P-toluic Acid Research Articles

Understanding the Mechanism of Magnetic Relaxation in Pentanuclear {MnIVMnIII2LnIII2} Single-Molecule Magnets.

A new family of heterometallic pentanuclear complexes of formulas [MnIVMnIII2LnIII2O2(benz)4(mdea)3(NO3)2(MeOH)] (Ln = Dy (1-Dy), Tb (2-Tb), Gd (3-Gd), Eu (4-Eu), Sm (5-Sm), Nd (6-Nd), Pr (7-Pr); benz(H) = benzoic acid; mdeaH2= N-methyldiethanolamine) and [MnIVMnIII2LnIII2O2(o-tol)4(mdea)3(NO3)2(MeOH)] (Ln = Gd (8-Gd), Eu (9-Eu); o-tol(H) = o-toluic acid) have been isolated and structurally, magnetically, and theoretically characterized. dc magnetic susceptibility measurements reveal dominant antiferromagnetic magnetic interactions for each complex, except for 2-Tb and 3-Gd, which reveal an upturn in the χMT product at low temperatures. The magnetic interactions between the spin centers in the Gd derivatives, 3-Gd and 8-Gd, which display markedly different χMT vs T profiles, were found to be due to the interactions of the GdIII-GdIII ions which change from ferromagnetic (3-Gd) to antiferromagnetic (8-Gd) due to structural differences. ac magnetic susceptibility measurements reveal a nonzero out-of-phase component for 1-Dy and 7-Pr, but no maxima were observed above 2 K (Hdc = 0 Oe), which suggests single-molecule magnet (SMM) behavior. Out-of-phase signals were observed for complexes 2-Tb, 4-Eu, 8-Gd, and 9-Eu, in the presence of a static dc field (Hdc = 2000, 3000 Oe). The anisotropic nature of the lanthanide ions in the benzoate series (1-Dy, 2-Tb, 5-Sm, 6-Nd, and 7-Pr) were thoroughly investigated using ab initio methods. CASSCF calculations predict that the origin of SMM behavior in 1-Dy and 7-Pr and the applied field SMM behavior in 2-Tb does not solely originate from the single-ion anisotropy of the lanthanide ions. To fully understand the relaxation mechanism, we have employed the Lines model to fit the susceptibility data using the POLY_ANISO program, which suggests that the zero-field SMM behavior observed in complexes 1-Dy and 7-Pr is due to weak MnIII/IV-LnIII and LnIII-LnIII couplings and an unfavorable LnIII/MnIII/MnIV anisotropy. In complexes 4-Eu, 8-Gd, and 9-Eu ab initio calculations indicate that the anisotropy of the MnIII ions solely gives rise to the possibility of SMM behavior. Complex 7-Pr is a Pr(III)-containing complex that displays zero-field SMM behavior, which is rare, and our study suggests the possibility of coupling weak SOC lanthanide metal ions to anisotropic transition-metal ions to derive SMM characteristics; however, enhancing the exchange coupling in {3d-4f} complexes is still a stubborn hurdle in harnessing new generation {3d-4f} SMMs.

Benzoic Acid and its Derivatives Increase Membrane Resistance to Osmotic Pressure in Isolated Sheep Erythrocytes

