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Abstract: Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92–100%) and in very short reaction times (1–5min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification. [Copyright &y& Elsevier]

Abstract: Poly(4-vinylpyridine) perchlorate, is a supported, recyclable, eco-benign catalyst for the reaction acetylation of structurally diverse alcohols, phenols and amines at room temperature under solvent-free conditions. The catalyst was studied by FT-IR, X-ray diffraction, Scanning Electron Microscope and Thermo-gravimetric Analyses. All the products were extensively characterized by 1H NMR, FT-IR, GC–MS and melting point analyses. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple filtration, followed by concentration of the crude product and purification. It is important to point out that a large-scale reaction is possible using a same amount of catalyst. [Copyright &y& Elsevier]

Thermal phase transitions of 1H,4H-piperazine-N,N′-diium diacetate were investigated by the differential scanning calorimetry (DSC) compared with piperazine and glacial acetic acid. The thermal stability of new sublimable molten salt was determined by thermogravimetric analysis (TGA), and the released gases after decomposition were identified by the thermogravimetric analysis–mass spectrometry (TG–MS). DSC profile of new sublimable organic molten salt was utterly different from those of its reactants, viz. piperazine and glacial acetic acid. Although the probability of reforming the acid and base remains negligible even at high temperatures (~ 300 °C) for some protic ionic liquids, the thermal behavior results exhibited that this molten salt could sublime at around 145 °C in the absence of high or ultrahigh vacuum. A new insight is described for sublimation and recondensation of the molten salt, including transforming the ionic salt in the solid phase into the molecular gas-phase cluster in the vapor phase, and reverse transformation during heating and cooling, respectively. The molten salt is nonhygroscopic contrary to piperazine and glacial acetic acid, which are highly hygroscopic. Furthermore, this work revealed for the first time that certain organic salts containing acceptor–donor hydrogen bonding moieties could be directly sublimed without liquefaction. [ABSTRACT FROM AUTHOR]

Regarding the importance of 1,3,4-thiadiazoles due to versatile biological activity and for investigation of the symmetry impact on thermal behavior and antibacterial activity of 2,5-bisalkylsulfenyl[1,3,4]thiadiazole, two new derivatives viz. 2-cyclohexylsulfenyl-5-cyclopentylsulfenyl[1,3,4]thiadiazole and 2-cyclohexylsulfenyl-5-dodecylsulfenyl[1,3,4]thiadiazole, were synthesized through the nucleophilic substitution reaction appropriate alkyl halide with 5-cyclohexyl-3H-[1,3,4]thiadiazole-2-thione in ethanol under reflux conditions. The chemical structure of the products was elucidated by the physical and spectroscopic techniques. After tedious work, the suitable snow-like crystals of 2-cyclohexylsulfenyl-5-dodecylsulfenyl[1,3,4]thiadiazole for single-crystal X-ray diffraction analysis could be isolated from a mixed solvent, namely ethanol and water in volume ratio of 9:1. Then, the influence of symmetry and cyclic or non-cyclic aliphatic substituents on the important structure parameters of the 2,5-bisalkylsulfenyl[1,3,4]thiadiazole derivatives were negligible, however, those structure characteristics were different for 5–cyclohexylsulfenyl–3H–[1,3,4]thiadiazole–2–thione, due to its thione structure. TGA/DTA study demonstrated the effect of the symmetry and van der Waals interaction on thermal stability, and the robust influence of the pseudo hydrogen bonding NH with C = S on the melting and crystallization phase transitions was revealed by DSC analysis. The pharmacokinetics, drug-likeness, medicinal chemistry friendliness, and toxicology of three derivatives of bis-alkylsulfenyl[1,3,4]thiadiazole were evaluated by two prediction tools of SwissADME and T.E.S.T tools predicted good pharmacokinetics, drug-likeness, and anti-toxicant properties in developmental toxicity for the bis-alkylsulfenyl[1,3,4]thiadiazoles and 5–cyclohexylsulfenyl–3H–[1,3,4]thiadiazole–2–thione. Finally, the in vitro antibacterial activity of two new 2-cyclohexylsulfenyl-5-cyclopentylsulfenyl[1,3,4]thiadiazole and 2-cyclohexylsulfenyl-5-dodecylsulfenyl[1,3,4]thiadiazole against S. aureus and E. coli, confirmed them as promising anti-bacterial agent. All obtained results proved that the physicochemical, thermal, pharmacokinetic, and biological properties of 2,5-bisalkylsulfenyl[1,3,4]thiadiazoles can be tuned by selecting appropriate substituents. [ABSTRACT FROM AUTHOR]

Given the abundance of functional groups, meso- and macro-pores, and a high surface area, the piperazine-based poly(amic acid) was employed as a heterogeneous catalyst in the multicomponent reaction to prepare pyrrolidinone scaffolds in a green solvent, acting as a medium for mass transfer and crystallization solvent. The important parameters of the reaction were investigated to find the optimal reaction conditions. A conversion of 100% was obtained at reflux conditions within 30–100 min using a catalytic amount of 200 mg of piperazine-based poly(amic acid) per 2 mmol of reactants (100 mg of cat./1 mmol of reactant). The piperazine-based poly(amic acid) exhibited high recyclability and the recovered catalyst could be used in successive runs without worthy loss in its activity. This work revealed the catalytic activity of the piperazine-based poly(amic acid) as a promising functional polymeric heterogeneous catalyst for organic synthesis. [ABSTRACT FROM AUTHOR]

