Methylated Benzene Derivatives Research Articles

Change in Abundance and Activity of Microbocenoses in the Area of Influence of a Large Landslide at the Bureya Reservoir

The results of field and experimental microbiological studies of water, soil, and rock samples in the influence zone of large landslide are presented. The landslide occurred in December 2018 and blocked the Bureya Reservoir from coast to coast. An artificial channel was created to restore the hydrological regime with the use of TNT (trinitrotoluene) and RDX (hexogen). A comparative analysis of the abundance of cultivated heterotrophic bacteria around the landslide body and in the artificial channel is carried out. The activity of microbial communities in relation to easily available (peptone, lactate, and starch) and difficult-to-mineralize humic compounds is also determined. With the use of spectrometry and gas chromatography, it is shown that an increase in the diversity of aromatic compounds in water is accompanied by an increase in the abundance of heterotrophic bacteria. A number of toxic substances, including methanol and methylated benzene derivatives, are found among the dominant components in the water. Its concentrations increased after the water drained through the landslide body and after imploding works. Many of the volatile organic compounds may have been products of microbial metabolism when water interacts with rocks. A hypothesis on the role of methanotrophic and methylotrophic bacteria in the genesis of methanol and toluene is discussed.

Water Composition Changes in the Bureiskoe Reservoir after a Landslide and Blasting

Data on changes in the qualitative composition of volatile organic compounds and content of elements in waters of the Bureiskoe Reservoir after a great landslide, which blocked access to the hydroelectric power station, were presented. Blasting with use of trinitrotoluene and hexogen carried out to restore the hydrological regime by creating an artificial channel. Maximum content of methanol and acetone were recorded in water samples taken at the right bank near the landslide, where a lot of disintegrated wood entered the water after river tsunami. After filtering water through a landslide body, the content of Al, Fe, and Pb increased, and content of Mg, Ca, Zn, and Cd decreased. After restoration of the reservoir flow in water samples from the artificial channel, the content of Fe, Mn, Al, Cu, and Zn was at a low level and did not reach the initial values established before the blasting began. However, an increase the content of Pb by 7 times and Hg by 80 times was recorded. Presence of methanol and methylated benzene derivatives in water could stimulate the formation of more toxic bioavailable methylmercury, posing risks to aquatic organisms.

The utilization of synthesis gas for the deoxygenation of cyclohexanone over alumina‐supported catalysts: Screening catalysts

AbstractEnvironmental regulations motivate the industries to replace conventional fuels and chemicals by those produced from biomass. In this regard, hydrodeoxygenation of lignin compounds is of a great deal of attention. Synthesis gas could be utilized instead of pure hydrogen for the cleavage of oxygen‐containing chemical bonds through hydrodeoxygenation. Following this, the utilization of synthesis gas is investigated in the present contribution. A wide range of commercial alumina‐supported catalysts is investigated. The experimental results of cyclohexanone hydrodeoxygenation in the presence of pure hydrogen and synthesis gas at 573 K and 20 bar of total pressure are presented and discussed. The whole investigated catalysts show good activity toward the hydrodeoxygenation of cyclohexanone. Methylatedbenzene derivatives are produced from cyclohexanone hydrodeoxygenation for the first time. The catalysts composed of platinum showed the best performance. By utilizing a chlorinated platinum catalyst, 89.6% cyclohexanone conversion, 100% total hydrocarbon selectivity, and 44.6% total hydrocarbon yield are obtained. In the case of syngas‐assisted hydrodeoxygenation, 80.1% cyclohexanone conversion, 100% total hydrocarbon selectivity, and 29.6% total hydrocarbon yield are obtained by utilizing the same catalyst. The presence of methylated aromatics proves the accomplishment of methanation or direct aromatization reactions in the presence of carbon oxides and hydrogen.

Assessment of the relationships between elements and organic matter in water after a large landslide in the Bureyskoye reservoir (Russia)

The article provides information on statistical approaches to identify the dominant factors that influenced the water quality in the Bureyskoye reservoir after a large landslide in December 2018 blocked access to a hydroelectric power plant. To restore the hydrological regime, blasting operations were carried out using trinitrotoluene and hexogen. The main indicators of water quality were volatile organic matters and elemental composition that varied along different banks above and below the landslide body and under the influence of explosives. In water samples from the artificial canal after the restoration of the reservoir flow, the content of Fe, Mn, Al, Cu and Zn remained at a low level and did not reach the initial values established prior to the blasting operations. However, an increase in the content of Pb by 7 times and Hg by 80 times was noted. The presence of methanol and methylated benzene derivatives in water could stimulate the formation of more toxic methylmercury, posing a risk to aquatic organisms. Correlation analysis was used to process the obtained data which made it possible to differentiate the contributions of natural (landslide, river tsunami) and anthropogenic factors (blasting) to the change in the chemical composition of water in the reservoir.