There have been many reports that osmotic fragility (OF) in red blood cells (RBCs) is a valuable tool for assessing the actions of various chemicals on the cell membrane in vitro. We determined the effects of benzoic acid and its derivatives on OF in sheep RBCs in vitro. Isolated sheep RBCs were exposed to these substances at 0-100 mM in a buffer solution for 1 h, and the 50% hemolysis was then determined by soaking in 0.1-0.8% NaCl solution. OF was determined as the NaCl concentration inducing 50% hemolysis which was colorimetrically measured by the released hemoglobin concentration. Benzoic acid decreased OF in a dose-dependent manner. Heptanoic acid and cyclohexane carboxylic acid, both of which have 6 carbons in their saturated hydrocarbon structure, did not change OF. Replacement of the COOH bound to the benzene ring with PO(OH)2 or SO2OH abolished the OF response obtained by benzoic acid. Replacement with OH did not affect OF up to 25 mM, but did induce hemolysis at 50 and 100 mM. Replacement with CONH2 decreased OF, with the degree of the OF-lowering effect being greater than that of benzoic acid. Most derivatives possessing other groups (OH, CH3 or NH3) or halogens (Cl or Br) decreased or tended to decreased OF, with the degree of change in OF dependent on the position of the group introduced onto the benzene ring. 4-methylbenzoic acid, and 3-,4- and 4-, 5-dichlorobenzoic acids demonstrated a biphasic effect on OF in sheep RBCs; lowering OF up to 50 mM followed by a lytic effect at 100 mM. The results of a regression analysis using the values of all substances tested revealed no significant correlations between the partition coefficient of the substances and their effects on OF response. However, some groups of substances at concentrations of 10-50 mM showed a negative and statistically significant correlation. For substances sharing very close chemical structures, partition coefficients can probably be used as an indicator for evaluating the effect on OF within an appropriate range of concentrations.

A high-throughput multi-microfluidic crystal generator (MMicroCryGen) platform for facile screening of polymorphism and crystal morphology for pharmaceutical compounds.

In this work, a novel multi-microfluidic crystallization platform called MMicroCryGen is presented, offering a facile methodology for generating individual crystals for fast and easy screening of the polymorphism and crystal habit of solid compounds. The MMicroCryGen device is capable of performing 8 × 10 cooling crystallization experiments in parallel using 8 disposable microcapillary film strips, each requiring less than 25 μL of solution. Compared to traditional microfluidic systems, the MMicroCryGen platform does not require complex fluid handling; it can be directly integrated with a 96-well microplate and it can also work in a "dipstick" mode. The produced crystals can be safely and directly observed inside the capillaries by optical and spectroscopic techniques. The platform was validated by performing a number of independent experimental runs for: (1) polymorph and hydrate screening of ortho-aminobenzoic acid, succinic acid and piroxicam; (2) co-crystal form screening of the p-toluenesulfonamide/triphenylphosphine oxide system; (3) studying the effect of o-toluic acid on ortho-aminobenzoic cooling crystallization (effect of structurally related additives). In all three cases, all known solid forms were identified with a single experiment using ∼200 μL of solvent and just a few micrograms of the solid material. The MMicroCryGen is simple to use, inexpensive and it provides increased flexibility compared to traditional crystallization techniques, being an effective new microfluidic solution for solid form screening in pharmaceutical, fine chemicals, food and agrochemical industries.

Synthesis, structure, and character of two rare earth carboxylic acid complexes

Two rare earth carboxylic acid complexes, [Sm(MeBA)3(2,2′-bipy)]2·2(2,2′-bipy) (MeBA = 3-methylbenzoic acid; 2,2′-bipy = 2,2′-bipyridine) (1) and [Pr(MeBA)3(H2O)2]n∙n(4,4′-bipy) (4,4′-bipy = 4,4′-bipyridine) (2), have been synthesized under hydrothermal conditions and structurally determined by single-crystal X-ray diffraction. Compound 1 is a dimer and further assembles into an infinite chain, two-dimensional net and three-dimensional supramolecular structure via weak π–π and C–H···π interactions. Some 2,2′-bipy coordinates with Sm and some exist by non-covalent C–H···π interactions. Compound 2 is a 1D infinite chain structure, with adjacent 1D chains connected into a 2D layer structure by O–H···N hydrogen bonds. The two complexes were characterized by elemental analyses, IR, photoluminescence, and TGA. In order to illustrate subtle structural characteristics of intermolecular interactions and magnetic sensitivity of the complex, 2D-IR correlation spectra (2D-IR COS) under magnetic perturbation for 1 were performed.

Rotational Spectroscopy of p-Toluic Acid and Its 1:1 Complex with Water.