• Recent research progress on surface modification of carbon-based nanoadsorbents • Applications of CNTs, G, and AC in adsorption of heavy metals • Overview on parameters and factors affecting the heavy-metal removal • Limits and drawbacks of carbon-based nanoadsorbents in wastewater treatment and recent advances to overcome their disadvantages Carbon-based nanoadsorbents (CNAs), including graphene (G), carbon nanotubes (CNTs), and activated carbon (AC), and their derivatives have been widely employed in wastewater treatment owing to their unique physical and chemical properties. Adsorption technology is considered as one of the eminent approaches for treating wastewater because of maximum efficiency, simplicity, flexibility, eco-friendliness, and selectivity for heavy metals. Thus, the critical review is ascertained towards the CNAs synthesis, functionalization, modification, and their adsorption behavior towards heavy metal ions. To ensure the economic aspects of CNAs, desorption studies and recyclability of adsorbents are also reviewed. Different parameters influencing the adsorption mechanism such as pH, temperature, contact time, adsorbent dosage, and sorbate concentration are discussed. Specific attention is paid to pH solution, a crucial parameter in the adsorption of heavy metals. Also, the adsorption capacity, sorbent selectivity, sorbent-sorbate interaction, and adsorption mechanism are observed and equated. Besides, the advantages and disadvantages of the CNAs are described in detail. Conclusively, this review contributes to current and future research prospects using CNAs with posed challenges in this area. [Display omitted] [ABSTRACT FROM AUTHOR]

• Synthesis of 1 H ,4 H -piperazine- N,N' -diium hydrogen sulfate as a new ionic liquid. • Structure elucidation of new ionic liquid together with of 1 H ,4 H -piperazine- N,N' -diium bromide as a new ionic liquid. • The great importance of FTIR analysis for the identification of hydrogen sulfate and sulfate anions. • Thermal behavior and thermal stability and determination of crystallization point of new ionic liquid. We decided to conduct the acid-base reaction of piperazine and sulfuric acid as a secondary diamine and diprotic acid, respectively. A new molten salt was obtained, which its structure elucidation was performed by FTIR, 1D NMR, 2D NMR, and mass spectrometry. In contrast to previous reports and our expectation, no characteristic signal was detected for the existence of hydrogen sulfate anion in 1H NMR of molten salt in DMSO‑ d 6. The 1H NMR of reactants, the new molten salt, and another derivative of this molten salt analyzed in the same deuterated solvent. Further support for the formation of 1 H ,4 H -piperazine- N,N' -diium dication was concluded by an NMR study of its bromide derivative i.e., 1 H ,4 H -piperazine- N,N' -diium dibromide. Based on the results of FTIR, NMR, pH, and titrimetry analyses, the formation of sulfate anion and the presence of an excess of sulfuric acid were excluded. The thermal behavior and thermal stability of new molten salt are also studied and reported. [ABSTRACT FROM AUTHOR]

Contaminated water resources, especially heavy metals, and dyes from industrial processes, pose a real threat to long-term and sustainable development goals. Activated carbon (AC) synthesis, their activation and modification to advanced and efficient material has been a target area of modern research work because of their distinguished properties; high surface areas (273–827 m2/g) and total pore volumes (0.27–0.69 ml/g), containing essentially micropores with diameters of 8.2 Å up to 12.4 Å, as well as surface chemistry. Most of the adsorption kinetics and isotherm for modified AC system fitted well with Langmuir and physical adsorption of pseudo-second order. The accumulate data on isotherm and kinetics indicate that modified AC has a huge potential for commercial applications, a part of its non-toxicity, low cost, and sustainability. Several parameters affecting the activation/modification and adsorption process including amount of adsorbent, pH medium, surface properties and concentration of water pollutants provide effect on adsorption efficiency of AC (75–96 %). Although, AC applications are rapidly growing, but still limited to batch levels. Considerations such as developing a simple and cost-effective approach for AC synthesis more specifically from non-degradable wastes have not been studied in detail. In addition, further studies on real wastewater systems are essential. This review highlights the wastewater treatment applications (heavy metals and dyes) of AC using adsorption technology and critically pinpoints the research gaps and suggestions for the future. [Display omitted] • Activated carbon synthesis and surface modification. • Adsorption isotherms and kinetics, and sorption mechanism. • Heavy metals and dyes removal using adsorption technique. [ABSTRACT FROM AUTHOR]

In the present study, the chemical structure of 4,4ʹ-trimethylene-N,Nʹ-dipiperidinium chlorosulfonate is elucidated by 1D NMR, and 2D NMR, FTIR, Raman analyses, and Mass spectra. It was indicated that the chlorosulfonic acid could not act as a sulfonating agent in the reaction with secondary amines like TMDP due to due more steric hindrance of the sulfur atom by chlorine and oxygen atoms. Raman and FTIR spectra are demonstrated as two high-value optical techniques to the elucidation and identification of chemical structures that confirmed C3 ν symmetry for chlorosulfonate anion in the ionic liquid. Then, the solvent-catalyst activity of ionic liquid was demonstrated in the one-pot synthesis of a series of novel triazolo-pyrimidines under mild conditions. The ionic liquid was retrieved and reused several times without reducing its catalytic efficiency. Image 1 • Correction and elucidation of the chemical structure of new ionic liquid. • Introducing of ClSO 3 H as an acid instead of a sulfonating agent in the reaction with the secondary amines. • The great importance of 2D NMR, FTIR and Raman analysis on the structure elucidation. • Introducing the dual solvent-catalyst activity of 4,4ʹ-trimethylene- N,Nʹ -dipiperidinium dichlorosulfonate. • The synthesis of dihydro-[1,2,4]triazolo[1,5- a pyrimidines under greener and low cost condition. [ABSTRACT FROM AUTHOR]

