Mixture Of Pyridine Research Articles

Mining electronics waste: Experimental and computational mechanistic insights into organic aqua regia as an extraction method

In the previous decade, organic aqua regia (OAR) was discovered as a mixture of pyridine and thionyl chloride that has been observed to surprisingly yet notably selectively dissolve precious metals, dissolution‐resistant gold. Given the novel combination is two common organic solvents, it has immense potential to contribute to a circular economy of metal recycling, economically and environmentally. The underlying mechanisms behind its metal dissolution and interesting properties are not well‐understood. Using both the original mixture and derivatives, the role of each OAR reagent was analyzed in the dissolution of gold to begin probing and illuminating the novel mechanism. Three mechanisms were proposed: radical based, oxidant and ligand, and Lewis acid and base. Computational means were used to propose possible mechanisms. Experiments were used to explicate the possible mechanisms. Discoveries from the original publication were used to verify assessments and suggest future areas of study for further confirmation. Based on the finding that 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) does not significantly affect the amount of gold dissolved, the radical mechanism was dismissed. Findings from experiments replacing pyridine with its derivatives disproved the likelihood of the oxidant and ligand mechanism. Finally, with the support of proton nuclear magnetic resonance (1H NMR) and other characterization techniques, the Lewis acid and base mechanism was determined to be the most probable mechanism of OAR. The mechanistic findings reported herein will pave the way for continued understanding of the mechanism to be exploited and optimized for other metals and organometallic chemistry in the recycling of metals.

The Gas Phase Protonation Sites of Six Naturally Occurring Nicotinoids.

The gas phase protonation sites of six naturally occurring nicotinoids, namely nicotine (NIC), nornicotine (NOR), anabasine (ANB), anatabine (ANT), cotinine (COT), and myosmine (MYO), consisting of a common Pyridine and differing non-Pyridine rings, have been determined for the first time at the physiological temperature from cryogenic ion trap infrared spectroscopy and electronic structure calculations. The protonation site on either of these two rings is related to the nicotinoid's biological activity. At room temperature, NIC is a mixture of Pyridine and Pyrrolidine (non-Pyridine) protomers, whereas NOR, ANB, ANT, and COT are pure Pyridine protomers and finally MYO is mostly a Pyroline (non-Pyridine) protomer. The nearly planar structure of MYO-H+, induced by the presence of a conjugated π system and confirmed from calculations and the UV absorption spectra, breaks from the trends observed for NIC, NOR, and ANB, since its structure is drastically different from the structures of the other nicotinoids.

Design and evaluation of semicarbazide-embeddedd stationary phases for liquid chromatography

Semicarbazide, as a derivative of urea, constitutes a great variety of functional molecules for different needs. Herein, novel stationary phases with an incorporated semicarbazide group were proposed. Using aliphatic (docosanoyl, C22) and aromatic (benzoyl, Bz) hydrazides, the semicarbazide-embedded ligands were synthesized before chemical modification of the silica gel, allowing for an accurate interpretation of the chromatographic properties of the corresponding packings. The new stationary phases were water-wettable, due to the presence of highly polar groups. In particular, Bz-semicarbazide (Bz-SCD) stationary phase was sufficiently hydrophilic to run in hydrophilic interaction (HILIC) mode, whilst the C22 (C22-SCD) equivalent, in spite of its reversed-phase nature, was markedly less hydrophobic than the referenced polar-embedded ones. The versatility of C22-SCD was demonstrated with a large selection of analytes, including geometric isomers and standard mixtures of polycyclic aromatic hydrocarbons, sulfonamides, sulfonylurea, substituted ureas, pyridines and carbamates, fat-soluble colorants, antifungal metabolites, angiotensin II receptor blockers and calcium channel blockers.

Synthesis and physicochemical properties of tin(IV), zirconium(IV), and hafnium(IV) 2(3),9(10),16(17),23(24)-tetrakis-(4-tritylphenoxy)phthhalocyaninates

The reaction of 4-tritylphenoxyphthalonitrile with SnCl2, ZrCl4 and HfCl4 in the presence of urea under ammonium molybdate catalysis was used to synthesize tetrakis-(4-tritylphenoxy)phthalocyaninates of tin(IV), zirconium(IV), and hafnium(IV). The complexes were characterized by spectral methods of analysis, including mass spectrometry, 1Н NMR, vibrational and electron spectroscopy. All of them form J -type dimer associates in chloroform at concentrations up to ~1.5×10-6 mol/L and lower, are not associated in a mixture of toluene and pyridine up to concentrations of ~3×10-5 mol/L and higher, have catalytic activity in electroreduction reactions of molecular oxygen. The complexes of zirconium and hafnium showed the highest activity. Tin and zirconium complexes are thermally stable in an inert atmosphere up to a temperature of 200°C.

