Kinetics of catalyzed esterification of acetic acid with n-butanol using carbonized agro-waste

The objective of this research work was to investigate the kinetics of esterification of acetic acid with n-butanol through the variation of experimental parameters. The reaction mixture was catalyzed heterogeneously by a sulfonated catalyst in batch mode of operation. The catalyst was prepared from abundantly available agro-waste, Cajanus cajan husk by chemical activation process, which produces a carbon-based solid catalyst with high surface area. The catalyst was characterized by a Brunauer-Emmet-Teller surface analyzer and Fourier transform infrared spectroscopy to know the surface morphology. Process parameters such as contact time, reaction temperature, and catalyst loading, which can influence the extent of conversion of reactants, were studied. Furthermore, the kinetic investigation was also carried out to estimate the kinetic parameters for uncatalyzed and catalyzed reaction using the second-order pseudo-homogeneous (P-H), Eley-Rideal (E-R), and Langmuir-Hinshelwood (LH) kinetic models for this research work. The kinetic parameters such as activation energy, preexponential factor, and the thermodynamic parameters such as enthalpy and entropy were estimated for uncatalyzed and catalyzed reactions using these three models. The process conditions were optimized for catalyzed and uncatalyzed reactions to obtain the maximum product yield by minimizing root mean square error of each experimental data using the MS-excel solver tool. Thus, this study reveals the high potential of an agro-waste, Cajanus cajan husk as raw material for the synthesis of catalyst. The results show that the E-R model is more appropriate for predicting the dynamic data of an esterification reaction, as the forward rate of reaction estimated using the E-R model are more modified than P-H and L-H models.     

Chain transfer agents in cationic photopolymerization of a bis‐cycloaliphatic epoxide monomer: Kinetic and physical property effects

The effects of chain transfer agents (CTA) on cationic ring‐opening polymerization of 3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexane carboxylate (EEC) were explored. EEC was polymerized in the presence of various CTAs, and epoxide conversions monitored via Raman spectroscopy. Polymer films were prepared and analyzed by dynamic mechanical analysis. Many of the organic alcohols studied greatly enhanced epoxide polymerization rates and conversion levels. The gel fraction of polymer specimens decreased rapidly with increasing amounts of octanol (gel fraction >90% up to 0.3 equiv OH) but remained high with increasing amounts of 1,2‐propanediol (gel fraction >90% up to 0.6 equiv OH). Increasing the size of primary alcohols had little effect on the polymerization rates and conversions. The polymerization rate decreased with increasing alcohol substitution (1°>2°>3°). Acidic alcohols had very low impact on conversion and polymerization rates relative to the neat epoxy resin. The glass transition temperature was inversely related to the size and amount of CTA. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm

We demonstrate the first Cr⁴⁺:YAG passively Q-switched c-cut Nd:YVO₄ self-Raman laser at 1168.6 nm based on the Stokes shift of 816 cm⁻¹. At the pump power of 4.7 W, the maximum output power of the Stokes line at 1168.6 nm is 270.5 mW, corresponding to an optical conversion efficiency of 5.8%. The pulse width, pulse repetition rate, pulse energy and peak power are 8.8 ns, 35.8 kHz, 7.6 μJ and 0.86 kW, respectively. At the pump of 5.0 W, the Stokes line at 1097.2 nm based on Raman shift of 259 cm⁻¹ also appears.     

Catalytic Aerobic Oxidation of Biomass‐based Furfural into Maleic Acid in Aqueous Phase with Metalloporphyrin Catalysts

Catalytic oxidation of renewable furfural into valuable maleic acid in aqueous solutions using metalloporphyrin catalysts was investigated for the first time. The synthesized catalysts were characterized by FT‐IR , UV –vis, ¹H NMR , elemental analysis, and TGA . The catalysts varied in metal active sites and functional groups, which had different effects on their catalytic activity. Furthermore, the effects of temperatures, reaction time, catalyst loading, and oxygen pressure were studied in detail. Maleic acid could be achieved in 44% yield by using FeT (p‐Cl)PPCl as catalyst under optimal conditions. Finally, FeT (p‐Cl)PPCl could be reused in five consecutive runs without a significant loss of activity.     

A new polymer acceptor containing naphthalene diimide and 1,3,4‐thiadiazole for all‐polymer solar cells

A n‐type conjugated polymer containing naphthalene diimide (NDI) and 1,3,4‐thiadiazole (TZ) moieties, named PNTZ, has been synthesized and applied for all‐polymer solar cells (all‐PSCs). By the incorporation of TZ unit into the polymer main chains, the lowest unoccupied molecular orbital level of this polymer has been adjusted effectively. In addition, the electron‐acceptor PNTZ shows a broad absorption spectrum in the range of 300–700 nm, and possesses complementary absorption spectrum with the electron‐donor PTB7‐Th. On the basis of PNTZ as the acceptor and PTB7‐Th as the donor, the all‐PSCs are fabricated. After optimization, the well blend morphologies with a continuous D/A interpenetrating network are observed and the best all‐PSC device exhibits a power conversion efficiency of 4.35% with a high short‐circuit current density of 13.26 mA cm^?2. This research demonstrates that the TZ‐containing polymer PNTZ is a promising non‐fullerene acceptor for high efficiency all‐PSCs. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 990–996     

Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists—Electrolytes and Cathodes Needed

Magnesium metal is a superior anode which has double the volumetric capacity of lithium metal and has a negative reduction potential of −2.37 V vs. the standard hydrogen electrode. A major benefit of magnesium is the apparent lack of dendrite formation during charging which is one of the crucial concerns of using a lithium metal anode. In this Review, we highlight the foremost research in the development of electrolytes and cathodes and discuss some of the significant challenges which must be overcome in realizing a practical magnesium battery.     

Highly efficient preparation of 5-hydroxymethylfurfural from sucrose using ionic liquids and heteropolyacid catalysts in dimethyl sulfoxide–water mixed solvent

Several types of ILs and solid acids were used as catalysts in one-pot conversion of sucrose to 5-hydroxymethylfurfural (abbreviated as 5-HMF) in a dimethyl sulfoxide (DMSO)/water mixed solvent under hydrothermal conditions. A remarkable 5-HMF yield of 91.8% was achieved catalyzed by the cesium salt of dodecatungstophosphoric acid (Cs_2.3H_0.7PW₁₂O₄₀) within 3 h at 180 ℃. The ionic liquid N-methylimidazolium hydrogen sulfate ([Hmim][HSO₄]) gave the 5-HMF in 82.0% yield from sucrose. To the best of our knowledge, it was almost the highest yield of HMF from sucrose by now. Various reaction parameters including reaction temperature and time and catalyst dosage were optimized. A possible mechanism for this catalytic process was proposed. Furthermore, fructose and glucose were also investigated, good yields of 5-HMF was obtained respectively. This increases the possibility of large-scale production of 5-HMF from carbohydrates.