Raman Spectra of Liquid Nitromethane under Singly Shocked Conditions

Raman spectra of liquid nitromethane were measured in single-shock experiments using transient Raman scattering system with high sensitivity. The measurement system was combined with a two-stage light gas gun to interrogate the vibrational mode-dependent behaviors of shock-compressed nitromethane molecules. Up to 12 GPa, all Raman peaks were able to be clearly detected, and showed the shock-induced shifting and broadening, but no signs of chemical changes occurred in the sample. Thus, it is concluded that chemical reactions could not be initiated in singly-shocked nitromethane below 12 GPa.

Industrial Synthesis of N-Methylhydroxylamine Hydrochloride by Electrochemical Reduction of Nitromethane

An industrial electrolytic cell was designed for the electrochemical synthesis of N-methylhydroxylamine hydrochloride （N-MHA）. Copper was used as the cathode, graphite as the anode, and a cation membrane as the separator. The results show that N-MHA with a high purity of 99% can be electrosynthesized directly from nitromethane in HC1 solution. Under a constant current of 1000-2500A.m^-2 in the temperature of 30-50℃, the average yield, current efficiency, and reaction selectivity were 65%, 70%, and 99%, respectively. Graphite electrode and membrane material can be used continuously in the preparative electrolysis for 5000h. Moreover, the effects of the electrode and membrane materials, current intensity, electrolyte temperature, and other associated parameters on the electrosynthesis results were investigated. The direct current power consumption was 8151.3kW-h-（1000kg N-MHA）^ -1. This method is a simple separation process with limited contamination and hence, is a new green synthesis method for the industrial production of N-MHA.

Calculation of Hugoniot properties for shocked nitromethane based on the improved Tsien's EOS

We have calculated the Hugoniot properties of shocked nitromethane based on the improved Tsien＇s equa- tion of state （EOS） that optimized by ＂exact＂ numerical molecular dynamic data at high temperatures and pressures. Comparison of the calculated results of the improved Tsien＇s EOS with the existed experimental data and the direct simu- lations show that the behavior of the improved Tsien＇s EOS is very good in many aspects. Because of its simple analytical form, the improved Tsien＇s EOS can be prospectively used to study the condensed explosive detonation coupling with chemical reaction.

Hugoniot curve calculation of nitromethane decomposition mixtures:A reactive force field molecular dynamics approach

We investigate the Hugoniot curve, shock-particle velocity relations, and Chapman-Jouguet conditions of the hot dense system through molecular dynamics （MD） simulations. The detailed pathways from crystal nitromethane to reacted state by shock compression are simulated. The phase transition of N2 and CO mixture is found at about 10 GPa, and the main reason is that the dissociation of the C-O bond and the formation of C-C bond start at 10.0-11.0 GPa. The unreacted state simulations of nitromethane are consistent with shock Hugoniot data. The complete pathway from unreacted to reacted state is discussed. Through chemical species analysis, we find that the C-N bond breaking is the main event of the shock-induced nitromethane decomposition.

Structural Properties of Nitromethane Molecular Crystal under High Pressure:An ab initio Investigation

The pressure-dependent structural properties under hydrostatic pressure up to 120 GPa and the decomposition under uniaxial compression along the b lattice vector up to 40 GPa of nitromethane molecular crystal using ab initio method are presented. The internal molecular bond lengths and bond angles were calculated for different pressures. All bond lengths decrease as the pressures are increased under hydrostatic compression. The obvious rotation of methyl group is 33.89° under hydrostatic pressure at 120 GPa. In addition, we observe the change of C-H bonds, which have been stretched under uniaxial compression along b lattice vector in the range of 0-40 GPa of nitromethane.