Physico-chemical and biological studies of some Copper(I) complexes in binary mixtures of polar solvents at variable temperature

Physico-chemical parameters like, conductance, viscosity, volumetric, thermo acoustic, thermodynamics of viscous flow, were thoroughly evaluated from the experimentally obtained data of specific conductance, viscosity, density, and ultrasonic velocity. These parameters were evaluated for Copper(I) nitrate complexes in binary mixtures of polar solvents, Dimethylsulfoxide (DMSO), Pyridine (Py), and Nitromethane (NM) at variable temperatures (298 K-318 K) and at 1 atmospheric pressure. Ionic B values were evaluated using Jones-Dole equation to determine the extent of molecular interactions. From the measured viscosity, using Erying's transition state theory, the thermodynamic parameters of viscous flow such as Gibb's energy of activation (ΔG)*, enthalpy of activation (ΔH)*, and entropy of activation (ΔS)* were also evaluated. The thermodynamic function showed the values of ΔH* as positive for all electrolytes and ΔS* as negative. From the conductance data, the Energy of Activation (Ea) and ionic walden product (λoη) were evaluated and tabulated. Further, in order to discover more about the solute–solvent interactions, limiting apparent molar volume (ɸ˚v), Masson’s coefficient (Sv), partial molar expansibilities (ɸ˚E) and Hepler’s constant were also calculated from density and velocity data at variable temperatures. Limiting apparent molar volume ɸ˚v values for both binary mixtures were positive, indicating strong solute–solvent interactions. Thermo acoustical parameters like internal pressure (πi), Rao’s constant (Rm) and Wada’s constant (W) were also evaluated. The results from all the studies showed the possible solvation in DMSO + Py solvent mixture as compared to DMSO + NM system. Further, the copper(I) nitrate complexes with bioactive ligands were tested against Gram positive strains (S mutans MTCC 497 and S aureus MTCC 7443), Gram negative strains (S enteric MTCC 164 and P aeruginosa MTCC 4673) and fungus (A parasiticus NCIM 696, Candida albicans MTCC 183 and A niger NCIM 501). The zone of inhibition was also measured for the complexes. All the complexes with potential bioactive ligand containing Nitrogen and Sulphur atom bonded to central copper atom showed antibacterial and antifungal activity.

Electron-Rich MoIV 3 -Polyoxomolybdates Resembling the Paratungstic Archetype.

The first polyoxometalates (POMs) composed of MoIV , MoV 2 , discrete d1 -MoV and MoVI , [MoIV 3 MoV 6 MoVI 4 O32 (μ2 -OH)(μ3 -OH)py9 ] (1), was prepared from the solvothermal partial oxidation of [MoIV 3 O2 (O2 CCH3 )6 (H2 O)3 ]ZnCl4 in a mixture of pyridine and water. The MoV =O adduct-free unit [H2 Mo12 O33 py9 ] presents the 11e-reduced Mo derivative of the paratungtic archetype. The use of methanol, ethanol, n-propyl alcohol and triglycol instead of water produced the isostructural [MoIV 3 MoV 6 MoVI 4 O32 (μ3 -OH)(μ2 -OR)py9 ](R=CH3 , 2; C2 H5 , 3; C3 H7 , 4; C2 H4 OH, 5), providing the first examples of MoIV 3 -POMs containing bridging alkoxyl groups. The addition of [CrIII Mo6 O24 ]9- led to the substitution of {MoV =O}3+ with {CrIII -py}3+ in the allomer [MoIV 3 MoV 5 MoVI 4 CrIII O32 (μ-OH)2 py10 ] (6). Using a mixture of Mo3 and MoW2 precursors afforded WVI -incorporated allomer [MoIV 3 MoV 6 MoVI WVI 3 O32 (μ-OH)2 py9 ] (7). The complete substitution of MoVI with WVI by using a mixture of the Mo2 W, MoW2 and W3 precursors produced the diamagnetic [MoIV 3 MoV 6 WVI 4 O33 (μ3 -OH)py9 ]- (syn-8) resulting from the anti→syn conversion between the top and bottom M3 triads concomitant with MoV -MoV bonding. Both anti-1-7 and syn-8 have been characterized by X-ray single crystal structural analyses. The spin distribution and magnetic interactions have been investigated by temperature-dependent magnetic susceptibility and DFT theoretical calculations. Heterogeneous hydrogen transfer catalysis has been examined by the Lewis catalysis field (LCF) theory.