The structure and internal dynamics of p-toluic acid and its 1:1 complex with water were investigated in the gas phase using chirped-pulse and cavity-based Fourier transform microwave spectroscopy. One conformer and one isomer were identified for the monomer and monohydrate, respectively. In the monohydrate, water acts as both a hydrogen bond donor and acceptor, participating in a six-membered intermolecular ring with the carboxyl group. Both a- and b-type transitions were observed for the monomer; only a-type transitions were observed for the monohydrate. Rotational transitions of both species show splittings originating from methyl internal rotation, for which the potentials include 3- and 6-fold symmetry terms of similar amplitude. For the monomer, a few b-type transitions are missing, and their intensities were found to be transferred to c-type transitions with common energy levels, which are otherwise forbidden. No splittings attributable to a water internal tunneling motion were observed for the monohydrate. Furthermore, the absence of c-type transitions in the spectrum of the monohydrate, despite the large μc dipole moment component of the equilibrium geometry obtained by ab initio calculations, is consistent with a barrierless wagging motion of the free hydrogen of water, leading to an average μc dipole moment component of zero. These results provide insights regarding the interactions between atmospheric p-toluic acid and water in prenucleation complexes and at the air-water interface of aqueous aerosols, where p-toluic acid may act as a surfactant.

Temperature-induced order-disorder structural phase transitions of two-dimensional isostructural hexamethylenetetramine co-crystals.

Hexamethylenetetramine-benzoic acid (1/2) (HBA) and hexamethylenetetramine-4-methylbenzoic acid (1/2) (HMBA) co-crystals undergo order-disorder structural phase transition from a low-temperature monoclinic crystal structure to a high-temperature orthorhombic crystal structure at the transition temperatures of 257.5 (5) K (Pn ↔ Fmm2) and 265.5 (5) K (P21/n ↔ Cmcm), respectively, using variable-temperature single-crystal X-ray diffraction analysis. The observed phase transitions were confirmed to be reversible first-order transitions as indicated by the sharp endothermic and exothermic peaks in the differential scanning calorimetry measurement. The three-molecule aggregate of HBA and HMBA consists of a hexamethylenetetramine molecule and two benzoic acid or two 4-methylbenzoic acid molecules, respectively. The acid molecules are ordered at the low-temperature phase and are equally disordered over two positions, which are related by a mirror symmetry, at the high-temperature phase. The two-dimensional supramolecular constructs common to both co-crystals are formed by three-molecule aggregates via weak intermolecular C-H...O and C-H...π interactions into molecular trilayers parallel to the ac plane with small XPac dissimilarity indices and parameters. The PIXEL interaction energies of all corresponding molecular contacts were calculated and the results are comparable between HBA and HMBA co-crystals, resulting in similar lattice energies and transition temperatures despite their two-dimensional isostructural relationship. The observed phase transitions of these two energetically similar co-crystals are triggered by similar mechanisms, i.e. the molecular rotator ordering and structural order-disorder transformation, which induced non-merohedral twinning with similar twin matrices in the low-temperature crystal form of both co-crystals.

Comparative study of electrochemical oxidation and electrochemical Fenton processes for simultaneous degradation of phthalic and para-toluic acids from aqueous medium

Degradation of binary component of purified terephthalic acid wastewater viz. phthalic acid and para-toluic acid from aqueous medium was investigated in this study. Aqueous solution was initially subjected to acid precipitation treatment at various pH (2–4) and temperature (15–60°C). After acid treatment, the solution was further subjected to electrochemical oxidation and electrochemical Fenton treatments using graphite electrodes. During electrochemical treatments, effect of process variables such as initial pH: (1–9), current density: (30.48–91.45A/m2), NaCl concentration: (0.5–1.5g/L), Fe2+ concentration: (0.5–1.5mmol/L) and time: (15–95min) was studied and optimized through central composite design. Maximum removal efficiencies during electrochemical oxidation treatment were 64.55%, 60.24% and 62.77% for phthalic acid, para-toluic acid and chemical oxygen demand respectively with an electric energy consumption of 28.50kWh/kgCODremoved at optimum conditions. The removal capacities during electro-Fenton treatment were found 75.21%, 65.19% and 68.15% for phthalic acid, para-toluic acid and chemical oxygen demand respectively with 20.11kWh/kgCODremoved energy consumption at optimum conditions. Both processes were compared based on removal efficiencies, electric energy consumption, kinetics and sludge characteristics. Sludge generated after electrochemical treatments was analyzed by various characterization techniques. In order to get maximum removal efficiencies and minimum energy consumption, electrochemical Fenton method was found more effective than electrochemical oxidation during this study.

