全氟烷基磺酰亚胺盐催化芳香化合物硝化反应的研究

利用系列全氟烷基磺酰亚胺盐[M(NPf₂)_n]作为一种新型的Lewis酸催化剂，用于催化芳香化合物与等摩尔65% (m∶m)硝酸的硝化反应. 通过考察不同的催化剂、反应时间、反应温度和反应介质效应等因素对甲苯硝化的影响，以及比较1 mol% Yb[N(C₄F₉SO₂)₂]₃催化不同结构的取代芳烃硝化反应的效果，表明全氟烷基磺酰亚胺盐不仅具有环境友好和原子经济的特点，而且是一类比常规Lewis酸更有效的、芳香化合物硝化反应的催化剂.     

Electrophilic tetraalkylammonium nitrate nitration. II. Improved anhydrous aromatic and heteroaromatic mononitration with tetramethylammonium nitrate and triflic anhydride,including selected microwave examples

A new one-pot nitration employing tetramethylammonium nitrate and trifluoromethanesulfonic anhydride in dichloromethane to provide a ready source of the nitronium triflate nitrating agent is presented. Rapid and selective nitration with a variety of aromatic and heteroaromatic substrates is achieved resulting in the synthesis of several novel organic compounds. A distinct advantage is the removal of undesired byproducts by aqueous workup. This very mild nitration permits large-scale syntheses and gives high isolated product yields that often require no further purification. This tetramethylammonium nitrate-based nitration also has been applied to microwave-assisted conditions, and the results with several compounds are outlined.     

Synthesis of Oxidized Nitro-Polycyclic Aromatic Hydrocarbons

A series of phenolic and cis-dihydrodiol derivatives of 6-nitrobenzo[a] pyrene and 7-nitrobenz[a]anthracene were synthesized. The common structural feature of these compounds is that their nitro groups are perpendicular or near perpendicular to the aromatic moieties. From the synthesis of these compounds, it was found that an acetoxy group does not affect the regioselectivity of electrophilic nitration to a polycyclic aromatic hydrocarbon (PAH) and that a nitro substituent can substantially reduce the concerted electrophilic 1,2-addition of osmium tetroxide to the most olefinic aromatic double bond of a PAH.     

The novel usage of thiourea nitrate in aryl nitration简

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.     

Vitamin E chemistry. Nitration of non-alpha-tocopherols: products and mechanistic considerations

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.     

Supported Tetramethylamonium Nitrate/Silicasulfuric Acid as a Useful Reagent for Nitration Aromatic Compounds Under Solvent‐Free Conditions

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.     

Practical neutral aromatic nitration with nitrogen dioxide in the presence of heterogeneous catalysts under moderate oxygen pressure

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.     

Fast and Efficient Nitration of Salicylic Acid and Some Other Aromatic Compounds over H_3PO_4/TiO_2-ZrO_2 Using Nitric Acid

TiO₂‐ZrO₂ (1/1)‐surf with Ti and Zr molar ratio of 1/1 was prepared with surfactant through a sol‐gel method. The optimum experimental condition was investigated for nitration of salicylic acid. Then, a number of nitration reactions were carried out with a variety of aromatic compounds in the optimum condition. The 25 wt% H₃PO₄/TiO₂‐ZrO₂ (1/1)‐surf catalyst showed good selectivity and yield in a short time for the nitration of salicylic acid and some other aromatic compounds.     

Electrophilic nitration of aromatics in ionic liquid solvents.

Potential utility of a series of 1-ethyl-3-methylimidazolium salts [emim][X] with X = OTf-, CF3COO-, and NO3- as well as [HNEtPri2][CF3COO] (protonated Hünig's base) ionic liquids were explored as solvent for electrophilic nitration of aromatics using a variety of nitrating systems, namely NH4NO3/TFAA, isoamyl nitrate/BF3.Et2O, isoamyl nitrate/TfOH, Cu(NO3)/TFAA, and AgNO3/Tf2O. Among these, NH4NO3/TFAA (with [emim][CF3COO], [emim][NO3]) and isoamyl nitrate/BF3.Et2O, isoamyl nitrate/TfOH (with [emim][OTf]) provided the best overall systems both in terms of nitration efficiency and recycling/reuse of the ionic liquids. For [NO2][BF4] nitration, the commonly used ionic liquids [emim][AlCl4] and [emim][Al2Cl7] are unsuitable, as counterion exchange and arene nitration compete. [Emim][BF4] is ring nitrated with [NO2][BF4] producing [NO2-emim][BF4] salt, which is of limited utility due to its increased viscosity. Nitration in ionic liquids is surveyed using a host of aromatic substrates with varied reactivities. The preparative scope of the ionic liquids was also extended. Counterion dependency of the NMR spectra of the [emim][X] liquids can be used to gauge counterion exchange (metathesis) during nitration. Ionic liquid nitration is a useful alternative to classical nitration routes due to easier product isolation and recovery of the ionic liquid solvent, and because it avoids problems associated with neutralization of large quantities of strong acid.     

