Articles de revues : « ALICYCLIC SYSTEMS »

1

EWING, D. F. « ChemInform Abstract : Large Alicyclic Ring Systems ». ChemInform 26, n^o 3 (18 août 2010) : no. http://dx.doi.org/10.1002/chin.199503280.

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Zhubanov, B. A., V. D. Kravtsova, R. F. Mukhamedova et K. Kh Bekmagambetova. « New polymer systems based on alicyclic polyimides ». Russian Journal of Applied Chemistry 79, n^o 11 (novembre 2006) : 1869–74. http://dx.doi.org/10.1134/s1070427206110255.

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Kappe, Thomas, Barbara Schnell, Krassimira Georgieva, Brigitte Jocham, Anna E. Mayrhofer, Bhagwan P. Nikam, Yvette Issac et Klaus Langhans. « Sulfidation of Alicyclic and Heterocyclic 1,3-Dicarbonyl Systems ». Phosphorus, Sulfur, and Silicon and the Related Elements 95, n^o 1-4 (octobre 1994) : 349–50. http://dx.doi.org/10.1080/10426509408034233.

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Oszczapowicz, Janusz, et Irena Oszczapowicz. « Substituent effects in13C NMR spectra. Part II-Alicyclic rigid systems ». Journal of Physical Organic Chemistry 18, n^o 8 (24 mai 2005) : 818–24. http://dx.doi.org/10.1002/poc.946.

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Mączka, Wanda Krystyna, et Agnieszka Mironowicz. « Biotransformation of Isoprenoids and Shikimic Acid Derivatives by a Vegetable Enzymatic System ». Zeitschrift für Naturforschung C 59, n^o 3-4 (1 avril 2004) : 201–4. http://dx.doi.org/10.1515/znc-2004-3-413.

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In biotransformations carried out under similar conditions enzymatic systems from carrot (Daucus carota L.), celeriac (Apium graveolens L. var. rapaceum) and horse-radish (Armoracia lapathifolia Gilib.) hydrolyzed the ester bonds of acetates of phenols or alicyclic alcohols. Nevertheless, methyl esters of aromatic acids did not undergo hydrolysis. Alcohols were oxidized to ketones in a reversible reaction.

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Werstiuk, Nick Henry, Gwen Irene Wade et Peter John Joseph Martin. « Facile H–D exchange of the bridgehead methyls of bicyclo[2.2.2]octan-2,5-diones. Evidence for a carbon analogue of the acyloin rearrangement ». Canadian Journal of Chemistry 63, n^o 9 (1 septembre 1985) : 2582–83. http://dx.doi.org/10.1139/v85-428.

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Hexamethyltwistyl-2,5-dione 4 has been synthesized and its H–D exchange studied in t-BuOK/t-BuOD at 125 °C. We find that the bridgehead methyl at C-3 undergoes exchange 7 × 105 times faster than the bridgehead methyl of bicyclo[2.2.1]heptan-2-one (fenchone). This result, along with a previous study, establishes the first examples of the carbon analogue of the acyloin rearrangement of alicyclic systems.

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Bishop, R., et GH Lee. « Detection of Non-Conjugative Interactions in Rigid Cyclic Molecules by Using Carbon-13 N.M.R. Shift Values ». Australian Journal of Chemistry 40, n^o 2 (1987) : 249. http://dx.doi.org/10.1071/ch9870249.

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In previous work, interaction between formally unconjugated unsaturated groups was detected by comparing the 13C n.m.r. shift values of the sp2 atoms of difunctional compounds with those of the corresponding monofunctional compounds. This procedure has now been used to investigate possible interactive effects in a range of rigid alicyclic systems where steric and conformational factors cannot be involved, namely, the 2,6-disubstituted adamantane (6), 4,8-disubstituted 2-thiaadamantane (7), 2,6-disubstituted noradamantane (8), and 2,5-disubstituted norbornane (9) systems. In each case interaction was detected between the unsaturated groups of the non-conjugated dimethylene, methylene ketone, and diketone derivatives of these ring systems. The nature of this effect is under further investigation.