Supported C-Scorpionate Vanadium(IV) Complexes as Reusable Catalysts for Xylene Oxidation.

C-Scorpionate vanadium(IV) [VOx Cl3-x {κ3 -RC(pz)3 }] [pz=pyrazol-1-yl; x=0, R=SO3 (1); x=1, R=CH2 OH (2) or CH2 OSO2 Me (3)] complexes supported on functionalized carbon nanotubes (CNTs) are the first V-scorpionate catalysts used so far for the neat oxidation of o-, m- or p-xylene, with TBHP (70 % aqueous solution), to the corresponding toluic acids (main products), tolualdehydes and methylbenzyl alcohols. Remarkably, a p-toluic acid yield of 43 % (73 % selectivity, TON=1.34×103 ) was obtained with 2@CNT in a simple microwave-assisted mild oxidation procedure, using a very low catalyst charge (3.2×10-2 mol % vs. substrate). Further, this occurred in the absence of any bromine source, what is significant towards the development of a greener and more sustainable process for oxidation of xylenes. Moreover, reuse of catalysts with preservation of their activity was found for up to six consecutive cycles. The effects of reaction parameters, such as reaction time, temperature, amount of catalyst or type of heating source, on the performance of the above catalytic systems are reported and discussed.

Impacts of biostimulation and bioaugmentation on the performance and microbial ecology in methanogenic reactors treating purified terephthalic acid wastewater

Up-flow anaerobic sludge blanket (UASB) processes treating purified terephthalic acid (PTA) wastewater often face challenges associated with biomass loss. As excessive biomass loss could lead to deterioration of PTA removal, biostimulation and bioaugmentation were often practiced without understanding the microbial impact in UASB. Three laboratory-scale UASB reactors were operated with synthetic PTA wastewater as the feed, with two added with co-substrate (glucose or molasses) on Day 170 for 90 days, and one with external granules on Day 118. Throughout the operation, treatment performance was measured together with the analysis of microbial communities of biomass samples using 16S rRNA-based gene Illumina sequencing. Glucose amendment destabilized both terephthalic acid and para-toluic acid removal, while molasses amendment improved para-toluic acid removal. Both substrate addition generally led to decreases in the abundances of syntrophs and methanogens and increases in carbohydrate-fermenting bacteria in the granular sludge. Regarding bioaugmentation, paper mill granule addition led to a temporary crash of terephthalic acid removal for 42 days, and deterioration of para-toluic acid removal throughout the operation. Syntrophs and methanogens were observed to colonize on the paper mill granules after three months, meanwhile growth of methanogens were stimulated on the PTA granules added initially. Overall, proper level of molasses amendment and external granule inoculation could be promising strategies to make up for biomass loss during the operation of PTA-degrading UASB.

Biotransformation of p-xylene into terephthalic acid by engineered Escherichia coli

Terephthalic acid (TPA) is an important industrial chemical currently produced by energy intensive and potentially hazardous p-xylene (pX) oxidation process. Here we report the development of metabolically engineered Escherichia coli system for biological transformation of pX into TPA. The engineered E. coli strain harbours a synthetic TPA pathway optimized through manipulation of expression levels of upstream and downstream modules. The upstream pathway converts pX to p-toluic acid (pTA) and the downstream pathway transforms pTA to TPA. In a two-phase partitioning fermentation, the engineered strain converts 8.8 g pX into 13.3 g TPA, which corresponds to a conversion yield of 96.7 mol%. These results suggest that the E. coli system presented here might be a promising alternative for the large-scale biotechnological production of TPA and lays the foundations for the future development of sustainable approaches for TPA production.

