Nitric Acid In Acetic Anhydride Research Articles

Effects of twelve organic solvents on process hazards and reaction selectivity of m-xylene nitration: Combined calorimetric technique and DFT calculations

Selection of appropriate solvents is of great significance for achieving efficient and safe m-xylene nitration. In this study, the exothermic behavior of m-xylene nitration under twelve organic solvents were studied by reaction calorimetry. The process hazards were assessed by calculation of thermal safety parameters. The reaction selectivity was quantified. The anhydrides exhibited the prominent promotion as water absorbent and active reagent in nitration, followed by selected aliphatic hydrocarbons, chlorinated hydrocarbons. While acetic acid, propionic acid and ethyl acetate had negative effects. The maximum yield of 95.6 % was achieved in nitric acid-acetic anhydride (HNO3-Ac2O) system. The thermal weight loss of the products appeared at around 150−230 °C by thermogravimetry experiments. The activation energy was determined to be 192.9 kJ/mol through adiabatic kinetic calculations. Furthermore, the solvent effects were analyzed by calculating the solvent polarity and its interaction energy with HNO3. The different action mechanisms of Ac2O and Pc2O on NO2+ generation were revealed. The density functional theory calculations were in agreement with the experimental results. These findings can provide guidance for understanding of the solvent effect on the reaction hazards and selectivity of m-xylene nitration, and provide experimental and theoretical basis for solvent screening for the nitration of similar aromatic compounds.

Process optimization, thermal hazard evaluation and reaction mechanism of m-xylene nitration using HNO3-Ac2O as nitrating reagent

Nitro-m-xylenes (NMX) was synthesized in semi-batch mode via m-xylene nitration using nitric acid-acetic anhydride (HNO3-Ac2O) as nitrating reagent in this work. The nitration process was optimized by response surface methodology. The yield of NMX could reach 92.40% under the optimal conditions of jacket temperature of 20 °C, 0.15 mol of HNO3 and 0.19 mol of Ac2O. Corresponding large reaction enthalpy (ΔH=240.9 kJ/mol) and adiabatic temperature rise (ΔTad,r =398.1 K) indicated the serious hazards of nitration in a thermal runaway scenario. Pyrolysis of nitration products occurred at about 320–400 °C by differential scanning calorimetry tests. The reaction order of the pyrolysis was determined to be 1.2 by adiabatic kinetic analysis. Thermal risk of the nitration process was assessed to be acceptable and level 1 via the risk matrix and Stoessel criticality diagram analyses, respectively. Furthermore, detailed nitration mechanisms for NO2+ generation and aromatic substitution were presented. The activation free enthalpy and free energy parameters for each step were calculated by density functional theory (DFT). These findings can help understand the exothermic sources of m-xylene nitration and guide the intrinsically safer design and scale-up of the process.

Selective Nitroxylation of Adamantane Derivatives in the System Nitric Acid–Acetic Anhydride

A number of new nitroxyadamantanes have been synthesized by nitroxylation of the corresponding substrates with nitric acid in acetic anhydride. High electrophilicity and reduced acidity of the system HNO3–Ac2O increases the stability of nitrates and significantly decreases the probability of formation of alcohols. In some cases, nitrolysis and oxidation of functional groups in the substrate are observed.

Nitro derivatives of 1,3-dihydrobenzimidazol-2-one: I. Synthesis of N-nitrobenzimidazol-2-ones

1,3,5,6-Tetranitro-2,3-dihydro-1H-benzimidazol-2-one, 1,5,6-trinitro-2,3-dihydro-1H-benzimidazol-2-one, and 1,4,5,6-tetranitro-2,3-dihydro-1H-benzimidazol-2-one were synthesized for the first time by nitration of 5,6-di- and 4,5,6-trinitro-2,3-dihydro-1H-benzimidazol-2-ones with concentrated nitric acid in acetic anhydride.

Synthesis of o-nitrosoacylbenzenes from o-nitrobenzyl alcohols and their derivatives

Nitration of substituted benzyl alcohols, as well as ethers and esters derived therefrom, with nitric acid in acetic anhydride was studied. The corresponding o-nitrobenzyl alcohols and their derivatives formed as the primary products are capable of being converted into o-nitrosoacylbenzenes by the action of acids.

