
- Sun, Meng,Du, Xiaobao,Wang, Huabang,Wu, Zhiwei,Li, Yang,Chen, Ligong
-
-
Read Online
- Crowded piperidines with intramolecularly hydrogen-bonded nitrogen: Synthesis and conformation study
-
2,2,6,6-Tetramethyl substituted piperidines with a β-branched N-alkyl substituent were synthesized by the photoreaction of N-Me precursors with ketones. The main conformation features of these sterically-hindered amines (established by NMR and IR spectroscopy) are a ring in the chair form, an eclipsed conformation for the N-substituent and an intramolecular OH···N bond. High barriers for the geminal substituent topomerization were measured for these piperidines at different temperatures by means of line-shape analysis of the temperature-dependent 13C and 1H NMR spectra. An MM3-derived conformation scheme indicated that, for one of the studied analogues, the rotation of the N-substituent determines a slow topomerization rate. A new mechanism of nitrogen inversion - a concerted hydrogen-bond dissociation/nitrogen inversion process - is considered for hydrogen-bonded amines.
- Belostotskii, Anatoly M.,Gottlieb, Hugo E.,Aped, Pinchas
-
-
Read Online
- A continuous process for the production of 2,2,6,6-tetramethylpiperidin-4- ol catalyzed by Cu-Cr/γ-Al2O3
-
A continuous processwas established for the production of 2,2,6,6-tetramethylpiperidin-4-ol over Cu-Cr/α-Al2O3 in a fixed-bed reactor. The catalystwas characterized by X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction. Cu was believed to be the active site for the hydrogenation, and the doped chromium was supposed to exert a positive impact on the dispersion of active species. The catalyst and parameters of hydrogenation were optimized. Thus, 2,2,6,6-tetramethylpiperidin-4-ol was obtained in the yield of 90% from 2,2,6,6-tetramethylpiperidin-4-one (purity, 95%) under the optimum reaction conditions.
- Fan, Xiaopeng,Liu, Shuai,Yan, Xilong,Du, Xiaobao,Chen, Ligong
-
-
Read Online
- Chemistry and anti-herpes simplex virus type 1 evaluation of 4-substituted-1H-1,2,3-triazole-nitroxyl-linked hybrids
-
Abstract: HSV disease is distributed worldwide. Anti-herpesvirus drugs are a problem in clinical settings, particularly in immunocompromised individuals undergoing herpes simplex virus type 1 infection. In this work, 4-substituted-1,2,3-1H-1,2,3-triazole linked nitroxyl radical derived from TEMPOL were synthesized, and their ability to inhibit the in vitro replication of HSV-1 was evaluated. The nitroxide derivatives were characterized by infrared spectroscopy and elemental analysis, and three of them had their crystal structures determined by single-crystal X-ray diffraction. Four hybrid molecules showed important anti-HSV-1 activity with IC50 values ranged from 0.80 to 1.32?μM. In particular, one of the nitroxide derivatives was more active than Acyclovir (IC50 = 0.99?μM). All compounds tested were more selective inhibitors than the reference antiviral drug. Among them, two compounds were 4.5 (IC50 0.80?μM; selectivity index CC50/IC50 3886) and 7.7 times (IC50 1.10?μM; selectivity index CC50/IC50 6698) more selective than acyclovir (IC50 0.99?μM; selectivity index CC50/IC50: 869). These nitroxide derivatives may be elected as leading compounds due to their antiherpetic activities and good selectivity. Graphic abstract: [Figure not available: see fulltext.]
- Cunha, Anna C.,Ferreira, Vitor F.,Vaz, Maria G. F.,Cassaro, Rafael A. All?o,Resende, Jackson A. L. C.,Sacramento, Carolina Q.,Costa, Jéssica,Abrantes, Juliana L.,Souza, Thiago Moreno L.,Jord?o, Alessandro K.
-
p. 2035 - 2043
(2020/05/25)
-
- General methodology for the chemoselective N-alkylation of (2,2,6,6)-tetramethylpiperidin-4-ol: Contribution of microwave irradiation
-
A convenient method to access a broad variety of N-alkyl-(2,2,6,6)-tetramethylpiperidin-4-ol compounds is reported. The thermal treatment of a mixture of (2,2,6,6)-tetramethylpiperidin-4-ol and allyl or benzyl bromide derivatives gave the corresponding N–alkylated compounds in good yields while leaving the hydroxyl functional group intact. Whereas 40 h were needed to reach complete conversion, microwave irradiation allowed the reaction time to be reduced (20 min) and improved the yields in most cases.
