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1,3,4-thiadiazole derivatives has been attracted great attention due to application in various areas. Synthesis and crystal structure is briefly investigated. Their application in high temperature and high pressure as anti-friction and antiwear, and improve the anti-wear and extreme pressure properties have been described. The effect of various 1,3,4-thiadiazole additives on the tribological properties of base oils is studied. This paper aims to present an overview of the role of 1,3,4-thiadiazole and its derivative in improving the tribological properties of base oils.

Ether derivatives are versatile organic compounds and have been applied in various fields of academia and the chemical industry. Therefore, it is highly desirable to create procedures for their manufacture that are more efficient and sustainable. Catalytic reductive etherification with carbonyl moiety such as ketones/ aldehydes and carboxylic acid derivatives has recently been recognized as a possible tool among the several techniques reported for ether production. These procedures offer promising methods to selectively produce ethers with higher molecular structures, both symmetrical and asymmetrical. This Review provides an update on current developments in the field of catalytic reductive etherification, which synthesize ethers utilising an alcohol and an aldehyde substrate. Applications for organic synthesis and catalyst design are given special attention.

N-Methyl imines, as simple Schiff bases, could be prepared using a more sustainable and greener system, including a 33 wt.% solution of methylamine in absolute ethanol, and poly(N-vinylimidazole) (PVIm) at room temperature within 45–60 min. PVIm is a biocompatible, biodegradable and water-soluble synthetic solid functional polymer. It was indicated that PVIm can act as a reagent with multiple tasks in this reaction, including (a) reducing activation energy and stabilizing the transition states through hydrogen bond acceptor sites and low acidity of C(2)–H and (b) dehydrating activity through trapping of the released water molecules as the association phase. Inexperienced chemists can handle it easily because it is solid and less toxic than conventional catalysts – that is, piperidine, pyridine or metal- or halogen-containing salts. Additionally, ethanol and PVIm could be recycled and reused in subsequent runs without any further purification. The regenerated PVIm demonstrated stable activity after several recycle runs. No changes were detected in its chemical structure, as confirmed by Fourier transform infrared and nuclear magnetic resonance spectrum analyses.

Abstract: Nitriles are employed in many academic and industrial fields, especially organic synthesis. They are crucial precursors to synthesize aldehydes, amines, amides, carboxylic acids, and tetrazoles. There are many routes to synthesize nitriles from various species such as aldehydes, alcohols and amines. This review summarized the recently developed direct conversion of aldehydes to nitriles, focusing on the simple and efficient reaction.

Knoevenagel condensation reaction counts as a vital condensation in organic chemistry due to the synthesis of valuable intermediates, heterocycles, and fine chemicals from commercially available reactants through forming new CC bonds between an aldehyde or ketone and active methylene compounds. Therefore, the catalytic Knoevenagel condensation reaction has continuously received significant interest in different aspects

Poly(N-vinylimidazole) (PVIm), as a biocompatible, efficient, halogen-free, and reusable catalyst, was ‎applied for the solvent-free synthesis of a library of bis(3-indolyl)methanes. The reaction was ‎smoothly carried out under mild conditions, and the crude products were purified easily, and ‎the pure products were obtained in high to excellent yields.‎

A novel sublimable organic salt was synthesized, and its chemical structure was characterized by FTIR, 1D NMR, 2D NMR, and elemental analysis. In addition, the thermal phase transitions and thermal stability of new organic salt were investigated. The DSC and TGA results showed that the organic salt could convert into constituent molecules at

An efficient solid/slurry-state synthesis of arylidene and alkylidene malonates as versatile intermediates is developed in the presence of mesoporous poly-melamine–formaldehyde. The condensation reaction was conducted through a ball milling process as a non-conventional procedure and a greener methodology at room temperature under solvent-free conditions. The mesoporous heterogeneous catalyst could be recovered and reused ten times, and the results showed a negligible loss of catalytic activity. Various aryl- and heteroarylidene malonates, as well as dimethyl (cyclohexylidene)malonate, were isolated in good to high yields under optimal conditions. The use of hazardous reagents and solvents were minimized in the current method, and separation of catalyst and products, as well as the recovery and reusing of catalyst, were performed by cost-effective procedures. This work revealed that the synergistic effect of numerous Lewis base sites together with acceptor-donner hydrogen bonding functional groups in porous organic polymer (POP), and its high porosity plays a vital role to promote the carbon–carbon coupling reaction in the solid phase synthesis.