This paper presents the design and synthesis of new ionic liquid containing dication of 1 H ,4 H -piperazine-diium ring and two chlorosulfonate as counterions. The structure elucidation of new ionic organo-compound was performed by 1D and 2D NMR, FTIR, Raman, and mass spectrum. Then, the correct structure was elucidated by COSY which was supported by Raman study. IR and Raman spectra of liquid and solid-state of 1 H ,4 H -piperazine-diium dichlorosulfonate are studied. Assignments are made for FTIR and Raman peaks, and our results are compared with previous reports in the literature. Image 1 • Identification of 1 H ,4 H -piperazine-diium chlorosulfonate as a new ionic liquid in liquid and solid-state. • Solvent-effect on the final state of new ionic liquid. • The great importance of 2D NMR analysis such as COSY on the structure elucidation. • Frequency assignments of FTIR and Raman peaks for chlorosulfonate anion in the pure liquid and solid-state. • Comparison of our FTIR and Raman assignments with previous reports in the literature. [ABSTRACT FROM AUTHOR]

In the current work, 1 D and 2D NMR analysis of the obtained product from the stirring equimolar of imidazole and 1,3-propane sultone at room temperature in acetonitrile and dichloromethane overnight is described. On contrary to previous reports, our results displayed that the reaction afforded a mixture of the zwitterionic and ionic structures. A possible mechanism route for the formation of these chemical structures is illustrated. Image 1 • Great importance of NMR analysis on the structure elucidation. • The reaction of imidazole and propanesultone leads to a mixture of zwitterionic and ionic chemical compounds. • Identification of novel sulfo-imidazolium zwitterionic-type salt. [ABSTRACT FROM AUTHOR]

4,4ʹ-Trimethylenedipiperidin-N,Nʹ-diium diacetate was obtained as a cream-like liquid with a pale yellow color. Its ionic structure was demonstrated by different spectroscopic techniques, and its thermal behavior was also studied by TGA/DTA and DSC techniques to record its phase transitions and thermal stability and compare those with another analog, i.e., 1H,4H-piperazine-N,Nʹ-diium diacetate. Due to the existence of monoprotic Brönsted base and conjugate acid of TMDP in the new ionic liquid, it can act as a promising hydrogen bond catalyst. Thus, the Knoevenagel condensation of various substituted benzaldehydes with malononitrile was investigated using the new ionic liquid in ethanol. Ethanol acts as a reaction medium and crystallization solvent, and pure products were obtained directly from ethanol with no costly separation and purification. The residue solution was employed in the next run without concentration or activation. Furthermore, the model reaction was carried out on a large scale using the current catalytic process, affording a conversion of 100% and a high yield of the crystalline product even after ten consecutive runs. Energy efficiency, cost- and time-saving, and waste prevention demonstrate the newly developed metal- and halogen-free catalytic system as a more sustainable catalytic process for preparing the substituted arylidene malononitriles on the laboratory and industrial scale. [ABSTRACT FROM AUTHOR]

• Structure and geometry elucidation of the organic salt components. • Using an online biochemoinformatic tool to predict toxicity and hazard. • Greener catalyst and milder conditions to prepare 3,4,5-trisubstituted furan-2-one. • Cost-effective, energy- and time-saving homogeneous catalytic method. The simultaneous presence of sulfate and hydrogen sulfate in the crystal structure of an organic molten salt was demonstrated by single-crystal X-ray diffraction. The plenty of intra-hydrogen bonding between the dication of the protonated 1,3-di(4-piperidinyl)propane (TMDP), anions of sulfate and hydrogen sulfate, and crystalline water, as well as the existence of Brönsted acid of [HSO 4 ]− gives a strong ionic network. Spectroscopic and single-crystal studies reveal that the origin of superior binding for organic molten salt is correlated with the formation of strong hydrogen bonds between organic dications, sulfate and hydrogen sulfate anions, and crystalline waters. Though FTIR spectroscopy is a useful tool to prove the presence of sulfate or hydrogen sulfate, the existence of simultaneous [HSO 4 ]− and [SO 4 ]2− cannot be differentiated from the presence of [HSO 4 ]− by the FTIR spectrum. Two protonated piperidinyl rings were in the chair conformation. The tetrahedral geometry was observed around sulfur atoms in sulfate and hydrogen sulfate ions. This salt is another sample of unique organic molten salts in the sense that both sulfate and hydrogen sulfate anions are simultaneously linked through hydrogen bonds with the protonated piperidinyl rings of TMDP in one unit cell; nevertheless, there is no direct hydrogen bond between hydrogen sulfate and sulfate anions. Its unit cell contains two protonated TMDP, one sulfate, two hydrogen sulfate, and three crystalline waters. The crystal structure is stabilized by classical N H⋯O and O H⋯O hydrogen bonds, generating a strong three-dimensional network. In addition, the catalytic activity of the organic salt was demonstrated by preparing various 3,4,5-trisubstituted furan-2-one using a catalytic amount of the organic salt under mild and greener conditions owing to the existence of donor-acceptor hydrogen bonding sites and the presence of Brönsted acid anion. [Display omitted] [ABSTRACT FROM AUTHOR]

