New protocols for the synthesis of 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate esters using an efficient additive

This work introduces a new additive named 4,4’-trimethylenedipiperidine for the practical and ecofriendly preparation of ethyl 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate derivatives. This chemical is commercially available and easy to handle. It also possesses a low melting point and a broad liquid range temperature, high thermal stability, and good solubility in water. Based on green chemistry principles, the reaction was performed in a) a mixture of green solvents i.e. water and ethanol (1:1 v/v) at reflux temperature, and b) the additive was liquefied at 65 ◦ C and the reaction was conducted in the liquid state of the additive. High yields of the desired triazolo-pyrimidines were obtained under both aforementioned conditions. Our results demonstrated that this additive, containing 2 Lewis base sites and able to act as an acceptor-donor hydrogen bonding group, is a novel and efficient alternative to piperidine, owing to its unique properties such as its reduced toxicity, nonflammable nature, nonvolatile state, broad liquid range temperature, high thermal stability, and ability to be safely handled. Furthermore, this additive could be completely recovered and exhibited high recyclability without any change in its chemical structure and no significant reduction in its activity

Synthesis and characterization of novel binuclear task-specific ionic liquid: an efficient and sustainable sulfonic-functionalized ionic liquid for one-pot synthesis of xanthenes

A new binuclear sulfonic-functionalized ionic liquid was synthesized in two steps and its dual solvent-catalytic activity was studied for the synthesis of a variety of xanthenes under mild conditions. The simple experimental and sustainable procedure, good yield of the desired products within short reaction times, and recyclability of the ionic liquid are some advantages of the present strategy, and the current work shows the great importance of task-specific ionic liquids in organic synthesis

A facile and sustainable protocol to the preparation of aryl iodides using stable arenediazonium bis(trifluoromethylsulfonyl)imide salts via the telescopic process

The preparation of aryl iodides in a telescopic reaction using tert-butyl nitrite as a diazotization reagent and a mixture of bis(trifluoromethane) sulfonamide and glacial acetic acid as a mild acidic agent in ethanol followed by iododediazoniation with tetraethylammonium iodide in water was investigated. The current method has other advantages such as minimized waste by avoiding solvent for the purification of products in diazotization step, simple experimental procedure, and good yield of the sterically hindered aryl amines, metal and strong acid-free waste and environmentally benign conditions. The noteworthy features of this study are the preparation of stable arenediazonium bis(trifluoromethylsulfonyl)imide salts that can be used with no significant loss activity after 1 week and bis(trifluoromethane)sulfonamide was recovered in high yields from reactions

Synthesis and characterization of some novel 4-arylglyoxal-chromene derivatives in the presence of a polymeric catalyst and biological evaluation against Escherichia coli

A poly(N-vinylimidazole)-catalyzed one-pot multicomponent reaction for the synthesis of 2-amino-4H-benzo[g]chromenes containing acyl group on the 4H-chromene ring has been developed. The products were obtained in generally good to excellent yields in the presence of low loading of poly(N-vinylimidazole) as a reusable basic catalyst via this synthetic strategy. Importantly, the catalyst has the unique ability of being easily separated and recycled. The products were screened for their antibacterial activity against Escherichia coli. The results of antibacterial studies showed that three 4-aroylchromene derivatives completely inhibited E. coli at 32 mg cm−3, whereas other derivatives were either moderately active or inactive up to 64 mg cm−3. Highest antimicrobial activity was observed when the phenylglyoxal hydrate was substituted with fluoro, nitro, and methoxy groups at para position

Introduction 1,1′-butylenebis(3-methyl-3H imidazol-1-ium) Hydrogen Sulfate as an Efficient Binuclear Brönsted Acidic Ionic Liquid for Three-Component and One-Pot Synthesis of Benzo[<i>f</i>]indenoquinoline Derivatives

<div><p>1,1′-Butylenebis(3-methyl-3<i>H</i>-imidazol-1-ium) hydrogen sulfate as an efficient, halogen-free and reusable Brönsted ionic liquid catalyzed the synthesis of 13-(aryl)-12<i>H</i>-benzo[<i>f</i>]indeno[1,2-<i>b</i>]quinoline-12-one derivatives in ethanol under refluxing conditions. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The ionic liquid catalyst could be recycled and reused seven times without significant loss of activity. The structures of the new compounds were confirmed by IR, ¹H NMR, ¹³C NMR and elemental analysis.</p></div

1,1′-butylenebis(3-methyl-3<i>H</i>-imidazol-1-ium) Hydrogen Sulfate Catalyzed One-Pot Multi-Component Synthesis of Unsymmetrical Polyhydroquinoline Derivatives

<p>1,1′-butylenebis(3-methyl-3H-imidazol-1-ium) hydrogen sulfate as an efficient<b>,</b> halogen-free, and reusable binuclear Brönsted ionic liquid catalyzed the synthesis of ethyl-4-aryl/heteryl-hexahydro-trimehtyl-5-oxoquinoline-3-carboxylates by the one-pot condensation of dimedone, aryl/heteryl aldehydes, ethyl acetoacetate, and ammonium acetate under solvent-free conditions. This method has the advantages of high yields, clean reaction, simple methodology, and short reaction time. The ionic liquid could be recycled and reused four times without significant loss of in the catalytic activity.</p

Student exploration of the Henderson-Hasselbach equation and pH readings to determine the pK a value of 4,4′-trimethylenedipiperidine (TMDP)

This educatory experiment uses an inexpensive pH meter to determine an approximate negative logarithm of the acid dissociation constant (pK a) value of 4,4′-trimethylenedipiperidine (TMDP). Using a pH meter and statistical data analysis by Excel tool presents an excellent opportunity to deepen student engagement with the Henderson-Hasselbalch equation and acid/base dissociation constant (K a/K b). Furthermore, students understand the importance determination of K a/K b and its relationship with the concentration and strength of acid/base. Four different concentrations of TMDP aqueous solutions were prepared and a series of pH readings were collected using a calibrated pH meter. Some statistical parameters were calculated and analyzed using the statistical program in Excel. Finally, students identified an unknown pK a for TMDP and compared their obtained value with a predicted pK a using software like ChemAxon. The experiment is inexpensive, safe, simple, and clean, and less experienced students can perform it. In addition, all pH recordings can be readily accessible for analysis and descriptive statistics by the Excel formula