Ultrasound-promoted one-pot five-components synthesis of biologically active novel bis((6-alkyl or phenyl-2-phenylpyrimidine-4-yl) oxy) alkane or methyl benzene derivatives

We have described a synthesis of novel five-component reaction (5-CR) of bis((6-alkyl or phenyl-2-phenylpyrimidine-4-yl) oxy) alkane or methyl benzene derivatives under ultrasound irradiation. A useful ultrasound effect was observed and title products were obtained with high yields after 25–40min sonication. Structural confirmation and characterization of the products based on the analytical, chemical, and spectral analysis. The results show obviously, that to reach a high efficiency of ultrasonic systems in synthetic chemical processes. Our procedure compared to the conventional heating method has the benefit of higher reaction yields and shorter reaction times. The in vitro antibacterial tests show that some of the target compounds have promising activities. Structure–activity relationships (SAR) were established for the substitutions on the pyrimidine rings and related length of linear chain linker.

Effects of beam polarization on coherent anti‐Stokes Raman scattering using noisy light

AbstractThe effects of different linear polarization schemes on the noisy light‐based coherent anti‐Stokes Raman scattering [I(2)CARS] signal were investigated. It was found that certain polarization schemes can selectively shut down the contributions from terms represented by various factorized time correlation (FTC) diagrams to the I(2)CARS spectrogram. FTC diagram analysis was used in conjunction with the symmetry properties of the hyperpolarizability to provide a theoretical understanding of this phenomenon and serve as the basis for simulation of the I(2)CARS spectrogram. Striking agreement is seen between the simulations and the experimental results for benzene and several methylated benzene derivatives. Copyright © 2005 John Wiley & Sons, Ltd.

Ultrasensitive fluorescent probe for the hydrophobic range of solvent polarities

The new 3-hydroxychromone derivative 2-(6-diethylaminobenzo[b]furan-2-yl)-3-hydroxychromone (FA) displays a dramatic solvent-dependent transformation of fluorescence spectra in the range of low-polarity solvents. The two well-separated emission bands change their relative intensities so that the short-wavelength band being of a very low intensity in hexane becomes dominant in the more polar ethyl acetate and trichloromethane. We suggest the participation in this effect of excited-state intramolecular proton transfer, which is characteristic for other 3-hydroxychromone and 3-hydroxyflavone derivatives, in the range of solvents of much higher polarities. Because of these unique properties, a number of spectroscopic parameters (positions of absorption and two fluorescence maxima, the ratio of their intensities and the fluorescence quantum yield) can be measured in this solvent range with multiparametric analysis of the data. In terms of solvent polarity, the shifts in both emission bands and their intensity ratio demonstrate a good correlation with empirical polarity scales E T N, P y and SPP, while the absorption spectra reveal some deviations for the tested oxygen-containing solvent molecules. A good cross-correlation is observed between fluorescence spectral shifts and the ratio of band intensities. The latter provides the means for a dramatic amplification of solvent response. Thus, a new approach for ultrasensitive scaling and probing the solvent polarity in the low-polararity range can be suggested. It involves very simple ratiometric measurements at two emission bands and can be posed for a variety of applications. We present examples of these applications for distinguishing of polarities between methylated benzene derivatives, for quantitative assay of polar impurities in low-polar solvents and for detection of the changes of solvent polarity as a function of temperature.

Hydrogen bonding NH/π interactions between betacarboline and methyl benzene derivatives

In the presence of benzene, toluene, m-xylene, mesitylene and durene, the pyrrolic NH stretching band of betacarboline, 9H-pyrido[3,4-b]indole, and its 1-methyl derivative, harmane, in tetrachloroethane diminishes in intensity while a new red-shifted band grows up. The shifts of the associated bands increase linearly with the π-electron density of the substrates. These spectral changes are attributed to the formation of 1:1 molecular association complexes between the betacarbolines and the benzenoid substrates. The complexes are stabilized by the hydrogen-bonding interaction between the pyrrolic NH group of betacarboline and the π-delocalized electrons of the benzene derivatives. The influence of these NH/π hydrogen-bonding interactions in the fluorescence spectra of betacarboline is discussed.