• A comparative study of Knoevenagel condensation of nitrogen-based organocatalysts. • A detailed study of the mechanism. • Energy efficient, time and cost-saving methodology for the production of CS. • Simple work-up without laborious separation, concentration, or purification. • Greener preparing 3-cyano-4-methylcoumarin and 2-imino-2H-benzopyran-3-carbonitrile. One of the important concerns in the field of catalysis is to find a reliable route to reduce the transition energies to reach the corresponding product. The mechanism of Knoevenagel condensation of 2-chlorobenzaldehyde and malononitrile in the presence of imidazole, an organocatalyst, is investigated through control experiments. In this study, the interactions and intermediates in synthesizing 2-chlorobenzylidenemahmonitrile (CS) are studied by FTIR and NMR analyses. First, a screen activity of seven nitrogen-based organocatalysts for preparing 2-chlorobenzylidenemahmonitrile (CS) was conducted in ethanol, an eco-friendly medium. The conversion of 100 % and excellent yields were obtained in a short reaction time. The products could be crystallized directly from the reaction solution. After separating pure products, the residue solution was employed directly in the next run without any concentration, activation, purification, or separation. Then, the generality and substrate scope of the new strategy were investigated in the presence of imidazole as a selected nitrogen-based organocatalyst. In addition, the scale-up synthesis of 2-chlorobenzylidenemahmonitrile (CS) was carried out, afforded crystalline products with 95 ± 2 % yield in five consecutive runs. Energy efficiency, cost saving, greener conditions, the use of catalytic loading organocatalyst and its high recyclability, prevention of waste, and recycling extractant by a rotary evaporator for non-crystallized products, demonstrate the newly developed metal-free and halogen-free catalytic methodology as a more sustainable process for the synthesis of (hetero-)arylidene malononitriles in the laboratory and industrial scale. [Display omitted] [ABSTRACT FROM AUTHOR]

• Metal-free and facile one-pot thermo-induced synthesis dimeric thiadiazole monosulfide. • A radical-radical cross-coupling directed synthetic process. • Efficient and practical synthetic route for large scale production. • Dimeric thiadiazole monosulfide reaction is thermodynamic favourable. The production of heterocyclic sulfide is the key building block in various applications, especially in the field of medicinal chemistry. Currently, heterocyclic sulfide was synthesized via deoxygenation of sulfoxide or cross coupling between sulfur sources and halogen compounds. However, these conventional methods suffer from drawbacks such as the use of toxic solvents, harsh reaction conditions, the requirement for transition metal catalysts, inert conditions, and the generation of toxic and corrosive halide-containing waste. In this study, a milder approach using hydrogen peroxide-mediated oxidative cross-coupling of 5-alkylsulfanyl-[1,3,4]thiadiazole-2-thiol successfully produces symmetrical dimeric thiadiazole monosulfide with an isolated yield of 73‒87 %. The molecular structure of bis(2-octylsulfanyl-[1,3,4]thiadiazolyl)-5,5′-sulfide was confirmed by X-ray crystal structure analysis. Interestingly, the formation of dimeric thiadiazole monosulfide undergoes a one-pot thermo-induced pathway. Density functional theory (DFT) indicates the formation of thiadiazole monosulfide is thermodynamically favorable through the cross-coupling reaction between thiadiazole thiyl radical and thiadiazole carbon-centered radical. [Display omitted] [ABSTRACT FROM AUTHOR]

The chemical structure of 4,4′-trimethylenedipiperidinium hydrogen sulfate hydrate was investigated by single-crystal XRD, thereby the existence of hydrogen sulfate anions and the crystallization waters was proved. This fact confirmed that the FTIR spectrum can be used to distinguish [HSO4]− and [SO4]2− anions in organic salts. The organic acid salt with both Brönsted acid and acceptor–donor hydrogen bond sites was employed in the laboratory scale of a fundamental industrial process. The catalytic efficiency of the organic acid salt was investigated for the selective transformation of glycerol into triacetin, a well-known fuel additive, under different conditions. The catalytic efficiency of the organic acid salt was investigated for the selective transformation of glycerol into triacetin, a well-known fuel additive, under different conditions. Furthermore, the selective separation of di- and tri-acetin from the reaction medium during the acylation was performed through a continuous liquid–liquid extraction in situ technique. The combinatory effect of Brönsted acid-hydrogen bond catalysis and separation process improves the preparation and separation of triacetin. The main merits of the current work are the easy preparation and selective separation of valuable products under solvent-free, metal-free, and halogen-free conditions with high recycling and reusing of the catalytic medium. [ABSTRACT FROM AUTHOR]