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Umerzakova, М. B., R. B. Sarieva et V. D. Kravtsova. « MODIFIED WITH VARIOUS ADDITIVES ARYLALYCLIC COPOLYIMIDES AND COMPOSITE FILMS BASED ON THEIR BASIS ». Chemical Journal of Kazakhstan 3 (30 septembre 2021) : 19–35. http://dx.doi.org/10.51580/2021-1/2710-1185.36.

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lopment of arylalicyclic copolyimides based on alicyclic dianhydride, aromatic dianhydrides of benzophenone- and diphenyloxidetetracarboxylic acids with 4,4'-diaminodiphenyl oxide at various ratios of alicyclic and aromatic dianhydrides, as well as various compositions based on these copolymers with low- or other high-molecular compounds that enhance the characteristics of the polymer matrix. Composite films were formed from solutions of the obtained polymer mixtures, and their properties were studied. It was noted that at optimal ratio of components, the films have improved thermal and strength properties, etc., exceeding the analogous properties of the initial arylalicyclic copolymer, while the elasticity has acceptable values for such material. The best characteristics had the composite films formed from a ternary composition of copo-lyimide-polyethylene glycol-alkylated montmorillonite. Metal-containing composite films, along with higher thermal stability compared to unmodified copolyimide, were resistant to aggressive reagents, lower values of specific volume and surface resistance, higher viscosity values, and different colors depending on the nature of the salt. By introducing a silicon-containing compound into the copolyimide solution, the new polymer systems have been obtained, and the porous films could be formed.

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Charton, Marvin. « The Nature and Transmission of Substituent Electrical Effects in Alicyclic Solvolysis ». Collection of Czechoslovak Chemical Communications 64, n^o 11 (1999) : 1849–76. http://dx.doi.org/10.1135/cccc19991849.

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The correlation of rate constants taken from the literature for 2-exo- and 2-endo-norbornyl derivatives substituted in positions 1, 4, 5-exo, 6-exo, 6-endo, and 7-anti with the triparametric LDR equation and relationships derived from it has been carried out. A delocalized (resonance) electrical effect has been found in all but the 4-substituted derivatives. The resonance effect may be somewhat greater when the leaving group is exo than when it is endo. Steric effects occur in the 6-endo-substituted derivatives. The transition state resembles a classical carbocation rather than the nonclassical norbornyl carbocation. The correlation of solvolysis rate constants for 2- and 3-substituted 1- and 4-exo-substituted 2-exo-adamantyl derivatives gave no reliable indication that a delocalized electrical effect existed in these systems. A study of solvolysis rate constants for 4-substituted 1-[2.2.2]bicyclooctanyl, 6-exo-substituted [2.2.2]bicyclooctan-2-exo-yl and 6-exo-substituted [2.2.2]bicyclo- octan-2-endo-yl derivatives showed a delocalized electrical effect only in the latter of these systems. Such an effect was also observed in 4-substituted 2-chloro-2-methylbutane solvolyses. The transmission of electrical effects is by a modified field effect. It is dependent on 1/n where n is the number of bonds intervening between substituent and reaction site.

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Mahesh, V. K., Mamta Maheswari, Rakesh Sharma et Rashmi Sharma. « Analogs of cannabinoids : synthesis of some 7H-indolo-, 5H-imidazolo, 7H-benzimidazolo[1,2-c] [1,3]benzoxazines – novel ring systems ». Canadian Journal of Chemistry 63, n^o 3 (1 mars 1985) : 632–35. http://dx.doi.org/10.1139/v85-103.

