490-91-5Relevant articles and documents
Fe(III) Protoporphyrin IX Encapsulated in a Zinc Metal-Organic Framework Shows Dramatically Enhanced Peroxidatic Activity
Dare, Nicola A.,Brammer, Lee,Bourne, Susan A.,Egan, Timothy J.
, p. 1171 - 1183 (2018)
Two MOFs, [H2N(CH3)2][Zn3(TATB)2(HCOO)]·HN(CH3)2·DMF·6H2O (1) and Zn-HKUST-1 (2), were investigated as potential hosts to encapsulate Fe(III) heme (Fe(III) protoporphyrin IX = Fe(III)PPIX). Methyl orange (MO) adsorption was used as an initial model for substrate uptake. MOF 1 showed good adsorption of MO (10.3 ± 0.8 mg g-1) which could undergo in situ protonation upon exposure to aqueous HCl vapor. By contrast, MO uptake by 2 was much lower (2 ± 1 mg g-1), and PXRD indicated that structural instability on exposure to water was the likely cause. Two methods for Fe(III)PPIX-1 preparation were investigated: soaking and encapsulation. Encapsulation was verified by SEM-EDS and showed comparable concentrations of Fe(III)PPIX on exposed interior surfaces and on the original surface of fractured crystals. SEM-EDS results were consistent with ICP-OES data on bulk material (1.2 ± 0.1 mass % Fe). PXRD data showed that the framework in 1 was unchanged after encapsulation of Fe(III)PPIX. MO adsorption (5.8 ± 1.2 mg g-1) by Fe(III)PPIX-1 confirmed there is space for substrate diffusion into the framework, while the UV-vis spectrum of solubilized crystals confirmed that Fe(III)PPIX retained its integrity. A solid-state UV-vis spectrum of Fe(III)PPIX-1 indicated that Fe(III)PPIX was not in a μ-oxo dimeric form. Although single-crystal XRD data did not allow for full refinement of the encapsulated Fe(III)PPIX molecule owing to disorder of the metalloporphyrin, the Fe atom and pyrrole N atoms were located, enabling rigid-body modeling of the porphine core. Reaction of 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) with H2O2, catalyzed by Fe(III)PPIX-1 and -2, showed that Fe(III)PPIX-1 is significantly more efficient than Fe(III)PPIX-2 and is superior to solid Fe(III)PPIX-Cl. Fe(III)PPIX-1 was used to catalyze the oxidation of hydroquinone, thymol, benzyl alcohol, and phenyl ethanol by tert-butyl-hydroperoxide with t1/2 values that increase with increasing substrate molecular volume.
Oxidation of Thymol and Carvacrol to Thymoquinone with KHSO5 Catalyzed by Iron Phthalocyanine Tetrasulfonate in a Methanol–Water Mixture
Günay, Tu??e,?imen, Yasemin,Karabacak, R. Bengü,Türk, Hayrettin
, p. 2306 - 2312 (2016)
Abstract: The oxidation of thymol and carvacrol to thymoquinone with potassium peroxymonosulfate (KHSO5) catalyzed by iron phthalocyanine tetrasulfonate (FePcTS) in a methanol (4.0?mL)–water (0.5?mL) mixture has been carried out. In a typical reaction, the amounts of the substrate, oxidant, and catalyst were 0.300, 0.600, and 1 × 10?3 millimoles, respectively. Ninety-nine percent conversions of thymol in 1?h and of carvacrol in 30?min were achieved at ambient temperature. The major product of both oxidation reactions was thymoquinone (2-isopropyl-5-methylbenzoquinone, TQ) and the reactions also yielded polymeric products poly(2-isopropyl-5-methyl-1,4-phenylene oxide) and poly(5-isopropyl-2-methyl-1,3-phenylene oxide). These polymers are novel and not reported before. When H2O2 or ButOOH was used as the oxidant, the yield of TQ was 1 %. Graphical Abstract: [Figure not available: see fulltext.]
