A Groundbreaking Stepwise Protocol to Prepare HMX from DPT: New Mechanism Hypothesis and Corresponding Process Study

1,3,5,7‐Tetranitro‐1,3,5,7‐tetraazacyclooctane(HMX) is one of the most powerful and widely used explosives. 3,7‐Dinitro‐1,3,5,7‐tetraazabicyclo[3.3.1] (DPT) is an important precursor in the production of HMX. A new reaction mechanism including nitrolysis, nitrosolysis and nitrolysis processes in fuming HNO₃ was put forward. The stable key intermediate 1‐nitroso‐3,5,7‐trinitro‐1,3,5,7‐tetraazacyclooctane (MNX) was isolated and characterized. Based on the new mechanism, a stepwise method to prepare HMX from DPT was developed. The influence factors on the yields of MNX such as reaction temperature, loading amounts of HNO₃, NaNO₂ and NH₄NO₃ were investigated. Under the optimized conditions, MNX was obtained with a satisfactory yield of 84.0 %. MNX could be efficiently and smoothly nitrolyzed in fuming nitric acid and afforded pure β‐HMX with excellent yield up to 92.8 %. The overall yield of the stepwise procedure was as high as 78.0 %, much higher than traditional one‐pot nitrolysis protocols.     

Selective Extraction of N‐Heterocyclic Precursors of 1,3,5,7‐Tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) Using Molecularly Imprinted Polymers

N‐heterocyclic compounds are key nitration precursors for some high energy density explosives such as 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX). Nitration of 1,3,5,7‐tetraacetyl‐1,3,5,7‐tetraazacyclooctane (TAT) yields HMX in high yields and purity. However, the analogue 1,3,5‐triacetyl‐1,3,5‐triazacyclohexane (TRAT) is easily co‐produced via the condensation of acetonitrile and 1,3,5‐trioxan. To selectively extract TAT from a mixture of TAT and TRAT, the molecular imprinting technology (MIT) was developed in this study. The capacity of the dry polymer is 16 mg g⁻¹ and the recovery surpasses 75 %.     

Synthesis of nitropyridine‐based π‐conjugated polymers and their chemical properties

π‐Conjugated poly(3‐nitropyridine‐2,5‐diyl) ( PPy‐3‐NO₂ ), poly(3,3′‐dinitro‐2,2′‐bipyridine‐5,5′‐diyl) ( PBpy‐3,3′‐diNO₂ ), and a poly(arylene ethynylene) type polymer consisting of a 3,3′‐dinitro‐2,2′‐bipyridine unit ( PAE‐1 ) were synthesized by Cu‐promoted Ullmann coupling reaction and Pd‐catalyzed coupling reaction. PPy‐3‐NO₂ and PAE‐1 were soluble in organic solvents such as DMSO, DMF, and chloroform, and gel permeation chromatography analysis showed a number average molecular weight (M_n) of 9,300 and 12,300, respectively. PPy‐3‐NO₂ gave intrinsic viscosity, [η], of 0.53 dL g^?1 in DMF. PBpy‐3,3′‐diNO₂ had somewhat lower solubility. The polymers exhibited a UV–vis peak at about 430 nm. PPy‐NO₂ received electrochemical reduction at ?1.5 V versus Ag⁺/Ag in acetonitrile, and gave an electrochemical redox cycle in a range from 0 to ?1.1 V versus Ag⁺/Ag in an aqueous solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1763–1767, 2006     

Chemical Transformation of Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) Induced by Low Energy Electron Beam Irradiation

The effects of 8.0×10⁻¹⁷ J (500 eV) and 3.2×10⁻¹⁹ J (2 eV) electrons on chemical structure of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) were studied in situ, under ultra‐high vacuum conditions using a combination of X‐ray photoelectron spectroscopy (XPS) and quadrupole mass spectrometry. XPS data indicated that electrons impact by 8.0×10⁻¹⁷ J for 30 s caused a decrease in nitro group concentration, and a little shift in the binding energy of the nitrogen 1s peak. Such a phenomenon was found at very low kinetic energy (3.2×10⁻¹⁹ J) with time evolution. Quadrupole mass spectrometry detected gas desorption after electron irradiation included H₂O and H₂ mostly. Microscopy‐IR spectroscopic investigations also proved that the intensity of nitro groups of HMX after irradiation decreased compared with those of the pristine HMX. We attributed the structure changes obtained by XPS and IR spectroscopy result in a chemical transformation, which was associated with low‐energy dissociative electron attachment (DEA) of surface contaminants followed by deoxidization reactions to form the product molecules.     