Blending Effects of Nitrogenous Bio-Fuel on Soot and NOx Formation during Gasoline Combustion

Bio-fuel plays an important role in addressing the issue of CO2 and pollutant emission during cocombustion with fossil fuels. In this work, the effects of nitrogenous bio-fuel on soot and NOx formation during gasoline combustion were numerically investigated. Three bio-fuels, modeled by mixtures of pyridine, ethyl acetate, and ethanol with different volume fractions of pyridine and named SIM1 (0%), SIM2 (0.5%), and SIM3 (1%), were adopted to investigate the formation of soot and NOx when coburning with gasoline. Two mechanisms, i.e., the Glarborg mechanism and the Okafor mechanism, were employed to study the difference in soot and NOx formation. Results showed that pyridine exhibited different effects on soot formation in different regions. Based on the Okafor mechanism, soot formation was suppressed at the height of z = 3–4 cm, while it was promoted at the height of z = 4.5–5.5 cm. However, a reverse trend was predicted by the Glarborg mechanism. Moreover, the peak soot volume fraction (SVF) calculated by the Okafor mechanism was obviously higher than that calculated by the Glarborg mechanism; the major reason for the inconsistency of SVF in the two mechanisms was that more C6H5CH3 reacted with OH radicals to form C6H5CH2 in the Glarborg mechanism, resulting in less C6H5CH3 forming benzene (A1). Along with the increase of the pyridine proportion in the bio-fuel, the concentrations of NO increased by 92.1 and 91.4% in both mechanisms, attributed to the pyrolysis of pyridine into HCN, which promoted the formation of NO precursors (N, NH, NCO, and HNO) and thus NO. The difference in NO formation between the two mechanisms was because the reaction rate of NO converted from NO precursors in the Glarborg mechanism was higher than that in the Okafor mechanism. The NO2 was converted from NO via the reaction of NO + HO2 = NO2 + OH, and it distributed in the region with a lower NO concentration.

Intercalated chitosan-ionic liquid ionogel in SnO nanoplate: band gap narrow and adsorption-photodegradation process

Ionogels are a category of hybrid material containing ionic liquid stabilized by polymeric network. These composites have some applications in solid-state, energy storage devices and environmental studies. In this research, chitosan (CS), ethyl pyridinium iodide ionic liquid (IL), and ionogel (IG) consisting of chitosan and ionic liquid were used in the preparation of a SnO nanoplate (SnO-IL, SnO-CS and SnO-IG). For the preparation of the ethyl pyridinium iodide, a mixture of pyridine and iodoethane (1: 2 molar ratio) was refluxed for 24 hours. The ionogel was formed using ethyl pyridinium iodide ionic liquid in chitosan that was dissolved in acetic acid (1 % v/v). By increasing NH3∙H2O, the pH of the ionogel reached 7‐8. Then, the resultant IG was mixed with SnO in an ultrasonic bath for 1 h. The microstructure of the ionogel was involved as assembled unit via π-π, electrostatic and hydrogen bonding interactions to be three-dimensional networks. The intercalated ionic liquid and chitosan influenced the stability of the SnO nanoplates and improved band gap values. When chitosan was contained as the interlayer space of the SnO nanostructure, the resulting biocomposite formed a well-ordered flower-like SnO structure. These hybrid material structures were characterized by FT-IR, XRD, SEM, TGA, DSC, BET, and DRS techniques. The changes in the band gap values for photocatalysis applications were investigated. In the case of SnO, SnO-IL, SnO-CS, and SnO-IG, the band gap energy was 3.9, 3.6, 3.2, and 2.8 eV, respectively. The dye removal efficiency of SnO-IG was 98.5, 98.8, 97.9, and 98.4 % via the second-order kinetic model for Reactive Red 141, Reactive Red 195, Reactive Red 198, and Reactive Yellow 18, respectively. The maximum adsorption capacity of SnO-IG was 540.5, 584.7, 1501.5, and 1100.1 mg/g for Red 141, Red 195, Red 198, and Yellow 18 dyes, respectively. Also, an acceptable result (96.47 % dye removal) was obtained with the prepared SnO-IG biocomposite for dye removal from textile wastewater.

