Microwave Synthesis of a Porous Metal-Organic Framework, Nickel(II) Dihydroxyterephthalate and its Catalytic Properties in Oxidation of Cyclohexene

Abstract

A porous coordination solid of nickel(II) dihydroxyterephthalate has been synthesized by the microwave-assisted (MW) method. The synthesized nickel(II) dihyroxylterephthalate was designated by the general formula of [Ni2(dhtp) (H2O)2]·8H2O (where, dhtp = 2,5-dihydroxyterephthalate, denoted by Ni-DHTP). The effect of microwave-irradiation temperature and time of irradiation on the porosity and morphological changes in the solids have also been investigated. The catalytic performance of Ni-DHTP synthesized by MW method has been studied in the oxidation of cyclohexene with aqueous H2O2, which gave cyclohexene oxide as the primary product and 2-cyclohexene-1-ol as a major product.

Nanocrystalline M–MOF‐74 as Heterogeneous Catalysts in the Oxidation of Cyclohexene: Correlation of the Activity and Redox Potential

“…Previous studies of MOF‐based catalysts in this reaction17b, 23b, 26 do not clarify anything about the influence of the nature of the oxidant. In our opinion, the oxidant deserves to be studied, not only because of its oxidizing potential but also because the solvent in which it is stabilized (water in the case of H 2 O 2 and n ‐decane for tert ‐butylhydroperoxide; TBHP) could play a key role in both the global catalytic activity and the MOF stability.…”

“…The choice of cyclohexene oxidation as the catalytic test in this work was based on the high versatility of this reaction. The versatility covers a large number of solvents,22 all M of the series of M–MOF‐74 (except Zn, taken as reference) already tested in the reaction,17b, 23 two different oxidation routes24 (Scheme ), and different oxidizing agents 25. Acetonitrile was selected as the solvent because it is one of the most widely used in cyclohexene oxidation and it is able to dissolve all reactants in a unique liquid phase even if 30 wt % H 2 O 2 in aqueous solution was used as the oxidant 24b…”

Metal-dioxidoterephthalate MOFs of the MOF-74 type: Microporous basic catalysts with well-defined active sites

“…[20,24,29,32] Reports of catalysis using M 2 dobdc are very limited hitherto; they focus on the role of the metal ion as a Lewis acid center, or in accelerating autoxidation reactions. [22,33,34] …”

<strong>Functional Group Modification of Metal-Organic Frameworks for Synthesis of Enol Carbamates</strong>

“…The catalytic performance of MOFs takes place at the metal centers. However, only a few proofs of concept of MOFs with catalytically-active functional organic sites have been reported [4][5]. The modification of amino groups on linkers of MOFs with second metal make them active catalysts for organic synthesis [6].…”