Synthesis, Structure, and Alkylation of 4‐Nitroamino‐1,2,4‐triazole.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis, Structure, and Alkylation of 4-Nitroamino-1,2,4-triazole *

Nitration of 4-amino-1,2,4-triazole with nitric acid in acetic anhydride gives the corresponding N-nitroamino derivative which has an inner salt structure. Its alkylation with alkyl halides, as well as with oxiranes, occurs only at the endocyclic nitrogen atom, while the exocyclic reaction center is not involved. All the 1-substituted products have the structure of 1-alkyl-1,2,4-triazol-1-io-4-N-nitroimides.

Synthesis of new proton‐ionizable crown ether compounds containing substituted lh‐pyridin‐4‐one subcyclic units

AbstractFive novel pyridono‐18‐crown‐6 (10‐14) and two new benzyloxy‐substituted pyridino‐18‐crown‐6 (15 and 16) ligands have been prepared. By the catalytic hydrogenative removal of the benzyl group from the benzyloxy moiety at position 4 of the pyridine ring of 15 and 16, pyridono‐18‐crown‐6 ethers 5 and 12 were obtained. These ligands were transformed to their 3,5‐dibromo (10 and 13) and 3,5‐dinitro derivatives (11 and 14) by treatment with bromine in methylene chloride and nitric acid in acetic anhydride, respectively. The latter proton‐ionizable crown ethers have pKavalues of about 7.5 for 10 and 13 and 4.5 for 11 and 14. Thus, they are good candidates for complexation and proton‐coupled transport of selected cations.

Synthesis, Characterization and Thermal Behaviour of 2,4,6,8-Tetranitro-2,4,6,8-Tetraazabicyclo[3.3.1]Nonane-3,7-Dione (TNPDU) and one of its Methylene Analogues

2,4,6,8 - Tetranitro – 2,4,6,8 - tetraazabicyclo[3.3.1]nonane-3,7-dione (TNPDU) has been synthesized from propane diurea by nitration with nitric acid-acetic anhydride with a yield of 85 %. The molecular structure of the compound has been determined by elemental analysis, IR and 1H-NMR spectroscopy. Some of the properties including thermal and explosion delay behaviour of the compound and its mixtures with high explosives, are reported. An analogous compound 2,5,7,9-tetranitro-2,5,7,9-tetraazabicyclo[4.3.0]nonane–8–one (TNABN) has also been evaluated for some of the explosive properties considering its good stability and insensitiveness as compared to other nitrodiurea derivatives.

Selective nitration of paclitaxel and related taxanes

Paclitaxel and some of its natural analogues are readily converted to their respective nitrate esters when reacted with nitric acid in acetic anhydride at 25° C in 30 minutes. Under milder conditions. partially esterified products can be prepared. The regioselectivity of these partial nitrations is studied.

A novel process for preparation of active carbon from sapropelitic coals

The aim of this work is the preparation of active carbons starting from sapropelitic coals. Firstly, a traditional route of manufacturing, coking and activation (820°C) was carried out. The specific area (BET) of the activated semicokes of six sapropelitic coal samples varied from a few square meters to about five hundred (for Taimylir coal). Secondly, using Taimylir coal, a novel way of active carbon preparation was attempted combining low temperature modification and chemical activation. The modification was carried out using nitric acid-acetic anhydride mixture at room temperature and tested by swelling and weight uptake measurements. The modified coal samples were analyzed by Thermogravimetry (TGA) and FT-IR spectroscopy. The chemical activation route included impregnation by an activant (KOH) and a subsequent heating (2 hr under argon) at selected temperatures ranging from 300 to 900°C. Surface areas were determined by BET and SAXS methods. The chemical modification resulted in new functional group formation and organic framework reorganization, which strongly affected the activation, as a value of 1200 m 2 g −1 was obtained after chemical activation.

