Benzene Compounds Research Articles

Investigating the reduction of BTEX in automotive paint sludge combined with biological sludge by vermicomposting process using Eisenia fetida

Background: Due to the fact that in the process of car painting in the automotive industry, sludge containing dangerous compounds of benzene, toluene, ethylbenzene, xylene which cannot be released into the environment without purification, is inevitably produced, this study was conducted to investigate the feasibility of removing BTEX (benzene, toluene, ethylbenzene, and xylene) from the paint sludge of Saipa Automotive Company using Eisenia fetida worms. Methods: This is an experimental study. First, mixtures with different proportions of sludge were prepared and loaded in suitable boxes. After preparing the desired sludge, their quantitative and qualitative characteristics were determined in terms of type and amount of BTEX, volatile materials, moisture content, and C/N ratio. Then, to check the changes in BTEX, sampling was performed on different days during 90 days. BTEX measurements were performed using GC-MS method (NIOSH Method 1501). Results: The results showed that in the best mixing ratio of sludge, the amount of benzene decreased from 3 mg to less than 0.01 mg in 30 days, toluene decreased from 1.5 mg to zero over a 45-day period, ethyl benzene was reduced from 7 mg to zero mg over 70 days, and xylene decreased from 18 mg to 0.9 mg over 90 days. In addition, in the same optimal mixing ratio, the amount of volatile organic matter, pH, and C/N ratio also had a decreasing trend in the vermicomposting process. Conclusion: According to the results, E. fetida worms are able to work in mixed sludge and have the ability to break down BTEX.

Concentration Analysis and Health Risk Assessment of Air Pollutants in Newly Decorated Public Places in Xi'an

In order to understand the levels of indoor air pollution and health risks in public places, our research group conducted air quality monitoring and human health risk assessments for five types of public places (offices, classrooms, laboratories, banks, and hospitals) in Xi'an City from December 2017 to July 2020. The test items included formaldehyde, benzene, toluene, xylene, n-butyl acetate, ethylbenzene, styrene, n-undecane, and total volatile organic compounds (TVOC). The results showed that formaldehyde had the highest exceedance rate (59.4%), followed by toluene, TVOC, benzene, and xylene. Among the five types of public places, hospitals had the highest rate of pollutants exceeding the standard (46.7%), and the main pollutants exceeding the standard were formaldehyde, benzene, and toluene. The results showed that the concentrations of formaldehyde and TVOC were positively correlated with temperature and humidity. The health risk assessment results showed that there were carcinogenic risks of formaldehyde and benzene in different places; people working in banks had a higher risk of formaldehyde carcinogenesis, and those working in hospitals had a higher risk of benzene carcinogenesis. This study provides a reference for the level of indoor air pollution in public places in Xi'an City, and is of great significance to the health risk research of related populations.

Hydrodeoxygenation of Anisole and Benzaldehyde Over Bifunctional CoMo/USY Catalyst

Hydrodeoxygenation (HDO) of anisole and Benzaldehyde over bifunctional zeolite USY (ultra-stable Y) supported CoMo catalysts has been studied. The catalyst consisted of metals that Co and Mo were loaded at three different sequences; Co loaded first (Co-Mo/USY), Mo loaded first (Mo-Co/USY), and simultaneously loaded (CoMo/USY). The experiments were conducted in a flow reactor within a temperature of 350 °C for an hour. The oxygen-free products from the HDO process were benzene and toluene compounds. CoMo/USY catalyst exhibited the best catalytic activity of anisole towards the total production of aromatic hydrocarbons yield by 9.17%. It was also found that Mo-Co/USY catalyst exhibited the best catalytic activity of Benzaldehyde with aromatic hydrocarbons yield by 10.46%.

