N-sulfonic acid poly(4-vinylpyridinium) chloride: an efficient and reusable solid acid catalyst in N-Boc protection of amines

N-sulfonic acid poly(4-vinylpyridinium) chloride is easily prepared by the reaction of poly(4-vinylpyridine) with neat chlorosulfonic acid. This reagent can be used as an efficient catalyst for the N-Boc protection of amines at room temperature and neat conditions. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be reused and recovered for several times.     

Microwave-assisted degradation of guaifenesin (GGE) to produce novel compounds in the presence of imidazolium-based ionic liquids

Journal of Thermal Analysis and Calorimetry - Nanocomposites based on poly(3-hydroxybutyrate) (P3HB) and Cloisite®30B were prepared by direct mixing in a co-rotating twin-screw micro-extruder....     

An alternative,practical, and ecological protocol for synthesis of arylidene analogues of Meldrum’s acid as useful intermediates

Research on Chemical Intermediates - This paper presents an ecological protocol for Knoevenagel condensation using a catalytic amount of 4,4′-trimethylenedipiperidine as a versatile,...     

Poly(4-vinylpyridinium) hydrogensulfate catalyzed synthesis of 12-aryl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-triones

A simple and facile synthesis of 12-aryl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione derivatives was accomplished via the one-pot condensation of 2-hydroxynaphthalene-1,4-dione, aldehydes, and 2H-indene-1,3-dione at 100 °C under solvent-free conditions in the presence of the solid acid catalyst, poly(4-vinylpyridinium) hydrogensulfate. This method has the advantages of high yields, clean reactions, simple methodology, and short reaction times. The catalyst could be recycled and reused four times without significant loss of activity. The structures of the novel compounds were confirmed by IR, ¹H NMR, and elemental analysis.     

A novel sublimable organic salt: Synthesis,characterization, thermal behavior,and catalytic activity for the synthesis of arylidene,heteroarylidene, and alkylidene malonates

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?<?145 °C before decomposition temperature (T_dec.?~?200 °C) under atmospheric pressure without forming the liquid phase. Then, it was recondensed to regenerate the initial organic salt in the cool part of the vial. Therefore, it can be a promising organic salt towards the regeneration of spent catalyst from synthesis processes when the reaction mixture contains poorly volatile components and includes its use in gas-phase procedures. Also, the catalytic efficiency of new organic salt was investigated in the Knoevenagel condensation reaction. A variety of substituted arylidene and alkylidene malonates were isolated in 78–95% yield within six hours.? Under the optimized reaction conditions, the current catalytic procedure exhibited superiority compared to the mixed piperazine/acetic acid, piperidine/acetic acid, and piperidinium acetate. There were no significant changes in the new organic salt chemical structure and catalytic activity even after the 5th run. This work revealed the importance of the existence of simultaneous hydrogen bond acceptor/donor groups in our environmentally friendly catalyst to promote the Knoevenagel condensation reaction without the use of metal-containing catalysts.

     

An Overview of Recent Advances in the Synthesis of Organic Unsymmetrical Disulfides

Organic unsymmetrical disulfides have been extensively applied in various academic and industrial fields including intermediates in organic synthesis, agriculture, and food science, natural materials, biochemistry, pharmaceutical and medicine chemistry, polymers, material engineering, etc. They play a crucial role in the fabrication of various biological active sulfur heterocycles. Due to broad and extensive applications, many methods have been developed for the synthesis of unsymmetrical S−S and efforts have been made to improve some issues such as cost, energy efficiency, green chemistry, avoid or minimizing waste generation. Several outstanding review articles have been previously published highlighting the advances of S−S bond formation, in general, using various reagents under different conditions in the absence or presence of oxidants/catalysts. In 2020, a review paper was published by our group focusing on recent developments since 2014 in the synthesis of organic symmetrical disulfides. However, investigations on new catalytic methods are being regularly reported and new types of unsymmetrical disulfides are synthesized. The present overview has attempted to systematically summarize recent advances in the process of unsymmetrical S−S bond formation with a major focus since 2010, highlighting mechanistic considerations, substrate scope, advantages, and limitations. The patents are not studied in this overview.     

液-固相体系中以聚(N-乙烯基咪唑)为非均相碱性催化剂在超声波照射和无溶剂条件下催化不同醛和酮羟醛缩合(英文)

An ultrasound‐assisted aldol condensation reaction has been developed for a range of ketones with a variety of aromatic aldehydes using poly(N‐vinylimidazole) as a solid base catalyst in a liquid‐solid system. The catalyst can be recovered by simple filtration and reused at least 10 times without any significant reduction in its activity. The reaction is also amenable to the large scale, making the procedure potentially useful for industrial applications.     

Application of nitrogen-rich porous organic polymer for the solid-phase synthesis of 2-amino-4H-benzo[b]pyran scaffolds using ball milling process

Molecular Diversity - 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...     

(Bbpy)(HSO_4)_2无卤素可重复使用 Brnsted 离子液体催化剂用于一锅法多组分合成非对称多氢喹啉衍生物（英文）

1,1'‐Butylenebispyridinium hydrogen sulfate is an efficient, halogen‐free and reusable Brnsted ionic liquid catalyst for the synthesis of ethyl‐4‐aryl/heteryl‐hexahydro‐trimehtyl‐5‐ oxoquino‐line‐3‐carboxylates by the one‐pot condensation of dimedone, aryl/heteryl aldehydes, ethyl aceto‐acetate, and ammonium acetate under solvent‐free conditions. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The ionic liquid can be re‐cycled five times without significant loss of the catalytic activity.     

Essential oil composition and antioxidant activity of different extracts of Nepeta betonicifolia C.A. Meyer and Nepeta saccharata Bunge

Aerial parts essential oil of Nepeta betonicifolia and N. saccharata were obtained by hydrodistillation and analysed by GC-FID and GC-MS. Thirty-three and eighteen components represented 97.9% and 98.2% of the total oils identified, respectively. Main compounds of the oil of N. betonicifolia were 4aα,7β,7aα-nepetalactone (42.0%), germacrene D (6.0%), triplal (5.2%), 1-nor-bourbonanone (4.0%) and 1,8-cineole (3.2%). The principal constituents of the essential oil of N. saccharata were found to be 4aβ,7α,7aβ-nepetalactone (66.9%), germacrene D (12.9%), sabinene (6.5%) and trans-caryophyllene (3.3%). The radical scavenging capacity (RSC) of methanol extracts and chloroform, butanol and water subfractions of aerial parts of N. betonicifolia and N. saccharata were evaluated by using DPPH, FRAP and ABTS assays. TPC of each extract was measured using Folin-Ciocalteau. The antioxidant activity of the butanolic subfractions of both plants was higher than other extracts examined.