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Tetrahydrocannabinol 1, the active constituent of CannabissativaLinn, is a well-known CNS-active compound and introduction of a nitrogen atom at the ring junction of the pyran and alicyclic ring is of considerable interest. This prompted the synthesis of 7H-indolo[1,2-c] [1,3]-, 5H-imidazolo[1,2-C] [1,3],- and 7H-benzimidazolo[1,2-c] [1,3]-benzoxazine, a novel heterocyclic system. 2-(2′-Hydroxyphenyl) indoles, 2-(2′-hydroxyphenyl) imidazoles, and 2-(2′-hydroxyphenyl) benzimidazoles are suitable intermediates for the preparation of this type of benzoxazines, as the second heterocycle (ring B) can then be constructed by introduction of a methylene bridge between the hydroxyl of the 2′-hydroxy phenyl substituent and the imino group of the heterocyclic system.

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Murray, Jane S., Paul C. Redfern, Jorge M. Seminario et Peter Politzer. « Anomalous energy effects in some aliphatic and alicyclic aza systems and their nitro derivatives ». Journal of Physical Chemistry 94, n^o 6 (mars 1990) : 2320–23. http://dx.doi.org/10.1021/j100369a024.

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Floriano, Belén, Eduardo Santero et Francisca Reyes-Ramírez. « Biodegradation of Tetralin : Genomics, Gene Function and Regulation ». Genes 10, n^o 5 (6 mai 2019) : 339. http://dx.doi.org/10.3390/genes10050339.

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Tetralin (1,2,3,4-tetrahydonaphthalene) is a recalcitrant compound that consists of an aromatic and an alicyclic ring. It is found in crude oils, produced industrially from naphthalene or anthracene, and widely used as an organic solvent. Its toxicity is due to the alteration of biological membranes by its hydrophobic character and to the formation of toxic hydroperoxides. Two unrelated bacteria, Sphingopyxis granuli strain TFA and Rhodococcus sp. strain TFB were isolated from the same niche as able to grow on tetralin as the sole source of carbon and energy. In this review, we provide an overview of current knowledge on tetralin catabolism at biochemical, genetic and regulatory levels in both strains. Although they share the same biodegradation strategy and enzymatic activities, no evidences of horizontal gene transfer between both bacteria have been found. Moreover, the regulatory elements that control the expression of the gene clusters are completely different in each strain. A special consideration is given to the complex regulation discovered in TFA since three regulatory systems, one of them involving an unprecedented communication between the catabolic pathway and the regulatory elements, act together at transcriptional and posttranscriptional levels to optimize tetralin biodegradation gene expression to the environmental conditions.

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Sukhanov, Gennady T., Yulia V. Filippova, Yuri V. Gatilov, Anna G. Sukhanova, Irina A. Krupnova, Konstantin K. Bosov, Ekaterina V. Pivovarova et Vyacheslav I. Krasnov. « Energetic Materials Based on N-substituted 4(5)-nitro-1,2,3-triazoles ». Materials 15, n^o 3 (31 janvier 2022) : 1119. http://dx.doi.org/10.3390/ma15031119.

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The regularities and synthetic potentialities of the alkylation of 4(5)-nitro-1,2,3-triazole in basic media were explored, and new energetic ionic and nitrotriazole-based coordination compounds were synthesized in this study. The reaction had a general nature and ended with the formation of N1-, N2-, and N3-alkylation products, regardless of the conditions and reagent nature (alkyl- or aryl halides, alkyl nitrates, dialkyl sulfates). This reaction offers broad opportunities for expanding the variability of substituents on the nitrotriazole ring in the series of primary and secondary aliphatic, alicyclic, and aromatic substituents, which is undoubtedly crucial for solving the problems related to both high-energy materials development and medicinal chemistry when searching for new efficient bioactive compounds. An efficient methodology for the separation of regioisomeric N-alkyl(aryl)nitrotriazoles has been devised and relies on the difference in their basicity and reactivity during quaternization and complexation reactions. Based on the inaccessible N3-substitution products that exhibit a combination of properties of practical importance, a series of energy-rich ionic systems and coordination compounds were synthesized that are gaining ever-increasing interest for the chemistry of energy-efficient materials, coordination chemistry, and chemistry of ionic liquids.