Hydrothermal synthesis, crystal structure and heterogeneous catalytic activity of a novel inorganic-organic hybrid complex, possessing infinite La-O-La linkages
Ay, Burak,Yildiz, Emel,Protasiewicz, John D.,Rheingold, Arnold L.
, p. 208 - 213 (2013)
In this paper, a novel lanthanum coordination polymer formulated as {[La2(Hpdc)3(H2O)4]·2H 2O}n (1, H3pdc = 3,5-pyrazoledicarboxylic acid) has been synthesized by the reaction of H3pdc with chloride salt of La(III) under hydrothermal conditions and characterized by elemental analysis, FT-IR, TGA and single-crystal X-ray diffraction. The complex crystallized in the monoclinic system Cc space group. The single-crystal X-ray structural analysis revealed that central metal La atoms are nine-coordinate and linked by bridging μ2-OCOO- groups to form [La(1)- (μ2-OCOO-)2-La(2)]n inorganic-organic chains that produce a supramolecular polymeric framework structure. The three-dimensional structure of 1 is accompanied by non-coordinating water molecules. Thermal behavior and catalytic performance of 1 have also been studied. The complex 1 showed 100% selectivity and a conversion rate of 24% on the oxidation of thymol (T) to thymoquinone (TQ).
Oxidation of Monoterpenes Catalysed by a Water-Soluble MnIII PEG-Porphyrin in a Biphasic Medium
Neves, Cláudia M. B.,Tomé, Jo?o P. C.,Hou, Zhanyao,Dehaen, Wim,Hoogenboom, Richard,Neves, M. Gra?a P. M. S.,Sim?es, Mário M. Q.
, p. 2804 - 2809 (2018)
It is well established that the transformation of abundant and cheap natural products, such as terpenoids, can produce other more valuable compounds. Thymoquinone, which has a commercial value significantly higher than that of its precursors, can be obtained by oxidation of carvacrol and thymol. In this work, a new water-soluble MnIII PEG-porphyrin is reported as catalyst in a water/hexane (1:1) biphasic medium for the oxidation of carvacrol and thymol into thymoquinone. The reactions were performed using tert-butyl hydroperoxide as oxidant in the presence of ammonium acetate as co-catalyst, reaching 94 and 78 % of conversion after 5 h of reaction for thymol and carvacrol, respectively. Experiments with oregano essential oil as substrate revealed selective transformation of thymol and carvacrol into thymoquinone. The main advantage of this biphasic system based on a water-soluble catalyst and on substrates and products soluble in hexane, is the straightforward isolation, recovery and recycling of the catalyst by simple phase separation. Recycling studies of the MnIII PEG-porphyrin using thymol as substrate showed high conversion values throughout four catalytic cycles.
Hydrothermal synthesis, structure, heterogeneous catalytic activity and photoluminescent properties of a novel homoleptic Sm(III)-organic framework
Ay, Burak,Yildiz, Emel,Felts, Ashley C.,Abboud, Khalil A.
, p. 61 - 68 (2016)
A novel metal-organic framework, (H2pip)n[Sm2(pydc)4(H2O)2]n (1) (H2pydc=2,6-pyridinedicarboxylic acid, H2pip=piperazine) has been synthesized under hydrothermal conditions and characterized by the elemental analysis, inductively coupled plasma (ICP) spectrometer, fourier transform infrared (FT-IR) spectra, thermogravimetric analysis (TGA), single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). The structure of 1 was determined to be three-dimensional, linked along Sm-O-Sm chains. The asymmetric unit consisted of one singly anionic fragment consisting of Sm(III) coordinated to two H2pydc ligands and one water, and one half of a protonated H2pip, which sits on an inversion center. 1 exhibited luminescence emission bands at 534?nm at room temperature when excited at 440?nm. Its thermal behavior and catalytic performance were investigated and the selectivity was measured as 100% for the oxidation of thymol to thymoquinone.