New Insights in the Synthesis of High-Molecular-Weight Aromatic Polyamides-Improved Synthesis of Rod-like PPTA.

By employing a variation of the polyamidation method using in situ silylated diamines and acid chlorides, it was possible to obtain a rod-type polyamide: poly(p-phenylene terephthalamide) (PPTA, a polymer used in the high-value-added material Kevlar), with a molecular weight much higher than that obtained with the classical and industrial polyamidation method. The optimization of the method has consisted of using, together with the silylating agent, a mixture of pyridine and a high-pKa tertiary amine. The research was complemented by a combination of nuclear magnetic resonance and molecular simulation studies, which determined that the improvements in molecular weight derive mainly from the formation of silylamide groups in the growing polymer.

Composite Proton-Conducting Membrane with Enhanced Phosphoric Acid Doping of Basic Films Radiochemically Grafted with Binary Vinyl Heterocyclic Monomer Mixtures.

A composite proton conducting membrane (PCM) was prepared by radiation-induced grafting (RIG) of binary mixtures of 4-vinyl pyridine (4-VP) and 1-vinylimidazole (1-VIm) onto poly(ethylene-co-tetrafluoroethylene) (ETFE) film followed by phosphoric acid (PA) doping. The grafting parameters such as absorbed dose, temperature, monomer concentration, time, and monomer ratio were varied to control the degree of grafting (DG%). The effect of the reactivity ratio of 4-VP and 1-VIm on the composition and degree of monomer unit alternation in the formed graft copolymer was investigated. The changes in the chemical and physical properties endowed by grafting and subsequent PA acid doping were monitored using analytical instruments. The mechanical properties and proton conductivity of the obtained membrane were evaluated and its performance was tested in H2/O2 fuel cell at 120 °C under anhydrous and partially wet conditions. The acid doping level was affected by the treatment parameters and enhanced by increasing DG. The proton conductivity was boosted by incorporating the combination of pyridine and imidazole rings originating from the formed basic graft copolymer of 4-VP/1-VIm dominated by 4-VP units in the structure. The proton conductivity showed a strong dependence on the temperature. The membrane demonstrated superior properties compared to its counterpart obtained by grafting 4-VP alone. The membrane also showed a strong potential for application in proton exchange membrane fuel cells (PEMFC) operating at 120 °C.

On pyridine chloronium cations.

We present the first solid-state structural evidence of mono- and bis(pyridine)chloronium cations. The latter was synthesized from a mixture of pyridine, elemental chlorine and sodium tetrafluoroborate in propionitrile at low temperatures. The mono(pyridine) chloronium cation was realized with the less reactive pentafluoropyridine, using ClF, AsF5, and C5F5N in anhydrous HF. During the course of this study, we also investigated pyridine dichlorine adducts and found a surprising disproportionation reaction of chlorine that depended on the substitutional pattern of the pyridine. Electron richer dimethylpyridine (lutidine) derivatives favor full disproportionation into a positively and a negatively charged chlorine atom which forms a trichloride monoanion, while unsubstituted pyridine forms a 1 : 1 py·Cl2 adduct.

The behaviour of tricyclic fused host systems comprising seven-membered B-rings in mixed pyridines

The intermolecular (host)π⋯π(host) and (guest)π⋯π(guest) (green dashed lines) and the (guest)C–H⋯π(host) and (host)C–H⋯π(host) (magenta) intermolecular interactions in H1·2(2MP) (in Å), the complex with the preferred pyridyl guest species.

Experimental Demonstration and Density Functional Theory Mechanistic Analysis of Arene C-H Bond Oxidation and Product Protection by Osmium Tetroxide in a Strongly Basic/Nucleophilic Solvent.

