Potassium Dodecatungstocobaltate Trihydrate Research Articles

Dodecatungstocobaltate heteropolyanion encapsulation into MIL‐101(Cr) metal–organic framework scaffold provides a highly efficient heterogeneous catalyst for methanolysis of epoxides

A heterogeneous catalyst was synthesized by encapsulation of a Keggin‐type heteropolytungstate, potassium dodecatungstocobaltate trihydrate, K5[CoW12O40]·(Co‐POM), into chromium(III) terephthalate (MIL‐101). Encapsulation was achieved via a ‘build bottle around ship’ strategy in aqueous media, following a hydrothermal method. The structure of the resulting crystalline solid was characterized using X‐ray diffraction, correlated with Fourier transform infrared and UV–visible spectroscopy. The metal content was analysed using optical emission spectroscopy. Transmission electron microscopy was used to measure particle size and N2 adsorption in a Brunauer–Emmett–Teller instrument to characterize the specific surface area. The catalytic activity was investigated using methanolysis of epoxides under mild conditions as a test reaction. The turnover frequency of the heterogeneous Co‐POM@MIL‐101 catalyst was more than 20 times higher than that of the homogeneous Co‐POM catalyst. The Co‐POM@MIL‐101 catalyst was reused several times with negligible leaching of Co‐POM and with no considerable loss of its initial efficiency. The simplicity of preparation, extraordinary stability and high reactivity make Co‐POM@MIL‐101 an exceptional catalytic matrix that is easily separable from reaction media.

An Efficient One-pot Synthesis of Substituted 1, 5-benzoxazepines and 1,5- benzothiazepines Using Potassium Dodecatungstocobaltate Trihydrate (PDTC, K<sub>5</sub>CoW<sub>12</sub>O<sub>40</sub>.3H<sub>2</sub>O) as Heterogeneous Catalyst

An efficient method has been developed for the synthesis of substituted 1,5-benzoxazepines and benzothiazepines under classical heating conditions or microwave irradiation in the presence of an efficient and reusable Potassium Dodecatungstocobaltate Trihydrate (PDTC, K5CoW12O40.3H2O) as heterogeneous catalyst which was found to be highly active and afforded excellent yields. The products 6,8,9 and 10 were synthesized using the starting compounds 4a-d, 1 mol% PDTC and achieved in good yields by reflux (70-80%) as well as microwave conditions (60-70%). The reactions of 17a-e with 7, in the presence of 1 mol % PDTC were refluxed in dry ethanol for 6-8 h to isolate the compounds 18a-e in good yields (70-85%) as syrups. Keywords: Potassium Dodecatungstocobaltate Trihydrate, 1, 5-benzoxazepines and 1, 5-benzothiazepines, solvent-free conditions, classical heating or microwave irradiation.

Efficient and environmentally-benign three-component synthesis of quinolines and bis-quinolines catalyzed by recyclable potassium dodecatungstocobaltate trihydrate under microwave irradiation

Microwave-assisted one-pot three-component reaction between aromatic amines, aromatic aldehydes and phenylacetylene is accomplished efficiently in the presence of catalytic amounts of potassium dodecatungstocobaltate trihydrate (K5CoW12O40·3H2O) to afford the corresponding quinolines and bis-quinolines in excellent yields. Selective conversion of aromatic aldehyde and also arylacetylene to their corresponding quinolines in the presence of aliphatic aldehyde and alkylacetylene, respectively, can be considered as noteworthy advantages of this method and makes it a useful and attractive process for the synthesis of quinoline derivatives. The catalyst could be reused for several cycles without any significant loss of its catalytic activity.

Potassium Dodecatungsto Cobaltate Trihydrate: A New Heterogeneous Catalyst for the Synthesis of Homoallylic Alcohols and Amines

A simple and efficient procedure has been developed for one-pot synthesis of homoallylic alcohols and amines in good to excellent yields using a variety of aldehydes, amines, and allyltributylstannane in the presence of a catalytic amount of potassium dodecatungsto cobaltate trihydrate (K5CoW12O40 · 3H2O) as a heterogeneous catalyst at room temperature. The catalyst exhibited remarkable reusability.

Potassium dodecatungstocobaltate trihydrate (K5CoW12O40· 3H2O): A mild and efficient reusable catalyst for the synthesis of amidoalkyl naphthols in solution and under solvent-free conditions

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, β-naphthol and urea or amides, in the presence of potassium dodecatungstocobaltate trihydrate [K5CoW12O40 · 3H2O, (1 mol%)] as a heterogeneous catalyst. The reactions were carried out in 1,2-dichloroethane at room temperature or under solvent-free media at elevated temperature. The present methodology offers several advantages such as excellent yields, simple procedure and the catalyst exhibited remarkable reusability.

