The 2-chloro-4-nitroaniline liquid-phase hydrogenation kinetics on supported palladium and platinum catalysts differing in the nature of the carrier and the active metal content was studied for the... Show moreThe 2-chloro-4-nitroaniline liquid-phase hydrogenation kinetics on supported palladium and platinum catalysts differing in the nature of the carrier and the active metal content was studied for the first time. The experiment was carried out at elevated hydrogen pressures in the range of 9 - 12 atm and 303 K in solvents 2-propanol-water and ethyl acetate in the reactor such as Vishnevsky autoclave. The main kinetic parameters of the reaction have been determined, and the influence of various parameters on the regularities of the process has been established. It is shown that an increase in the active metal content in the catalyst leads to an increase in the rate of the hydrogenation reaction of 2-chloro-4-nitroaniline. When using platinum supported catalysts, the rate of hydrogenation of 2-chloro-4-nitroaniline is significantly higher than when using supported palladium catalysts. The replacement of the liquid phase of the catalyst system with 2-propanol by ethyl acetate adversely affects the reaction rate. The influence of the catalytic system nature and composition on the target product dehalogenation degree was determined. It was found that when carrying out the reaction at elevated hydrogen pressures, it is preferable to use low-percentage platinum catalysts, rather than palladium catalysts, since the former provide less dehalogenation of the target product. For citation: Klimushin D.M., Krasnov A.I., Filippov D.V., Sharonov N.Yu. Hydrogen pressure, solvent and catalyst nature influence on 2-chloro-4-nitroaniline hydrogenation regularities. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 30-35 Show less
A study of the kinetics of liquid phase hydrogenation of nitrobenzene, 4-nitrotoluene, 4-nitroaniline and 2-chloro-4-nitroaniline on supported palladium catalyst in aqueous solutions of 2-propanol... Show moreA study of the kinetics of liquid phase hydrogenation of nitrobenzene, 4-nitrotoluene, 4-nitroaniline and 2-chloro-4-nitroaniline on supported palladium catalyst in aqueous solutions of 2-propanol of different composition was carried out. The influence of the substituent on the value of the total amount of hydrogen absorbed during the reaction and the kinetics of the hydrogenation of substituted nitrobenzenes was discussed. It was found out that the reaction selectivity to 2-chloro-1,4-phenylenediamine decreases due to by-reaction dehalogenation. The degree of dehalogenation depends on the composition of solvent and may be approximately estimated by the values of the absorbed hydrogen volume during the reaction. Also, the presence of the donor-acceptor substituents is capable of exerting influence on the reaction rate of hydrogenation of the nitro compound. Show less
Interstellar absorption-line spectroscopy of NGC 2264 is reported which shows that the CO molecule has a column density of 5 x 10 to the 18th/sq cm and a rotational excitation temperature of 28 K.... Show moreInterstellar absorption-line spectroscopy of NGC 2264 is reported which shows that the CO molecule has a column density of 5 x 10 to the 18th/sq cm and a rotational excitation temperature of 28 K. A direct upper limit on the H2 column density implies that at least 6 percent of a solar carbon abundance is in the form of CO. The upper limit on the H3(+) abundance implies that the cosmic-ray ionization rate is of the order of 10 to the -16th/s or less. The H3(+) upper limit, together with a previous radio detection of H2D(+) emission, implies either an enormous overabundance of the deuterated molecule or else that most of the radio emission comes from clouds not located directly between use and the infrared source. Observations of the sources AFGL 2591 and NGC 2024 IRS2 indicate that upper limits on H3(+) imply cosmic ray ionization rates of less than 3 and 60 x 10 to the -17th/s, respectively. Show less
A spectrum of Pi Sco showing numerous atomic lines and 70 absorption features from the Lyman and Werner transitions of interstellar H2 in rotational level J from zero to five is presented. Their... Show moreA spectrum of Pi Sco showing numerous atomic lines and 70 absorption features from the Lyman and Werner transitions of interstellar H2 in rotational level J from zero to five is presented. Their shapes of the composite column density profiles are very nearly Gaussian with a one-dimensional rms velocity dispersion of 3 km/s. The behavior of shifts in the inferred N(H2) as a function of velocity are consistent with the overall profiles being composed of nearly symmetrical, tightly paced assemblies of about seven unresolved components. The relative overall column densities in the higher J levels of H2 are consistent with a model where these states are populated by optical pumping through the Lyman and Werner transitions, powered by UV radiation from nearby stars. The slight narrowing of the high-J profiles may be due to small clumps of H2 at radial velocities some 5-8 km/s from the core of the profile are exposed to a pumping flux about 10 times lower than that for the material near the profile's center. Show less
The 1-0S(1), 2-1S(1), 1-0S(0) and 1-0Q branch transitions of molecular hydrogen (H2) towards the giant emission nebula (HII region) NGC 604 in M33 have been detected. The line ratios are... Show moreThe 1-0S(1), 2-1S(1), 1-0S(0) and 1-0Q branch transitions of molecular hydrogen (H2) towards the giant emission nebula (HII region) NGC 604 in M33 have been detected. The line ratios are incompatible with shock-excited H2, but indicate the widespread presence of fluorescent H2 at a mean temperature T = 70 + or - 15 K. This is the first detection of fluorescent H2 emission associated with a giant (extragalactic) HII region complex. Show less
Interstellar absorption lines of CH and CH(+) have been detected toward the star HD 210121, which is located behind a previously unknown high-latitude cloud. The CH observations and the measured... Show moreInterstellar absorption lines of CH and CH(+) have been detected toward the star HD 210121, which is located behind a previously unknown high-latitude cloud. The CH observations and the measured extinction toward the star provide independent measures of the H2 column density along the line of sight, which are compared with that deduced from CO mm observations. The inferred CH(+) column density is comparatively small, suggesting that shocks do not play a dominant role in the chemistry in the cloud. Show less
Recent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line... Show moreRecent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line broadening, self-shielding, shielding by H and H2, and isotope-selective shielding are examined as functions of depth into interstellar clouds. The photodissociation rates of the isotopic species are larger than that of (C-12)O inside the clouds by up to one to two orders of magnitude. A simple approximation to the attenuation by line absorption is given in tabular form. Computed abundances of CO and related species C and C+ are presented for a variety of interstellar clouds ranging from diffuse clouds to dense photodissociation regions. Several series of models of translucent clouds are presented which illustrate how the CO abundance increases rapidly with total cloud thickness. The variations of the isotopic abundances with depth and their sensitivity to temperature and total cloud thickness are explored in detail. Show less