Green and sustainable synthesis is considered as a safer alternative to the conventional synthetic processes owing to its environmental friendly nature, atom economy, cost‐effectiveness, and easy handling. Herein, the catalytic efficiency of poly(4‐vinylpyridine) supported iodine (P4VP/I2) as a metal‐free and organocatalyst system was studied and approved for an efficient chemical fixation of CO2 into cyclic carbonates which is performed via the coupling of CO2 with epoxides. The high conversion and excellent selectivity were obtained for a broad range of epoxides in the presence of catalytic amount of P4VP/I2 under solvent‐free conditions. The heterogeneous catalyst could be recovered and regenerated over several times with no significant loss of catalytic activity. The possible mechanism was described for the catalytic performance of P4VP/I2 based on the synergetic effect of the Lewis acid and base sites and nucleophilic anion. [ABSTRACT FROM AUTHOR]

The commercially available 4,4ʹ-trimethylenedipiperidine (TMDP) was used in the solid state to activate various aldehydes and controlled the libration of methyl amine for preparing the corresponding N-methyl imines. It was indicated that TMDP could play multiple roles simultaneously in this reaction, including (a) a bifunctional base with a predicted pKa ~ 11 and a good scavenger of acid, (b) a catalyst able to form strong hydrogen bonding and chemical interactions with aldehyde functional group through hemiaminal and/or iminium intermediate, and (c) liberating methyl amine from its salt viz. methylammonium chloride. TMDP could be regenerated by neutralization. It was also regenerated by heating at 70 °C, which is reported for the first time according to the best of our knowledge. The regenerated reagent was stable regarding its chemical structure, and there was no significant loss in the catalytic efficiency even after several runs. The mechanism was investigated by performing several control reactions and studying the FTIR and NMR spectra in the solid-state synthesis. The current work demonstrated TMDP as a safe and greener promoter-acid scavenger for organic transformations compared with toxic, flammable, volatile liquid secondary amines such as piperidine. [ABSTRACT FROM AUTHOR]

• Prepare spearmint essential oil (Mentha spicata L.) stabilized with basil seed mucilage emulsion formulations. • Using different type of Tween surfactant as non-ionic emulsifier. • Investigation of influence of different Tweens on physicochemical properties of as-prepared emulsions. • Investigation of stability of as-prepared emulsions after five weeks storage at 4 °C. The influence of three non-ionic emulsifying agents, including Tween 20, Tween 40, and Tween 80, was investigated on the formation and some properties of nanoemulsions prepared from spearmint essential oil. The nanoemulsions were prepared using the ultrasonic emulsification method. The average particle size (Z-average), particle size dispersion index (PDI), zeta potential, viscosity, turbidity, pH, and physical stability of nanoemulsions were monitored at 4 °C for 35 days. The results showed that the nature and type of emulsifying agent had a significant effect (P < 0.05) on the properties mentioned above. As-prepared samples with Tween 20 exhibited the lowest value (Z-average). It demonstrated that the emulsifiers Tween 20 and Tween 80 could be used to form nanoemulsions, in which the stability of nanoemulsion increased in the presence of Tween 20. The effect of storage time on the parameters of particle size (Z-average), particle size dispersion index (DPI), zeta potential, turbidity, and viscosity was statistically significant (P < 0.05). [ABSTRACT FROM AUTHOR]

[Display omitted] • A new dimercaptobenzothiadiazole consists of four and five sulfur atoms. • Excellent EP and AW performance of dimercaptobenzothiadiazole additives. • The dimercaptobenzothiadiazole additives are non-corrosive and ashless. • Sulfonitrided tribofilm serve as an excellent boundary lubrication layer and surface protection. Lubricant additives are essential to protect mechanical devices. Although sulfur (S)-based dialkylpentasulfide (RC2540) exhibits acceptable extreme pressure (EP) performance, a high amount of S causes severe corrosion and poorer anti-wear (AW) performance. Herein, dimercaptobenzothiadiazole-based additives (DMTDs) consist of four and five S atoms, namely 2-(benzyldisulfanyl)-5-(benzylsulfanyl)-1,3,4-thiadiazole (4SBZ), 2-(octyldisulfanyl)-5-(octylsulfanyl)-1,3,4-thiadiazole (4SC8), 2,5-bis(benzyldisulfanyl)-1,3,4-thiadiazole (5SBZ), and 2,5-bis(octyldisulfanyl)-1,3,4-thiadiazole (5SC8) were synthesized. The synthesized DMTDs are non-corrosive (Grade 1a-1b) compared to RC2540 (Grade 4c). The 10 wt% 5SBZ demonstrated exceptional EP and AW performance than RC2540. The 10 wt% 5SBZ has improved weld load and reduced wear scar area by 5.0 folds and 94.1% compared to naphthenic base oil. The exceptional tribological properties of 5SBZ are attributed to the strong non-covalent interaction between the benzene ring and metal surfaces, high S content, and synergistic effect between S and N. Alternatively, the DMTDs exhibit better AW performance compared to RC2540. The XPS depth profiling demonstrated the formation of sulfonitrided tribofilm after lubrication with synthesized DMTDs. This tribofilm contributed to an excellent boundary lubrication layer for wear protection. The lubrication mechanism was discussed and proposed. This work provides promising DMTDs as EP and AW additives for industrial applications. [ABSTRACT FROM AUTHOR]