This study aimed to compare the ability of glutaric and succinic anhydrides for surface modification of cellulose using the green and solvent-free grafting method. The conductometric titration results showed that both anhydrides could successfully introduce carboxylate functional groups on the cellulose surface with 1.5±0.2 and 3.5±0.2 mmol carboxylic acid/g cellulose for glutaric and succinic anhydride, respectively. The FTIR spectra demonstrated the presence of carboxyl functional groups on all samples, and the zeta potential results confirmed increasing surface charge from −10.9±0.6 to −23.03±1.7 mV for grafting with glutaric and succinic anhydride, respectively. SEM showed all samples had fibrous structure; however, fiber diameter and length decreased after the grafting process. DSC profiles showed that grafting could slightly change the apex temperature of treatments while not significantly changing the transition phases. The findings of this work suggest that glutaric anhydride can be used as a promising esterification agent in a greener, solvent-free, and catalyst-free grafting process.

Sulfur-based additives have excellent extreme pressure (EP) performance. However, a high amount of sulfur causes metal corrosion. The non-corrosive and ashless organo-disulfides have been synthesized via Bunte salt method. The unsymmetrical dodecyl octyl disulfide (DDODS) with good oil-solubility provides better EP and anti-wear (AW) properties. The DDODS shows outstanding EP value (1961 N) and small WSA (9 mm²) in naphthenic base oil (NBO), respectively. This performance is superior compared to symmetrical didodecyl disulfide (DDDS). The outstanding performance of DDODS is due to the good solubility in NBO and the formation of a sulfur film on the metal surface. The formation of iron sulfide (FeS) under EP conditions provides excellent tribofilm compared to iron (III) oxide (Fe2O3) and iron sulfate (FeSO4).

A new acid molten salt was prepared and its structure elucidation was conducted by FTIR, 1D NMR, 2D NMR, and mass spectrometry. Further support to elucidate the chemical structure of the 1H,4H-piperazine-N,N′-diium ring of the new acid molten salt was achieved by 1H and 13C NMR, and COSY analyses of 1H,4H-piperazine-N,N′-diium dibromide, which is synthesized and characterized for the first time in the current work. The analysis of FTIR and NMR spectra as well as pH and titrimetric analysis excluded the formation of [SO4]2− and the presence of an excess of H2SO4. Moreover, no distinguishing peak was detected for the acid proton of [HSO4]− in DMSO-d6. The thermal phase transition and thermal stability of the acid molten salt were also recorded, which approved the strong interaction between a dication and hydrogen sulfate anions. According to the acidity of the new molten salt, we encourage the study of its catalytic activity for the acetylation of n-pentanol using glacial acetic acid. Pentyl acetate was obtained in 89.0% conversion and 78.0% isolated yield. The 1H NMR spectrum of the residue showed an excess of HOAc together with molten salt, whereas the 1H NMR spectrum of the upper phase exhibited pure pentyl acetate. After separation of the upper phase, the residue was concentrated and used in the next run without further purification. No significant changes in the chemical structure and catalytic activity of the new molten salt were observed even after the 5th run. Two chiral alcohols, including (−)-menthol and (+)-borneol, as well as α-tocopherol (α-TCP) were also acetylated with acetic acid in the presence of the new acid molten salt under optimized reaction conditions, which afforded the desired acetates in high yields.

This work presents a new catalytic application of 4,4′-trimethylenedipiperidine for the efficient synthesis of a series of dihydro-[1,2,4] triazolo[1,5-a]pyrimidines. According to the principles of green chemistry, the reaction was performed (a) in a solvent mixture comprised of water and ethanol (1:1 v/v) at reflux temperature and (b) solvent-free grinding in a mortar by a pestle. The organocatalyst could be reused up to 10 runs, and no reduction of catalytic activity was detected. A variety of substituted dihydro-[1,2,4] triazolo[1,5-a]pyrimidines were obtained in good to excellent yields under eco-friendly conditions. 4,4′-Trimethylenedipiperidine is commercially available and easy to handle, and it also shows high thermal stability and good solubility in water. This work revealed that this organocatalyst, a hydrogen bond donor to active carbonyl groups and simultaneously a Lewis base through the nitrogen atom of second piperidine moiety, could play a vital role in the promotion of the one-pot multi-component reactions. The main merits of the current methodology include short reaction time, wide substrate scope, use of a metal-free catalyst and green solvents, and simple work-up process. Furthermore, this organocatalyst can be an alternative to piperidine for organic transformations.