Hydrothermal synthesis of a novel μ-dihydroxo-bis(2,6- pyridinedicarboxylatoaquachromium(III)) complex and investigation of its catalytic activity
Ay, Burak,Yildiz, Emel,Jones, Stephanie,Zubieta, Jon
, p. 15 - 19 (2012)
A new chromium(III) compound [Cr(H2O)(OH)(C7H 3NO4)]2, μ-dihydroxo-bis(2,6- pyridinedicarboxylatoaquachromium(III)), has been successfully synthesized by the hydrothermal reaction of 2,6-pyridinedicarboxylic acid (H2pydc) and CrCl3·6H2O in the alkali medium. This metal complex was characterized by elemental analysis, IR spectroscopy, thermal analysis and single-crystal X-ray diffraction. The X-ray analysis showed that the structure is molecular and consists of units of two Cr(H2O)(OH) (C7H3NO4) groups linked through two OH groups. In the complex, each Cr centre is in a distorted octahedral environment, defined by two hydroxyl bridges, an aqua ligand and a tridentate pyridinedicarboxylate anion. The thermal stability and catalytic properties of the complex were also investigated. The complex affected the oxidation of thymol to thymoquinone with 100% selectivity and a conversion rate of 20.25%.
Two novel isostructural and heteroleptic Nd(III) and Dy(III)-organic frameworks constructed by 2,5-pyridinedicarboxylic acid and in situ generated 2-pyridinecarboxylic acid: Hydrothermal synthesis, characterization, photoluminescence properties and heterogeneous catalytic activities
Ay, Burak,Yildiz, Emel,Kani, ?brahim
, p. 165 - 175 (2017)
The crystal structures, heterogeneous catalytic activities and photoluminescent properties of two novel three dimensional (3D) metal organic frameworks (MOFs), [Nd(pyc)(pydc)(H2O)]n (1) and [Dy(pyc)(pydc)(H2O)]n (2) (H2pydc?=?pyridine-2,5-dicarboxylic acid, Hpyc?=?2-pyridinecarboxylic acid) are presented. The synthesized complexes under hydrothermal conditions were characterized by the elemental analysis, inductively coupled plasma (ICP), fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), single crystal X-ray diffraction and powder X-ray diffraction (PXRD) analysis. For morphological analysis, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used. The compounds are isostructural and each Ln3+ (Nd(III) and Dy(III)) centers are eight-coordinated. MOFs have the distinct 3D open-framework architectures due to the presence of Hpyc ligands, which are converted from H2pydc ligands in-situ decarboxylation under the hydrothermal conditions. Photoluminescence properties and thermal stabilities of the compounds have been investigated. Their heterogeneous catalytic activities have also been examined on the oxidation of the thymol (T) to thymoquinone (TQ). The structures of the MOFs were stable after three catalytic cycles. The maximum T conversion values, 40.37% and 36.45% were recorded with nearly 100% selectivities by using 1 and 2, respectively.
PHOTOOXIDATION OF PHENOLIC COMPOUNDS
-
Page/Page column 17-18, (2021/11/26)
The present invention relates to the photooxidation of phenolic compounds to the respective quinoid compounds using methylene blue as photosensitizer in a solvent mixture of water and alcohols using light of the high wavelength range of the visible spectrum.
PHOTOOXIDATION OF 2,3,5-TRIMETHYLPHENOL
-
Page/Page column 14-17, (2021/11/26)
The present invention relates to the photooxidation of 2,3,5-trimethyl- phenol to yield 2,3,5-trimethylbenzoquinone using methylene blue as photo- sensitizer in a solvent mixture of water and alcohols using light of the high wavelength range of the visible spectrum.
Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor
Wellauer, Jo?l,Miladinov, Dragan,Buchholz, Thomas,Schütz, Jan,Stemmler, René T.,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
supporting information, p. 9748 - 9752 (2021/05/27)
A mild photocatalytic phenol oxygenation enabled by a continuous-flow photoreactor using visible light and pressurized air is described herein. Products for wide-ranging applications, including the synthesis of vitamins, were obtained in high yields by precisely controlling principal process parameters. The reactor design permits low organophotocatalyst loadings to generate singlet oxygen. It is anticipated that the efficient aerobic phenol oxygenation to benzoquinones and p-quinols contributes to sustainable synthesis.
