Oxidation Of Indene Research Articles

Ozone-assisted low temperature oxidation of indene: An experimental and computational study

Elucidating the oxidation chemistry of polycyclic aromatic hydrocarbons (PAHs) aids in understanding the degradation reaction processes of PAHs, as well as their competitive roles in PAH growth. In this work, ozone-assisted oxidation of indene, the smallest prototype PAH molecule, was investigated in an atmospheric jet stirred reactor at 400–550 K. Ab initio quantum chemistry calculations were conducted to characterize the oxidation kinetics of indene and interpret the experimental observations. Fingerprint oxidation products including 2-(2-oxoethyl) benzoic acid, 2-(formylmethyl) benzaldehyde, 1,2-indanedione and 1-indanone were identified by synchrotron vacuum ultraviolet photoionization mass spectrometry. The initial C9H8O3 adduct resulting from O3-addition to indene exhibits high instability and is primarily detected as 2-(2-oxoethyl)benzoic acid following ozonolysis reactions. Minor amounts of vinylhydroperoxide were also observed as isomeric products of the C9H8O3 adduct. Theoretical calculations indicate that indene ozonolysis is highly structure-dependent, where the conformation of the C9H8O3 adduct determines the configuration of the resulting Criegee intermediates (CI). The distinctive reaction pathways introduced by the bifunctionalized characteristics of indene-derived large CIs are emphasized in this study. syn-Configuration CI features more conversion pathways compared to anti-CI due to the interaction between CI functionality and the neighboring aldehyde group, among which the bicyclic ring-closure reaction yielding secondary ozonide is most favored. The dioxirane intermediates generated from anti-CIs can undergo the Crossed Acid-forming channel to yield the target acid products, which provides an alternative way for dioxirane conversion. Further theoretical analyses demonstrate that ozonolysis is not the exclusive mechanism for indene oxidation under O3-assisted conditions. Instead, it is accompanied by low-temperature reactions initiated by OH/O2, leading to key products such as 2-(formylmethyl) benzaldehyde and 1-indanone. The present work aims to unravel the elusive chemistry involved in the O3-initiated oxidation of indene, providing new insights into the distinctive kinetics introduced by large bifunctionalized CIs in the ozonolysis of structurally similar PAHs.

Quantum chemical modeling of enantioselective sulfoxidation and epoxidation reactions by indole monooxygenase VpIndA1.

Indole monooxygenases (IMOs) are enzymes from the family of Group E monooxygenases, requiring flavin adenine dinucleotide (FAD) for their activities. IMOs play important roles in both sulfoxidation and epoxidation reactions. The broad substrate range and high selectivity of IMOs make them promising biocatalytic tools for synthesizing chiral compounds. In the present study, quantum chemical calculations using the cluster approach were performed to investigate the reaction mechanism and the enantioselectivity of the IMO from Variovorax paradoxus EPS (VpIndA1). The sulfoxidation of methyl phenyl sulfide (MPS) and the epoxidation of indene were chosen as the representative reactions. The calculations confirmed that the FADOOH intermediate is the catalytic species in the VpIndA1 reactions. The oxidation of MPS adopts a one-step mechanism involving the direct oxygen-transfer from FADOOH to the substrate and the proton transfer from the -OH group back to FAD, while the oxidation of indene follows a stepwise mechanism involving a carbocation intermediate. It was computationally predicted that VpIndA1 prefers the formation of (S)-product for the MPS sulfoxidation and (1S,2R)-product for the indene epoxidation, consistent with the experimental observations. Importantly, the factors controlling the stereo-preference of the two reactions are identified. The findings in the present study provide valuable insights into the VpIndA1-catalyzed reactions, which are essential for the rational design of this enzyme and other IMOs for industrial applications. It is also worth emphasizing that the quantum chemical cluster approach is again demonstrated to be powerful in studying the enantioselectivity of enzymatic reactions.