97/01637 Oxidation of natural coal in the nitric acid-acetic anhydride system

97/01637 Oxidation of natural coal in the nitric acid-acetic anhydride system

Di- and trinitrophenanthrenes: synthesis, separation, and reduction property.

Although nitrated polycyclic aromatic hydrocarbons (nitrated PAHs), specifically, dinitrated PAHs, have been indicated as potent mutagenic and carcinogenic environmental pollutants, only a few di- and trinitrophenanthrenes (DNPHs and TNPHs) have been reported up to the present time. Methods for the preparation of DNPHs and TNPHs by direct nitration of phenanthrene were established in this study. The reaction of phenanthrene with fuming nitric acid in acetic anhydride gave a complex mixture of DNPHs. Eleven DNPHs were isolated by using preparative HPLC with a total of 62.6% yield. Their chemical structures were determined using 1H NMR and electron impact mass spectrometry (EI-MS). The isolated DNPHs and their yields were 2,10-DNPH (14.2%), 1,10-DNPH (8.0%), 3,10-DNPH (6.9%), 3,6-DNPH (6.6%), 2,9-DNPH (5.3%), 1,6-DNPH (5.1%), 3,5-DNPH (4.6%), 4,9-DNPH (3.2%), 4,10-DNPH (3.1%), 1,5-DNPH (2.8%), and 2,6-DNPH (2.8%). Similarly, nine TNPHs were obtained from the nitrated reaction mixture of phenanthrene with fuming nitric acid without solvent: 3,6,9-TNPH (9.2%), 2,6,9-TNPH (9.0%), 1,6,9-TNPH (8.2%), 1,5,10-TNPH (9.0%), 2,6,9-TNPH (9.0%), 1,6,9-TNPH (4.0%), 1,7,9-TNPH (3.4%), 2,5,10-TNPH (2.5%), 2,6,10-TNPH (2.4%), 3,5,10-TNPH (1.8%), and 2,7,9-TNPH (0.2%) in 46.5% of the total yield. The reduction properties of the DNPHs and TNPHs were examined using cyclic voltammetry. The LUMO energy levels of the DNPHs and TNPHs calculated by the AM1 method were correlated to the first reduction potentials (E1/2). The coplanar or noncoplanar conformations of the nitro substituents to the phenanthrene ring system were also discussed.

Fe 3+-Montmorillonite catalyst for selective nitration of chlorobenzene

High para-selectivity (upto 92%) and isolated yield (90%) are achieved in the nitration of chlorobenzene catalysed by Fe 3+-exchanged K10-montmorillonite in the presence of a mixture of fuming nitric acid-acetic anhydride as nitrating agent.

Ortho-selective side-chain nitration of α-Bromoacylpolymethylbenzenes and its application to the syntheses of indan-1-one and inden-1-one derivatives

α-Bromoacylpolymethylbenzenes 2a-m react with fuming nitric acid in acetic anhydride to give 2-(nitromethyl)-(α-bromoacyl)polymethylbenzenes 3a-m in good isolated yields. Compounds 3a-j undergo the intramolecular nucleophilic substitution/cyclization in the presence of 1 equiv. of base either in benzene or N,N-dimethylformamide (DMF) to provide the corresponding substituted 3-nitroindan-1-ones 4a-j in quantitative yields as mixtures of diastereomers ( cis and trans). The cis/trans ratios of 4 vary with the steric factor and the nature of solvent: cis < trans in benzene, whereas cis > trans in DMF. On the contrary, 3-unsubstituted 2-nitromethyl compounds 3k-m afford 3,2-benzoxazepin-5(4 H)-ones 7k-m under the same reaction condition. On the other hand, the reactions of 3a-j in the presence of 2 equiv. of base give the substituted inden-1-ones 5 in satisfactory isolated yields.