A Facile Synthesis of Highly Porous Silica Aerogel Hybrid Materials for BTX Adsorption

Abstract Benzene, toluene, and m-xylenes are among the pollutants in the environment that may harm human health. These fugitive volatile organic compound (VOC) emissions from refineries and petrochemical industries are perennial, although at low concentrations in ppm levels. On similar grounds, the separation of benzene, toluene, and m-xylene compounds (BTX) from the feed gas of the sulfur recovery unit in natural gas processing industries is critical, as it is known to severely poison the catalyst in the Claus process. In this connection, a new hybrid material was synthesized using a precursor (metal-organic framework (MOF)) and silica aerogels (SA). The precursor (ZIF-8) proportion was varied to understand its effect on the structural and adsorption characteristics. Various advanced analytical characterizations were performed to understand the physicochemical characteristics of the synthesized material. Additionally, the synthesized materials were subjected to gas-phase adsorption of BTX to generate the adsorption isotherm at 25 °C. The hybrid material SA-ZIF-8 (20%) having a ZIF-8 proportion of 20% were found to have better adsorption capacity than the virgin ZIF-8 and silica aerogel adsorbents. The maximum adsorption capacity near the 90% saturation vapor pressure corresponds to 337 mg/g, 227 mg/g, and 263 mg/g at 25 °C for BTX, respectively.

Risk assessment of workers' exposure to BTEX and hazardous area classification at gasoline stations.

Vaporization of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds pollutes the air and causes health hazards at gasoline stations. This study revealed the risk of BTEX exposure according to the hazardous area classification at gasoline stations. The risk assessment of gasoline workers from a representative group of 47 stations, which followed the United States Environmental Protection Agency-IRIS method of assessing BTEX exposure, was expressed as the hazard index (HI). A result of matrix multipliers of the hazardous exposure index and fire possibility from flammable gas classified hazardous area-I and area-II at the fuel dispensers. BTEX concentrations were actively sampled in ambient air and a flammable gas detector was used to measure the flammability level. Results showed that the BTEX concentrations from ambient air monitoring were in the range of 0.1-136.9, 8.1-406.0, 0.8-24.1 and 0.4-105.5 ppb for benzene, toluene, ethylbenzene, and xylene, respectively, which exceeded the NIOSH exposure limit of 100 ppb of benzene concentration. The risk assessment indicated that five stations reached an unacceptable risk of worker exposure to BTEX (HI>1), which correlated with the numbers of gasoline dispensers and daily gasoline sold. The risk matrix classified hazardous area-I at 4 meters and hazardous area-II at 4-8 meters in radius around the fuel dispensers. This study revealed the hazardous areas at gasoline stations and suggests that entrepreneurs must strictly control the safety operation practice of workers, install vapor recovery systems on dispenser nozzles to control BTEX vaporization and keep the hazardous areas clear of fire ignition sources within an eight-meter radius of the dispensers.

Pyrolysis waste char supported metallic catalyst for syngas production during catalytic reforming of benzene

Waste rice husk char supported Fe and Ni were synthesized to prepare the monometallic and bimetallic catalysts for removing the tar model compound benzene in a laboratory dual-stage reactor. The prepared catalysts were examined by microstructure and textural characterization to analyse catalytic performance and stability. The molar proportions of CO, H2, CO2 and CH4 in the generated gas and the influence of residence time (τ) and the steam-to-carbon ratio (S/C) on the catalytic reaction were investigated. The results show that the rice husk char-based catalysts showed excellent catalytic activity for syngas production and benzene conversion. Under optimized conditions, the benzene conversion can reach 95.2%, and the mol% of syngas in the generated gas is greater than 93.0%, of which 91.0% is H2. The experimental results show that the influence of residence time on catalytic performance is greater than that of the steam-to-carbon ratio, and that excessive τ or S/C values will have no more positive effect on the performance of the catalyst. The stable active sites on the catalyst surface can guarantee the catalytic activity in the reaction. Ultimately, rice husk char-based catalysts can be used to remove tar and produce syngas.

METHOD FOR DETERMINING BTX (BENZENA, TOLUENA, AND XILENE) USING GAS-FID CHROMATOGRAPHY (FLAME IONIZATION DETECTOR)

At present, the petrochemical industry is growing rapidly. Products from the petrochemical industry are produced from petroleum or natural gas which produces various compounds such as BTX (Benzene, Toluene, and Xylene). BTX is such a poisonous aromatic compound that the International Cancer Research Agency classifies benzene as carcinogenic to humans and other BTX species have a variety of detrimental health effects even at low concentrations. Thus the separation of benzene, toluene and xylene compounds is very important. The analysis technique that is commonly used to determine the BTX compound is gas chromatography, which in this case uses GC-FID. The results shown by this instrument show that all the data obtained meet the acceptance requirements with the test parameters performed.