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Nowak, Paulina, Karolina Kucharska et Marian Antoni Kaminski. « The New Test Procedure for Group-Type Composition of Base Oils of Lubricating Oils, Especially Emitted into the Environment ». Energies 13, n^o 15 (22 juillet 2020) : 3772. http://dx.doi.org/10.3390/en13153772.

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Mineral base oil, a product of multistep fine refining of the relevant fractions from vacuum distillation of crude oil, is a main component of so-called mineral lubricating oils containing aliphatic and alicyclic substituted aromatic hydrocarbons, i.e., derivatives of benzene and biphenyl. Mineral lubricating oil is composed mostly of mineral base oil and a low amount of enriching additives, most often products of advanced organic chemical technology. The application of mineral lubricating oils in open cutting systems has a very negative impact on environment and on the operator’s health. This work presents a simple, cheap and fast methodology allows identification of the group-type composition of base oil in lubricating oil and to estimate the content or total absence of base oil of mineral and vegetable origin in lubricating oil. The first step of the test is an in-situ screening for fluorescence of petroleum fraction under the 365 nm light. The next is the performance of infrared spectra with Fourier transformation (FT-MIR) to identify and estimate the content of vegetable oil and its derivatives and the performance of UV-Vis spectra to identify and determine the content of aromatic hydrocarbons, as well as dyes present in the lubricating oil. The last stage is normal phase thin layer chromatography (NP-TLC) using different visualization methods to evaluate the group-type composition of lubricating oil. Effectivity of the developed procedure has been confirmed during control of group-type composition evaluation of lubricating oils in cutting systems. The procedure can be also applied with respect to different oil matrices.

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Li, Shuang Cui, et Chun Cheng Hao. « Molecular Dynamics Simulations of DGEBA/OSC Epoxy Composites for Improving Heat-Resistance and Elastic Modulus ». ECS Journal of Solid State Science and Technology 11, n^o 10 (1 octobre 2022) : 103012. http://dx.doi.org/10.1149/2162-8777/ac972d.

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Thermal and mechanical properties of DGEBA/OSC epoxy composite polymers composed of both bisphenol A diglygde ether (DGEBA) and alicyclic epoxy resin (OSC) as co-polymerization monomers and 3,3-diaminodiphenyl sulfone (DDS) as curing agent are evaluated and investigated by molecular dynamics (MD) simulations, in which NPT ensembles and annealing cycles in a wide temperature range are utilized for modeling the thermodynamic equilibrium systems and heating processes. Glass transition and thermal-decomposition temperatures are calculated by linear fitting on the temperature dependence of elastic modulus, cohesive energy, fractional free-volume (FFV). It is verified that the two DGEBA/OSC epoxy composite can effectively improve the thermal and mechanical performances of epoxy polymer, in which DGEBA/OSC(1:1) epoxy composite are most significant of promoting mechanical stiffness and render a elevated glass transition temperature by 28 K and thermal-decomposition temperatures by 91 K, the two DGEBA/OSC epoxy composite are capable of efficiently reduce fractional free volume by 4.4% and 8.6% for DGEBA/OSC(3:1) and DGEBA/OSC(1:1) epoxy composite respectively, which is in consistent with the lower rotation amplitudes of crosslinking bonds for DGEBA/OSC composite EP polymers that vdW interaction forces between molecular-chains can be promoted by OSC co-polymeric blocks to inhibit thermal motions of EP molecular-chains.

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Kiss, Loránd, Márton Kardos, Csaba Vass et Ferenc Fülöp. « Application of Metathesis Reactions in the Synthesis and Transformations of Functionalized β-Amino Acid Derivatives ». Synthesis 50, n^o 18 (26 juillet 2018) : 3571–88. http://dx.doi.org/10.1055/s-0036-1591600.