Synthesis of some sugar nitrates

hydroxyl groups were converted into nitrate by esters using fuming nitric acid in acetic anhydrideTe5. Benzyl2-U-benzoyl-~-~-arabinopyranoside~ 1, treated with fuming nitric acid in acetic anhydride at 20”, gave benzyl2-O-benzoyl-3,4-di-O-nitro-/3-L-arabinopyranoside 2 (58%) and benzyl2-O-benzoyld-Q-nitro-P-L-arabinopyranoside 3 (3.2%). The isolation of 3, although in Iow yield, suggests that the axial OH-4 group in 1 is more reactive than the equatorial OH-3. This behavior may be due, as has been pointed out7-‘, to intramolecular hydrogen-bonding between OH-4 and O-5, which would enhance the nucleophilic character of OH-4. Treatment of 2 with sodium iodide in acetone”.” afforded partial selective denitration’~12 at O-3, with retention of con~guration and without rearrangement, to give 3. The structure of 3 was confirmed by its transformation into benzyl 2,3-di-0~nzoyl-4-~-nitro-~-L-arabino~yranoside 4 and the subsequent denitration of 4 to give benzyl~,3-di-0-benzoyl-~~L*arabinopyranoside 5, which was identical with the product previously described%. The structure of 5 was confirmed by its reaction with methanesulfonyl chloride to give benzyl 2,3-di-0-benzoyl-4-U-methylsulfonyl-/I-L-arabinopyranoside’.

Bimanes (1,5‐diazabicyclo[3.3.0]octadienediones): Laser activity in syn‐bimanes

AbstractThe conversion of 3‐methyl‐4‐benzyl‐4‐chloro‐2‐pyrazolin‐5‐one 10b was catalyzed by a mixture of potassium fluoride and alumina to give syn‐(methyl, benzyl)bimane 6 (62%) without detectable formation of the anti isomer,A6 [a 1 : 1 mixture (87%) of the isomers 6 and A6 was obtained when the catalyst was potassium carbonate]. In a similar reaction syn‐(methyl,carboethoxymethyl)bimane 7 (15%) with the anti isomer A7 (36%) was obtained from 3‐methyl‐4‐carboethoxymethyl‐4‐chloro‐2‐pyrazolin‐5‐one 10c. syn‐(Methyl, β‐acetoxyethyl)bimane 8 (70%) was obtained from 3‐methyl‐4‐β‐acetoxyethyl‐4‐chloro‐2‐pyrazolin‐5‐one 10d (potassium carbonate catalysis) and was converted by hydrolysis to syn‐(methyl, β‐hydroxyethyl)bimane 9 (40%). Acetyl nitrate (nitric acid in acetic anhydride) converted anti‐(amino,hydrogen)bimane 11 to anti‐(amino,nitro)bimane 15 (91%), anti‐(methyl,hydrogen)bimane 13 to anti‐(methyl,nitro)(methyl,hydrogen)bimane 16 (57%), and degraded syn‐(methyl,hydrogen)bimane 12 to an intractable mixture. Treatment with trimethyl phosphite converted syn‐(bromomethyl,methyl)bimane 17 to syn‐(dimethoxyphosphinylmethyl,methyl)bimane 18 (78%) that was further converted to syn‐(styryl,methyl)bimane 19 (29%) in a condensation reaction with benzaldehyde. Treatment with acryloyl chloride converted syn‐(hydroxymethyl,methyl)bimane 20 to its acrylate ester 21 (22%). Stoichiometric bromination of syn‐(methyl,methyl)bimane 1 gave a monobromo derivative that was converted in situ by treatment with potassium acetate to syn‐(acetoxymethyl,methyl)(methyl,methyl)bimane 47. N‐Amino‐μ‐amino‐syn‐(methylene,methyl)bimane 24 (68%) was obtained from a reaction between the dibromide 17 and hydrazine. Derivatives of the hydrazine 24 included a perchlorate salt and a hydrazone 25 derived from acetone. Dehydrogenation of syn‐(tetramethylene)bimane 26 by treatment with dichlorodicyanobenzoquinone (DDQ) gave syn‐(benzo,tetramethylene)bimane 27 (58%) and syn‐(benzo)bimane 28 (29%). Bromination of the bimane 26 gave a dibromide 29 (92%) that was also converted by treatment with DDQ to syn‐(benzo)bimane 28. Treatment with palladium (10%) on charcoal dehydrogenated 5, 6, 10, 11‐tetrahydro‐7H,9H‐benz [6, 7] indazol [1, 2a]benz[g]indazol‐7,9‐dione 35 to syn‐(α‐naphtho)bimane 36 (71%). The bimane 35 was prepared from 1,2,3,4‐tetrahydro‐1‐oxo‐2‐naphthoate 37 by stepwise treatment with hydrazine to give 1,2,4,5‐tetrahydro‐3H‐benz[g]indazol‐3‐one 38, followed by chlorine to give 3a‐chloro‐2,3a,4,5‐tetrahydro‐3H‐benz[g]indazol‐3‐one 39, and base. Dehydrogenation over palladium converted the indazolone 34 to 1H‐benz[g] indazol‐3‐ol 36. Helicity for the hexacyclic syn‐(α‐naphtho)bimane 36 was confirmed by an analysis based on molecular modeling.The relative efficiencies (RE) for laser activity in the spectral region 500–530 nm were obtained for 37 syn‐bimanes by reference to coumarin 30 (RE 100): RE &gt; 80 for syn‐bimanes 3, 5, 18, and μ‐(dicarbomethoxy)methylene‐syn‐(methylene,methyl)bimane 22: RE 20–80: for syn‐bimanes 1,2,4,20,24,26, and μ‐thia‐syn‐(methylene,methyl)bimane 50: and RE 0‐20 for 26 syn‐bimanes. The bimane dyes tended to be more photostable and more water‐soluble than coumarin 30. The diphosphonate 18 in dioxane showed laser activity at 438 nm and in water at 514 nm. Presumably helicity, that was demonstrated by molecular modeling, brought about a low fluorescence intensity for syn‐(α‐naphtho)bimane 36, Φ0.1, considerably lower than obtained for syn‐(benzo)bimane 28, Φ0.9.