Bio-monitoring of non-metabolized BTEX compounds in urine by dynamic headspace-needle trap device packed with 3D Ni/Co-BTC bimetallic metal-organic framework as an efficient absorbent

In this work we try to develop a new analytical procedure for extraction and analysis of the Benzene, Toluene, Ethylbenzene and Xylene isomer compounds in the urine samples. In this way, we employed the 3D Ni/Co-BTC bimetallic metal–organic framework as new and efficient solid absorbent packed inside a Dynamic Headspace Needle Trap Device for extraction of the Benzene, Toluene, Ethylbenzene and Xylene isomer compounds. For more details, full characterization of the synthesized adsorbent performed by X-ray diffraction, Field emission scanning electron microscopes, Fourier-transform infrared spectroscopy and elemental mapping techniques. In the bench scale, the extraction and thermal desorption parameters such as temperature, time, and percentage salt optimized by Response Surface Methodology and Box Behnken Design. The obtained results exhibited that the optimal extraction time, extraction temperature and salt content of the sample were 35 min, 35°C and 7.5%, respectively. Also, the optimal temperature and time of thermal desorption were determined to be 275°C and 3 min, respectively. The method detection limit of mentioned compounds by this method were in the range of 0.2–1.1 ng.mL−1 that proves the high sensitivity of the proposed method. Moreover, the percentage relative recovery of desired analytes was obtained in the range of 95–99%. The repeatability and reproducibility of proposed method were obtained in the range 1.9–5.8% and 5.5–8.2% respectively, which indicates the acceptable precision of the method. Eventually, this method was successfully employed to determination of Benzene, Toluene, Ethylbenzene and Xylene isomer compounds in the real urine samples. Findings indicated that proposed method can be used to fast, simple and sensitive biological monitoring of non-metabolized Benzene, Toluene, Ethylbenzene and Xylene compounds in the urine samples.

CHARACTERISTIC OF LIQUID SMOKE PRODUCED FROM SLOW PYROLYSIS OF CACAO POD SHELLS (THEOBROMA CACAO L)

This study evaluated the characteristics of liquid smoke produced from cacao pod shells (Theobroma cacao L) through the slow pyrolysis process at various temperatures of 300, 340, 380 and 400 °C. Prior to chemical analyses, the liquid smoke was purified by distillation at 190 °C to remove tar and remaining carbon and some benzene compounds. The compounds contained in liquid smoke were then analysed using various analytical techniques. The results showed that temperature plays a significant role in the composition of liquid smoke. Results of Gas Chromatography Mass Spectrometry (GC-MS) analysis showed that the number of chemical compounds produced at pyrolysis temperatures of 300, 340, 380 and 400 °C were 9, 14, 10 and 18 compounds, respectively. Pyrolysis temperatures did not have significant effects on the pH (3-4) value of produced liquid smoke. Phenolic compounds, furan and ketone have been found to be the main components in liquid smoke. The highest amount of phenol (763.76 mg GAE) was found at 400 °C.

Effect of zeolite catalyst concentration on bio-fuel characteristics of corncobs (Zea mays l.) produced by pyro-catalytic method

One alternative energy source that can be renewed is the conversion of biomass into bio-fuel. This study aims to produce bio-fuel from corn cobs and determine effect of catalyst concentration on physical and chemical properties. The pyro-catalytic process was carried out at 400? with 5%, 6% and 7% catalyst variations. Bio-fuel physical ssscharacterization tests include density, viscosity, and calorific value, while the analysis of hydrocarbon compound content uses GC-MS instrumentation. The results showed optimum biofuel volume was obtained at 7% catalyst variation that is 232 ml, while for physical and chemical characteristics the best results were obtained at 6% catalyst percentage with a density of 0.9636 gr/ml, viscosity 28.59 cP, and the calorific value is 10,350 kcal/kg. GC-MS analysis showed the content of Phenol, Furfural, acetic acid, Benzene, and Toluene compounds with a fuel percentage of 56.13% on a 6% catalyst. Based on the overall analysis that has been done shows that bio-fuel can be used as a substitute material for diesel or alternative energy substitute for conventional fuel.