Atmospheric oxidation of indene initiated by OH radical in the presence of O2 and NO: A mechanistic and kinetic study

The atmospheric degradation of polycyclic aromatic hydrocarbons (PAHs) can generate organic pollutants that contribute to the formation of secondary organic aerosols (SOAs) and exacerbate their carcinogenicity. Indene is an example of styrene-like bicyclic hydrocarbons that are not fully aromatic. The OH-initiated atmospheric oxidation of indene in the presence of O2 and NO was investigated using quantum chemical methods at M06–2X/6–311++G(3df,2p)//M06–2X/6-311+G(d,p) level. The oxidation products are oxygenated polycyclic aromatic hydrocarbons (OPAHs) containing hydroxyindene, indenone, dialdehydes and 2-(formylmethyl)benzaldehyde. Calculation results showed that 7-indene radical, which is the precursor of various PAHs, has a high production ratio that is 35.29% in the initial reaction, indicating that the OH-initiated oxidation increase the environmental risks of indene in the atmosphere. The rate constants for the crucial elementary reactions were calculated based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The overall rate constant of the initial reaction is calculated to be 1.04 × 10−10 cm3 molecule−1 s−1 and the atmospheric lifetime of indene is determined as 2.74 h. This work provides a comprehensive understanding on the oxidation mechanisms of indene and the findings could help to clarify the fate of indene in the atmosphere.

Comparison of Catalytic Activity of Chromium–Benzenedicarboxylate Metal–Organic Framework Based on Various Synthetic Approach

MIL-101(Cr), as a prototypical mesoporous metal–organic framework (MOF), can be facially prepared by involving different modulators to fit various demands. In this paper, a range of MIL-101(Cr) products were prepared under similar conditions. It was found that one of the additives, phenylphosphonic acid (PPOA), could give a stable hierarchical structure material. Compared to other MIL-101(Cr)s, though hierarchical MIL-101(Cr) showed less porosity, it gave a better catalytic performance in the oxidation of indene and 1-dodecene.

Facile Fabrication of Nano-MIL-101(Cr) with Enhancement of Catalytic Activity in Oxidation of Indene

Facile Fabrication of Nano-MIL-101(Cr) with Enhancement of Catalytic Activity in Oxidation of Indene

Synthesis of Stable Hierarchical MIL-101(Cr) with Enhanced Catalytic Activity in the Oxidation of Indene

Nowadays, the controllable synthesis of stable hierarchical metal–organic frameworks (MOFs) is very important for practical applications, especially in catalysis. Herein, a well-known chromium–benzenedicarboxylate metal–organic framework, MIL-101(Cr), with a stable hierarchical structure, was produced by using phenylphosphonic acid (PPOA) as a modulator via the hydrothermal method. The presence of phenylphosphonic acid could create structural defects and generate larger mesopores. The synthesized hierarchical MIL-101(Cr) possesses relatively good porosity, and the larger mesopores had widths of 4–10 nm. The hierarchical MIL-101(Cr) showed significant improvement for catalytic activity in the oxidation of indene. Further, the presence of a hierarchical structure could largely enhance large dye molecule uptake properties by impregnating.

Nanocoating of Hydrophobic Mesoporous Silica around MIL-101Cr for Enhanced Catalytic Activity and Stability.

The metal-organic framework (MOF) MIL-101Cr was readily encapsulated by a very thin shell (around 30 nm) of hydrophobic mesoporous silica, which replicates the irregular shape of the MOF nanocrystals. Such a silica shell facilitates the diffusion of hydrophobic reactants with enhancement of the catalytic activity of the MOF and significantly improved catalytic stability of the MOF in the oxidation of indene.

One-pot synthesis of 3,4-dihydro-3-hydroxyisochroman-1-one and evaluation of acetal derivatives as antibacterial and antifungal agents

Abstract A one-pot synthesis of 3,4-dihydro-3-hydroxyisochroman-1-one (lactol) 3 by oxidation of indene using tungstic acid-hydrogen peroxide is reported. The synthesized lactol was converted into acetal derivatives 5a–h, which were evaluated for their in vitro antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative) strains, and antifungal activity against Candida albicans and Aspergillus niger by broth dilution method. The compounds show potent activity against S. aureus in comparison with ampicillin and exhibit modest antifungal activity.