Preparation and Performance of Nano HMX/TNT Cocrystals

Cocrystals of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) and 2,4,6‐trinitrotoluene (TNT) with high energy and low sensitivity were obtained by a spray drying method. Scanning electron microscopy (SEM), X‐ray diffraction (XRD), and Fourier Transform Raman spectroscopy (FT‐Raman) were used to characterize the raw materials and cocrystals. Impact sensitivity and thermal decomposition properties of the cocrystals were tested and analyzed. The results show that microparticles prepared by the spray drying method are spherical in shape and 1–10 μm in size. The particles are aggregates of many tiny cocrystals, ranging from 50 nm to 200 nm. The formation of cocrystals originates from the N O ⋅⋅⋅ H hydrogen bonding between  NO₂ (HMX) and  CH₃ (TNT). Compared with raw HMX, the impact sensitivity of the cocrystals reduces obviously and it is much harder to decompose the cocrystal thermally.     

Analysis of Polar Precursors of 1,3,5,7‐Tetranitro‐1,3,5,7‐tetrazocine (HMX) Using Hydrophilic Interaction Chromatography

Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) is currently one of the most widely used explosives. 1,3,5,7‐Tetraacetyl‐1,3,5,7‐tetraazacyclooctane (TAT) is an attractive precursor for the synthesis of HMX; the nitration of this key precursor results in both high yield and purity under mild condition. TAT can be prepared either by acetylation of 2,6‐diacetyl‐pentamethylenetetramine (DAPT) or by the condensation of ACN and 1,3,5‐trioxane. However, TAT and DAPT are polar compounds, and are difficult to analyze using reverse phase liquid chromatography. Herein, a chromatography method for the direct separation of these polar compounds was developed using hydrophilic interaction chromatography (HILIC) using a Venusil HILIC column, with ACN/water (95/5, v/v) as the mobile phase. The chromatographic analysis and identification of these polar compounds provide valuable information for the optimization of the synthetic process of TAT.     

Quantum Chemical Studies on the Structure and Performance Properties of 1,3,4,5‐Tetranitropyrazole: A Stable New High Energy Density Molecule

Molecular orbital calculations were performed for the geometric and electronic structures, band gap, thermodynamic properties, density, detonation velocity, detonation pressure, stability and sensitivity of 1,3,4,5‐tetranitropyrazole ( R23 ). The calculated density (approx. 2060 kg m⁻³), detonation velocity (approx. 9.242 km s⁻¹) and detonation pressure (approx. 41.30 GPa) of the model compound are appearing to be promising compared to hexahydro‐1,3,5‐trinito‐1,3,5‐triazine (RDX) and octahydro‐1,3,5,7‐tetranitro‐l,3,5,7‐tetrazocine (HMX). Bader’s atoms‐in‐molecules (AIM) analysis was also performed to understand the nature of the intramolecular N ⋅⋅⋅ O interactions and the strength of trigger X NO₂ bonds (where XC, N) of the optimized structure computed from the B3LYP/aug‐cc‐pVDZ level.     

The β‐δ‐Phase Transition and Thermal Expansion of Octahydro‐1,3,5,7‐Tetranitro‐1,3,5,7‐Tetrazocine