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Because of their biological relevance, cyclic β-amino acids have generated increasing interest and had significant impact in drug research over the past two decades. Their preparation and further functionalization towards new types of molecular entities have received large interest in synthetic and medicinal chemistry. Various types of metathesis reactions, such as ring-opening (ROM), ring-closing (RCM), or cross metathesis (CM) are used widely for access to either alicyclic β-amino acids or other densely functionalized derivatives of this group of compounds. This account intends to provide an insight into the most relevant synthetic routes to this class of derivatives with the application of metathesis reactions. The review focuses on the presentation of selective and stereocontrolled methodologies in view of versatility, robustness, limitations and efficiency.1 Introduction2 Synthesis and Transformation of Cyclic β-Amino Acids through Metathesis Reactions2.1 Synthesis of Five- and Six-Membered Cyclic β-Amino Acids by Ring-Closing Metathesis2.2 Synthesis of Five- and Six-Membered Cyclic β-Amino Acids by Cross Metathesis2.3 Synthesis of β-Amino Acids with Larger Ring Systems by Ring- Closing Metathesis2.4 Synthesis of β-Amino Acids with Condensed Ring Systems by Ring-Rearrangement Metathesis2.5 Stereocontrolled One-Step Synthesis of Functionalized Cispentacin and Transpentacin Derivatives2.5.1 Stereocontrolled Synthesis of Functionalized Cispentacin and Transpentacin Derivatives through Ring-Opening Metathesis of Norbornene β-Amino Acid Derivatives2.5.2 Stereocontrolled Synthesis of Functionalized Azetidinones and β-Amino Acid Derivatives from Condensed Ring β-Lactams by Ring-Opening Metathesis2.5.3 Carbon–Carbon Double Bond Functionalization of β-Amino Acid Derivatives and β-Lactams with α,β-Unsaturated Carbonyl Compounds through Cross Metathesis2.5.4 Synthesis of Functionalized β-Amino Acid Derivatives and β-Lactams through Chemoselective Cross Metathesis3 Conclusions and Outlook

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ODA, K., Y. FUKUZAWA, K. OHNO, M. MACHIDA et Y. KANAOKA. « ChemInform Abstract : Photochemistry of the Nitrogen-Thiocarbonyl Systems. Part 21. Photoreaction of 1- and 3-Aralkyl Alicyclic Thioimides : Facile Synthesis of Various Azabicycloalkanes via Norrish Type II Process. » ChemInform 24, n^o 12 (20 août 2010) : no. http://dx.doi.org/10.1002/chin.199312183.

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DRAGUTAN, V., I. DRAGUTAN, C. CONDEIU et A. M. GLATZ. « ChemInform Abstract : Friedel-Crafts Chemistry in Alicyclic Systems. Part 5. Reaction of Cyclohexylidene- and 1-Cyclohexenylacetic Acids with Benzene in the Presence of AlCl3×CH3NO2 as the Catalyst. » ChemInform 22, n^o 44 (22 août 2010) : no. http://dx.doi.org/10.1002/chin.199144137.

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Goranov, Aleksandar I., Andrew S. Wozniak, Kyle W. Bostick, Andrew R. Zimmerman, Siddhartha Mitra et Patrick G. Hatcher. « Microbial labilization and diversification of pyrogenic dissolved organic matter ». Biogeosciences 19, n^o 5 (14 mars 2022) : 1491–514. http://dx.doi.org/10.5194/bg-19-1491-2022.