- Membrat, Romain,Vasseur, Alexandre,Giordano, Laurent,Martinez, Alexandre,Nuel, Didier
-
supporting information
p. 240 - 243
(2019/01/04)
-
- Phosphinous Acid Platinum Complex as Robust Catalyst for Oxidation: Comparison with Palladium and Mechanistic Investigations
-
Secondary phosphine oxides proved to be effective preligands to stabilise a hydroxy-platinum based catalyst that allows the aerobic/anaerobic oxidation of challenging substrates. Kinetic comparisons showed that this system is more efficient and stable than previously reported similar palladium-based catalysts. A neutral platinum dimer bearing bridging hydroxy ligands has been isolated and fully characterised by X-ray diffraction and its involvement in the mechanism has been evidenced by mechanistic studies.
- Membrat, Romain,Vasseur, Alexandre,Martinez, Alexandre,Giordano, Laurent,Nuel, Didier
-
supporting information
p. 5427 - 5434
(2018/10/20)
-
- 2′-Alkynylnucleotides: A Sequence- and Spin Label-Flexible Strategy for EPR Spectroscopy in DNA
-
Electron paramagnetic resonance (EPR) spectroscopy is a powerful method to elucidate molecular structure through the measurement of distances between conformationally well-defined spin labels. Here we report a sequence-flexible approach to the synthesis of double spin-labeled DNA duplexes, where 2′-alkynylnucleosides are incorporated at terminal and internal positions on complementary strands. Post-DNA synthesis copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with a variety of spin labels enable the use of double electron-electron resonance experiments to measure a number of distances on the duplex, affording a high level of detailed structural information.
- Haugland, Marius M.,El-Sagheer, Afaf H.,Porter, Rachel J.,Pe?a, Javier,Brown, Tom,Anderson, Edward A.,Lovett, Janet E.
-
supporting information
p. 9069 - 9072
(2016/08/05)
-
- A 2, 2, 6, 6-tetramethyl-4-piperidinol preparation method
-
The invention discloses a preparation method of 2,2,6,6-tetramethyl-4-piperidinol. The preparation method comprises the following steps: A, adding acetone, an organic solvent and a catalyst into a high-pressure reactor, slowly introducing ammonia into the reactor at 20-80 DEG C, and reacting for 1-5 hours; B, slowing introducing hydrogen into the reactor at 20-180 DEG C and reacting for 1-5 hours; and C, cooling the reaction liquid to room temperature, standing and dissolving out 2,2,6,6-tetramethyl-4-piperidinol as white crystal. The organic solvent is one of toluene, dimethylbenzene, mesitylene, petroleum ether, dimethoxyethane or aliphatic alcohol. The catalyst is a metal chloride loaded by activated carbon. In the invention, the technology of one-pot cascade catalytic reaction is adopted, the operation is simple, the product yield is high, and little three-waste is produced, therefore, the method is a economic, practical and pollution-free synthetic technology.
- -
-
Paragraph 0021-0022; 0024; 0026; 0028; 0030
(2017/09/12)
-
- A monolith immobilised iridium Cp catalyst for hydrogen transfer reactions under flow conditions
-
An immobilised iridium hydrogen transfer catalyst has been developed for use in flow based processing by incorporation of a ligand into a porous polymeric monolithic flow reactor. The monolithic construct has been used for several redox reductions demonstrating excellent recyclability, good turnover numbers and high chemical stability giving negligible metal leaching over extended periods of use.
- Rojo, Maria Victoria,Guetzoyan, Lucie,Baxendale, Ian. R.
-
p. 1768 - 1777
(2015/02/19)
-
- MODIFIED ZNO NANOPARTICLES
-
Process for the preparation of modified zinc oxide nanoparticles, which comprises reacting zinc oxide nanoparticles, which are dissolved in a solvent, in the presence of ammonia or amines with a tetraalkyl orthosilicate and optionally with an organosilane, with the proviso that the reaction takes place at a content of less than 5% by weight of water, based on the total amount of solvent and water. Modified zinc oxide nanoparticles which have Si—O-alkyl groups and are soluble in organic solvents, obtainable by this process for the preparation. Liquid or solid formulations which comprise modified ZnO nanoparticles. Inanimate organic materials, for example plastics or coatings, which comprise modified ZnO nanoparticles. Method of stabilizing inanimate organic materials against the effect of light, free radicals or heat, where modified ZnO nanoparticles, which optionally comprise UV absorbers and/or stabilizers as further additives, are added to the materials.
- -
-
-
- PROCESS FOR THE PREPARATION OF 4-AMINO-2,2,6,6-TETRAMETHYLPIPERIDINE
-
4-amino-2,2,6,6-tetramethylpiperidine is prepared by reacting 2,2,6,6-tetramethylpiperidine-4-one with ammonia and hydrogen in the presence of nickel and/or cobalt catalyst and water. The main reaction is carried out at a pressure of at most 50 bar and a temperature of at most 120° C. up to a conversion of the 2,2,6,6-tetramethylpiperidine-4-one of at least 80%. Then, an after-reaction takes place at a higher temperature and at a higher pressure compared to the pressure and temperature of the main reaction.