Phase behavior of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) is investigated by X‐ray powder diffraction (XRD). The XRD patterns at elevated temperature show that there is a co‐existing temperature range of β‐ and δ‐phase during the phase transition process. Additionally, mechanical forces can catalyze the conversion from δ‐ back to β‐phase. Based on the diffraction patterns of β‐ and δ‐phase at different temperatures, we calculate the coefficients of thermal expansion by Rietveld refinement. For β‐HMX, the linear coefficients of thermal expansion of a‐axis and b‐axis are about 1.37×10⁻⁵ and 1.25×10⁻⁴ °C⁻¹. A slight decrease in c‐axis with temperature is also observed, and the value is about −0.63×10⁻⁵ °C⁻¹. The volume coefficient of thermal expansion is about 1.60×10⁻⁴ °C⁻¹, with a 2.2% change from 30 to 170 °C. For δ‐HMX, the linear coefficients of thermal expansion of a‐axis and c‐axis are found to be 5.39×10⁻⁵ and 2.38×10⁻⁵ °C⁻¹, respectively. The volume coefficient of thermal expansion is about 1.33×10⁻⁴ °C⁻¹, with a 2.6% change from 30 to 230 °C. The results indicate that β‐HMX has a similar volume coefficient of thermal expansion compared with δ‐HMX, and there is about 10.5% expansion from β‐HMX at 30 °C to δ‐HMX at 230 °C, of which about 7% may be attributed to the reconstructive transition.     

Degradation of TNT,RDX, and HMX Explosive Wastewaters Using Zero‐Valent Iron Nanoparticles

The high‐energy explosives 2,4,6‐trinitrotoluene (TNT), hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), and the high melting explosive octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) are common groundwater contaminants at active and abandoned munitions production facilities causing serious environmental problems. A highly efficient and environmentally friendly method was developed for the treatment of the explosives‐contaminated wastewaters using zero‐valent iron nanoparticles (ZVINs). ZVINs with diameters of 20–50 nm and specific surface areas of 42.56 m² g⁻¹ were synthesized by the co‐precipitation method. The explosives degradation reaction is expressed to be of pseudo first‐order and the kinetic reaction parameters are calculated based on different initial concentrations of TNT, RDX, and HMX. In addition, by comparison of the field emission scanning electron microscopy (FE‐SEM) images for the fresh and reacted ZVINs, it was apparent that the ZVINs were oxidized and aggregated to form Fe₃O₄ nanoparticles as a result of the chemical reaction. The X‐ray diffraction (XRD) and X‐ray absorption near edge structure (XANES) measurements confirmed that the ZVINs corrosion primarily occurred due to the formation of Fe₃O₄. Furthermore, the postulated reaction kinetics in different concentrations of TNT, RDX, and HMX, showed that the rate of TNT removal was higher than RDX and HMX. Furthermore, by‐products obtained after degradation of TNT (long‐chain alkanes/methylamine) and RDX/HMX (formaldehyde/methanol/hydrazine/dimethyl hydrazine) were determined by LC/MS/MS, respectively. The high reaction rate and significant removal efficiencies suggest that ZVINs might be suitable and powerful materials for an in‐situ degradation of explosive polluted wastewaters.     

Structures and Properties Prediction of HMX/TATB Co‐Crystal

In this study, a new co‐crystal explosive of 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX)/1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) (molar ratio 1 : 1) was designed based on crystal engineering. The crystal structure was predicted using the polymorph predictor (PP) method. The main properties of co‐crystal consisting of mechanical properties, stability, and interaction formats were simulated through molecular dynamics methods. Simulated results indicate that the crystal structure of the HMX/TATB co‐crystal may belong to the P , P2₁2₁2₁ or P2₁/c space group. The calculations of the binding energy and the analysis for radial distribution function show that the two components are connected through electrostatic hydrogen bonding and strong van der Waals interactions. The new co‐crystal has better mechanical properties with the moduli systematically decreased. With the appearance of the new crystal, the trigger bond N NO₂ has little change.     

Energetic Characteristics of HMX‐Based Explosives Containing LiH

The high energy density compound octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) and the strong exothermic compound LiH represent an excellent principal explosive and an active fuel, respectively. Herein, the energetic characteristics of HMX‐based explosives are explored by adding LiH as fuel additive. The detonation parameters of HMX‐based explosives containing LiH were tested with free‐field explosion experiments and compared with those of traditional TNT, HMX, and aluminized explosives. The results show that the explosives exhibit higher energy and present preferable explosion effect when LiH is added as an explosive ingredient. The improvement of impulse is more than 32.8 % at 2 m. The shock wave peak overpressure increases by almost 40 % at a distance of 3 m from detonation center specially for the explosive containing both LiH and Al additives. Elemental H and Li are expected to release tremendous energy to effectively improve the explosives instant damage power, but the detonation duration is shorter than that of Al‐containing mixed explosives, which may limit the advantage over Al in the impulse. Li₂CO₃ powder is the solid product of HMX/LiH, which explains the LiH oxidation during the explosion. The exothermic processes in the formation are the reason for the increased energy of HMX/LiH explosives. These results can provide guidance to a potential energetic system formed by HMX and LiH.     

