Co-Zeolite Imidazolate Frameworks (ZIF-9@Zeolite) as Heterogen Catalyst for Alcohols Oxidation

Enhancement strategies for efficient activation of persulfate by heterogeneous cobalt-containing catalysts: A review

As a clean and efficient technology for the degradation of organic contaminants, sulfate radical based advanced oxidation processes (SR-AOPs) have attracted more and more attention in the past decades. Cobalt is regarded as the most reactive and efficient non-noble metal catalyst for the activation of persulfate including peroxymonosulfate (PMS) and peroxydisulfate (PDS) to produce sulfate radicals. Due to the limitations of homogeneous catalytic systems, the heterogeneous cobalt-containing catalysts have been emerged and rapidly developed. Various strategies have been schemed to further enhance the activation ability of persulfate by heterogeneous cobalt-containing catalysts. This paper provides an overview on the recent progress in enhancement strategies for the highly efficient activation of persulfate by heterogeneous cobalt-containing catalysts. With a brief introduction on the chemistry and feature of sulfate radical reactions catalyzed by homogeneous Co²⁺/Co³⁺ species, the main strategies for enhancing persulfate activation by heterogeneous cobalt-containing catalysts are summarized, such as surface and morphology design, multiple reactive centers design, organic-inorganic hybrids and heterostructure composites. Future perspectives of heterogeneous SR-AOPs systems catalyzed by cobalt-containing catalysts are outlined.

Green Solvents as an Alternative to DMF in ZIF-90 Synthesis

The use of green solvents as an alternative to dimethylformamide (DMF) in the synthesis of zeolitic imidazolate framework-90 (ZIF-90) was investigated. Two biobased aprotic dipolar solvents CyreneTM and γ-valerolactone (GVL) proved to successfully replace DMF in the synthesis at room temperature with a high product yield. While the CyreneTM-based product shows reduced porosity after activation, the use of GVL resulted in materials with preserved crystallinity and porosity after activation, without prior solvent exchange and a short treatment at 200 °C. The primary particles of 30 nm to 60 nm in all products further form agglomerates of different size and interparticle mesoporosity, depending on the type and molar ratios of solvents used.

A new porous Co(ii)-metal–organic framework for high sorption selectivity and affinity to CO2 and efficient catalytic oxidation of benzyl alcohols to benzaldehydes

A new porous Co(ii)-MOF I has been prepared. Gas sorption and catalytic experiments show that the guest-free sample I′ shows the high capacity and selectivity to CO₂ over CH₄ and catalytically oxidize benzyl alcohols efficiently into benzaldehydes.

Ionic-liquid-modified CMK-3 as a support for the immobilization of molybdate ions (MoO42-): Heterogeneous nanocatalyst for selective oxidation of sulfides and benzylic alcohols

A nanometric carbon CMK-3 modified with octylimidazolium ionic liquid and MoO₄^2- as a new hybrid catalyst was synthesized. The study is the first to report a successful immobilization of MoO₄⁼ on the CMK-3/OctIm as a hybrid nanocatalyst. A variety of analytical methods were utilized to determine the properties of the structure and morphology of the synthesized nanocatalyst [CMK-3/Im/MoO₄^2-]. The analytical techniques were transmission electron microscopy (TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma (ICP), X-ray diffraction (XRD), N₂ isotherms (BET), IR spectroscopy and thermogravimetric analysis (TGA). CMK-3/OctIm/MoO₄^2- hybrid catalyst demonstrated a considerable catalytic activity. It is a recyclable nanocatalyst that is utilized to chemoselectively oxidize different types of sulfides to the corresponding sulfoxides and benzylic alcohols to aldehydes using the green oxidant, hydrogen peroxide (H₂O₂) in high-yields. With a little leaching and variation in activity, it is possible to recover and reuse the catalyst frequently. A combination of molybdate anion and the CMK-3 order mesoporous carbon resulted in an improvement in the performance of catalysis and ease of separation for the reaction procedure.