- -
-
Page/Page column 3-4
(2009/09/05)
-
- Method for preparing nitroxides
-
The invention concerns a method for preparing nitroxides, which consists in oxidising, in a two-phase medium, using an aliphatic peroxide, secondary amines with steric hindrance or having a —CH in the nitrogen atom α.
- -
-
-
- 15N NMR spectroscopy of labeled alkoxyamines. 15N-labeled model compounds for nitroxide-trapping studies in free-radical (Co)polymerization
-
Eight 15N-labeled derivatives of 1-ethoxy-2,2,6,6-tetramethylpiperidine were synthesized in order to investigate the effects of their structural units on 15N NMR spectra. A single peak is found for each alkoxyamine. The chemical shift depends extensively on the nature of the α carbon atom of the alkoxy group. The remote functional group attached to position 4 of the piperidine ring has a smaller but still significant effect. The results of the 15N NMR measurements are supported by the detection of the N-H and N-C spin-spin coupling from the 1H and 13C NMR. The investigated alkoxyamines are model compounds for the radical-trapping products of styryl, methyl methacryloyl, α-methylstyryl, and methyl acryloyl radicals by 15N-labeled nitroxides. The potential of 15N NMR spectroscopy to analyze such products is discussed. In addition, it is shown that the 13C chemical shifts of the α carbon atom of the alkoxy group fall in an empty part of the 13C NMR spectrum, which allows the identification of trapped (macro)radicals via natural abundance 13C NMR.
- Kelemen, Peter,Lugtenburg, Johan,Klumperman, Bert
-
p. 7322 - 7328
(2007/10/03)
-
- Application of 4-hydroxy-, 4-Oxo-, and 4-hydroxyimino derivatives of stable 2,2,6,6-tetramethylpiperidine N-oxyl radical for the measurements of lewis acidity of solvents
-
UV-VIS spectra of 2,2,6,6-tetramethylpiperidine N-oxyl (TMPNO) stable radical measured in 18 solvents were compared with the spectra of its derivatives functionalized in the 4 position (4-hydroxy-(h-TMPNO), 4-oxo-(o-TMPNO) and 4-hydroxyimino-(i-TMPNO)). The results obtained proved, that the λmax values corresponding to the n → π* transition in the N-O? chromophore are for all TMPNO derivatives intercorrelated, and they also correlate very well with other acidity parameters (Z, E"T" and AN). Thus, all these compounds could be used as standard bases for determination of the experimental acidity of solvents. Detailed analysis of the spectral characteristics of all compounds leads to the conclusion, that the molar absorptivities (ε) of TMPNO and h-TMPNO corresponding to the n → π* transition are of the order of 10 dm3 mol-1 cm-1, whereas those of the o-TMPNO and i-TMPNO are two times lower. In the case of the π → π* transition we observed an opposite behaviour - the molar absorptivities (ε) of TMPNO and h-TMPNO are close to 2×103 dm3 mol-1 cm-1, whereas those of the oxo and hydroxyimino derivatives are equal to ～4.4×103 dm3 mol-1 cm-1. The integral intensities of both bands behave accordingly. These differences were attributed to the formation of the head-to-tail dimers, in which the N-O? chromophore interacts with the exocyclic double bond in the 4-position of the piperidine.
- Glowacka,Szczepek,Wrona
-
p. 1341 - 1348
(2007/10/03)
-
- Synthesis, electrosynthesis and electrochemical properties of substituted 2,2,6,6-tetramethylpiperidine and the respective stable nitroxyl radicals. XIV
-
The various derivatives of 2,2,6,6-tetramethylpiperidine and their stable nitroxyl radicals were investigated by means of chemical, electrochemical and empirical calculation methods. The titration results were calculated by means of TURBO BASIC with PKAS and MINIGLASS algorithm, and the prototropic experimental data were obtained. The reaction ways were calculated on the basis of the formation enthalpie values which were calculated by means of AM 1 (MOPACK) method. On the basis of a voltammetry and an electrolysis under controlled potential the reaction products were analyzed and the yields of the investigated processes were received. The various quasireversible redox reactions of the type stable nitroxyl radical oxoannonium cation were investigated by means of a cyclic voltammetry and electrochemical impedance spectroscopy. The mechanisms of the investigated reactions have been discussed and the reaction schemes are presented. - Key words: derivatives of 2,2,6,6-tetramethylpiperidine; electrolysis; electrochemical impedance spectroscopy; formation enthalpy values; prototropic constants
- Avrutskaya, Inna A.,Novikov, Vasilii T.,Dziegiec, Jozef,Grzejdziak, Andrzej,Krzyczmonik, Pawel,Scholl, Henryk
-
-
- Interaction of tert-Butylcalixarenes with Cyclic Amines
-
p-tert Butylcalixarenes 1 and 2 react with the cyclic amines 3 - 8, 10 by proton transfer forming so -called "exo-complexes" between the ammonium and phenolate groups.As well endocyclic as exocyclic amino groups are reactive.The nitroxyl radical 9 does not react with 1 or 2 by the proton transfer reaction.These results demonstrate that an interaction between the nitrogen atom of HALS-compounds, esp. compound 10, with calixarene hydroxylgroups is possible, but an interaction between the corresponding nitroxyl radicals with calixarene hydroxylgroups does not occur.