Improved Synthesis and X‐Ray Structure of 5‐Aminotetrazolium Nitrate

5‐Aminotetrazolium nitrate was synthesized in high yield and characterized using Raman and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁵N). The molecular structure of 5‐aminotetrazolium nitrate in the crystalline state was determined by X‐ray crystallography: monoclinic, P 2₁/c, a=1.05493(8) nm, b=0.34556(4) nm, c=1.4606(1) nm, β=90.548(9)°, V=0.53244(8) nm³, Z=4, ϱ=1.847 g cm⁻³, R₁=0.034, wR₂ (all data)=0.090. The thermal stability of 5‐aminotetrazolium nitrate was determined using differential scanning calorimetry; the compound decomposes at 167 °C. The enthalpy of combustion (Δ_combH) of 5‐aminotetrazolium nitrate ([CH₄N₅]⁺[NO₃]⁻) was determined experimentally using oxygen bomb calorimetry: Δ_combH([CH₄N₅]⁺[NO₃]⁻)=−6020±200 kJ kg⁻¹. The standard enthalpy of formation (Δ_fH°) of [CH₄N₅]⁺[NO₃]⁻ was obtained on the basis of quantum chemical computations at the electron‐correlated ab initio MP2 (second order Møller‐Plesset perturbation theory) level of theory using a correlation consistent double‐zeta basis set (cc‐pVTZ): Δ_fH°([CH₄N₅]⁺[NO₃]⁻(s))=+87 kJ mol⁻¹=+586 kJ kg⁻¹. The detonation velocity (D) and the detonation pressure (P) of 5‐aminotetrazolium nitrate were calculated using the empirical equations by Kamlet and Jacobs: D([CH₄N₅]⁺[NO₃]⁻)=8.90 mm μs⁻¹ and P([CH₄N₅]⁺[NO₃]⁻)=35.7 GPa.     

Ionic polymers with expanded π‐conjugation systems derived from through‐space interaction in piperazinium and homopiperazinium rings

Reactions of N‐(2,4‐dinitrophenyl)‐4‐arylpyridinium chlorides (aryl (Ar) = phenyl and 4‐biphenyl) with piperazine or homopiperazine caused opening of the pyridinium ring and yielded polymers that consisted of 5‐piperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂)₂N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) or 5‐homopiperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂CH₂)(CH₂CH₂)N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) units. ¹H NMR spectral analysis suggested that the π‐electrons of the penta‐2,4‐dienylideneammonium group of the polymers were delocalized. UV‐visible spectral measurements revealed that the π‐conjugation system expanded along the polymer chains because of the orbital interaction between electrons of the two nitrogen atoms of the piperazinium and homopiperazinium rings. However, the π‐conjugation length depended on the distance between the two nitrogen atoms; that is, the polymers containing the piperazinium ring had a longer π‐conjugation length than those containing the homopiperazinium ring. Conversion of the piperazinium and homopiperazinium rings from the boat to the chair form led to a decrease in the π‐conjugation length. The surface of pellets that were molded from the polymers exhibited metallic luster, and these polymers underwent electrochemical oxidation in solution. Copyright © 2010 Society of Chemical Industry     

A Combined Experimental and Theoretical Study of HMX (Octogen,Octahydro‐1,3,5,7‐Tetranitro‐1,3,5,7‐Tetrazocine) in the Gas Phase

The structures of α‐ and β‐HMX were fully optimized and the vibrational frequencies computed at the hybrid DFT B3LYP/6‐31G(d, p) level of theory. The DCI+mass spectrum of HMX using ammonia (NH₃) as a “soft” ionising gas is reported. Field desorption mass spectrometry (FD) was used because of the high molecular intensities and low fragmentation. The FD spectrum shows only one significant peak at m/e 297 due to the protonated molecular ion [M+H]⁺. These observations clearly establish that under the conditions of CI and FD mass spectrometry experiments HMX is present in the gas phase (without decomposition) prior to the chemical ionisation.     

