Asian Journal of Green Chemistry

Abstract The combination of isatins, active methylene reagents and 4-phenylurazole/ phthalhydrazide in the presence of ionic liquid ([BMIm]Cl) as a solvent catalyst was found to be a suitable and efficient method for the synthesis of the biologically important spirooxindoles. The features of this procedure were characterized by one-pot procedure, reasonable reaction times, fairly high yields, and simple isolation procedures. The ionic liquid can be easily separated and reused for several times.

Abstract A green protocol is described for sulfonation of aromatic compounds that has been accomplished using sodium bisulfite (NaHSO₃) in the presence of reusable green heterogeneous SiO₂/HClO₄ and SiO₂/KHSO₄ (Silica-supported HClO₄ and KHSO₄ catalysts) under conventional and solvent-free microwave irradiation.  The reactions afforded very good yields of products within 3 to 5 hour under conventional conditions. However, the reaction times in microwave-assisted protocol are drastically reduced to 3 to 5 minutes (from 3 to 5 hour under conventional conditions) followed by increasing product yields. Moreover, the developed silica-supported catalysts could be  recycled for at least three to four times.

Abstract A simple, efficient and convenient route is described for the synthesis of bis-indolyl methanes by using recyclable catalyst sulfonylbis(1,4phenylene)bissulfamic acid (SPSA). In this procedure, we synthesize a bis-indolyl methane derivative via the three component reactions of two equivalent indoles with one equivalent of various aromatic aldehydes in the presence of 10 mol% SBSA as a heterogeneous catalyst under solvent-free conditions at 110 °C for the convinced reaction times (30–60 min). The advantages of this protocol towards the synthesis of bis-indolyl methane derivatives are: I) use of solvent-free conditions, II) inexpensive catalyst, III) using commercially available precursors, d) reusability of SBSA up to several cycles without much loss in reactivity, IV) simple work-up, V) high yields of pure products, VI) short reaction times. The structure of all bis(indolyl)methane derivatives were confirmed by melting point, FT-IR, ¹H NMR spectra and were compared with reliable references.

Abstract Herein, we report a fast synthesis of 1,4-dihydropyridines, decahydroacridine-1,8-diones by one-pot multi-component reaction of 1,3-cyclohexanedione or dimidone, arylaldehydes, and ammonium acetate under solvent-less condition using Cu(II)-schiff base-SBA-15 as  a reusable heterogeneous catalyst in high yields. These kinds of catalysts are built from mesoporous silica SBA-15 which was covalently anchored with Cu(II) schiff base complex. The shorter reaction times, good yields, simple work-up procedure and environmentally friendly conditions are the main advantages of this method compared to the last one. This method is also  the first example of synthesizing acridines by Cu(II)-schiff base-SBA-15 as an efficient catalyst in solvent-free media which can be valuable to be used or investigated for similar systems. The product was identified by its ¹H NMR, mass and IR spectra, which were compared to those reported previously.

Abstract Polyphosphotungstate (denoted as PPT) was supported on polypyrrol as organic support (abbreviated as PTT@Ppy) to produce catalytic active supported catalyst. This catalyst was characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM) and UV-vis diffuse reflectance spectroscopy (UV-DRS). The catalyst showed high catalytic activity in the oxidation of alkenes under optimized conditions. In this work, cyclooctene was selected as model alkene for investigation of oxidation procedure, and then under optimized condition, other alkenes were examined. The catalyst could be readily separated from the catalytic system using the centrifuging and loss of activity was negligible when the catalyst was recovered in five consecutive cycles. For this research, a statistical method called response surface methodology (RSM) has been used to economize the number of experiments and their meaningful interpretation. The effect of various factors such as catalyst amount, time, oxidant amount and temperature on oxidation of alkenes were investigated. Optimization results for 0.2 mmol cyclooctene showed that maximum oxidation efficiency 88% was achieved at the optimum conditions: catalyst amount 200 mg, temperature 63, time 5 h and oxidant = 2.15 mmol.

Abstract Life and its extraction fuels climate change. We performed studies upon an extended series of petroleum hydrocarbons, with octanol-water partition coefficients (log Kow), by using the quantitative structure-activity relationship (QSAR) methods that imply analysis of correlations and representation of models. A suitable set of molecular descriptors was calculated and the genetic algorithm (GA) was employed to select those descriptors, resulting in the best-fit models. The partial least squares PLS (PLS) was utilized to construct the linear QSAR model. The best GA-PLS model contains 27 selected descriptors in 10 latent variables space. The R2 and RMSE for training and test sets were (0.827, 0.088) and (0.716, 0.185), respectively. Inspection of the results reveals a higher R2 and lowers the RMSE value parameter for the data set GA-PLS. The GA-PLS linear model has good statistical quality with low prediction error. This is the first research on the QSAR which uses GA-PLS for the presiction octanol-water partition coefficients of some of the environmental toxic of the petroleum substances.

Abstract The Cu (II) surfactantsof  stearic and palmitic acids were synthesized which are greenish blue in colour and chosen for thermogravimetric and derivative thermal analysis. Their structure has been confirmed by elemental analysis, and mass spectroscopy. Thermogravimetric degradation of Cu (II) palmitate soap was studied  for energy of activation. This shows that two step thermal degradation in the range of 423 K to 703 K. Various equations like coats-redfern (CR), horowitz-metzger (HM) and broido equations (BE) were applied to evaluate the energy of activation. Thermal degradation of solid components will be a good and  significant method for the removal of the pollutant from the environment. The present study will play an important role for pollution controlling and in the field of green chemistry.