- Goermar, Gerhard,Seiffarth, Klaus,Schulz, Manfred,Chachimbombo, Chitula Leopoldina
-
p. 475 - 479
(2007/10/02)
-
- A Reaction of Nitroxides with Ethyl Mercaptane: A Mild Method for the Conversion of Nitroxides into Their Corresponding Amines
-
The mild reduction of the nitroxides 1a-j to the corresponding sterically hindered amines 2a-j by means of ethyl mercaptane is reported.The reaction mixtures of 1a,b,g were analyzed by glc/ms.
- Zakrzewski, Jerzy
-
p. 803 - 808
(2007/10/02)
-
- A HIGH YIELD ONE STEP SYNTHESIS OF HYDROXYLAMINES
-
Oxidation of secondary amines with dimethyldioxirane gives hydroxylamines in a simple, one step and high yield process.
- Murray, Robert W.,Singh, Megh
-
p. 3509 - 3522
(2007/10/02)
-
- Malonate-based light stabilizers for plastics
-
Malonate-derived acetal esters and amides possessing the polyalkyl piperidin-4-yl moiety are useful light stabilizers with synthetic polymer resins such as polyolefins and, in particular, polypropylene.
- -
-
-
- PREPARATION OF 2,2,6,6-TETRAMETHYL-4-AMINOPIPERIDINE AND ITS SUBSTITUTED COMPOUNDS BY ELECTROREDUCTION OF AZOMETHINES OF 2,2,6,6-TETRAMETHYL-4-OXOPIPERIDINE (TRIACETONAMINE)
-
Five methods have been developed for electrosynthesis of 2,2,6,6-tetramethyl-4-aminopiperidine in 95 - 98 percent yield via the lead-cathode reduction of 2,2,6,6-tetramethyl-4-oxiimino-piperidine, a mixture of triacetonamine with inorganic salts of hydroxylamine, and a mixture of triacetonamine with nitric acid in a solution of sulphuric acid, via the reduction of azine triacetonamine and of a mixture of triacetonamine with inorganic salts of hydrazine in a neutral solution.The corresponding saturated derivatives of 2,2,6,6-tetramethyl-4-aminopiperidine have been obtained in 60 - 80 percent yield by ele ctroreduction of phenylimine and ethylene diimine.
- Fioshin, M. Ya.,Avrutskaya, I. A.,Surov, I. I.,Novikov, V. T.
-
p. 182 - 191
(2007/10/02)
-
- The Reaction of Diphenylcarbene with Nitroxides
-
Diphenylcarbene reacts with 2,2,6,6-tetramethylpiperidine N-oxide with a rate constant of 2.7 x 108 M-1 s-1 in acetonitrile at room temperature.The reaction involves the thransfer of an oxygen atom, leading to benzophenone and 2,2,6,6-tetramethylpiperidinyl radical in essentially quantitative yields.In the case of 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide insertion at the O-H bond competes with reaction at the nitroxide center, with rate constants of 1.9 x 107 and 2.8 x 108 M-1 s-1, respectively.The reaction of the OH site is not enhanced significantly by the presence of a paramagnetic center in the molecule.
- Casal, H. L.,Werstiuk, N. H.,Scaiano, J. C.
-
p. 5214 - 5217
(2007/10/02)
-
- PATHWAYS OF PHOTOOXIDATION OF 1,2,2,6,6-PENTAMETHYL-4-PIPERIDOL BY KETONES
-
The photochemical oxidation of 1,2,2,6,6-pentamethyl-4-piperidol by ketones occurs exclusively at the methylamino group and, in the case of photolytically stable ketones, may lead to products of dimerization of the aminoalkyl radicals and recombination of the aminoalkyl and ketyl radicals and to a product of N-demethylation of the starting amino alcohol.When ketones that are unstable with respect to irradiation are used, photooxidation competes to a considerable extent with photodecomposition of such ketones.Spatial proximity of the aryl and α-methyl groups are observed for the products of reductive addition of the ketones on the basis of the PMR spectra.
- Belostotskii, A.M.,Kostochka, L.M.,Skoldinov, A.P.
-
p. 1280 - 1284
(2007/10/02)
-