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Abstract. With the increased occurrence of wildfires around the world, interest in the chemistry of pyrogenic organic matter (pyOM) and its fate in the environment has increased. Upon leaching from soils by rain events, significant amounts of dissolved pyOM (pyDOM) enter the aquatic environment and interact with microbial communities that are essential for cycling organic matter within the different biogeochemical cycles. To evaluate the biodegradability of pyDOM, aqueous extracts of laboratory-produced biochars were incubated with soil microbes, and the molecular changes to the composition of pyDOM were probed using ultrahigh-resolution mass spectrometry (Fourier transform–ion cyclotron resonance–mass spectrometry). Given that solar irradiation significantly affects the composition of pyDOM during terrestrial-to-marine export, the effects of photochemistry were also evaluated in the context of pyDOM biodegradability. Ultrahigh-resolution mass spectrometry revealed that many different (both aromatic and aliphatic) compounds were biodegraded. New labile compounds were produced, 22 %–40 % of which were peptide-like. These results indicated that a portion of pyDOM has been labilized into microbial biomass during the incubations. Fluorescence excitation–emission matrix spectra revealed that some fraction of these new bio-produced molecules is associated with proteinaceous fluorophores. Two-dimensional 1H–1H total correlation nuclear magnetic resonance (NMR) spectroscopy identified a peptidoglycan-like backbone within the microbially produced compounds. These results are consistent with previous observations of peptidoglycans within the soil and ocean nitrogen cycles where remnants of biodegraded pyDOM are expected to be observed. Interestingly, the exact nature of the bio-produced organic matter was found to vary drastically among samples indicating that the microbial consortium used may produce different exudates based on the composition of the initial pyDOM. Another potential explanation for the vast diversity of molecules is that microbes only consume low molecular-weight compounds, but they also produce reactive oxygen species (ROS), which initiate oxidative and recombination reactions that degrade high molecular-weight compounds and produce new molecules. Some of the bio-produced molecules (212–308 molecular formulas) were identified in estuarine and marine (surface and abyssal oceanic), and 81–192 of these formulas were of molecular composition attributed to carboxyl-rich alicyclic molecules (CRAM). These results indicate that some of the pyDOM biodegradation products have an oceanic fate and can be sequestered into the deep ocean. The observed microbially mediated diversification of pyDOM suggests that pyDOM contributes to the observed large complexity of natural organic matter observed in riverine and oceanic systems. More broadly, our research shows that pyDOM can be substrate for microbial growth and be incorporated into environmental food webs within the global carbon and nitrogen cycles.

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Nosova, Natalia V., Daria D. Lezhnina, Daria D. Rubtsova et Vladimir L. Gein. « Reaction of substituted 6-oxocyclohexane- 1,3-dicarboxamides with hydroxylamine ». Butlerov Communications 63, n^o 9 (30 septembre 2020) : 31–34. http://dx.doi.org/10.37952/roi-jbc-01/20-63-9-31.

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Functionalized cyclohexanones are multifunctional highly reactive available substrates. They are convenient for the synthesis of new compounds, including practically significant ones. The presence of a 1,3-dicarbonyl fragment in their composition makes it possible to obtain various heterocyclic systems in reactions with binucleophilic reagents: indazoles, benzisoxazoles, and diazepines. The interaction of cyclohexanones functionalized with acetyl or alkoxycarbonyl substituents with hydroxylamine was previously studied. It was shown that, depending on the nature of the substituents, the reaction can proceed with the formation of the corresponding oximes, or give products of heterocyclization – benzisoxazoles. The interaction of cyclohexanones containing amide groups in an alicycle with hydroxylamine has not been studied. We studied the reaction of unsubstituted 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxamides with hydroxylamine hydrochloride in the presence of an equivalent amount of alkali. When boiling in ethanol in the absence of a catalyst, new 2-aryl-4-hydroxy-6-(hydroxyimino)-4-methylcyclohexane-1,3-dicarboxamides were obtained. Cyclization with the formation of benzisoxazoles does not occur in this case due to a lower positive charge on the carbon atom of the amide group compared to the carbon atom of the acetyl or alkoxycarbonyl groups. The structure of the synthesized compounds was established based on the data of IR, 1H NMR and 13C NMR spectroscopy. The IR spectra of the obtained oximes contain bands of valence vibrations of the OH, NH, and CON groups. The 1H NMR spectra contain four NH-proton singlets of two amide groups, the proton singlet =N-OH group. The 13C NMR spectra of solutions of compounds contain signals of two carbon atoms of amide groups and a carbon atom of the C=N-OH group, which fully confirm the assumed structure.