Reactions that result in the oxy-functionalization of sp2 C-H bonds to give phenols are relatively rare. Here we report experiments and density functional theory (DFT) calculations that demonstrate selective C-H bond hydroxylation of nitroarenes to their corresponding mono-phenoxide as the exclusive product using OsO4 in a highly basic solvent mixture of water, hydroxide, and pyridine. DFT calculations using a mixed explicit/continuum solvent approach indicate that there is likely a mixture of OsO4-hydroxide/pyridine ground-state structures that have competitive reactivity and that the mechanism involves the nucleophilic addition of an anionic metal-oxo species to the arene followed by a hydride transfer process that is different from the standard [3 + 2] mechanism often invoked for the OsO4 oxidation of σ and π bonds. This work demonstrates the utility of using a strongly basic solvent for C-H bond oxidation reactions as this effectively converts any reactive phenolic product into the corresponding phenoxide, which is protected and essentially inert to further oxidation by the nucleophilic metal-oxo species.

Comparative Study of Molecular Interaction in Ternary Liquid Mixtures of Polar and Non-Polar Solvents

Ultrasonic velocity measurements, density measurements, and viscometric studies were conducted for the ternary mixture of pyridine and toluene separately with N, N-dimethylformamide (DMF) in butanol, at different temperatures and for different concentrations of component liquids. Using these basic experimental data, various acoustic and thermodynamic parameters, such as adiabatic compressibility (β), free length (Lf,), free volume (Vf), etc. were calculated. Also, Excess thermo-acoustical parameters were calculated from the experimentally measured data. The outcomes were expressed in terms of the molecular interactions and the variations in parameters under varying solute concentrations. A comparative study is discussed. Variation in the above parameters for the different mixtures is indicative of the nature of the interactions between the components in the liquid mixture. Concluding remarks regarding intermolecular interactions are provided.

Double-Cavity Nor-Seco-Cucurbit[10]uril Enables Efficient and Rapid Separation of Pyridine from Mixtures of Toluene, Benzene, and Pyridine.

Benzene, toluene and pyridine are widely used as essential raw materials in industry and laboratory research, with stringent purity requirements. Herein, we show that solid double-cavity host nor-seco-cucurbit[10]uril (ns-Q[10]) functions as an efficient adsorption separator for pyridine; benzene and toluene can be obtained in >99.9 % purity by this method. Thermal removal of pyridine from ns-Q[10]⋅Py2 allows 10 separation cycles without erosion of performance. The geometry of the ns-Q[10]⋅Py2 ternary complex was established by single-crystal X-ray diffraction methods. The ns-Q[10] cage facilitates the removal of pyridine from toluene and benzene, with >99.9 % purity for the separated compounds.

Gas phase protonated nicotine is a mixture of pyridine- and pyrrolidine-protonated conformers: implications for its native structure in the nicotinic acetylcholine receptor.

The infrared (IR) spectra of gas phase protonated nicotine has been measured in the never-before probed N-H "fingerprint region" (3200-3500 cm-1). The protonated molecules generated by an electrospray source are thermalized in the first ion trap with water vapor and He gas at a pre-determined temperature prior to being probed by IR spectroscopy in the second ion trap at 4 K. The IR spectra exhibit two N-H stretching bands which are assigned to the pyridine and pyrrolidine protomers with the aid of high-level electronic structure calculations. This finding is in sharp contrast to previous spectroscopic studies that suggested a single population of the pyridine protomer. The relative populations of the two protomers vary by changing the temperature of the thermalizing trap from 180-300 K. The relative conformer populations at 240 K and 300 K are well reproduced by the theoretical calculations, unequivocally determining that gas phase nicotine is a 3 : 2 mixture of both pyridine and pyrrolidine protomers at room temperature. The thermalizing anhydrous vapor does not result in any population change. It rather demonstrates the catalytic role of water in achieving equilibrium between the two protomers. The combination of IR spectroscopy and electronic structure calculations establish the small energy difference between the pyridine and pyrrolidine protomers in nicotine. One of the gas phase nicotine pyrrolidine protomers has the closest conformational resemblance among all low-lying energy isomers with the X-ray structure of nicotine in the nicotinic acetylcholine receptor (nAChR).

Quantitation of Neuroblastoma Markers Homovanillic Acid (HVA) and Vanillylmandelic Acid (VMA) in Urine by Gas Chromatography-Mass Spectrometry (GC/MS).

Neuroblastoma and other neural crest tumors can be characterized by the increased production and excretion of catecholamines and their metabolites. Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are important catecholamine metabolites that can be measured to provide relatively rapid laboratory diagnosis and clinical follow-up of neuroblastoma. We present a procedure to quantify HVA and VMA in urine samples which have been diluted to a creatinine concentration of 2mg/dL. Diluted samples are spiked with deuterated internal standards, acidified, and extracted with an organic solvent. A bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) and pyridine mixture is added to the dried extract to create trimethylsilyl derivatives of HVA and VMA. The derivatized compounds are measured using gas chromatography-mass spectrometry (GC/MS).

