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1.
A variety of aromatic compounds are nitrated to the parent nitro aromatic compounds under solvent‐free conditions using supported tetramethylammonium nitrate/silicasulfuric acid as a useful reagent. This methodology is useful for nitration of activated and deactivated aromatic rings. 相似文献
2.
Ajay K. Bose Subhendu N. Ganguly Sheetal Rao Jeffrey Speck Esteban Pombo-Villars 《Tetrahedron letters》2006,47(12):1885-1888
Highly accelerated and safe nitration of phenolic compounds has been found to be feasible with a mixture of calcium nitrate and acetic acid as an efficient nitration agent under brief microwave irradiation. This method is compatible with the green chemistry approach because calcium salts—the inorganic byproducts—can be useful agrochemicals rather than waste chemicals. Commercially available 15N-labeled calcium nitrate is convenient for the preparation of 15N-labeled compounds for metabolic studies and mass spectrometry. This safe nitration method can be included in laboratory experiments for high school and college students. 相似文献
3.
Thiourea nitrate (TN) was easily prepared from thiourea and nitric acid to explore its use as a new nitration reagent, Nitrations of various aromatic compounds utilizing TN in concentrated sulfuric acid were studied, TN could convert aromatic compounds to the corresponding nitrated derivatives with various abnormal yields under mild conditions. The results suggested that the reaction mechanism might be different from those of traditional nitration reagents. 相似文献
4.
Arash Ghorbani-Choghamarani Hamid Goudarziafshar Mohsen Nikoorazm Zahra Naseri 《中国化学快报》2011,22(12):1431-1434
A mixture of guanidinium nitrate and silica sulfuric acid acts as mild and heterogeneous media for the efficient mono nitration of phenolic compounds in dichloromethane at room temperature. 相似文献
5.
Urea nitrate (UN) and nitrourea (NU), easily prepared from urea and nitric acid, convert deactivated aromatic compounds to the corresponding nitrated derivatives with a high yield and a high regioselectivity under very mild conditions. The performance of the two reagents is quite similar indicating that NU is an intermediate in the UN nitration process. 相似文献
6.
Najmeh Nowrouzi Abdol Mohammad MehranpourElham Bashiri Zohre Shayan 《Tetrahedron letters》2012,53(36):4841-4842
The use of N-bromosuccinimide and silver nitrate as a convenient reagent system for the nitration of aromatic compounds under neutral and environmentally safer reaction conditions is described. 相似文献
7.
The disguise of the intrinsic selectivity of competitive, consecutive reaction systems by the mixing process is demonstrated experimentally using the fast nitration of a number of aromatic compounds with nitronium salts in nitromethane. The measured product distributions were compared with the distributions predicted from our mixing-reaction model developed previously [2] [4]. This comparison enabled the relative intrinsic rate constants for the second nitration step of the aromatic compounds investigated to be determined. 相似文献
8.
Hamid Goudarziafshar 《中国化学快报》2012,23(4):458-461
This procedure works efficiently for high selective mono nitration of phenol and substituted phenol to corresponding nitro compounds in moderate to high yield using poly(4-vinylpyridinium nitrate) and silica sulfuric acid in dichloromethane at room temperature. 相似文献
9.
Jin Ku Cho Young-Tae Kim Young Gyu Kim Yoon-Sik Lee Si-Young Sung Kyoo-Hyun Chung Bon-Su Lee 《Research on Chemical Intermediates》2006,32(8):759-766
A practical neutral aromatic nitration process using nitrogen dioxide in the presence of FeCl3 · 6H2O under 40–100 psig of oxygen was developed, and nitration of several aromatic compounds, including the deactivated nitrobenzene, was performed in a successful manner. The correlation of reaction rate with equivalents nitrogen dioxide, oxygen pressure, amount of catalyst and temperature was investigated through the nitration of benzene. Following the optimization of reaction conditions, the nitration of benzene was scaled up to 476 mol. Furthermore, inorganic solid catalysts with pore size over 5 Å and surface area over 100 m2/g were applied to newly developed neutral nitration. 相似文献
10.
A simple two step synthesis route for the preparation of several energetic multivalent nitrocarbamates of easily available alcohols is presented. The carbamates were obtained by the reaction of the alcohols and the reactive reagent chlorosulfonyl isocyanate (CSI) with subsequent aqueous work‐up. The nitration of the carbamates was performed with mixed acid (nitric and sulfuric acid). The thermal stabilities were explored by using differential scanning calorimetry and the energies of formation were calculated on the CBS‐4M level of theory, as well as several detonation and propulsion parameters for the application as energetic materials. All compounds were fully characterized and discussed in addition with single X‐ray diffraction. 相似文献
11.