Porous manganese oxide synthesized through organic-electrolyte templates and their catalytic applications

We report a facile approach to the preparation of porous manganese oxide materials by the organic-electrolyte templates based on strategy. The final products are thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and Brunauer–Emmett–Teller (BET) techniques. The results reveal that porosity (pore size and distribution, surface area) of these manganese oxides has strong relationship with the templates used, which implies a simple way to obtain a series of porous materials. By comparing the catalytic effects of these manganese oxides in oxidation of indene and benzyl alcohol, we find that the pore size and distribution are also crucial to the catalytic properties of these porous materials.

Synthesis, Characterization, and Catalytic Applications of Manganese Oxide Octahedral Molecular Sieve (OMS) Nanowires with a 2 × 3 Tunnel Structure

Romanechite is a natural manganese oxide with a 2 × 3 tunnel structure containing a majority of Ba2+ and trace amounts of Na+, K+, and Sr2+ as tunnel cations. Many attempts have been made to synthesize the 2 × 3 tunnel structured manganese oxide in laboratories using Ba2+ as the template. However, no successful work has been reported due to (1) the presence of intergrown hollandite impurities (barium-2 × 2 tunnel structure manganese oxide) in the synthesized products and (2) the absence of romanechite characteristic X-ray diffraction (XRD) peaks in the products, such as the (001) and (200) diffraction peaks which correspond to d ≈ 9.7 and 7.0 Å, respectively. Hydrated Na+ ions have been utilized as structure directors to successfully synthesize the Na-2 × 3 tunnel structure manganese oxide (OMS-6) from hydrothermal treatment of Na-birnessite. XRD gave a pattern in very good agreement with the pattern of romanechite (JCPDS file 14-627) without impurity phases. High-resolution microscopy measurements showed a nanofibrous morphology of the materials with an average fiber diameter of 40 nm. Under N2 environments, the 2 × 3 tunnel structure is stable below 550 °C and transforms into hausmannite (Mn3O4) at temperatures of 550 °C or higher; however, under O2 environments, the 2 × 3 tunnel structure is preserved at 550 °C as measured by in situ XRD. The density functional theory (DFT) method indicated that the 2 × 3 tunnel structure has a major micropore size of 7.5 Å. NH3 and CO2 chemisorption results indicated that the amount of strong acidic and basic sites on the Na-2 × 3 material is about 0.22 and 0.002 mmol/g sample, respectively. Catalytic oxidation of indene by the Na-2 × 3 manganese oxide showed a 96% conversion for indene and a 73% selectivity toward phthalic anhydride for a 40 h reaction at 80 °C.

Detection of genes for alkane and naphthalene catabolism in Rhodococcus sp. strain 1BN.

Rhodococcus sp. 1BN was isolated from a contaminated site and showed various biodegradative capabilities. Besides naphthalene, strain 1BN degraded medium- (C6) and long-chain alkanes (C16-C28), benzene and toluene, alone or when the hydrocarbons were mixed in equal proportions. The nucleotide sequence of an alk polymerase chain reaction (PCR) fragment revealed a 59% nucleotide homology to the Pseudomonas oleovorans alkB gene. The nar fragments were highly homologous to genes coding for large and small subunits of cis-naphthalene 1,2-dioxygenase (narAa and narAb) and to cis-naphthalene dihydrodiol dehydrogenase (narB) from other rhodococci. The oxidation of indene to cis-(1S,2R)-1,2-dihydroxyindan by toluene-induced cells allows to hypothesize that strain 1BN also carries a toluene dioxygenase-like system.

Allylic Oxidation of Cyclohexene and Indene by cis-[RuIV(bpy)2(py)(O)]2+

The kinetics of oxidation of cyclohexene, cyclohexen-1-ol, and indene by cis-[RuIV(bpy)2(py)(O)]2+ (bpy = 2,2‘-bipyridine and py = pyridine) have been studied in CH3CN. The reactions are first-orde...