Potassium dodecatugstocobaltate trihydrate (K5CoW12O40·3H2O): A mild and efficient reusable catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles under conventional heating and microwave irradiation

An efficient method for the synthesis of 1,2,4,5-tetrasubtituted imidazoles by four-component condensation of benzil or benzoin, aldehydes, amines and ammonium acetate under microwave irradiation or classical heating conditions using potassium dodeca tungstocobaltate trihydrate [K5CoW12O40·3H2O (0.1mol%)] as catalyst is reported. The catalyst exhibited remarkable reusable activity.

Potassium dodecatungstocobaltate trihydrate (K5CoW12O40· 3H2O): A mild and efficient reusable catalyst for the synthesis of aryl-14H-dibenzo[a.j]xanthenes under conventional heating and microwave irradiation

A simple and efficient procedure has been developed for the preparation of aryl-14H-dibenzo[a.j]xanthenes by a one-pot condensation of β-naphthol and aryl aldehydes, in the presence of potassium dodecatungstocobaltate trihydrate [K5CoW12O40 · 3H2O, (0.01 mol%)] as a heterogeneous catalyst in a solvent-free media using both conventional heating and microwave irradiation. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times (1.5–2.0 h and 2.0–3.0 min) and milder conditions and the catalyst exhibited remarkable reusable activity.

Potassium dodecatungstocobaltate trihydrate (K 5CoW 12O 40·3H 2O): A mild and efficient reusable catalyst for the synthesis of β-acetamido ketones under solvent-free conditions

A simpler and greener protocol has been developed for the preparation of β-acetamido ketones by a one-pot reaction of aryl aldehydes, enolisable ketones, acetyl chloride and acetonitrile in the presence of potassium dodecatungstocobaltate trihydrate [K 5CoW 12O 40·3H 2O (0.01 mol%)] as a heterogeneous catalyst in a solvent-free media at room temperature. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times (1–2 h) and milder conditions and the catalyst exhibited remarkable reusable activity.

Potassium Dodecatungstocobaltate Trihydrate (K5CoW12O40×3H2O) as an Efficient Catalyst for Aminolysis of Epoxides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Mild, Efficient and α‐Selective Glycosidation by Using Potassium Dodecatungstocobaltate Trihydrate as Catalyst.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A mild, efficient and α-selective glycosidation by using potassium dodecatungstocobaltate trihydrate as catalyst

Treatment of tri- O-acetyl- d-glucal 1 3,4,6-Tri- O-acetyl-1,5-anhyro-2-deoxy- d-arabinahex-1-enitol. 1 1 with several alcohols in the presence of catalytic amount of POM (K 5CoW 12O 40·3H 2O) as a heterogeneous, reusable, efficient and environmentally benign catalyst under neutral conditions and ambient temperature gave the corresponding 2,3-unsaturated glycopyranosides in excellent yields, with good anomeric selectivity. This catalyst proved to be not efficient for phenols.

Potassium Dodecatungstocobaltate Trihydrate (K5CoW12O40 · 3H2O) as an Efficient Catalyst for Aminolysis of Epoxides

Aminolysis of epoxides using various amines was catalyzed with potassium dodecatungstocobaltate trihydrate in a convenient and efficient method with good selectivities.

Catalytic Acetylation of Alcohols and Phenols with Potassium Dodecatungstocobaltate Trihydrate

Alcohols and phenols are converted to esters in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of potassium dodecatungstocobaltate trihydrate (K5CoW12O40 · 3H2O).

Novel catalytic acetylation and formylation of alcohols with potassium dodecatungstocobaltate trihydrate (K5CoW12O40·3H2O)

Acetylation and formylation reactions of alcohols with ethyl acetate, acetic acid and ethyl formate were catalyzed with potassium dodecatungstocobaltate trihydrate (K5CoW12O40·3H2O) in a mild, efficient and convenient method with high to excellent yields.

K5CoW12O40⋅3H2O: A Novel Cobalt Polyoxometalate Catalyst for Conversion of Epoxides to Acetonides

A mild and efficient preparation of 1,3-dioxolanes from epoxides and acetone has been carried out in high to excellent yields under catalysis of potassium dodecatungstocobaltate trihydrate (K5CoW12O40⋅3H2O) (0.01 molar equiv.).