Catalyst‐Free Reductive Coupling of Aromatic and Aliphatic Nitro Compounds with Organohalides

A rare reductive coupling of nitro compounds with organohalides has been realized. The reaction is initiated by a partial reduction of the nitro group to a nitrenoid intermediate. Therefore, not only aromatic but also aliphatic nitro compounds are efficiently transformed into monoalkylated amines, with organohalides as the alkylating agent. Given the innate reactivity of the nitrenoid, a catalyst is not required, resulting in a high tolerance for aryl halide substituents in both starting materials.     

The controlled potential coulometric and controlled potential polarographic determinations of substituted nitrobenzene compounds in dimethylsulfoxide

The n-values for the reduction of the isomers of nitrophenol and nitrobenzoic acid and for several other nitro compounds were determined in dimethylsulfoxide by controlled potential coulometry. A procedure is given in which one μmole of nitro compound may be determined in less than 8 min with an error of approximately ±l%. The associated background currents were quantitatively evaluated, and electrolysis conditions for their minimization were discussed. A procedure and results are given for the controlled potential polarography of these nitro compounds in dimethylsulfoxide.     

A new spot test for nitro compounds

A simple, rapid, and highly sensitive method for the detection of micro amounts of nitro compounds has been developed. Nitro compounds are reduced into corresponding hydroxylamines with zinc dust and acetic acid and coupled with diazonium chloride to give hydroxytriazines which give an intense pink to violet color with diphenylamine in acetic acid medium. Quantities of 0.1 μg or less of nitro compounds can be detected in 0.25 ml of total solution by this method. The method is free from the common interference.     

One step synthesis of azo compounds from nitroaromatics and anilines

A general and efficient method for synthesis of both symmetric and asymmetric aromatic azo compounds in one single step has been developed. The nitro compounds were reduced and the substituted anilines were oxidized by each other without any metal in the base condition. Various azo compounds with halogen, methyl and methoxy functional group were obtained by using available, cheap nitro compounds and substituted anilines. In addition, the electronic effect and substituent effect of the compounds have been discussed.     

Pharmacophore mapping and electronic feature analysis for a series of nitroaromatic compounds with antitubercular activity

A five point pharmacophore was generated using PHASE for a series of nitroaromatic compounds and their congeners as antitubercular agents. The generated pharmacophore yielded significant 3D‐QSAR model with r² of 0.890 for a training set of 92 molecules. The model also showed excellent predictive power with correlation coefficient Q² of 0.857 for a test set of 31 compounds. The pharmacophore indicated that presence of a nitro group, a piperazine moiety, one aromatic ring feature and two acceptor features are necessary for potent antitubercular activity. The pharmacophore was supported by electronic property analysis using density functional theory (DFT) at B3LYP/3–21*G level. Molecular electrostatic profile of the compounds was consistent with the generated pharmacophore model, particularly appearance of localized negative potential regions near both the oxygen atoms of nitro group extending laterally to the isoxazole ring system/amide bond in the most active compounds. Calculated data further revealed that all active compounds have smaller LUMO energies located over the nitro group, furan ring, and isoxazole ring/amide bond attached to it. Higher negative values of LUMO energies concentrated over the nitro group are indicative of the electron acceptor capacity of the compounds, suggesting that these compounds are prodrugs and must be activated by TB‐nitroreductase. The results obtained from this study should aid in efficient design and development of nitroaromatic compounds as antitubercular agents. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Contemplation on Detonation Pressures of Nitramines and ­Nitro Aromatics

A physical model and a mathematical theory for the detonation pressures of explosives materials were developed. The pressure values are expressed as function of the detonation velocity (D) and the average mass (m) of the gaseous products, and are applied for various nitramines and aromatic nitro compounds including nitro pyrimidines and nitro triazines. Some regression equations were obtained and discussed. The pressure values show poor linear dependence on the average mass of the products but good dependence on the detonation velocities alone or Dm. Moreover, for the same Dm value nitramines should produce more pressure than aromatic nitro compounds. This work deals with pressure developed by explosion products and interrelates it with detonation pressure within the constraints of certain assumptions and pays attention to so far unnoticed relationships at least under certain circumstances.     

interaction of nitro compounds with radicals: a quantum chemical study

Photoreduction of nitro compounds is accompanied by formation of various radical products that can react with the starting nitro compound, thus causing deviation of the decomposition kinetics from the first-order kinetics with respect to the nitro compound. The results of quantum chemical modeling of the reactions of nitro compounds with radicals and the pathways of further transformations of radical adducts formed in the reactions are presented. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 202–206, February, 2006.     