A new ionic liquid is synthesized, and its chemical structure is characterized by FTIR, 1D NMR and 2D NMR, and mass analyses. The thermal behavior and thermal stability of this ionic liquid are investigated. The results approved the formation of 4,4ʹ-trimethylene-N,Nʹ-dipiperidinium sulfate instead of 4,4ʹ-trimethylene-N,Nʹ-dipiperidinium hydrogen sulfate. Moreover, the synthesis of triazolo-pyrimidine derivatives was successfully conducted in the presence of new ionic liquid at room temperature under metal-free conditions, which demonstrated the catalytic efficiency of this ionic liquid. The workup was carried out without the utilization of high-cost column chromatography. After extraction of desired products, the residual ionic liquid could be recycled and reused in the next runs. New ionic liquid exhibited high catalytic activity even after fifth run with no significant change in the chemical structure.

A new catalytic application of tetraethylammonium L-prolinate for the facile and cleaner synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s is developed. This amino acid-based ionic liquid could be recycled up to five runs, and a negligible reduction of catalytic activity was detected within the experimental error. A variety of substituted 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s were obtained in good to high yields under eco-friendly conditions. Tetraethylammonium L-prolinate is easy to prepare, as well as it shows moderate thermal stability and good solubility in water. This work revealed that this amino acid-based ionic liquid, containing L-prolinate anion, can catalyze the tandem Knoevenagel-Michael condensation reaction due to hydrogen bond donor and Lewis base moieties. The current methodology has other advantages, including (a) wide substrate-scope, (b) relatively short reaction times, (c) the use of a nontoxic, biocompatible, biodegradable and metal-free ionic liquid, and (d) simple workup procedure.

Pyrans have been extensively explored in both academic organizations and pharmaceutical industries owing to their biological characteristics, including anticancer activity.1,2 Among the pyrans, pyr...

Organic symmetric disulfides have been broadly studied in various fields such as synthetic intermediates for various organic transformations, agro-chemicals, biochemistry, pharmacological chemistry, industrial polymers, peptidomimetics, self-assembled monolayers (SAMs), etc. Owing to versatile applications, the search and development of efficient, environmentally friendly, mild and inexpensive methods for the preparation of organic disulfides play an important role in the organic functional group transformations. Various aspects of the S–S bond formation are available in some books on organic functional group transformations, as well as two review articles that have been published in the years 2008 and 2014 highlighting the developments of disulfide bond formation using a variety of reagents. However, investigations on new catalytic methods are being regularly reported and new types of disulfides are synthesized. The present review has attempted to systematically summarize recent catalytic advances in the process of S–S bond formation with a major focus since 2014 on highlighting mechanistic considerations, scope, advantages, and limitations. This review does not include patent literature.

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.

In the current protocol, the arene diazonium saccharin derivatives were initially produced from various substituted aromatic amines; subsequently, these intermediates were treated with a greener organic iodide for the preparation of the aryl iodide. We tried to choose low-cost, commercially available, biodegradable, recoverable, ecofriendly, and safe reagents and solvents. The arene diazonium saccharin intermediates could be stored in the liquid phase into a refrigerator for a long time with no significant loss activity. The outstanding merits of the current protocol (a) included the partial recovering of saccharin and tetraethylammonium salt, (b) reduce the use of solvents and the reaction steps due to eliminating separation and purification of intermediates, (c) good yield of the sterically hindered substrates, and (d) avoid the generation of heavy metal or corrosive waste.

The metal-free feature of mechanosynthesis of bis(3-indolyl)methane derivatives using poly(4-vinyl pyridine), a commercially available functional polymer, by ball mill technique at ambient conditions was studied. The condensation of various carbonyl compounds with two indoles smoothly proceeded, and pure products were easily isolated in high to excellent yields. Poly(4-vinylpyridine) exhibited high recyclability without any loss of catalytic activity or change in the chemical structure. The influence of polymer M̅W with a certain PDI on the mechanosynthesis of BIMs was investigated. In addition, the effect of the ball and jar with zirconium oxide material was studied on the rate and yield of the BIMs synthesis process. The method was scalable and generated minimal hazardous wastes. Some merits of the current methodology are such as the good to high yields for various carbonyl compounds and avoiding the use of toxic, expensive, and metal-containing catalysts with a tedious process of preparation, separation, and purification.