Catalytic behavior of a magnesium oxide supported polysilazane-ruthenium complex for the oxidation of indene with molecular oxygen to indanones

A new magnesium oxide supported polysilazane ruthenium complex has been prepared and found to be capable of catalyzing the oxygenation of indene in 62.9% conversion to indanones without by-products under mild conditions, i.e. 1 atm oxygen and 80°C. The supported ruthenium complex was effective without need for a cocatalyst. Also, it can be reused several times without apparent loss of activity.

Desaturation, dioxygenation, and monooxygenation reactions catalyzed by naphthalene dioxygenase from Pseudomonas sp. strain 9816-4.

The stereospecific oxidation of indan and indene was examined with mutant and recombinant strains expressing naphthalene dioxygenase of Pseudomonas sp. strain 9816-4. Pseudomonas sp. strain 9816/11 and Escherichia coli JM109(DE3)[pDTG141] oxidized indan to (+)-(1S)-indanol, (+)-cis-(1R,2S)-indandiol, (+)-(1S)-indenol, and 1-indanone. The same strains oxidized indene to (+)-cis-(1R,2S)-indandiol and (+)-(1S)-indenol. Purified naphthalene dioxygenase oxidized indan to the same four products formed by strains 9816/11 and JM109(DE3)[pDTG141]. In addition, indene was identified as an intermediate in indan oxidation. The major products formed from indene by purified naphthalene dioxygenase were (+)-(1S)-indenol and (+)-(1R,2S)-indandiol. The results show that naphthalene dioxygenase catalyzes the enantiospecific monooxygenation of indan to (+)-(1S)-indanol and the desaturation of indan to indene, which then serves as a substrate for the formation of (+)-(1R,2S)-indandiol and (+)-(1S)-indenol. The relationship of the desaturase, monooxygenase, and dioxygenase activities of naphthalene dioxygenase is discussed with reference to reactions catalyzed by toluene dioxygenase, plant desaturases, cytochrome P-450, methane monooxygenase, and other bacterial monooxygenases.

Activation of molecular oxygen by copper salts in acetic acid and application to oxidation of 1,4-diphenylbutadiene and of 2,6-di-t-butylphenol: a 2,4-diphenylfuran synthesis

The stoichiometry and the kinetics of molecular oxygen absorption by the Cu(OAc) 2-LiBr system in solution in acetic acid-acetic anhydride (1:1) mixture has been investigated in the presence respectively of 1,4-dipheny1-1,3-butadiene ( 3) and of phenols as substrates. The former affords 2,5-diphenylfuran ( 5), whereas 2,6-di-t-butylphenol ( 10) leads to the formation of quinoid derivatives ( 12). The results are discussed on the basis of a duality of mechanism: the copper-LiBr catalyst used acts both as a dioxygen activation catalyst and as a halogenation system, this last aspect receiving further support from the copper halide-catalyzed oxidation of indene.

Kinetics of Cr(VI) and V(V) oxidation of trans-stilbene and indene

Title reactions are acid catalyzed and strongly dependent on the permittivity of the medium. With Cr(VI) indene reacts faster than trans-stilbene, but with V(V), trans-stilbene reacts faster than indene. The mechanism is discussed.

Regioselective substitution in hindered aromatics. 4-Nitrophthalic acid from nitration and nitric acid oxidation of indene, 1,2-dihydronaphthalene, and their polymers

Regioselective substitution in hindered aromatics. 4-Nitrophthalic acid from nitration and nitric acid oxidation of indene, 1,2-dihydronaphthalene, and their polymers

The mechanism of the antioxidant action of zinc dialkyl dithiophosphates

Zinc dialkyl dithiophosphates have been shown to inhibit the azonitrile-initiated oxidation of cumene and squalane and the non-initiated oxidation of indene by acting as chain-breaking agents. Several related compounds have been tested as chain-breaking inhibitors and a mechanism is proposed to account for this behaviour.

Polymerization and Oxidation of Indene in the Vapor Phase.

Polymerization and Oxidation of Indene in the Vapor Phase.