Reactions of Aromatic Nitro Compounds with Bases

Aromatic nitro compounds can react in many ways with bases. The reaction path followed depends mainly on the degree of nitration (with a sharp jump from mononitro to di- and trinitro compounds) and the base used. Redox reactions or nucleophilic aromatic substitutions predominate with mononitro compounds, whereas Meisenheimer additions together with nucleophilic aromatic substitutions are preferred by dinitro and trinitro compounds; deprotonations are less common. The bromine in nitrobromobenzenes can be replaced by metal at low temperatures. Very weak bases generally give electron donor-acceptor complexes.     

Nitric acid in the presence of P2O5 supported on silica gel—a useful reagent for nitration of aromatic compounds under solvent-free conditions

A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P₂O₅ supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.     

Perfluorinated rare earth metals catalyzed nitration of aromatic compounds

The nitration of aromatic compounds can be carried out in the presence of perfluorinated rare earth metal catalyst without halogenated organic solvent.     

Engineering Cytochrome P450BM3 Enzymes for Direct Nitration of Unsaturated Hydrocarbons

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.     

Reactions of (η6-Arene)tricarbonylchromium Complexes: Hydrogenation,Nitration, and Bromination

In this study, we explore the reactions of coordinated arenes, e.g., hydrogenation, nitration, and bromination, to prepare compounds which are not accessible from conventional organic synthesis. The reaction products formed from reactions with the coordinated and the uncoordinated arenes are compared. The polycyclic aromatic hydrocarbons (PAHs) employed for this study include phenanthrene, methyl- and acetyl-phenanthrene, and benz[a]anthracene (BA), The tricarbonylchromium group demonstrated various characteristics which influence the reactions in this work, such as an electronic effect to deactivate hydrogenation, a steric effect to exhibit, highly positional selective nitration, and a free radical mechanism to direct bromine to attack at the ring coordinated to tricarbonylchromium.     

Reactivities of heterocyclic compounds in nitration. 5. Kinetics of nitration of 5-substituted 2-picrylaminopyridines

The kinetics of nitration of 5-bromo-, 5-chloro-, and 5-nitro-2-picrylaminopyridines in 80–96% sulfuric acid were studied by a spectrophotometric method. The kinetic parameters of nitration were calculated. The UV spectra of the neutral and protonated forms in aqueous sulfuric acid solutions were identified. It was established that the indicated compounds are nitrated in the protonated form. The relative (as compared with benzene) rates of nitration were calculated.See [1] for communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1632–1636, December, 1980.     

Design of ionic liquid 3-methyl-1-sulfonic acid imidazolium nitrate as reagent for the nitration of aromatic compounds by in situ generation of NO(2) in acidic media

3-Methyl-1-sulfonic acid imidazolium nitrate ([Msim]NO(3)) as a new Br?nsted acidic ionic liquid and nitrating agent was prepared and used for the efficient nitration of aromatic compounds (even aniline derivatives). The dramatic effect of this reagent by in situ generation of nitrogen dioxide as a radical on aromatic compounds to give nitroarenes has been studied.     

Potassium Periodate/NaNO2/KHSO4‐Mediated Nitration of Aromatic Compounds and Kinetic Study of Nitration of Phenols in Aqueous Acetonitrile

Synthesis and kinetics of potassium periodate(KIO₄)/NaNO₂/KHSO₄)‐initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent‐free microwave conditions. Reaction times in microwave‐assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first‐order dependence on [phenol], [NaNO₂], and [KIO₄]. An increase in [KHSO₄] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D )). Observed results were in accordance with Amis and Kirkwood plots [log k ′ vs. (1/D ) and [(D − 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate‐determining step. In addition, the plots of (log k ′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron‐donating groups and retarded with electron‐withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH ^# vs. ΔS ^#) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration.     

Electrophilic aromatic nitration using perfluorinated rare earth metal salts in fluorous phase

In this paper, we describe a practical, useful electrophilic aromatic nitration process in fluorous phase by using perfluorodecalin (C10F18, cis- and trans-mixture) as a fluorous solvent and perfluorinated rare earth metal salt [Yb(OSO2C8F17)3] as a catalyst for the electrophilic aromatic nitration.     

Aromatic nitration under neutral conditions using N-bromosuccinimide/silver(I) nitrate

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.     

The Chemical Behavior of Multibridged [2n] Cyclophanes

Multibridged [2_n] cyclophanes comprise a novel class of aromatic compounds, in which two benzene rings are connected by three up to a maximum of six ethano bridges. Compared to classical nonannelated arenes, their most distinct chemical property is the ease with which, particularly the higher-bridged homologs, take part in addition reactions (Diels-Alder additions, hydrogenations, and ionic additions). On the other hand, the typical regenerative behavior of aromatic molecules is not fully suppressed in the [2_n]cyclophanes as evidenced by such typical electrophilic aromatic substitution reactions as bromination, Friedel-Crafts acylation, and nitration. Besides these reactions in which the benzene rings are either destroyed or retained, reactions at and with the ethano bridges, e.g. their cleavage, isomerization, and functionalization can also occur.