Activation of Nitromethane to Cyanide by a Mononuclear Cu(Ⅱ) Complex

The tridentate ligand DPA-Me（2） was readily prepared from DPA（DPA = 2,2-dipicolylamine） in high yield. The mixture of 2 and Cu（ClO4）26H2O in methanol gave a five-coordinated mononuclear complex [（DPA-Me）Cu（Me CN）（ClO4）]（ClO4）（3）. Recrystallization of 3 in CH3NO2 led to an activation of CH3NO2 to CN- by the formation of product as a dinuclear cyanide bridged complex {[Cu（DPA-Me）]2（CN）（ClO4）3CH3NO2}n（4）. Both 3 and 4 were characterized by X-ray crystallography, IR spectroscopy and elemental analysis. The crystal of 4 was grown in space group P21/c with a = 17.74582（15）, b = 13.89877（11）, c = 14.92546（13） A, β = 91.4246（8）°, V = 3680.15（5） 3, Z = 4, Dc = 1.695 g/cm^3, F（000） = 1912, C28H33Cl3Cu2N8O14, Mr = 939.05, μ = 1.602 cm^-1, Cu Kα radiation（λ = 1.54184 ）, R = 0.0485 and w R = 0.1246 for 6414 observed reflections with I 〉 2σ（I）.

Structural deformation of nitro group of nitromethane molecule in liquid phase in an intense femtosecond laser field

The structural deformation of NO2 group induced by an intense femtosecond laser field of liquid nitromethane（NM）molecule is detected by time-and frequency-resolved coherent anti-Stokes Raman spectroscopy（CARS） technique with the intense pump laser. Here, we present the mechanism of molecular alignment and deformation. The CARS spectra and its FFT spectra of liquid NM show that the NO2 torsional mode couples with the CN symmetric stretching mode and that the NO2 group undergoes ultrafast structural deformation with a relaxation time of 195 fs. The frequency of the NO2 torsional mode in liquid NM（50.8±0.3 cm^-1） at room temperature is found. Our results prove the structural deformation of two groups in liquid NM molecule occur simultaneously in the intense laser field.

A first-principles study of the structural,electronic and elastic properties of solid nitromethane under pressure

The structural,electronic and elastic properties of solid nitromethane are investigated under pressure by performing first-principles density functional theory(DFT)calculations within the generalized gradient approximation(GGA)and the local density approximation(LDA).The obtained ground state structure properties are found to be consistent with existing experimental and theoretical results.The pressure-induced variations of structure parameters(a,b,c and V)indicate that the solid nitromethane has an anisotropic compressibility,and the compression along the c direction is more difficult than along a and b directions.From the vibration curves of intermolecular bond length and bond angle,we find that the C—N bond is the most sensitive among these bonds under pressure,suggesting that the C—N bonds may be broken first under external loading.The influence of pressure on the electronic properties of solid NM has been studied,indicating that solid NM is an insulating compound with a large indirect band gap and tends to be a semiconductor with increasing pressure.Finally,we predict the elastic constants and their pressure dependence for the solid NM with the bulk modulus,Young’s modulus,shear modulus and the Poisson’s ratio derived.

Nitromethane-Enabled Fluorination of Styrenes and Arenes

The electrophilic fluorination of unsaturated compounds provides a reliable approach to the generation of organofluorides,which are used widely in agrochemicals,pharmaceuticals,and other materials.Numerous active electrophilic fluorine reagents,such as the fluorine molecule(F_(2))or xenon difluoride(XeF_(2)),have been applied in fluorination.However,these reagents suffer from their hazardous,toxic,corrosive,and poor selective properties,and the relatively weak electrophilicity of Selectfluor or N-fluorobenzenesulfonimide(NFSI)usually limits their broad applications.Herein,we disclose nitromethane(MeNO_(2))as an efficient activator of Selectfluor and NFSI,as well as a stabilizer of carbocations.Therefore,the fluoro-azidation,fluoroamination,fluoroesterification of styrenes,and C–H fluorination of(hetero)arenes were well realized just by the facilitation of MeNO_(2).The mild reaction conditions and practicability made our current method a versatile protocol for accessing organofluorides.