• Synthesis of a new derivative of mono-cyclopentyl-substituted bismuthiol. • X-ray crystallography demonstrated the existence of C=S and C–N–H for the new product. • Investigate the differences in thermal stability and phase transitions of three bismuthiol derivatives. • Potential of mono-cyclohexyl-substituted bismuthiol as an anticancer and antitumor compound. • A more potent agent than cefazolin against negative and positive bacteria. A new derivative of 2-cyclohexyl-substituted bismuthiol was synthesized via a sequential one-pot procedure in ethanol under reflux conditions. After many trials, the long colorless needle-like crystals could be isolated, suitable for X-ray crystallography. The chemical structure of the new bismuthiol derivative was characterized by spectroscopic techniques. The characteristic vibrations for differentiation of thiol-thione tautomers were defined regarding the comparative FTIR study of bismuthiol and two of its derivatives viz mono- and bis-cyclohexyl-substituted bismuthiol. The presence of a hyper-conjugative interaction between the S–H and π bond of C=N was indicated. In addition, the existence of C=S and C–N–H for the new product was demonstrated through single crystal XRD analysis, which supports thiol or thione tautomer determination using IR spectra. The TGA/DTA and DSC profiles of bismuthiol and mono- and bis-cyclohexyl-substituted bismuthiol were studied to determine the influence of hydrogen bonding, packing, and symmetric and unsymmetric structure on the transition phases and thermal stability. Finally, the biological activity of bismuthiol and bis- and mono-cyclohexyl-substituted bismuthiols were screened in silico by SwissADME tool and in vit ro against the gram-negative (Escherichia coli ATCC 25,922) and gram-positive (Staphylococcus aureus ATCC 25,923) bacterial species. [Display omitted] [ABSTRACT FROM AUTHOR]

• Introducing two new bismuthiol derivatives containing five- and six-membered cyclic substituents. • The influence of six-membered and five-membered cycloalkyl substituents on the physical properties and thermal behavior of bismuthiol. • Single-crystal X-ray diffraction study of 2,5-bis-cyclohexylsulfanyl-1,3,4-thiadiazole. • Determine the bond length of endo and exo C‒S, and Cα‒S and cyclohexane ring and 1,3,4-thiadiazole ring conformation. • Study of antibacterial activity of new bismuthiols against gram-positive and gram-negative bacteria. Two new derivatives of 2,5-bis-cycloalkylsulfanyl-[1,3,4]thiadiazoles, i.e., 2,5-bis-cyclopentylsulfanyl-[1,3,4]thiadiazole and 2,5-bis-cyclohexylsulfanyl-[1,3,4]thiadiazole, were synthesized for a first time through a one-pot two-step procedure through the nucleophilic substitution of the potassium salt of 1,3,4-thiadiazole-2,5-dithiolate with chlorocyclopentane or bromocyclohexane in ethanol under reflux conditions. A cost-effective work-up was applied for the separation and purification of desired products. The products were characterized by physical and spectroscopic techniques. The long colorless needle-like crystals of 2,5-bis-cyclohexylsulfanyl-[1,3,4]thiadiazole were obtained, and its crystal structure was studied by single-crystal X-ray diffraction analysis. The transition phases and thermal stability of bismuthiol and two new bis-cycloalkyl bismuthiol were investigated by TGA/DTG and DSC. The thermal decomposition of bismuthiol was reported in the literature; herein, a detailed of its thermal behavior is analyzed for the first time. Finally, the biological activity of bismuthiol and two new bis-cyclopentylsulfanyl and bis-cyclohexylsulfanyl substituted bismuthiol derivatives were screened in vitro against the gram-negative (Escherichia coli ATCC 25922) and gram-positive (Staphylococcus aureus ATCC 25923) bacterial species by the disk diffusion method. [Display omitted] [ABSTRACT FROM AUTHOR]