Dynamics of radiative-reactive Walters-b fluid due to mixed convection conveying gyrotactic microorganisms, tiny particles experience haphazard motion, thermo-migration, and Lorentz force

The significance of the dynamics of mixture of polymethyl methacrylate and pyridine at 25 C containing 30.5 g of polymer per litre with density 0.98 g per litre has led to countable published facts with the intention to come up with insightful suggestions and recommendations for the expert in biofuel, bioengineering, biomedical, and mechanical engineering applications. However, nothing is known on the increasing bioconvection Rayleigh number, velocity ratio, Lorentz force, Prandtl number, bioconvection Peclet number, bioconvection Lewis number, and microorganisms concentration Biot number. The Spectral Local Linearization Method (SLLM) and MATLAB in-built package were adopted to solve the dimensionless form of the corresponding governing equation for the dynamics of radiative-reactive Walters-B fluid due to mixed convection when tiny particles experience haphazard motion, thermo-migration, and Lorentz force are significant and analyzed. It can be concluded that the Nusselt number proportional to the heat transfer rate can be declined by rising Lorentz force. The microorganism’s flux at the wall is a decreasing property of Prandtl number and bioconvection Peclet number. Increasement in the temperature distribution of the fluid flow is a property that could be enhanced through enhancement in the Lorentz force.

SYNTHESIS OF 3,3´-(1,4-PHENYLENE)BIS(1-(4-R-PHENYL)-5-PHENYL-5,6-DIHYDRO-1,2,4,5-TETRAZINIUM) PERCHLORATES

A series of 3,3'-(1,4-phenylene)bis(1-4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium) perchlorates containing hydrogen, methyl, bromio, methoxy, acetyl and nitro groups (R = H, Me, Br, OMe, COMe, NO2) as substituents were obtained as a result of a three-stage synthesis from terephthalic aldehyde. The synthesis of tetrazinium salts was carried out by reaction of the corresponding formazans with formalin in the presence of perchloric acid in dioxane. Formazans were obtained by reaction of terephthalic aldehyde phenylhydrazone with arenediazonium tosylates in a mixture of DMF and pyridine. The usage of arenediazonium tosylates made it possible to extremely simplify the segregation and purification of formazans. The phenylhydrazone was synthesized according to the standard procedure from terephthalic aldehyde and phenylhydrazine/hydrochloric acid in aqueous dioxane. The formazans and tetrazinium perchlorates were isolated in individual state and characterized by elemental analysis, IR, UV, 1H and 13C NMR spectroscopy data. The process of electrochemical reduction of tetrazinium perchlorates was studied using the method of cyclic voltammetry (CV). Thus, the CV curves of all salts in the cathode region contain two one-electron reduction peaks, which are related to the sequential formation of a radical cation and a biradical. It was found that electron-donating substituents (R = Me, OMe) in the aromatic ring at position 1 facilitate the reduction of tetrazinium cation, while electron-withdrawing substituents (R = COMe, NO2) hinder this process. On this basis, it was suggested that the corresponding bis-verdazyl radicals should be easily formed in the presence of electron-donating substituents in the aromatic ring at position 1. Thus, 3,3´-(1,4-phenylene)bis(1-(4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium-1) perchlorates are perspective precursors of symmetric biradical systems based on verdazyl radicals.

Optimal separation of acetonitrile and pyridine from industrial wastewater

A mixture of water, pyridine and acetonitrile is obtained as a by-product during the pharmaceutical industry. Azeotropic-extractive distillation (AED) and azeotropic-pressure swing distillation (APSD) are used to separate this mixture. In this work, we perform an optimization study of the total energy consumption of both processes by using a single factor analysis and response surface methodology (RSM). Compared to single factor optimization, the results showed that the energy saving optimized by RSM of AED and APSD was 37.27% and 27.36% respectively. The heat exchange network is optimized according to ASPEN ENERGY ANALYSIS. The results showed that the energy saving of AED and APSD after heat transfer optimization was 12.3% and 33%, respectively. By comparing the energy consumption of the two processes, it was found that the optimized AED process had an energy saving of about 1.05% compared with APSD. However, since there is no extractant entrainment in the APSD process, the APSD process is finally selected.