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Freiherr von Richthofen, Carl-Georg, Bastian Feldscher, Kai-Alexander Lippert, Anja Stammler, Hartmut Bögge et Thorsten Glaser. « Electronic and Molecular Structures of Heteroradialenes : A Combined Synthetic, Computational, Spectroscopic, and Structural Study Identifying IR Spectroscopy as a Simple but Powerful Experimental Probe ». Zeitschrift für Naturforschung B 68, n^o 1 (1 janvier 2013) : 64–86. http://dx.doi.org/10.5560/znb.2013-2241.

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The vicinity of a hydrogen bond donor (O-H) and a hydrogen bond acceptor (C=O or C=N- R) in salicylaldehydes and ortho-Schiff bases results in significant structural variations compared to the monosubstituted derivatives that are reflected in the electronic structure and thus in the spectroscopic properties. This interplay between intramolecular hydrogen bonding and multicenter p- electron delocalization is the origin of the concept of resonance-assisted hydrogen bonding (RAHB). Herein, the complexity is extended from one hydrogen bond donor-acceptor pair in salicylaldehyde and ortho-Schiff bases to three hydrogen bond donor-acceptor pairs in 2,4,6-tricarbonyl- and 2,4,6- triimine-substituted phloroglucinols (1,3,5-trihydroxybenzene), respectively. To evaluate the changes in the molecular and electronic structures, we have performed a comprehensive computational, spectroscopic, and structural study starting from monosubstituted benzene derivatives as references over ortho-disubstituted derivates to the sixfold-substituted derivatives. Whereas in salicylaldehydes, ortho- Schiff bases, and 2,4,6-tricarbonyl-phloroglucinols the phenolic O-protonated tautomers represent the energy minima, the N-protonated tautomers represent the energy minima in 2,4,6-triiminephloroglucinols. The analysis provides a keto-enamine resonance structure with six exocyclic double bonds to be dominant for these species reminiscent of [6]radialenes, which were termed heteroradialenes. These heteroradialenes are non-aromatic alicycles. However, the predominance of this resonance structure does not represent a sudden change going from the 2,4,6-tricarbonyl- to the 2,4,6-triimine-phloroglucinols, but a gradual increase of analogous resonance structure contributions is observed even in salicylaldehyde and ortho-Schiff bases demonstrating some hetero-orthoquinodimethane character. These changes are, besides in the molecular structures, well reflected in the IR spectra, which can therefore be used as a simple tool to probe the electronic structures in these systems. Interruption of the delocalized p system supporting the intramolecular hydrogen bond, i. e. going from 2,4,6-triimine- to 2,4,6-triamine-substituted phloroglucinols, reestablishes an O-protonated aromatic phloroglucinol system.

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Nonn, Melinda, László Drahos et Loránd Kiss. « A Convenient Synthesis of Some Phenyl‐Substituted Aliyclic β‐Amino Esters and β‐Lactams ». ChemistrySelect 8, n^o 47 (15 décembre 2023). http://dx.doi.org/10.1002/slct.202303898.

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AbstractA convenient synthetic procedure has been developed for the access of phenyl‐substituted alicyclic β‐amino acid derivatives. The substrate‐directed palladium‐catalyzed cross‐coupling of phenylboronic acid with five‐ or six‐membered cycloalkene β‐amino esters and bicyclic β‐lactams in the presence of Selectfluor as oxidant provided phenyl‐substituted alicyclic β‐amino esters and azetidin‐2‐ones. Phenylations were investigated under various experimental conditions with different ligands and solvent systems. The structural architecture of the starting compounds and the position of their ring olefin bond influenced and predetermined the structure of the products.