According to the 12 principles of green chemistry, surface functionalization was performed using glutaric anhydride under solvent-free and catalyst-free conditions. FTIR spectra and DS analyses demonstrated the functionalization of HCl-hydrolyzed cellulose. The influence of two parameters, i.e., the glutaric anhydride concentration and the reaction time, on the functionalization of HCl-hydrolyzed cellulose was investigated. Protocol efficiency was studied by a degree of substitution (DS). It was found that higher concentrations of glutaric anhydride cause an enhancement of DS to 0.75 and 0.87 for GA3–12 and GA9–12, respectively. In addition, the longer reaction time increased zeta potential from −12.2 ± 1.7 for G9–6 to −34.57 ± 2.2 for GA9–12. Morphology analysis by SEM showed a decrease in fiber length for the functionalized cellulose. DSC profiles confirmed dehydration at a range of 17 to 134 °C. A glass transition was revealed at −30 to −20 °C for all studied samples. The fusion, the depolymerization of cellulose chains, the cleavage of glycosidic linkages, and the decomposition of the crystalline parts of cellulose occur at 195 to 374 °C. Therefore, an efficient and greener process was developed to functionalize the HCl-hydrolyzed cellulose by glutaric anhydride, a safe and non-toxic anhydride, in the absence of the solvent and catalyst. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of two bis(imidazole) derivatives. • A comparative study of chemical structure of two bis(imidazole) derivatives. • Study the methyl group effect on spectra data and thermal behavior. • Study of the methyl group effect on the crystal structure parameters. Two bis(imidazole) derivatives, 1,4-di(1H-imidazol-1-yl) butane dihydrate (DImB·2H 2 O) and 1,4-di(1H-2-methylimidazol-1-yl) butane tetrahydrate (DMImB·4H 2 O were synthesized. The crystallization was performed from an aqueous ethanol by slow evaporation technique. X-ray crystallography was used to confirm the molecular structures of both crystals. The results from crystal structure analysis displayed that DImB·2H 2 O was crystallized in the orthorhombic crystal system and Pbca space group with a = 14.7805(4) Å, b = 5.22600(10) Å, and c = 15.6110(4) Å. The molecule lies in the center of inversion, making the asymmetric unit consist of half of the parent molecule with one unit of the water molecule, whereas DMImB·4H 2 O displayed the triclinic crystal system and R-3 space group with a = 21.526(3) Å, b = 21.526(3) Å, and c = 9.3333(12) Å. The molecule lies on a center of inversion, making the asymmetric molecules consist of half of the parent molecule with two units of the water molecules. The effect of replacing hydrogen atoms at C2 of two imidazole rings with the methyl groups on spectroscopic properties was investigated using FTIR, MS, 1H, and 13C NMR. The infrared spectrum demonstrated the presence of water molecules in DMImB·4H 2 O, which showed a more intense O‒H group peak than DImB·2H 2 O. The effect of methyl groups was studied on the chemical shifts, multiplicity, and coupling constants of hydrogen atoms, and carbon chemical shifts of imidazole rings. Mass spectra of both compounds showed [M+Na]+ and [2M+Na]+ in positive ion mode (ESI+). In addition, the thermal phase transitions and thermal stability of the bis(imidazole) derivatives were studied using the DSC and TGA/DTG. The crystalline structures of DImB and DMImB recorded and the methyl effect was investigated on the size of molecules, arrangement of molecules in the crystal lattice, lattice planes, solvent void, length, angle, and torsion. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A convenient, highly versatile and eco-friendly protocol for the synthesis of quinoline derivatives via the Friedländer reaction is presented. The method is based on the use of 1,3-disulfonic acid imidazolium hydrogen sulfate (DSIMHS) as an efficient and reusable ionic liquid catalyst. A variety of ketones afforded the substituted quinolines in excellent yields during relatively short reaction times under solvent-free conditions; the catalyst could be easily recovered and reused for several times without any appreciable loss of activity. [Copyright &y& Elsevier]

• Synthesis of two new molten acid salts and the characterization of their chemical structures. • FTIR, pH, and titrimetric analyses as the important tools to identify hydrogen sulfate and sulfate anions. • [HSO4]− and [SO4]2− influence on the physical properties of new molten acid salts. • Demonstration of the catalytic efficiency of the new molten acid salts for the cinnamic acid production. • High recyclability of the new molten acid salts. • Two new acid salts were Synthesized and characterization of two new molten acid salts and their catalytic activity for the hydrolytic conversion of (1,3,3,3-tetrachloropropyl)benzene to cinnamic acid. Available online Two new acid salts were synthesized, and their chemical structures were characterized by various spectra data analyses. Although 1H NMR did not show acid proton of [HSO 4 ]−, the FTIR spectra of molten acid salts act as key support to approve of their chemical structures. The structure elucidation of the molten acid salts demonstrated the existence of 4,4ʹ-trimethylene-N,Nʹ-dipiperidinium dication with sulfate and hydrogen sulfate anion(s). Thus, sulfuric acid can act as a diprotic or monoprotic Brönsted acid when it is treated by a secondary amine regarding the initial mole ratio of sulfuric acid and amine. Also, the catalytic activity of these molten acid salts was investigated for the hydrolytic conversion of (1,3,3,3-tetrachloropropyl)benzene to cinnamic acid. The desired product was obtained in 88 ± 2.0% yield under optimal conditions. The molten acid salts were high recyclable and their chemical structure and catalytic efficiency showed no significant change even after the 5th run. Furthermore, TMDP-SA (1:1) showed a much weaker corrosive property compared with TMDP-SA (1:2) and SA (98%), and the surface of stainless steel was intact even after 24 h. This fact and the acidity of two molten acid salts also confirm the proposed chemical structures. [Display omitted] [ABSTRACT FROM AUTHOR]