Function of the auditory and visual systems, and of peripheral nerve, in rats after long-term combined exposure to n-hexane and methylated benzene derivatives. I. Toluene.

Rats were exposed to n-hexane, toluene, or toluene together with n-hexane, each solvent 1000 p.p.m. (1000 + 1000 p.p.m. in combined exposure), 21 hr/day, 7 days/week during 28 days. Neurophysiological recordings were made 2 days, 3 months, and one year after end of exposure. A reduction in auditory sensitivity, recorded by click evoked auditory brainstem response, was observed 2 days after exposure to toluene alone, or to toluene together with n-hexane, but not after exposure to n-hexane alone. The reduction lasted one year after the exposure. Three months after combined exposure, a synergistic enhancement of loss of auditory sensitivity was observed in the mixed exposure group. One amplitude in the flash evoked potentials was lowered in the n-hexane exposed group 2 days after exposure. No such reduction was seen after simultaneous exposure to toluene. Exposure to n-hexane alone caused a marked decrease in peripheral nerve conduction velocity 2 days and 3 months after exposure, while exposure to n-hexane together with toluene had only a small effect on this velocity.

Function of the auditory and visual systems, and of peripheral nerve, in rats after long-term combined exposure to n-hexane and methylated benzene derivatives. II. Xylene.

Rats were exposed to xylene, to n-hexane, or to xylene together with n-hexane, each solvent 1000 p.p.m. (1000 + 1000 p.p.m. in mixed exposure), 18 hr/day, 7 days/week during 61 days. Neurophysiological recordings were made 2 days, 4 months, and 10 months after the end of exposure. Exposure to n-hexane alone, or xylene alone, caused a slight loss of auditory sensitivity as recorded by auditory brainstem response 2 days after the exposure. Exposure to n-hexane together with xylene caused persistent loss of auditory sensitivity (7-17 dB; P < 0.05) which was non-additively enhanced (P < 0.01). The latencies of the flash evoked potentials in the group exposed to n-hexane alone were prolonged (re C group) 2 days after exposure, while smaller prolongations were found in the group exposed to xylene together with n-hexane. Exposure to n-hexane alone caused a marked decrease in nerve conduction velocity, while simultaneous exposure to xylene inhibited n-hexane-induced velocity reduction in peripheral nerve (P < 0.01).

Volatile Constituents of the Headspace and Essential Oil ofPlectranthus coleoidesMarginatus (Labiatae)

ABSTRACT The headspace and essential oil of the whole plant of Plectranthus coleoides Marginatus were analyzed by GC/FID, GC/FTIR/MS and GC-sniffing techniques. The headspace was found to be rich in monoterpenes, fenchone (14.2%), bornyl acetate (9.3%), isobornyl acetate (8.2%) and β-caryophyllene (11.3%), while the essential oil comprises of additional odorous N-compounds (especially amines) as well as minor aromatic (methyl benzene derivatives) components. Totally 41 constituents were identified. Also an odor characterization of the headspace sample and the essential oil is given.

Formation of cyanide ion or cyanogen chloride through the cleavage of aromatic rings by nitrous acid or chlorine. IX. On the reactions of chlorinated, nitrated, carboxylated or methylated benzene derivatives with hypochlorous acid in the presence of ammonium ion

Chlorinated, nitrated, carboxylated or methylated benzenes, phenols and anilines reacted with chloramine to give cyanogen chloride, independently of the positions and the numbers of the substituents. Among these compounds, 2,4,6-trichlorophenol afforded cyanogen chloride in a relatively high yield of 13.3%, and the intermediates in the reaction were 2,6-dichloro-1,4-benzoquinone-4-(N-chloro)imine and 4,6-dichloro-1,2-benzoquinone-2-(N-chloro)-imine, of which the latter was the main intermediate.

Reactions of the radical cations of methylated benzene derivatives in aqueous solution

The radical cations of methylated benzene decompose in acid solution into the corresponding methylbenzyl radical and a proton. The rate constant for this reaction decreases by three orders of magnitude as the number of methyl groups increases from one to five. The rate constants can be correlated with the ionization potential of the parent compound. In neutral solution the reverse reaction to the acid-catalyzed OH adduct conversion occurs and the radical cations react with water to form the OH adduct. In slightly alkaline solution the radical cations of the higher methylated benzenes (n greater than or equal to 3) react with hydroxide ions forming the OH adduct.