Thermodynamic models for determination of solid-liquid equilibrium of the 4-methylbenzoic acid in pure and binary organic solvents

Data on corresponding solid-liquid equilibrium of 4-methylbenzoic acid in different solvents are essential for a preliminary study of industrial applications. In this paper, the solid-liquid equilibrium of 4-methylbenzoic acid in methanol, ethanol, isopropanol, 1-butanol, acetone and acetonitrile pure solvents and (acetone+acetonitrile) mixture solvents were explored in the temperatures (from 278.15 to 323.15K) under atmosphere pressure. For the temperature range investigated, the solubility of 4-methylbenzoic acid in the solvents increased with increasing temperature. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model had more advantages than the other two models. The solubility data were fitted using a modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model and Ma model in (acetone+acetonitrile) binary solvent mixture. In addition, the calculated thermodynamic parameters indicated that in each studied solvents the dissolution of 4-methylbenzoic acid is endothermic and entropy-driven process.

A Comparative Study of Electrochemical Treatment of Para-Toluic Acid (p-TA) from Aqueous Solution: Process Optimization and Sludge Analysis

The present study deals with the removal of para-toluic acid (p-TA) as well as chemical oxygen demand (COD) from synthetic solution. Pretreatment of aqueous solution was done by acid precipitation at different pH levels (3–6) and temperatures (15–60 °C). The pretreated solution was further treated by electrocoagulation (EC) and electro-Fenton (EF) treatment technologies using iron anode and graphite cathode. Optimization of various independent operating parameters viz. initial pH (1–9), current density (30.48–152.44 A/m2), electrolyte concentration (for EC) (0.03–0.07 mol/L), H2O2 concentration (for EF) (300–700 mg/L), and electrolysis time (10–90 min) was performed using central composite design (CCD) in response surface methodology (RSM). At optimum operating conditions, maximum removal percent of p-TA 64.83, 74.50; COD 61.27, 68.21; and energy consumption (kWh/kg COD removed) 69.71, 41.60 were obtained by EC and EF processes, respectively. In this study, it was observed that the EF process was more efficient than EC process based on percent removal of p-TA and COD with minimum energy consumption (E.consumption). Sludge obtained after EC and EF treatments was analyzed for various physicochemical characteristics like settling, point of zero charge, XRD, FTIR, SEM/EDX, and DTA/TGA.

Supramolecular hydrogen-bonding patterns in 1:1 cocrystals of 5-fluorouracil with 4-methylbenzoic acid and 3-nitrobenzoic acid.

The design of a pharmaceutical cocrystal is based on the identification of specific hydrogen-bond donor and acceptor groups in active pharmaceutical ingredients (APIs) in order to choose a `complementary interacting' molecule that can act as an efficient coformer. 5-Fluorouracil (5FU) is a pyrimidine derivative with two N-H donors and C=O acceptors and shows a diversity of hydrogen-bonding motifs. Two 1:1 cocrystals of 5-fluorouracil (5FU), namely 5-fluorouracil-4-methylbenzoic acid (5FU-MBA), C4H3FN2O2·C8H8O2, (I), and 5-fluorouracil-3-nitrobenzoic acid (5FU-NBA), C4H3FN2O2·C7H5NO4, (II), have been prepared and characterized by single-crystal X-ray diffraction. In (I), the MBA molecules form carboxylic acid dimers [R22(8) homosynthon]. Similarly, the 5FU molecules form two types of base pair via a pair of N-H...O hydrogen bonds [R22(8) homosynthon]. In (II), 5FU interacts with the carboxylic acid group of NBA via N-H...O and O-H...O hydrogen bonds, generating an R22(8) ring motif (heterosynthon). Furthermore, the 5FU molecules form base pairs [R22(8) homosynthon] via N-H...O hydrogen bonds. Both of the crystal structures are stabilized by C-H...F interactions.

