The use of Lewis acid AlCl3as a promoter in the Pd-complex catalytic system of the cyclohexene hydroethoxycarbonylation reaction

This paper presents the results of detailed studies of the possibility of using Lewis acid AlCl3as a promoter of the catalytic three-component system PdCl2(PPh3)2–PPh3–AlCl3in the hydroethoxycarbonylation reaction of cyclohexene at low carbon monoxide pressures (2.5 MPa). As a result a high catalytic activity of the three-component system was established and the reaction proceeds regioselectively with the formation of ethyl ether of cyclohexanecarboxylic acid. The optimal conditions of the process have been elaborated (molar ratio of the starting reagents [Cyclohexene]:[Ethanol] = 1:1; molar ratio of the components of the catalytic system = =[PdCl2(PPh3)2]:[PPh3]:[AlCl3] = 1:6:9; carbon monoxide pressure PCO=2.5MPa; process temperature T=120°C and reaction time τ= 5 h) at which the target product yield reaches 80.7%. To identify the obtained ethyl ester of cyclohexane carboxylic acid gas chromatographic analysis and mass-and IR-spectra were carried out. Based on the data obtained, a possible mechanism of the reaction route of cyclohexene carbonylation with carbon monoxide and ethanol in the presence of the three-component system PdCl2(PPh3)2–PPh3–AlCl3is pro-posed and discussed.

PB01 suppresses radio-resistance by regulating ATR signaling in human non-small-cell lung cancer cells

Despite the common usage of radiotherapy for the treatment of human non-small-cell lung cancer (NSCLC), cancer therapeutic efficacy and outcome with ionizing radiation remains a challenge. Here, we report the antitumor effects and mechanism of a novel benzothiazole derivative PB01 (4-methoxy-cyclohexane carboxylic acid [2-(3,5-dimethyl-isoxazole-4-yl) sulpanil-benzothiazole-6-yl]-amide) in radiation-resistant human NSCLC cells. PB01 treatment is cytotoxic because it induces reactive oxygen species, ER stress, Bax, cytochrome c expression, the ATR-p53-GADD45ɑ axis, and cleavage of caspase-3 and -9. Additionally, we found that radio-resistant A549 and H460 subclones, named A549R and H460R, respectively, show enhanced epithelial-to-mesenchymal transition (EMT), whereas PB01 treatment inhibits EMT and mediates cell death through ER stress and the ATR axis under radiation exposure in radio-resistant A549R and H460R cells. Together, these results suggest that PB01 treatment can overcome radio-resistance during radiotherapy of NSCLC.

GC-MS ANALYSIS OF PHYTOCHEMICALS FROM THE EXTRACT OF Hibiscus sabdariffa GROWN IN NORTHERN NIGERIA

Hibiscus sabdariffa, also known as Roselle belongs to Malvacae family. It is popularly known in Nigeria as Zobo. It has been used traditionally to cure certain ailments like cold, due to its rich pharmacological potential. Hence this study aimed at validating the pharmacological potential of Hibiscus sabdariffa by identification of the compounds present in its leaves using GC-MS technique. The extract was obtained by heating the leaves in ethanol under reflux. The ethanol extract was then subjected to GC-MS analysis. The constituents were identified by comparing their mass fragmentation (MS) pattern with those gathered in the library of NIST-MS and with those reported in literature. The graph obtained from the study revealed the presence of nine (9) organic compounds in Hibiscus sabdariffa leaf extract (HSLE) namely cyclohexane carboxylic acid ester, cyclopropane carboxylic acid methyl ester, hexanoic acid-4-octyl ester, hexadeca-2-11-dienoic acid, n-hexadecanoic acid, oleic acid, octadecanoic acid, E-13-docosenoic acid and E-11-hexadecanal. Oleic acid has the highest peak value with the retention time of 20.711 which makes it the most abundant fraction and the active ingredient in the HSLE. The presence of some of these bioactive compounds has proved the scientific evidences for the antihypertensive and anti-inflammatory properties of the plant.

Carbon Nanotubes-Supported Well-Dispersed Pd Nanoparticles for the Efficiently Selective Hydrogenation of Benzoic Acid to Synthesize Cyclohexane Carboxylic Acid

Pd and carbon nanotube (CNT) composites were prepared by well-dispersed deposition of Pd nanoparticles on commercial CNT, and applied to the selective hydrogenation of benzoic acid (BA) to synthesize cyclohexane carboxylic acid (CCA). The catalysts and the hydrogenation products were analyzed by XRD, TEM, TG, FTIR, UV-Vis absorption, GC and GC-MS, respectively. Hydrogenation process was also optimized through varying the reaction parameters. The results demonstrate that Pd/CNT catalysts possess the highest hydrogenation efficiency, give the full conversion of BA and 100.0% selectivity towards CCA at the optimal hydrogenation conditions, by comparing with some commercial hydrogenation catalysts and Pd/C catalysts with commercial carbonaceous supports. The excellent hydrogenation performance of Pd/CNT is attributed to the stable crystalline CNT support and the high dispersion of Pd nanoparticles. In addition, the protic solvent is also beneficial to lower the activation energy barrier of BA hydrogenation, and further to improve the hydrogenation rate. This work implies that CNT can be potentially chosen as an effective carbonaceous support to prepare Pd/C catalyst with an outstanding performance of BA selective hydrogenation.

Study of kinetics of degradation of cyclohexane carboxylic acid by acclimated activated sludge

Activated sludge contains complex microorganisms, which are highly effective biodegrading agents. In this study, the kinetics of biodegradation of cyclohexane carboxylic acid (CHCA) by an acclimated aerobic activated sludge were investigated. The results showed that after 180 days of acclimation, the activated sludge could steadily degrade >90% of the CHCA in 120 h. The degradation of CHCA by the acclimated activated sludge could be modeled using a first-order kinetics equation. The equations for the degradation kinetics for different initial CHCA concentrations were also obtained. The kinetics constant, kd, decreased with an increase in the CHCA concentration, indicating that, at high concentrations, CHCA had an inhibiting effect on the microorganisms in the activated sludge. The effects of pH on the degradation kinetics of CHCA were also investigated. The results showed that a pH of 10 afforded the highest degradation rate, indicating that basic conditions significantly promoted the degradation of CHCA. Moreover, it was found that the degradation efficiency for CHCA increased with an increase in temperature and concentration of dissolved oxygen under the experimental conditions.

Solid state synthesis of Ru–MC with highly dispersed semi-embedded ruthenium nanoparticles in a porous carbon framework for benzoic acid hydrogenation

A dry grinding approach was reported for mesoporous Ru–carbon catalysts with semi-embedded Ru nanoparticles, which shows excellent performance in aromatic hydrogenation of benzoic acid to cyclohexane carboxylic acid.