DFT Studies on a Series of Nitramines Containing Pyridine Ring

In this article, a series of nitramines containing pyridine ring were studied by density functional theory (DFT). The gas-phase heats of formation were predicted based on the isodesmic reactions and the condensed-phase heats of formation and heats of sublimation were estimated with the Politzer's approach. The detonation velocity and pressure were calculated using the empirical Kamlet-Jacobs equation. Many title compounds have better performance than RDX (hexahydro-1,3,5-trinitro-1,3,5-trizine) and HMX (1,3,5,7-tetranitro-1,3,5,7- tetraazacyclooctane). The impact sensitivity was evaluated with the characteristic height (h₅₀). It is found that most of the studied compounds have lower sensitivities than CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12- hexaazaisowurtzitane). The crystal structures were predicted with the molecular mechanics method and optimized by the CA-PZ local density approximation of DFT. Analysis of the crystal energy gap indicates I-13, II-1, III-1, and IV-1 are nearly conductors and other compounds are semiconductors. For I-1～I-8 and I-11, the largest contribution to the valence bands is mainly from the p states of the C and N atoms in the pyridine and fused ring and for the other compounds, from the p states of the C and N atoms in the amino group and pyridine.     

An Ab Initio Theoretical Study of 2,4,6‐Trinitro‐1,3,5‐Triazine, 3,6‐Dinitro‐1,2,4,5‐Tetrazine,and 2,5,8‐Trinitro‐Tri‐s‐Triazine

In order to evaluate 2,4,6‐trinitro‐1,3,5‐triazine (TNTAz), 3,6‐dinitro‐1,2,4,5‐tetrazine (DNTAz), and 2,5,8‐trinitro‐tri‐s‐triazine (TNTsTAz), the geometries of these compounds have been fully optimized employing the B3LYP density functional method and the AUG‐cc‐pVDZ basis set. The accurate gas phase enthalpies of formation have been obtained by using the atomization procedure and designing isodesmic reactions in which the parent rings are not destroyed. Based on B3LYP/AUG‐cc‐pVDZ calculated geometries and natural charges, the crystal structures have been predicted using the Karfunkel–Gdanitz method. Computed results show that there exists extended conjugation over the parent rings of these compounds. More energy content is reserved in DNTAz than in both TNTAz and TNTsTAz. The title compounds are much more sensitive than 1,3,5‐trinitrobenzene. The calculated detonation velocity of DNTAz reaches 9.73–9.88 km s⁻¹, being larger than those of CL‐20 and TNTAz. TNTsTAz has no advantage over the widely used energetic compounds such as RDX and HMX.     

2，4，6-三硝基-2，4，6-三氮杂环己酮的合成Ⅱ以DPT或PHX为原料的合成

报道了以DPT（或PHX）与脲（或硝基脲）为原料在几种硝化剂中合成2,4,6－三硝基－2,4,6－三氮杂环己酮（RDX酮）的方法,对由DPT、PHX和BSX这三种反应物的硝解碎片分子参加反应的形式和反应副产物的特点作了初步分析,结果表明：在硝解碎片中,非硝基取代的N,N－二羟甲基胺类碎片分子参加了与脲（或硝基脲）的缩合反应,生成了产物RDX酮,N,N－二羟甲基硝胺碎片分子不参加反应。以DPT为原料时,RDX酮得率为69％,副产物为HMX、RDX和小分子碎片;用PHX作原料时,RDX酮得率最高达36％,副产物为HMX和小分子碎片;用BSX作原料时则无产物和环状硝胺副产物生成。     

Polyamides obtained by direct polycondesation of 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl] fluoren‐9‐YL]‐2‐methyl‐phenoxy]aniline with dicarboxylic acids based on a diphenyl‐silane moiety