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.

A variety of processes were reported for efficient removing of heavy metal from wastewater, including but not limited to ion exchange, reverse osmosis, membrane filtration, flotation, coagulation, chemical precipitation, solvent extraction, electrochemical treatments, evaporation, oxidation, adsorption, and biosorption. Among the aforementioned techniques, adsorption/ion exchange has been known as a most important method for removing heavy metal ions and organic pollutants due to great removal performance, simple and easy process, cost-effectiveness and the considerable choice of adsorbent materials. : Nanotechnology and its applications have been developed in most branches of science and technology. Extensive studies have been conducted to remove heavy metal ions from wastewater by preparation and applications of various nanomaterials. Nanomaterials offer advantages in comparison to other materials including an extremely high specific surface area, low-temperature modification, short intraparticle diffusion distance, numerous associated sorption sites, tunable surface chemistry, and pore size. In order to evaluate an adsorbent, two key parameters are: the adsorption capacity and the desorption property. The adsorption parameters including the absorbent loading, pH and temperature, concentration of heavy metal ion, ionic strength, and competition among metal ions are often studied and optimized. : Several reviews have been published on the application of Graphene (G), Graphene Oxide (GO) in water treatment. In this minireview, we attempted to summarize the recent research advances in water treatment and remediation process by graphene-based materials and provide intensive knowledge of the removal of pollutants in batch and flow systems. Finally, future applicability perspectives are offered to encourage more interesting developments in this promising field. This minireview does not include patent literature.

This mini-review will present the recent applications of Tert-Butyl Nitrite (TBN) in organic synthesis. Due to its unique structural feature and wide application, TBN holds a prominent and great potential in organic synthesis. The applications of TBN in three areas viz. aerobic oxidation, annulation, and diazotization were reviewed recently; now, the current mini-review will describe the studies carried out to date in areas such as nitration of alkane, alkene, alkyne, and aromatic compounds, nitrosylation and sequential nitrosylation reactions, using TBN as source of oxygen and nitrogen. The mechanisms of these transformations will be briefly described in this mini-review.

This review article provides a brief assessment of the biological and pharmaceutical developments of fluorinated drugs. It also discusses possible impacts on the further development of new fluoro-containing pharmaceuticals. Structural aspects of new drug-candidates currently under development and their biological properties, therapeutic potential and syntheses are critically evaluated

Dual solvent-catalytic activity of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride was studied for the synthesis of coumarins under mild conditions. In addition, the catalytic efficiency of so...

4-Imidazol-1-yl-butane-1-sulfonic acid (ImBu-SO3H) has been successfully synthetized and fully characterized by FT-IR and high-resolution NMR spectroscopy (1H, 13C). The “plausible” alterna...

The PVP and its derivatives have been broadly applied in polymers, organic syntheses, and catalysis processes. The crosslinked PVP is a well-known polymer support for numerous reagents and catalysts. Cross-linked PVPs are commercially available polymers and have attracted much attention over the past due to their interesting properties such as the facile functionalization, high accessibility of functional groups, being nonhygroscopic, easy to prepare, easy filtration, and swelling in many organic solvents. A brief explanation of the reported applications of PVPs in different fields followed by the discussion on the implementation of methodologies for catalytic efficiency of PVP-based reagents in the organic synthesis is included. The aim is to summarize the literature under a few catalytic categories and to present each as a short scheme involving reaction conditions. In the text, discussions on the synthesis and the structural determination of some typical polymeric reagents are presented, and the mechanisms of some organic reactions are given. Where appropriate, advantages of reagents in comparison with the previous reports are presented. This review does not include patent literature.