Aim and Objective: The establishment of a green and sustainable Knoevenagel condensation reaction in organic chemistry is still crucial. This work aimed to provide a newly developed metal-free and halogen-free catalytic methodology for the synthesis of CS and (hetero-) arylidene malononitriles in the laboratory and industrial scale. The Knoevenagel condensation reaction of various carbonyl groups with malononitrile was investigated in ethanol, an ecofriendly medium, in the presence of seven nitrogen-based organocatalysts., Materials and Methods: A comparative study was conducted using two as-obtained and four commercially available nitrogen-based organocatalysts in Knoevenagel condensation reactions. The synthesis of CS gas (2-chlorobenzylidene malononitrile) using a closed catalytic system was optimized based on their efficiency and greener approach., Results: The conversion of 100% and excellent yields were obtained in a short time. The products could be crystallized directly from the reaction mixture. After separating pure products, the residue solution was employed directly in the next run without any concentration, activation, purification, or separation. Furthermore, the synthesis of 2-chlorobenzylidenemahmonitrile (CS) was carried out on a large scale using imidazole as a selected nitrogen-based catalyst, afforded crystalline products with 95 ± 2% yield in five consecutive runs., Conclusion: Energy efficiency, cost saving, greener conditions, using only 5 mol% of organocatalyst, high recyclability of catalyst, prevention of waste, recycling extractant by a rotary evaporator for non-crystallized products, demonstrated the potential commercial production of CS using imidazole in ethanol as an efficient and highly recyclable catalytic system., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The Knoevenagel condensation is a powerful and primary step for the development of carbon-carbon bond transformations. These condensations offer versatile products/ intermediates for diverse uses in polymers, cosmetics, chemical industries, and medicinal chemistry. Various homogenous and heterogenous catalysts have been found to promote the Knoevenagel condensation reaction, both environmentally and economically. Due to their attractive use in the production of pharmaceutical drugs, they are proven to be the main force that drives the synthesis involving numerous multi-component and multistep reactions. The present study, therefore, aims to summarise reported Knoevenagel condensation reactions using metal-free catalysts resulting in pharmaceutically useful compounds with anti-cancer, anti-tumor, anti-oxidant, anti-malarial, anti-diabetic, and anti- bacterial activities. By considering factors like their structure-activity relationships (SARs), the reaction conditions, and the steps involved, as well as the advantages and limitations of the particular approach, we also provide a general framework and direction in order to achieve superior characteristics of the catalyst., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The conventional medium chain chlorinated paraffin (MCCP) and zinc dialkyl dithiophosphate (ZDDP) additives have greatly enhanced the extreme pressure (EP) and anti-wear (AW) performance of the metalworking fluids. However, chlorine- and zinc-containing additives are restricted in use due to eco-toxicity issue. Herein, ashless and non-corrosive dimercaptobenzothiadiazole derivatives, namely bis-2,5-benzylsulfanyl-[1,3,4]thiadiazole (BBST) and bis-2,5-octylsulfanyl-[1,3,4]thiadiazole (BOST) consist of three sulfur atoms have been synthesized and evaluated. The performance of BBST shows a weld load ( P D ) of 3089 N and AW value of 5 mm 2 , which represents an improvement of 3.1 and 7.4 folds over naphthenic base oil (NBO). In addition, BBST also outperformed BOST, MCCP, and ZDDP in terms of its weld load and AW properties. Based on XPS analysis and molecular electrostatic potential maps (MEPS), BBST exhibits superior tribology performance due to the interaction between the sulfur (S), nitrogen (N), and π-electrons of the benzene ring with the metal surface. The formation of FeS, Fe 2 O 3 and Fe⋯N coordinate bonds contributes to the creation of an excellent tribofilm., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Myrtus, commonly called myrtle, is a genus of flowering plants in the Myrtaceae family. This study aimed to review myrtle's pharmaceutical, food, and other uses. The pharmacological effects of myrtle for antioxidant, antibacterial, and anti-inflammatory activities, reduction of COVID-19 symptoms, anti-diabetic in the animal model, hepatoprotective in the rat model, antihypertensive, control of intestinal helminthiasis in mice model, inhibition of glucosyltransferase activity, protective effect on oxidative metabolism in the hypothyroidism model, and reducing the damage caused by skin burns are reviewed. In addition, the food uses of this plant such as improving the oxidative and microbial stability of products containing salmon, antimicrobial activity in meat and dairy products, flavoring in sea salt, microbial improvement of fresh fruits during post-harvest storage, animal nutrition, and bio-oil production are summarized., Supplementary Information: The online version contains supplementary material available at 10.1186/s41110-023-00194-y., Competing Interests: Competing interestThe authors declare no competing interests., (© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

A practical and facile synthesis of various coumarin derivatives was conducted using a liquid phase of 4,4'-trimethylenedipiperidine as a safe and greener dual-task reagent under catalyst-free and solvent-free conditions. This reagent is a commercially available solid and can be handled easily, having a liquid phase over a vast temperature range, high thermal stability, low toxicity, and good solubility in green solvents such as water and ethanol. It is worth mentioning that 4,4'-trimethylenedipiperidine could be completely recovered and regenerated after a simple process. The current method has other merits, including (a) minimizing the use of high-risk and toxic reagents and solvents; (b) the use of a secure and recoverable medium-organocatalyst instead of metal-based catalysts, (c) avoid tedious processes, harsh conditions, and a multi-step process for the preparation of catalysts, (d) transform phenol and salicyladehyde derivatives into the corresponding coumarin derivatives in good to high yields, (e) minimize hazardous waste generation. TMDP could be easily recovered and reused several times with no change in its activity. Furthermore, the current work demonstrated that the liquid phase of 4,4'-trimethylenedipiperidine can be a promising medium in organic reaction at higher temperatures due to its broad liquid range temperature, thermal stability, acceptor/donor hydrogen bond property, and other unique merits. New methodology for the synthesis of coumarines using liquid phase of TMDP under mild conditions., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This paper presents the efficient synthesis of 2-amino-4H-benzo[b]pyrans using mesoporous poly-melamine-formaldehyde as a polymeric heterogeneous catalyst. According to the principals of green chemistry, the reaction was performed by the planetary ball milling process at ambient and neat conditions. The heterogeneous catalyst could be reused up to five runs with no reducing of catalytic efficiency. A variety of substituted 2-amino-4H-benzo[b]pyrans were obtained in good to excellent yields under eco-friendly conditions. Other advantages of the current methodology include short reaction time, wide substrate-scope, and use of a metal-free polymeric catalyst. Also, the current method avoids the use of hazardous reagents and solvents, tedious workup and multi-step purification. This work revealed that porous organic polymers containing Lewis base sites having acceptor-donner hydrogen bonding functional groups, and high porosity could play a vital role in the promotion of the one-pot multicomponent reactions in the solid-phase synthesis.