AbstractThree neutral Cu(II)/ƞ4-NNNO Schiff base complexes (1-3) were prepared from the (E)-4-nitro-2-(((2-(piperazin-1-yl)ethyl)imino)methyl)phenol, tetradentate Schiff base (SB) ligand, and the corresponding copper(II) salts. The new SB and its complexes were fully characterized by CHN-EA, standard spectroscopic, thermal, and fluorescence analyses. The formation of the complexes was monitored by EDX, FT-IR, and UV-Vis. The chromotropism studies of the complexes reflected remarkable findings, in which bathochromic solvato- and thermochromism shifts were detected. The turn-off-on halochromism phenomena were observed in the acidic and basic medium. On the other hand, the fluorescence of the free SB ligand was turned off via complexation to the Cu(II) center. In the presence of H2O2 as green oxidant and under mild oxidation catalytic condition, the three complexes successfully catalyzed the formation benzaldehyde from benzyl alcohol.
In this study, hydrothermal liquefaction (HTL) of wheat straw (WS) in sub (350 °C) and supercritical (400 °C) water with and without alkali catalyst was performed to investigate the potential of WS for the production of biocrude. The influences of temperature and catalyst were studied for the HTL products. Results showed that maximum biocrude yield (32.34 wt. %) with least solid residue (4.34 wt. %) was obtained at subcritical catalytic condition, whereas the carbon content was slightly higher in biocrude at supercritical. The higher heating value (HHV) for biocrude is around 35 MJ/kg for all four conditions. The major compounds in biocrude were observed as ketones, alcohols, acids, and hydrocarbons. At 350 °C, 44–55% of the carbon recovered into biocrude. The products were characterized in terms of elemental composition, higher heating values, organics, and inorganic compounds in different phases. To keep in consideration the scale-up of HTL process for continuous plant, aqueous phase from HTL was also recirculated which showed the fruitful outcomes by increasing the biocrude yield at each cycle.
For the purpose of establishing a method of deprotein from the shrimp shell powder that is ready to prepare chitin by pepsin, which is a environment more friendly method compare to the other traditional methods. One factor experiment was applied to study the optimal deproteinization conditions., The data of one factor experiments indicates that the proper catalytic condition might be as follows, pH1.5, temperature 35°C, enzyme dose 500U/g, and the process time 4 hours, take the cost of production into account. On the basis of these results, response surface methodology (RSM) was used to study the optimal process conditions, the data indicates that the optimal condition occurs at 700 U/g, 36.09°C, and 5 hours, and the maximum deproteinization rate approaches 8.47%.
Two unnatural α-amino acid esters were prepared in good yields via phase transfer catalyzed Michael addition of ethyl N-acetylaminocyanoacetate to chalcone and benzalketone. For both α- enones, a progressive increase in product diastereomeric excess (d.e.) was observed during the course of reaction, even in the absence of quaternary ammonium salt. However, for a fixed reaction time, higher d.e. values were obtained under phase transfer catalytic condition. Analogous reactions were performed using S-aryl thiocinnamates as Michael acceptors, affording a 2-pyrrolidinone in good yield but low d.e. These results were interpreted on the basis of the reversibility of the Michael reaction
New tetradentate Schiff base Cu(II) complexes: synthesis, physicochemical, chromotropism, fluorescence, thermal, and selective catalytic oxidation