Selective hydrogenation of 4-carboxybenzaldehyde over palladium catalysts supported with different structural organization

The palladium-incorporated catalyst, (0.5% Pd/C) (nanospace engineering KOH-activated carbon material) catalyst with macro-structured carbon nanofibers aggregates and micro-nano-porous activated carbons, has been studied as a candidate for hydro-purification of crude terephthalic acid containing of 4- carboxybenzaldehyde (4-CBA) as an impurity. The efficiency of different carbon structures (macro/micro) was investigated over selectivity catalyst. The reaction products were analyzed by HPLC to determine the amounts of 4-CBA, benzoic acid (BA), 4-Hydroxymethyl benzoic acid (4-HMBA) and para-toluic acid (p-tol). It has been confirmed that 0.5% Pd/microporous catalyst gave an excellent performance to catalyze the hydrogenation of 4-CBA to para-toluic acid due to high micro-porous surface area and the most desirable selectivity to 4-HMBA was obtained with macro-structured carbon nanofibers. Pd/AC catalyst with more micro surface area (85.26%) achieved a maximum yield to the intermediate product of 4-HMBA only 30% whereas the macro-structured CNFs achieved typically 66%. The desired selectivity to para-toluic acid was found to be deep dependent on the micro-porous structure.

Adsorption of terephthalic acid and p-toluic acid from aqueous solution using metal organic frameworks: Effect of molecular properties of the adsorbates and structural characteristics of the adsorbents

Adsorption of terephthalic acid and p-toluic acid from aqueous solution using metal organic frameworks: Effect of molecular properties of the adsorbates and structural characteristics of the adsorbents

The formation of p-toluic acid from coumalic acid: a reaction network analysis

Diels–Alder cycloaddition of biomass-derived 2-pyrone coumalic acid (CMA) with propylene provides an alternative pathway to produce toluic acid (TA), a precursor to terephthalic acid (TPA) which is a key component in the manufacture of polyethylene terephthalate (PET).

Monoclinic-to-orthorhombic phase transition of the hexamethylenetetramine-2-methylbenzoic acid (1/2) cocrystal with temperature-dependent dynamic molecular disorder.

As a function of temperature, the hexamethylenetetramine-2-methylbenzoic acid (1/2) cocrystal, C6H12N4·2C8H8O2, undergoes a reversible structural phase transition. The orthorhombic high-temperature phase in the space group Pccn has been studied in the temperature range between 165 and 300 K. At 164 K, a t2 phase transition to the monoclinic subgroup P21/c space group occurs; the resulting twinned low-temperature phase was investigated in the temperature range between 164 and 100 K. The domains in the pseudomerohedral twin are related by a twofold rotation corresponding to the matrix (100/0-10/00-1. Systematic absence violations represent a sensitive criterium for the decision about the correct space-group assignment at each temperature. The fractional volume contributions of the minor twin domain in the low-temperature phase increases in the order 0.259 (2) → 0.318 (2) → 0.336 (2) → 0.341 (3) as the temperature increases in the order 150 → 160 → 163 → 164 K. The transformation occurs between the nonpolar point group mmm and the nonpolar point group 2/m, and corresponds to a ferroelastic transition or to a t2 structural phase transition. The asymmetric unit of the low-temperature phase consists of two hexamethylenetetramine molecules and four molecules of 2-methylbenzoic acid; it is smaller by a factor of 2 in the high-temperature phase and contains two half molecules of hexamethylenetetramine, which sit across twofold axes, and two molecules of the organic acid. In both phases, the hexamethylenetetramine residue and two benzoic acid molecules form a three-molecule aggregate; the low-temperature phase contains two of these aggregates in general positions, whereas they are situated on a crystallographic twofold axis in the high-temperature phase. In both phases, one of these three-molecule aggregates is disordered. For this disordered unit, the ratio between the major and minor conformer increases upon cooling from 0.567 (7):0.433 (7) at 170 K via 0.674 (6):0.326 (6) and 0.808 (5):0.192 (5) at 160 K to 0.803 (6):0.197 (6) and 0.900 (4):0.100 (4) at 150 K, indicating temperature-dependent dynamic molecular disorder. Even upon further cooling to 100 K, the disorder is retained in principle, albeit with very low site occupancies for the minor conformer.