This paper presents an ecological protocol for Knoevenagel condensation using a catalytic amount of 4,4′-trimethylenedipiperidine as a versatile, efficient, safe, commercially available, inexpensive, and recyclable organocatalyst by a ball-milling process at room temperature. The scope of the present protocol was explored and demonstrated for Knoevenagel condensation of the active methylene, such as Meldrum’s acid with various aryl and heteroaryl aldehydes. The developed protocol provides a good to excellent conversion of various aldehydes to respective Knoevenagel products in an environmentally friendly process. Furthermore, this efficient process displays a combination of the synthetic virtues of conventional Knoevenagel condensation with ecological benefits and the convenience of a facile mechanochemistry procedure.

In the present study, a new low-viscous sulfonic acid-functionalized ionic liquid (SAIL) viz. 4,4′-trimethylene-N,N′-sulfonic acid-dipiperidinium chloride was synthesized and characterized by FTIR, 1D and 2D NMR, and Mass spectra. Then, some properties of new SAIL were determined including pH, viscosity, density, and solubility in some common solvents. The catalytic activity of new SAIL was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]pyrans, dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyrans using planetary ball mill under solvent-free conditions. This current mechanosynthesis methodology for the synthesis of 4H-pyran-annulated heterocyclic scaffolds displays a combination of the synthetic virtues of conventional multi-component reaction with ecological benefits and convenience of a simple mechanocatalytic procedure. New SAIL was easily recycled and reused several times with no significant loss of activity.

The reaction of the equimolar mixture of imidazole and 1,4-butane sultone was performed at 90 °C in ethylbenzene for 12 h, and the structure of the product was investigated by the NMR analysis in CD3OD and DMSO‑d6. This work demonstrated that 4-imidazol-1-yl-butane-1-sulfonic acid could not be obtained through the above reaction and the mixture of zwitterionic (I) and ionic (II) structure is produced. The structure of the liquid salt (I + II) was characterized and analyzed by 2D NMR. Then, the dual solvent-catalytic efficiency of the liquid salt (I + II) was studied for the synthesis of a variety of xanthenes under mild conditions which afforded the desired products in good to excellent yields within short reaction times. The recyclability of the liquid salt (I + II) was studied with an average recovered yield of 89% for three subsequent runs. The recycled liquid salt showed no significant loss of the catalytic activity even after three runs and its structure remain same as fresh liquid salt (I + II).

The reaction of the equimolar mixture of imidazole and 1,4-butanesultone was performed at 90 °C in ethylbenzene for 12 h and the zwitterionic and ionic structures of the product investigated by the NMR analysis. The present work displayed the great importance of 2D NMR analysis on the structure elucidation of this sulfonic acid functionalized liquid salt. The results of NMR analysis demonstrate that 4-imidazole-1-yl-butane-1-sulfonic acid did not exist and really a mixture of zwitterionic and ionic compounds is produced.

In the present study, the catalytic efficiency of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) hydrogensulfate (BBSI-HSO4) as a versatile sulfonic acid-functionalized ionic liquid was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]-pyrans using planetary ball mill at room temperature under solvent-free conditions. This efficient mechanosynthesis approach to the 4H-pyran scaffolds displays a combination of the structure–activity relationship of ionic liquids with ecological benefits of a mechanocatalytic procedure. The ionic liquid was easily recycled and reused several times with no significant loss of its catalytic activity.

Many disulfide and 1,3,4-thiadiazole-1,2-dithiol compounds have been extensively investigated in pharmaceutical industry due to their unique biological properties. A series of new bis(2-alkylsulfanyl-[1,3,4]thiadiazolyl)-5,5’-disulfide derivatives containing two 1,3,4-thiadiazole rings linked by S-S bond spacer were synthesized via the oxidative self-coupling of 5-alkylsulfanyl-[1,3,4]thiadiazole-2-thiol using hydrogen peroxide and ethanol as green oxidant and solvent, respectively. The excellent yields of 93-97% with 100% conversion was achieved with simple one-pot synthesis. There is no over-oxidation of 5-alkylsulfanyl-[1,3,4]thiadiazole-2-thiol and 2-mercaptobenzothiadiazole that lead to formation of by-product such as thiosulfinate, thiosulfonate, and sulfonic acid. In this process, a straightforward, short reaction time, metal-free, reusable solvent and mild reaction conditions are applied to produce bis(2-alkylsulfanyl-[1,3,4]thiadiazolyl)-5,5'-disulfides‎ and 2,2’-dibenzothiadiazole disulfide. This suggested that oxidative self-coupling is potential for other disulfide compounds.