ChemInform Abstract: An Interpretation of the Puzzling Dichotomy of the Reaction Modes Observed During the Side‐Chain Nitration of Alkylaromatics with HNO3/ CH2Cl2 and HNO3/(CH3CO)2O.

AbstractSide‐chain nitration of the pentamethylarenes (I) is performed using either nitric acid in acetic anhydride or nitric acid in methylene chloride.

The insertion and extrusion of heterosulfur bridges. XIV. Synthesis of nitrotriphenyleno[1,12‐bcd]thiophenes

AbstractSulfur bridging to form triphenyleno[1,12‐bcd]thiophene (2) in ca. 46% yield has been effected at 540° by direct addition of crystalline triphenylene (1) or dodecahydrotriphenylene (4) to a heterogeneous catalyst in a stream of hydrogen sulfide. Treatment of a reaction mixture of 1 and 2 with hydrogen peroxide‐glacial acetic acid gives 2 sulfone 2d and 1,4‐triphenylenoquinone (3). Reduction of 2d with lithium aluminum hydride in tetrahydrofuran leads back to 2 (80%), while reductive acetylation of 3 produces 1,4‐diacetoxytriphenylene. Treatment of 2 with nitric acid in acetic anhydride at 65° gives a mixture of 1‐nitro (30%), 3‐nitro (47%), and 1,7‐dinitro (11%) derivatives, separable by chromatography on alumina. Structures of these derivatives are assigned on the basis of ultraviolet‐visible absorption and proton magnetic resonance spectra, as well as the chemical conversion 1‐nitro‐2 → 1,7‐dinitro‐2. The substitution pattern in 2 is correlated with Hückel molecular orbital calculations on reactivity and with substitution in analogous polycyclic, condensed aromatic compounds.

ChemInform Abstract: Regioselective Side‐Chain Nitration of Polymethylbenzenes Directed by an Acyl Function and Its Application to the Synthesis of Polysubstituted Phthalic Acid Derivatives.

AbstractNitration of the polymethylphenyl ketones (I), (IV), (V), and (XIII) with fuming nitric acid in acetic anhydride shows regioselectivity in most cases, and predominantly forms the ortho‐nitromethyl derivatives (III), (VII), and (XIV).