Acting as in situ sources of triflyl nitrate (TfONO(2)) and trifluoroacetyl nitrate (CF(3)COONO(2)), the EAN/Tf(2)O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf(2)O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K(T)/K(B) = 5-10) in between values reported for covalent nitrates and preformed nitronium salts. 相似文献
12.
The crystals of tetramethylammonium triiodolead(II) are hexagonal with = 9.7823(11) A, c = 7.9167(8) A and γ = 120.0, Z = 2, space group P63/m. The structure was solved by direct methods and refined by least-squares techniques to a conventional R = 2.97% for the 312 independent reflections. The structure consists of chains of PbI3 units running along the c axis. Each lead atom is octahedrally coordinated to six iodides with a Pb---I bond distance of 3.223 A. The tetramethylammonium cations sit in holes in the packing of the iodide ions. The cations are disordered.
The Raman spectra of salts of this species formed with several tetraalkylammonium cations are also reported and the bands tentatively assigned. 相似文献
13.
Patel A Liebner F Netscher T Mereiter K Rosenau T 《The Journal of organic chemistry》2007,72(17):6504-6512
In contrast to the alpha-form permethylated at the aromatic ring, non-alpha-tocopherols possess free aromatic ring positions which enable them to act as potent scavengers of electrophiles in vivo and in vitro. In preparation of enzymatic studies involving peroxynitrite and other nitrating systems, the behavior of non-alpha-tocopherols under nitration conditions was studied. The nitration products of beta-, gamma-, and delta-tocopherol were identified, comprehensively analytically characterized, and their structure was supported by X-ray crystal structure analysis on truncated model compounds. Even under more drastic nitration conditions, no erosion of the stereochemistry at 2-C occurred. The nitrosation of gamma-tocopherol and delta-tocopherol was re-examined, showing the slow oxidation of the initial nitroso products to the corresponding nitro derivatives by air to be superimposed by a fast equilibrium with the tautomeric ortho-quinone monoxime, which only in the case of gamma-tocopherol released hydroxyl amine at elevated temperatures to afford the stable ortho-quinone. Mononitration of delta-tocopherol selectively proceeded at position 5. This selectivity can be explained by the theory of strain-induced bond localization (SIBL) to the quinoid nitration intermediates. Bisnitration was only insignificantly disfavored by the first nitro group, so that under normal nitration conditions offering an excess of nitrating species only the bisnitration product was found. 相似文献
14.
Nakagawa H Sumiki E Takusagawa M Ikota N Matsushima Y Ozawa T 《Chemical & pharmaceutical bulletin》2000,48(2):261-265
The inhibitory effects of various endogenous and synthetic compounds on the nitration and oxidation of L-tyrosine by peroxynitrite were examined. Nitrating and oxidizing activities were monitored by the formation of 3-nitrotyrosine and dityrosine with a HPLC-UV-fluorescence detector system, respectively. Glutathione, serotonin and synthetic sulfur- and selenium-containing compounds inhibited both the nitration and oxidation reaction of L-tyrosine effectively. However, 5-methoxytryptamine, melatonin and alpha-lipoic acid only inhibited the nitration reaction, and enhanced the formation of an oxidation product. This is important evidence that there are different intermediates in the nitrating and oxidizing reactions of L-tyrosine by peroxynitrite. It was suggested that 5-methoxytryptamine, melatonin and alpha-lipoic acid reacted only with the nitrating intermediate of peroxynitrite and inhibited nitration of L-tyrosine. Actually, the DNA strand breakage, which is believed to be a typical reaction of hydroxyl radical-like species, caused by peroxynitrite was not effectively inhibited by 5-methoxytryptamine. 5-Methoxytryptamine, melatonin and alpha-lipoic acid were viewed as useful reagents for investigating the mechanisms of damage by peroxynitrite in vitro. 相似文献
15.
Xiling Wang Xiaodan Lin Yiping Jiang Xiangquan Qin Nana Ma Fuquan Yao Sheng Dong Chuanfei Liu Yingang Feng Longyi Jin Mo Xian Zhiqi Cong 《Angewandte Chemie (International ed. in English)》2023,62(13):e202217678
Applications of the peroxidase activity of cytochrome P450 enzymes in synthetic chemistry remain largely unexplored. We present herein a protein engineering strategy to increase cytochrome P450BM3 peroxidase activity for the direct nitration of aromatic compounds and terminal aryl-substituted olefins in the presence of a dual-functional small molecule (DFSM). Site-directed mutations of key active-site residues allowed the efficient regulation of steric effects to limit substrate access and, thus, a significant decrease in monooxygenation activity and increase in peroxidase activity. Nitration of several phenol and aniline compounds also yielded ortho- and para-nitration products with moderate-to-high total turnover numbers. Besides direct aromatic nitration by P450 variants using nitrite as a nitrating agent, we also demonstrated the use of the DFSM-facilitated P450 peroxidase system for the nitration of the vinyl group of styrene and its derivatives. 相似文献
16.