Evaluation of Neuroendocrine and Immunological Parameters in Animals Following Chronic Combined Exposure to Xenobiotics

Background: A high prevalence of chromium and benzene compounds in the environment associated with motor vehicle and industrial operations arouses interest in the study of these xenobiotics in a long-term experiment. The objective of this work was to analyze effects of a chronic combined exposure to chromium and benzene on the hypothalamic-pituitary-adrenocortical (HPA) and immune systems of male Wistar rats. Materials and methods: Eighty male Wistar rats were administered potassium dichromate and benzene with drinking water in doses equaling one maximum permissible concentration (MPC) during 135 days. The hypothalamus, pituitary gland, adrenal glands, thymus, and spleen were then studied using morphometric, histological, and electron microscopy methods. The streptavidin-biotin peroxidase method was used to determine the expression of pro-apoptotic protein p53 and anti-apoptotic protein bcl2. We also measured the body, thymus and spleen weights of animals, nucleated cell counts in the thymus, spleen, and bone marrow and evaluated the cellular composition of the spleen and bone marrow as well as spontaneous and concanavalin A-induced secretion of interferon gamma (IFN-γ), IL-4, IL-6, and IL-10 cytokines by splenocytes. Results: We established an adverse effect of the exposure on the HPA function expressed in the activation of its secretory activity, blocking the release of hypothalamic neuropeptides at the level of the neurohypophysis and leading to ultrastructural damage to the neurosecretory cells of the hypothalamus, pituitary adenocytes and adrenal cortical cells, as well as in an increase in the programmed death of thymocytes. We also observed a decrease in the thymus weight and thymocyte counts and a complex of structural and functional changes indicating the status of its accidental involution in the exposed rats. The revealed decrease in the splenocyte count in the experimental group was accompanied by an increase in the size of the white spleen pulp. An increase in the induced production of the main immunoregulatory cytokines IFN-γ and IL-4 by splenocytes was found. Conclusion: Our findings can be used to analyze impairments of the HPA and immune systems in workers with a chronic combined exposure to benzene and chromium compounds in the occupational setting.

Enhancement CT Scan Image and Study Electronic, Structural and Vibrational Properties of Iobenguane

This work is divided into two parts first part study electronic structure and vibration properties of the Iobenguane material that is used in CT scan imaging. Iobenguane, or MIBG, is an aralkylguanidine analog of the adrenergic neurotransmitter norepinephrine and a radiopharmaceutical. It acts as a blocking agent for adrenergic neurons. When radiolabeled, it can be used in nuclear medicinal diagnostic techniques as well as in neuroendocrine antineoplastic treatments. The aim of this work is to provide general information about Iobenguane that can be used to obtain results to diagnose the diseases. The second part study image processing techniques, the CT scan image is transformed to frequency domain using the LWT. Two methods of contrast enhancement of medical images Histogram Equalization and Adaptive Histogram Equalization used to improvement images properties. Canny edge detection operator used as a comparison tool between enhancement methods. The result show the absorbance of iobengaune in the range (1000 – 0 cm-1) of these single bonds from C-C, C-N, C-I, and C-O High absorbency and sharp peak of Maximum wavelength absorbed (640.66 nm) and the biggest energy (1.9353 eV). And half width is (0.333 eV) at half height is (2685.83cm-1). Electrostatic potential, electron deficiency were especially marked in rings benzene compounds exclusively of carbon and hydrogen atoms (focusing on areas of carbon), establishing this area as more electropositive. From the results of measures many functions like signal to noise ratio, mean, entropy and histogram of image, CT Scan images are best enhanced obtained using AHE technique in frequency. The dark regions of enhanced CT Scan images became clarity for input CT Scan image that having low contrast.