Low temperature trapping mechanisms in molecular solids using PMDR spectroscopy. III. molecular aggregation and the formation of hexachlorobenzene triplet excimer

The triplet of hexachlorebenzene (HCB) at 1.6 K is found to form only at the defect sites of the crystal lattice. These defects can be created by introducing chemical impurities of higher field energies that of HCB, e.g., other chlorinated or methylated benzene derivatives, or by applying external pressure. The Phosphorescence-Microwave Double Resonance (PMDR) technique is used to study this broad “excimer” type emission. The followin conclusions are made: 1. Since the emission has zf transitions of energies and decay characteristics that are independent of the manner by which the defects are created, it is concluded that the emission must be due to a species involving HCB itself. 2. Since the emission is not observed in undoped pure HCB crystals and its emission intensity is independent of the UV radiation exposure time, it is believe that the emissions is not originated from photochemical products. 3. The observed band width of the zf absorptions and the chlorine quadrupole splittings are similar to those found for the monomer species of HCB and other chlorobenzenes, suggesting that the excited triplet state is not dissociative. The observed diffuseness of the optical spectrum is thus explained in terms of a repulsive ground state potential, thus supporting the assignment of an “excimer” type species. Temperature effects of the HCB triplet excimer emission spectra have been examined from 1.6 to 65 K. The following results are obtained: 1. At temperature higher than 8 K, two new emission maxima appear, replacing the old one in the optical spectrum. This is explained in terms of either the formation of two new excimers of different configurations or emission from vibrationally excited excimer. 2. The intensity of the excimer emission is found to decrease as the temperature increases with an activation energy of 20 cm −1 (which is of magnitude of the frequency of some lattice vibrations). 3. The fact that the emission lifetime decreases at a much slower rate than the emission intensity suggests that the decrease in intensity with temperature is a result of annealing the chemically induced defects and thus decreasing the rate of formation of the excimer. Polarization and lifetimes of the phosphorescence from the individual magnetic sublevels of HCB triplet excimer are determined experimentally. The polarization is predicted group theoretically for both types of excimers made of the translationally “equivalent” and “inequivalent” HCB molecules in the crystal. The results are consistent with an excimer formed from translationally equivalent HCB molecules in the crystal. Using phosphorescence microwave photoexcitation spectroscopy, it was further concluded that the excimer is formed as a result of trapping HCB triplet-rather than singlet-excitons.

Phosphorescence Decay of Benzene and Methylbenzene Derivatives

Phosphorescence lifetimes of benzene and methylbenzene derivatives, deuterated and undeuterated, have been measured in glassy matrices at 4.2 and 77°K. Spin–orbit coupling calculations have been performed for benzene (D6h), distorted benzene (D2h), and toluene; these calculations included spin–own-orbit, spin–other-orbit, and vibronic considerations and were extended to all the methylbenzenes by a vector-sum semiempirical method. Franck–Condon calculations were performed for all methylated, deuterated, and distorted benzene derivatives. The results of these calculations lead to a general understanding of phosphorescence lifetimes, at least insofar as these are affected by either methylation or deuteration or both. Matrix effects and temperature effects on the phosphorescence lifetimes are largest in the case of benzene and toluene and decrease with increasing methylation of benzene and with increasing size of the polynuclear hydrocarbon. We attribute this sensitivity to the small size of the space available to the π subsystem in benzene, to the forbiddenness of the electric-dipole T1 → S0 process in this system, and to the ease with which matrix effects may perturb the rather “naked” skeleton of this molecule and its less-methylated derivatives. A concept of solvent-assisted distortions is introduced in order to explain the direction of solvent and temperature effects and the means whereby these effects become operative. This last is a very tenuous suggestion, its primary merit being that it provides some rationalization of the observed phenomenology.

Comments on phosphorescence decay times of benzene and methyl-benzene derivatives

It is shown that methyl substitution in benzene increases σ, π-mixing to an extent which is readily observable in the intrinsic phosphorescence lifetime. It is also shown that C-H vibrational modes which are external to the benzene ring (i.e. in the CH 3 group) contribute to phosphorescence quenching. Finally, some recently reported ‘relaxation effects’ are shown to be caused by poor temperature controls.