J. Jon Paul Selvam 《Tetrahedron letters》2006,47(15):2507-2509
Zirconyl nitrate was found to be an excellent reagent in the nitration of phenol and substituted phenols to give nitrated phenols. This procedure works efficiently on most of the examples at room temperature yielding nitro derivatives in fair to good yields with high regioselectivity. 相似文献
17.
In this work we have examined the nitration by acetyl nitrate of a range of activated and deactivated aromatic substrates in two ionic liquids and compared the results to the same reaction in dichloromethane. Both ionic liquids are stable to the reaction conditions, and in both ionic liquids the yields of reaction are higher after unit time than the same reactions in dichloromethane, although the regioselectivity is little affected by solvent choice. This result gives further support to the suggestion that in the ionic liquid, acetyl nitrate dissociates to give the nitronium ion, and that this is the effective nitrating agent here. However, it is shown that [bmpy][N(Tf)(2)] is a better solvent for aromatic nitration than [bmpy][OTf]. This is due to the ease of formation of nitronium ion in the former ionic liquid, and is consistent with the fact that [bmpy][N(Tf)(2)] is a weaker hydrogen bond acceptor solvent than [bmpy][OTf]. Finally, a method by which [bmpy][N(Tf)(2)] may be recovered and reused for aromatic nitration has been demonstrated. 相似文献
18.
Retention study of inorganic and organic selenium compounds on a silica-based reversed phase column with mixed ion-pairing reagents 总被引:1,自引:0,他引:1
Summary Separation of seven inorganic and organic selenium compounds, namely selenic acid [Se(VI)], selenous acid [Se(IV)], trimethylselenonium
iodide (TMSe+), selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (Seet), and selenocystamine (SeCM), has been performed
on a LiChrosorb C 18 column by using mixed ion-pair reagents; 1-butanesulfonic acid and tetramethylammonium hydroxide. Flame
atomic absorption spectrometry (FAAS) was used as an element-specific detector. The retention behaviors of selenium compounds
in terms of several chromatographic parameters, such as pH of the mobile phase, the concentrations of ion-pair reagents, and
the content of organic modifier (methanol) were investigated. It was found that the separation of both inorganic and organic
selenium compounds can be achieved within 12 min with a mobile phase of 10 mM 1-butanesulfonic acid −4 mM tetramethylammonium
hydroxide −4 mM malonic acid −0.05% methanol adjusted to pH 4.5 at a flow rate of 1.0 mL min−1. The results obtained in this study showed that the use of mixed ion-pair reagents is very useful to improve the separation
of selenium compounds. The applicability of this technique for the speciation of selenium compounds in real samples was demonstrated
by the determination of selenium compounds in a selenium nutritional supplement. The results were found to be in good agreement
with those obtained by ion-exchange HPLC-ICP-MS. 相似文献
19.
Dimitrios Tsikas Frank-Mathias Gutzki Jürgen C. Frölich 《Fresenius' Journal of Analytical Chemistry》1992,342(1-2):95-97
Summary A reversed-phase HPLC method for the determination of nitrite and nitrate in aqueous solutions, biological buffers and human urine is described. The method is based on the conversion of nitrite and nitrate into their 1-nitro-2,4,6-trimethoxybenzene (NTBM) derivatives by using 1,3,5-trimethoxybenzene and concentrated sulphuric acid. NTMB is extracted by benzene, the solvent evaporated, the residue reconstructed in methanol/water (3/4, v/v) and subsequently analyzed by reversed-phase HPLC and UV detection (360 nm). The specificity of the nitration reaction, good reproducibility (C.V. 6.2%) and high sensitivity (8.4 ng nitrite) show the applicability of this method to the quantitative analysis of nitrite and nitrate in several matrices including human urine. 相似文献
20.
G. P. Sharnin I. F. Falyakhov D. N. Butovetskii 《Chemistry of Heterocyclic Compounds》1975,11(5):571-573
The mechanism of nitration of 2-nitro-, 3-nitro-, 1-methyl-, and 2-and 1-methyl-3-nitropyrroles in a mixture of sulfuric and nitric acids is similar to the mechanism of nitration of benzene. A 1-methyl group activates the investigated compounds only slightly. 相似文献