Adsorption of volatile benzene series compounds by surface-modified glass fibers: kinetics, thermodynamic adsorption efficiencies, and mechanisms.

The presence of volatile benzene series compounds (VBSCs) in the environment is continually increasing, with the potential for negative effects on human health. It is therefore important to develop new materials for the adsorption of these compounds using various modification techniques. Glass fibers are a promising adsorbent for VBSCs and offer a number of advantages. In the present work, the surfaces of glass fibers were modified using hydrogen peroxide, a sodium hydroxide solution, or Piranha solution (a mixture of concentrated sulfuric acid and hydrogen peroxide). The adsorption characteristics of the resulting specimens were investigated, employing 10 volatile benzene-based compounds, and the activated glass fibers showed significantly improved adsorption efficiencies. The fibers activated with the Piranha solution were further modified with a triethoxysilyl benzene compound to obtain an aryl-modified material that demonstrated enhanced adsorption of aniline, salicylaldehyde, benzyl alcohol, and xylene relative to that obtained from a combination of polyurethane foam and XAD-2 resin. The adsorption efficiency of benzyl alcohol by these aryl glass fibers was found to be as high as 93% and the adsorption mechanism is believed to be associated with hydrogen bonding and π-π conjugation. This study provides a reliable technique for the quantification of VBSCs and a basis for the evaluation of various adsorption materials.

Evaluation of airborne exposure to volatile organic compounds of benzene, toluene, xylene, and ethylbenzene and its relationship to biological contact index in the workers of a petrochemical plant in the west of Iran.

Nowadays, workers in petrochemical industry might be exposed to organic volatile compounds, including benzene, toluene, ethylbenzene, and xylene (BTEX). The aim of this study was to investigate the concentration of BTEX contaminations and the biological index in employees of petrochemical sites in the west of Iran. The study was conducted as a cross-sectional study on 30 stations and 60 inhalation and biological samples collected in winter and summer. The NIOSH 2549 and 1501 methods were used for sampling and analyzing the inhaled samples. Gas chromatography-mass spectrometry (GC-MS) equipped with flame ionization detector and high-performance liquid chromatography (HPLC) was used to measure the volatile contaminations. The results showed that the mean concentrations of benzene, toluene, and xylene were significantly different in summer and winter. Significant and strong correlations were observed between the concentrations of benzene, toluene, and xylene and the biological values (r > 0.7). Moreover, the concentration of benzene (β = 0.836), toluene (β = 0.718), and xylene (β = 0.786) predicted the changes in their biological values. Given the hazardous concentrations of benzene and toluene in industrial plants and the correlation of the concentration levels and biological values, management and control strategies should be implemented to eliminate and reduce the pollutants and the effects.

Synthetic Organic Compounds From Paper Industry Wastes: Integrated Biotechnological Interventions.

Synthetic organic compounds (SOCs) are reported as xenobiotics compounds contaminating the environment from various sources including waste from the pulp and paper industries: Since the demand and production of paper is growing increasingly, the release of paper and pulp industrial waste consisting of SOCs is also increasing the SOCs’ pollution in natural reservoirs to create environmental pollution. In pulp and paper industries, the SOCs viz. phenol compounds, furans, dioxins, benzene compounds etc. are produced during bleaching phase of pulp treatment and they are principal components of industrial discharge. This review gives an overview of various biotechnological interventions for paper mill waste effluent management and elimination strategies. Further, the review also gives the insight overview of various ways to restrict SOCs release in natural reservoirs, its limitations and integrated approaches for SOCs bioremediation using engineered microbial approaches. Furthermore, it gives a brief overview of the sustainable remediation of SOCs via genetically modified biological agents, including bioengineering system innovation at industry level before waste discharge.