Hydrogen Peroxide as a Green Oxidant for the Selective Catalytic Oxidation of Benzylic and Heterocyclic Alcohols in Different Media: An Overview

Among a plethora of known and established oxidant in organic chemistry, hydrogen peroxide stands in a special position. It is commercially and inexpensively available, highly effective, selective, and more importantly it is compatible with current environmental concerns, dictated by principles of green chemistry. Several chemicals or their intermediates that are important in our daily life such as pharmaceuticals, flavors, fragrances, etc. are products of oxidation of alcohols. In this review, we introduce hydrogen peroxide as an effective, selective, green and privileged oxidant for the catalyzed oxidation of primary and secondary benzylic and heterocyclic alcohols to corresponding carbonyl compounds in different media such as aqueous media, under solvent-free conditions, various organic solvent, and dual-phase system.

ZIF@ZnTiO3 Nanocomposite as a Reusable Organocatalyst for the Synthesis of 3, 4-dihydropyrano[c]chromene Derivatives

Background:

Dihydropyrano [3, 2-c]chromenes and their derivatives have great attention for scientists. They have different activities such as biological properties, spasmolytic, diuretic, anticoagulant, anti-cancer, and anti-anaphylactic activity. For these vary biological activities, chromene derivatives have made significant for further progress in medicinal and organic synthesis studies. So, in view of the importance of chromenes, we aimed to synthesis of 3, 4-dihydropyrano [3, 2-c] chromene derivatives. ZIF@ZnTiO3nanocomposite as organocatalyst was used.

Method:

An effective and applicable technique was used for preparation of 3, 4-dihydropyrano [3, 2- c] chromene derivatives. Dihydropyrano [c] chromenederivatives were prepared by using ZIF@ZnTiO3compositeas a recyclable catalyst. One-pot three-component reaction of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin was done for synthesis of dihydropyrano [c] chromenederivatives over composite catalyst with excellent yields. The as prepared dihydropyrano [c] chromenederivatives were measured by melting point, FTIR, 1H NMR, and 13C NMR. The nano catalyst could be recycled several times.

Result:

A novel nano catalyst of MOF containing Mn2+ ions and 2- methyl imidazole (ZIF) and zinctitanate (ZIF@ZnTiO3) composite was prepared. The synthesized organocatalyst was studied for preparation of 3, 4-dihydropyrano [3, 2-c] chromene derivatives. One-pot three-component reaction of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin was done for synthesis of dihydropyrano [c] chromene derivatives over composite catalyst with excellent yields. The reaction was optimized.

Conclusion:

The organocatalyst composite of consist of ZIF and zinctitanate was prepared. The ZIF@ZnTiO3 was used as catalyst for synthesis of 3, 4-dihydropyrano [3, 2-c] chromene derivatives via one-pot three-component condensations of aromatic aldehydes,malononitrile, and 4 hydroxycoumarin. The results of melting point, FTIR, 1H NMR, 13C NMR also confirmed the formation of high yield of 3, 4-dihydropyrano [3, 2-c] chromene derivatives at short time. The appealing properties of this method are environmentally friendly, mild reaction conditions (low reaction time and high yields of pure products), easy work up and recyclability of reaction catalyst.

Needle ball-like nanostructured mixed Cu-Ni-Co oxides: Synthesis, characterization and application to the selective oxidation of sulfides to sulfoxides

A mixed nano-metal oxides of Cu-Ni-Co has been synthesized. Several characterization techniques (EDS, XRD, TEM, and SEM) have been used to provide insight into the nature and structure of the catalyst. The size of this mixed metal oxide is 22 nm. The SEM images indicate that the sample with spherical particles, of which spherical assembly is comprised of elongated rod/needle-like subunits pointing radially outward, creates a needle ball-like structure. To efficiently catalyze the selective oxidation of sulfide towards sulfoxide, this heterogeneous catalyst uses an oxidizing agent (hydrogen peroxide- H₂O₂) and a solvent (acetonitrile) in mild conditions. The influence of reaction temperature and sulfide/oxidant molar ratio was evaluated with respect to sulfide conversion and chemoselectivity towards the sulfoxide product. Under optimized conditions, product yields in the range from 70 to 97% were obtained.

Application of an electron-transfer catalyst in light-induced aerobic oxidation of alcohols

The first heterogeneous photocatalysis system including a bipyridinium-based complex as the electron-transfer catalyst was developed for aerobic oxidation of alcohols without the use of any noble-metal, external N-oxide or peroxide co-oxidant. The current work provides an efficient strategy for alcohol oxidation through a cost-effective, convenient and eco-friendly route.