Non-dispersive solvent extraction of p-toluic acid from purified terephthalic acid plant wastewater with p-xylene as extractant

Non-dispersive solvent extraction (NDSE) with p-xylene as extractant was employed as a novel separation method to recover both p-toluic (PT) acid and water from purified terephthalic acid (PTA) wastewater. The mass transport behavior of PT acid from aqueous solution to p-xylene was investigated by experiments and numerical simulation. Experiments showed that NDSE is feasible and effective. Residual PT acid in the raffinate can be reduced to lower than the permitted limit of wastewater re-use (100 g/m3) with extraction time longer than 60 s in industrial conditions. A mathematical model of PT acid mass transport was developed to optimize the membrane module performance. The model was validated with the experimental results with relative errors of less than 6%. Numerical analysis for mass transfer through the lumen side, the porous membrane layer, and the shell side showed that PT acid transport in the aqueous solution is the rate determining step. The effects of the membrane and operating parameters on membrane module performance were investigated by means of computational simulations. The key parameters suggested for industrial NDSE design are: fiber inner radius r1=200–250 µm, extraction time te=50–60 s, aqueous/organic volumetric ratio a/o=9.0, and temperature T=318 K.

Experimental Investigation on the Removal of p-Toluic Acid from Aqueous Solution using Functionalized Polymeric Sorbent

Polystyrene-divinylbenzene copolymer (PsDVB) was covalently functionalized with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) by a simple method. The functionalized sorbents were characterized in terms of functionality and morphology, and used for the removal of p-toluic acid (p-TA) from aqueous solution. It was found that DEA-PsDVB has higher adsorption capacity than MEA- and TEA-PsDVB due to more accessible nitro and hydroxyl groups on its surface. Further investigation on the adsorptive properties of DEA-PsDVB indicated that the maximum uptake of p-TA occurred at the optimum pH of 5.3. The kinetics data was successfully represented by the pseudo-first-order model, and the behavior of the adsorption isotherms followed the Freundlich model well. Thermodynamic studies showed that the adsorption of p-TA onto DEA-PsDVB was an endothermic and spontaneous process along with the positive change in entropy. The regeneration of DEA-PsDVB was performed with 0.1 M NaOH solution, and results showed that 99% of the initial capacity was conserved after eight successive adsorption/regeneration cycles.

Synthesis, characterization, thermal behavior and antimicrobial activity of 3-methyl benzoate complexes of transition metal with hydrazine

Reaction of the ligands, 3-methyl benzoic acid (mbH) and hydrazine with transition metal ions form the complexes of formulae, [M(N 2 H 4 ) 2 (mb) 2 ].H 2 O where M = Co(II) and Zn(II) at pH = 5-6, [M(N 2 H 4 ) n (mb) 2 ].xH 2 O where M = Ni(II), n = 2, x = 0 at pH = 5 and M = Cd, n = 1, x = 1 at pH = 6. The same acid also forms metal carboxylates with zinc and copper of formula, [Zn(mb) 2 H 2 O].H 2 O at pH = 6 and [Cu(mb) 2 ].H 2 O at pH = 5, respectively. The IR spectra of the complexes show that hydrazine is present as bridging bidentate ligand and the carboxylic acid as monodentate bridging carboxylate anion. The electronic spectra, magnetic moments and ESR spectral data suggest the coordination number. Thermal studies show that cobalt, zinc and nickel complexes containing hydrazine, and carboxylates of copper, zinc on their thermal decomposition form the corresponding metal oxides in nano size in the temperature range 755-815 °C. The antibacterial and antifungal activity show that both activities of the complexes are higher than that of the acid and among the complexes, cadmium compound shows more antimicrobial activity towards bacteria and fungi. KEY WORDS : Hydrazinium complexes, 3-Methyl benzoic acid, Thermal analysis, IR, Electronic spectra, Biological activity Bull. Chem. Soc. Ethiop. 2016 , 30(2), 241-252. DOI: http://dx.doi.org/10.4314/bcse.v30i2.8