On symmetric division deg index of unicyclic graphs and bicyclic graphs with given matching number

<abstract> Nowadays, it is an important task to find extremal values on any molecular descriptor with respect to different graph parameters. In a molecular graph, the vertices represent the atoms and the edges represent the chemical bonds in the terms of graph theory. For one thing, the molecular graphs of some chemical compounds are unicyclic graphs or bicyclic graphs, such as benzene compounds, napthalene, cycloalkane, et al. For another, the symmetric division deg index is proven to be a potentially useful molecular descriptor in quantitative structure-property/activity relationships (QSPR/QSAR) studies recently. Therefore, we present the maximum symmetric division deg indices of unicyclic graphs and bicyclic graphs with given matching number. Furthermore, we identify the corresponding extremal graphs. </abstract>

Optical Studies of Binary Mixture of Chloro Substituted Benzene and n-Hexane or Cyclohexane or 1,4-Dioxane

Thermophysical properties of binary liquid mixtures are highly beneficial for getting information about the intermolecular interactions and geometrical effects in the system. The chloro-substituted benzene compounds like 2-chlorotoluene, 4-chlorotoluene, 1,3-dichlorobenzene also have wide range of industrial and biomedical areas. In present work, the refractive indices (n) of haloarenes, hydrocarbons, ether, and respective possible binary mixtures were experimentally determined over the entire compositions at T= (298.15-318.15) K. The mixtures selected were 2-chlorotoluene or 4-chlorotoluene or 1,3-dichlorobenzene (1) + n-hexane or cyclohexane or 1,4-dioxane (2) with its possible combinations. The Δn is positive for all binary mixtures at all investigated compositions. Different rules of mixing like Lorentz-Lorentz, Erying-John, Arago-Biot, etc. were also used to predict n values. The Δn values were also analyzed in terms of ongoing intermolecular interactions among the components of the selected system.

Derivative UV-Vis Spectroscopy of Crude Oil and Asphaltene Solutions for Composition Determination

The determination of the first and second derivatives in the UV spectra of crude oil and asphaltene solutions allows the identification of signals attributed to compounds in the crude oil that cannot be seen in the normal spectrum. This processing of the crude oil UV-Vis spectrum to determine first and second derivatives allowed the identification of five maxima. The maxima observed in the first derivative spectrum can be related to different types of compounds in crude oil: ~230 nm for benzene compounds, 259 nm for naphthalene compounds and their derivatives, 295 nm for pure phenanthrene, 328 nm for aromatic chromophores with three or four aromatic rings, and 401 nm for the Soret electronic absorption band of vanadyl porphyrins. The shape of the spectra was analyzed to predict the presence of colloids or particles in the solutions.

Multidimensional Structure Conformation of Persulfurated Benzene for Highly Efficient Phosphorescence.

It is a challenge to acquire, realize, and comprehend highly emissive phosphorescent molecules. Herein, we report that, using persulfurated benzene compounds as models, phosphorescence can be strongly enhanced through the modification of molecular conformation and crystal growth conditions. By varying the peripheral groups in these compounds, we were able to control their molecular conformation and crystal growth mode, leading to one- (1D), two- (2D), and three-dimensional (3D) crystal morphologies. Two kinds of typical molecular conformations were separately obtained in these crystals through substituent group control or the solvent effect. Importantly, a symmetrical 3,3-conformer exhibits that a planar central benzene ring prefers a 3D-type crystal growth mode, demonstrating high phosphorescence efficiency. Such outcome is attributed to the strong crystal protection effect of the 3D crystal and the bright global minimum (GM) boat-like T1 state of the symmetrical 3,3-conformer. The conformation studies further reveal small deformation of the inner benzene ring in both singlet and triplet states. The GM boat-like T1 state is indicated by theoretical calculations, which is far away from the conical intersection (CI) point between the S0 and T1 potential energy surfaces. Meanwhile, the small energy gap between S1 and T1 states and the considerable spin-orbit coupling matrix elements allow an efficient population of the T1 state. Combined with the crystal protection and conformation effect, the 3,3-conformer crystal shows high phosphorescence efficiency. The unsymmetrical 2,4-conformer conformation with the twisted central benzene ring leads to 1D or 2D crystal growth mode, which has a weak crystal protection effect. In addition, the unsymmetrical conformation has a dark GM T1 state that is very close to the T1-S0 CI point, implying an efficient nonradiative T1-S0 quenching. Thus, weak phosphorescence was observed from the unsymmetrical conformation. This study provides an insight for the development of highly emissive phosphorescent materials.

Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex

A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.