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Dong, Jiufeng, Li Li, Yujuan Niu, Zizhao Pan, Yupeng Pan, Liang Sun, Li Tan et al. « Scalable High‐Permittivity Polyimide Copolymer with Ultrahigh High‐Temperature Capacitive Performance Enabled by Molecular Engineering ». Advanced Energy Materials, 31 décembre 2023. http://dx.doi.org/10.1002/aenm.202303732.

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AbstractPolymer capacitors are essential components of advanced electronic and power systems. However, the deficient high‐temperature capacitive performance of polymer dielectrics fails to meet the demand for harsh condition applications, due to the mutually restrictive relationships in permittivity (εr), glass transition temperature (Tg), and bandgap (Eg). Here, a modularized molecular engineering strategy is reported to enhance the high‐temperature capacitive performance of polymer dielectrics. First, the potential influences of multiple structural units on εr, Tg, and Eg of polymers are elucidated by comparing a set of polyimides (PIs). After screening out an excellent sulfonated PI with concurrently high εr (4.2), Eg (3.4 eV), and Tg (311.2 °C), a semi‐alicyclic sulfonyl‐containing PI copolymer is further synthesized that exhibits a superior discharged energy density of 4.3 J cm−3 above 90% efficiency at 200 °C and 485 MV m−1. Density functional theory calculations demonstrate that the combination of polar sulfonyl group, ether linkage, and alicyclic group in the backbones of the copolymer decouples the dipole orientation and the segmental motion of backbones, and reduces conjugation effects of aromatic groups, thereby minimizing the polarization relaxation loss and the conduction loss while retaining excellent thermal stability and high permittivity.

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MURRAY, J. S., P. C. REDFERN, J. M. SEMINARIO et P. POLITZER. « ChemInform Abstract : Anomalous Energy Effects in Some Aliphatic and Alicyclic Aza Systems and Their Nitro Derivatives. » ChemInform 21, n^o 26 (26 juin 1990). http://dx.doi.org/10.1002/chin.199026063.

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Kim, Hye Won, Na Kyung Kim, Alex P. R. Phillips, David A. Parker, Ping Liu, Rachel J. Whitaker, Christopher V. Rao et Roderick I. Mackie. « Genomic insight and physiological characterization of thermoacidophilic Alicyclobacillus isolated from Yellowstone National Park ». Frontiers in Microbiology 14 (26 septembre 2023). http://dx.doi.org/10.3389/fmicb.2023.1232587.

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IntroductionAlicyclobacillus has been isolated from extreme environments such as hot springs, volcanoes, as well as pasteurized acidic beverages, because it can tolerate extreme temperatures and acidity. In our previous study, Alicyclobacillus was isolated during the enrichment of methane oxidizing bacteria from Yellowstone Hot Spring samples.MethodsPhysiological characterization and genomic exploration of two new Alicyclobacillus isolates, AL01A and AL05G, are the main focus of this study to identify their potential relationships with a thermoacidophilic methanotroph (Methylacidiphilum) isolated from the same hot spring sediments.Results and discussionIn the present study, both Alicyclobacillus isolates showed optimal growth at pH 3.5 and 55°C, and contain ω-alicyclic fatty acids as a major lipid (ca. 60%) in the bacterial membrane. Genomic analysis of these strains revealed specific genes and pathways that the methanotroph genome does not have in the intermediary carbon metabolism pathway such as serC (phosphoserine aminotransferase), comA (phosphosulfolactate synthase), and DAK (glycerone kinase). Both Alicyclobacillus strains were also found to contain transporter systems for extracellular sulfate (ABC transporter), suggesting that they could play an important role in sulfur metabolism in this extreme environment. Genomic analysis of vitamin metabolism revealed Alicyclobacillus and Methylacidiphilum are able to complement each other’s nutritional deficiencies, resulting in a mutually beneficial relationship, especially in vitamin B1(thiamin), B3 (niacin), and B7 (biotin) metabolism. These findings provide insights into the role of Alicyclobacillus isolates in geothermal environments and their unique metabolic adaptations to these environments.

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