Polyamides (PAs) containing fluorene, oxyether, and diphenyl‐silane moieties in the repeating unit were synthesized in > 85% yield by direct polycondesation between a diamine and four dicarboxylic acids. Alternatively, one PA was synthesized from an acid dichloride. The diamine 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl]fluoren‐9‐yl]‐2‐methyl‐phenoxy]aniline ( 3 ) was obtained from the corresponding dinitro compound, which was synthesized by nucleophilic aromatic halogen displacement from p‐chloronitrobenzene and 9,9‐bis (4‐hydroxy‐3‐methyl‐phenyl)fluorene ( 1 ). Monomers and polymers were characterized by FTIR and ¹H, ¹³C, and ²⁹Si‐NMR spectroscopy and the results were in agreement with the proposed structures. PAs showed inherent viscosity values between 0.14 and 0.43 dL/g, indicative of low molecular weight species, probably of oligomeric nature. The glass transition temperature (T_g) values were observed in the 188–211°C range by DSC analysis. Thermal decomposition temperature (TDT_10%) values were above 400°C due to the presence of the aromatic rings in the diamine. All PAs showed good transparency in the visible region (>88% at 400 nm) due to the incorporation of the fluorene moiety. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Pyrrole‐based narrow‐band‐gap copolymers for red light‐emitting diodes and bulk heterojunction photovoltaic cells

A series of narrow‐band‐gap conjugated copolymers (PFO‐DPT) derived from pyrrole, benzothiadiazole, and 9,9‐dioctylfluorene (DOF) is prepared by the palladium‐catalyzed Suzuki coupling reaction with the molar feed ratio of 4,7‐bis(N‐methylpyrrol‐2‐yl)‐2,1,3‐benzothiadiazole (DPT) around 1, 5, 15, 30, and 50%. The obtained polymers are readily soluble in common organic solvents. The solutions and the thin solid films of the copolymers absorb light from 300 nm to 600 nm with two absorbance peaks at around 380 nm and 505 nm. The PL emission consists mainly of DPT unit emission at around 624–686 nm depending on the DPT content in solid film. The EL emission peaks are red‐shifted from 630 nm for PFO‐DPT1 to 660 nm for PFO‐DPT50. Bulk heterojunction photovoltaic cells fabricated from composite films of copolymer and [6,6]‐phenyl C₆₁ butyric acid methyl ester (PCBM) as electron donor and electron acceptor, respectively, in device configuration: ITO/PEDOT : PSS/PFO‐DPT : PCBM/Ba/Al shows power conversion efficiencies 0.15% with open‐circuit voltage (V_oc) of 0.60 V and short‐circuit current density (J_sc) of 0.73 mA/cm² under AM1.5 solar simulator (100 mW/cm²). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of electrolytes on the reduction of 2,4‐dinitrotoluene by zero‐valent iron

BACKGROUND: Dinitrotoluenes (DNTs) are environmentally persistent, making the remediation of contaminated streams and groundwater difficult. Zero‐valent iron (Fe⁰) can be used as an electron source for the reduction of recalcitrant DNTs in waste‐water and thus enhance their biodegradability. However, little is known about the qualitative effects of major anions and cations present in waste‐water on the reduction of DNTs by Fe⁰. RESULTS: The presence of Na₂SO₄ and NaCl at levels between 0.25 and 2 mmol L^?1 was observed to enhance the reactivity of Fe⁰ towards 2,4‐DNT. The positive effect of K₂SO₄ is stronger than that of Na₂SO₄ at the same level (1 mmol L^?1). Varying (NH₄)₂SO₄ from 0.1 to 1.0 mmol L^?1 improved the efficiency of 2,4‐DNT degradation by Fe⁰. The effects of varying NaNO₃ and NaNO₂ from 0 mmol L^?1 to 4.7 mmol L^?1 and 0 mmol L^?1 to 5.8 mmol L^?1, respectively, were also investigated. Both NaNO₃ and NaNO₂ at low concentration improved the efficiency of 2,4‐DNT degradation by Fe⁰, however, at high concentration, inhibiting effects appeared. CONCLUSION: SO₄^2?, Cl^?, Na⁺, K⁺ and NH₄⁺ notably enhanced 2,4‐DNT reduction by Fe⁰ at the tested concentrations. The positive effect of K⁺, Cl^? was relatively stronger than that of Na⁺ and sulfate (SO₄^2?). However, the effect of NH₄⁺ was relatively weaker at concentrations greater than 1.0 mmol L^?1. The presence of low concentrations of NO₃^? and NO₂^? promoted 2,4‐DNT reduction by Fe⁰ and inhibited the reaction. The results suggest that 2,4‐DNT reduction by Fe⁰ can be controlled by the ions composition of the waste‐water. Copyright © 2010 Society of Chemical Industry