Low toxic nitromethane based monopropellant for gas generator cycle air turbo ramjet engine

The present study proposes ethanol-nitromethane mixture as a safe, storable, andlow toxic monopropellant for a gas generator cycle air turbo ramjet engine and evaluates itspropulsion performance. The present study proposes that nitromethane is mixed with ethanolto adjust gas generator combustion temperature. The author developed the computational codefor the present analysis and verified its accuracy. The specific thrust of ethanol-nitromethane isnearly identical to that of ethanol-liquified oxygen and is higher than methanol-hydroxylammonium nitrate aqueous solution and hydrazine. Hydrazine has the highest Ispamong the propellants in the present analysis. However, Isp of ethanol-nitromethane is nearlyequal to that of ethanol-liquified oxygen and higher than those of methanol-hydroxylammonium nitrate aqueous solution, and hydroxyl terminated polybutadiene-ammonium perchlorate. With the propellant-to-air ratio range in the present study, ethanol-nitromethane has the stoichiometric condition at the ram combustor around the propellant-to-air ratio range from 0.2 to 0.25 and can obtain high ram combustion temperature. This resultis favorable for ethanol-nitromethane because it improves the specific thrust and the specificimpulse. Therefore, ethanol-nitromethane can be a promising low-toxic liquid monopropellantfor the air turbo ramjet engine.

Nitromethane as a nitrogen donor in Schmidt-type formation of amides and nitriles

With the support by the National Natural Science Foundation of China,the National Basic Research Program of China and the Drug Innovation Major Project,the research team led by Prof.Jiao Ning(焦宁)at the State Key Laboratory of Natural and Biomimetic Drugs,School of Pharmaceutical Sciences,Peking University,discovered a new nitrogen donor for the Schmidt-type formation of amides and nitriles,which was published as research report in Science(2020,367:281—285).

A theoretical study on the intermolecular interaction of energetic system-Nitromethane dimer

Three optimized geometries of nitromethane dimer have been obtained at the HF/6–31G* level. Dimer binding energies have been corrected for the basis set superposition error (BSSE) and the zero point energy. Computed results indicate that the cyclic structure of (CH3NO2)2 is the most stable of three optimized geometries, whose corrected binding energy is 17.29 kJ·mol?1 at the MP4SDTQ/6–31G*/HF/6–31G* level. In the optimized structures of nitromethane dimer, the inter-molecular hydrogen bond has not been found; and the charge-transfer interaction between CH3NO2 subsystems is weak; and the correlation interaction energy makes a little contribution to the intermolecular interaction energy of the dimer.

Influence of temperature on mechanical stimulation threshold of typical liquid propellant

In order to study the variation of temperature to mechanical stimulation threshold of typical liquid propellants(ADN-based HAN-based and nitromethane),the critical impact energy and critical friction of three propellants under different temperatures were studied by using BAM fall hammer impact sensitivity tester and BAM friction sensitivity tester.Experiments show that under 80℃,60℃,40℃and 20℃,the critical impact energy of HAN-based are 20 J,15 J,15 J,15 J;the critical impact energy of nitromethane are 2 J,2 J,2 J,2 J;and the critical impact energy of ADN-based are<1 J,3 J,7.5 J,15 J.It reveals that HAN-based propellant has the highest critical impact energy,while nitromethane propellant has the lowest critical impact energy.ADN-based propellant has a notable decrease on its critical impact energy with temperature decreasing,indicating that temperature has a significant effect on impact sensitivity of ADN-based propellant.The critical friction of three samples are all higher than 360 N at 80℃,60℃,40℃and 20℃,which shows that the samples are not sensitive to friction,and temperature has no significant effect on the critical friction of three samples.The mechanical stimulations that may be encountered during the production and use of liquid propellants are analyzed,which takes certain working conditions and the temperature coupling effect into consideration,thereby providing support for safety management of liquid propellants during production and storage process.

Multicomponent reactions for the synthesis of functionalized 1,4-oxathiane-3-thiones under microwave irradiation in water

A series of substituted l,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane,carbon disulfide and oxiranes in the presence of Et;N in water as the solvent under microwave irradiation.Particularly valuable features of this method include high yields of products,broad substrate scope,short reaction time and straightforward procedure.

Ethylenediamine： A Highly Effective Catalyst for One-Pot Synthesis of Aryl Nitroalkenes via Henry Reaction and Dehydration

Ethylenediamine （H2NCH2CHeNH2） was found to be a highly effective catalyst for the condensation of aryl aldehydes with nitromethane （or nitroethane）. When 1%-2% （tool%） of ethylenediamine was used as the catalyst, the one-pot reaction of aryl aldehydes with nitromethane （or nitroethane） by refluxing for 3-10 h efficiently afforded various arylnitroalkenes la-ly in 85%-97% yields.