Investigation of correlation between impact sensitivities and nitro group charges in nitro compounds

A new method of calculating the Mulliken net charges of the nitro group, Q(NO)()2, to assess impact sensitivities for nitro compounds is established. All calculations including optimizations and Mulliken population and frequency analyses are performed by density functional theory (DFT) and the general gradient approximation (GGA) method in Acceryls' code Dmol(3) with the Beck-LYP hybrid functional and the DNP basis set. As a result, the charges on nitro group can be regarded as a structural parameter to estimate the impact sensitivity on the bond strength, oxygen balance, and molecular electrostatic potential. The compound with more -Q(NO)()2 will be insensitive and gives a large value of impact sensitivity H(50)(). This method considering the molecular structure is applicable for almost all nitro compounds when the C-NO(2), N-NO(2), or O-NO(2) bond is the weakest in the molecule. According to the results in this paper, the compounds with -Q(NO)()2 >0.23e show H(50)() 相似文献   

Two dominant factors influencing the impact sensitivities of nitrobenzenes and saturated nitro compounds

The factors governing the impact sensitivity (H(50)) of nitrobenzenes and saturated nitro compounds were studied. It was observed that the oxygen balances (OB(100)) and nitro group charge (Q(NO2)) are two important factors influencing the stability of these nitro compounds. Employing the square of nitro group charge (Q(NO2)2) and OB(100) as the parameters, a good quantitative model was built for predicting H(50) of the above two sorts of nitro compounds. The predictive ability of the model was assessed by the cross-validation method (i.e., leave-one-out cross-validation). The cross-validation result shows that the model is significant and stable, and the predicted accuracy is within 0.21 m. This quantitative model may be a useful tool for the design of high-energy-density materials.     

钯催化甲酸为氢源的芳硝基化合物直接加氢和一锅法酰胺化

Pd/C催化剂实现了甲酸为氢源的芳硝基化合物的直接加氢及甲酸为氢源和羰基源的一锅法芳硝基化合物的酰胺化.在芳硝基化合物的直接加氢过程中,该体系体现了很好的催化活性,实现了对同时带有其它可还原官能团的芳硝基化合物的选择性加氢,得到较高收率的胺类化合物.同时,通过提高反应温度和增加甲酸的量,实现了芳硝基化合物的加氢和甲酰化的串联反应,该体系体现了较高的催化活性.     

Investigation on the correlation between the interaction energies of all substituted groups and the molecular stabilities of nitro compounds

A model, similar to an isodesmic reaction, is for the first time presented in this paper for describing, defining, and calculating the interaction energies of the indirectly linked groups or atoms within one molecule. Its applications to nitro substitutes of methane, benzene, and cubane verify its validity for a separate group of closely related compounds by the reasonable correlation between the calculated interaction energies of all substituted groups and the molecular stabilities or experimental impact sensitivities. Comparing with some existing rules of assessing the molecular stability, this so-called interaction energy is calculated using a model considering the chemical structures, that is, the electronic environments of compounds, and can be well related with the stabilities of nitro compounds. All investigation results show that the so-called interaction energy is a new, quantitative, and useful tool to evaluate the stabilities of nitro compounds.     

Silylation as a new strategy of the use of aliphatic nitro compounds in organic synthesis

Silylation of aliphatic nitro compounds is considered as a versatile multistage process. Due to activation of the - and -carbon atoms of the initial nitro substrates, these reactions give rise to a series of products untypical of the traditional chemistry of nitro compounds. A new redox process proposed in the present study involves controlled incomplete reduction of the nitro group with simultaneous oxidation of the carbon skeleton of the initial aliphatic nitro compound.     

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.     

Reaction of haloadamantanes with salts of nitro compounds

Silver and mercury salts of nitro compounds react with bromo- or chloroadamantanes with the formation of products of C- and/or O-alkylation, the ratio of which depends on the structure of the initial reactants. The direct experimental evidence of nitronic esters to be isomerized into nitro derivatives and of their role as intermediates in the formation of the nitro derivatives in the alkylation of nitro compounds has been presented for the first time.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiva Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1798–1803, August, 1992.     

Geminal (difluoroamino)nitro compounds

A novel preparative method for the synthesis of geminal (difluoroamino)nitro compounds was developed, The method involves the reaction ofN,N-difluoro-O-fluorosulfonyl- hydroxylamine with the corresponding salts of nitro compounds, Dependences of the yields of (difluoroamino)nitro compounds on the reaction conditions, the nature of the cation in the salts, and the properties of solvents were studied.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11. pp. 2689–2692, November, 1996.     

用分子子图法计算硝基呋咱化合物的生成热

用新的分子子图法计算硝基呋咱类化合物的生成热,将呋咱基团视为母体,即基子图项;硝基、叠氮基、甲基、氰基拆分为一个个原子,从原子的角度来分分子子图,将碳、氢、氧、氮原子视为取代基,即亚子图项.同时考虑呋咱基团的个数,考虑1位、 2位、 3位、 4位上碳、氢、氧、氮原子及双键、叁键对生成热的影响,还考虑不饱和度、总硝基个数、环的个数(除呋咱环)、氮氮及氮氧双键的个数对生成热的影响.用这种新的分子子图编码方法,对硝基呋咱化合物的生成热进行了拟合和预估,取得了满意的结果,其回归方程的相关系数达到了0.9954.     

The Raman spectra of some aromatic nitro compounds

The paper provides a re-appraisal of the analytical value of Raman spectroscopy in the investigation of aromatic nitro compounds. Correlations are found between the frequencies of the NO vibrations and the electron-donating and -withdrawing effects of substituents on the phenyl rings. Further, relations are discussed between the highest-frequency CH stretching mode and the electron density and number of nitro groups. The paper contains a large number of spectra of typical aromatic nitro compounds.     

Technique for complete oxidation of organic compounds in supercritical water

Results are presented of tests of a pilot stationary installation for supercritical water oxidation of organic compounds, first created in Russia. A high oxidation efficiency of nitro compounds formed as waste in manufacture of explosives is demonstrated.     

First and Efficient Method for Reduction of Aliphatic and Aromatic Nitro Compounds with Zinc Borohydride as Pyridine Zinc Tetrahydroborato Complex: A New Stable Ligand‐Metal Borohydride

Pyridine zinc tetrahydroborate, [(Py)Zn(BH₄)₂], as a new stable ligand‐metal borohydride, is prepared quantitatively by complexation of 1:1 zinc borohydride and pyridine at room temperature. This reagent efficiently reduces different aromatic and aliphatic nitro compounds to their primary amines in refluxing THF. In addition, the reduction shows chemoselectivity for aliphatic nitro compounds over the aromatic nitro compounds.     

Enantioselective Sequential‐Flow Synthesis of Baclofen Precursor via Asymmetric 1,4‐Addition and Chemoselective Hydrogenation on Platinum/Carbon/Calcium Phosphate Composites

Continuous‐flow synthesis of baclofen precursor ( 2 ) was achieved using achiral and chiral heterogeneous catalysts in high yield with high enantioselectivity. The key steps are chiral calcium‐catalyzed asymmetric 1,4‐addition of a malonate to a nitroalkene and chemoselective reduction of a nitro compound to the corresponding amino compound by using molecular hydrogen. A dimethylpolysilane (DMPS)‐modified platinum catalyst supported on activated carbon (AC) and calcium phosphate (CP) has been developed that has remarkable activity for the selective hydrogenation of nitro compounds.