Influence of Ti-incorporated Zeolite Topology and Pore Condensation on Vapor Phase Propylene Epoxidation Kinetics with Gaseous H2O2

Vapor-phase propylene (C3H6) epoxidation kinetics with hydrogen peroxide (H2O2) strongly reflects the physical properties of Ti-incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady-state turnover rates of C3H6 epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)x) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CH3CN) molecules nearby active sites, under identical reaction mechanisms sharing activated H2O2 intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring-opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following C3H6 epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CH3CN. Thus, higher PO selectivities achieved in hydrophilic Ti-MFI at steady-state reflect the preferential stabilization of transition states for C3H6 epoxidation (a primary reaction) relative to PO ring-opening and oxidative cleavage (secondary reactions) that solvation effects that reflect interactions among condensed CH3CN within pores and the extended pore structure.

K2S2O8-Mediated or Azobisisobutyronitrile-Catalyzed Regioselective Aerobic Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes

This work reveals the regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes mediated by K2S2O8 or catalyzed by azobisisobutyronitrile, a very common free radical initiator, in an easy to handle, simple procedure and free of transition metals. This approach demonstrates excellent regioselectivity, mild reaction conditions, and compatibility with a broad range of functional groups (45 examples).

Iron-incorporated metal-organic frameworks for oxidative cleavage of trans-anethole to p-anisaldehyde

An iron-incorporated Zn-MOF catalyst Zn-bpydc·Fe was fabricated for the oxidative cleavage of trans-anethole to p-anisaldehyde under facile conditions, under 1 atm of O2. The Fe coordinated bipyridine serves as the catalytically active center inside the structural skeleton of Zn-MOFs. This work affords a new avenue for the mild oxidation of olefins.

Carbon-Carbon Bond Cleavage for Late-Stage Functionalization

Late-stage functionalization (LSF) introduces functional group or structural modification at the final stage of the synthesis of natural products, drugs, and complex compounds. It is anticipated that late-stage functionalization would improve drug discovery's effectiveness and efficiency and hasten the creation of various chemical libraries. Consequently, late-stage functionalization of natural products is a productive technique to produce natural product derivatives, which significantly impacts chemical biology and drug development. Carbon-carbon bonds make up the fundamental framework of organic molecules. Compared with the carbon-carbon bond construction, the carbon-carbon bond activation can directly enable molecular editing (deletion, insertion, or modification of atoms or groups of atoms) and provide a more efficient and accurate synthetic strategy. However, the efficient and selective activation of unstrained carbon-carbon bonds is still one of the most challenging projects in organic synthesis. This review encompasses the strategies employed in recent years for carbon-carbon bond cleavage by explicitly focusing on their applicability in late-stage functionalization. This review expands the current discourse on carbon-carbon bond cleavage in late-stage functionalization reactions by providing a comprehensive overview of the selective cleavage of various types of carbon-carbon bonds. This includes C-C(sp), C-C(sp2), and C-C(sp3) single bonds; carbon-carbon double bonds; and carbon-carbon triple bonds, with a focus on catalysis by transition metals or organocatalysts. Additionally, specific topics, such as ring-opening processes involving carbon-carbon bond cleavage in three-, four-, five-, and six-membered rings, are discussed, and exemplar applications of these techniques are showcased in the context of complex bioactive molecules or drug discovery. This review aims to shed light on recent advancements in the field and propose potential avenues for future research in the realm of late-stage carbon-carbon bond functionalization.

Donor-Acceptor Covalent Organic Frameworks as a Heterogeneous Photoredox Catalyst for Scissoring Alkenes to Carbonyl Constituents

The conversion of alkenes to carbonyl constituents via the cleavage of the C═C bond is unique due to its biological and pharmacological significance. Though a number of oxidative C═C cleavage protocols have been demonstrated for terminal and electron-rich alkene systems, none of them were optimized for electron-deficient and conjugated alkenes. In this work, a covalent organic framework containing triphenylamine and triazine units was revealed to cleave the C═C bond of alkenes under very mild conditions involving visible light irradiation due to its photoredox property. The alkenes can be conveniently broken across the double bond to their constituent carbonyl derivatives on light irradiation in the presence of air and the covalent organic framework photocatalyst. This protocol is applicable for a wide range of alkenes in an aqueous acetonitrile medium with high functional group tolerance and regioselectivity. Though the electron-deficient alkenes required tetramethylethylene diamine as a sacrificial donor, the electron-rich alkenes do not demand any additives.

Prospects and challenges for nitrogen-atom transfer catalysis

Conversion of C-H bonds to C-N bonds via C-H amination promises to streamline the synthesis of nitrogen-containing compounds. Nitrogen-group transfer (NGT) from metal nitrenes ([M]-NR complexes) has been the focus of intense research and development. By contrast, potentially complementary nitrogen-atom transfer (NAT) chemistry, in which a terminal metal nitride (an [M]-N complex) engages with a C-H bond, is underdeveloped. Although the earliest examples of stoichiometric NAT chemistry were reported 25 years ago, catalytic protocols are only now beginning to emerge. Here, we summarize the current state of the art in NAT chemistry and discuss opportunities and challenges for its development. We highlight the synthetic complementarity of NGT and NAT and discuss critical aspects of nitride electronic structure that dictate the philicity of the metal-supported nitrogen atom. We also examine the characteristic reactivity of metal nitrides and present emerging strategies and remaining obstacles to harnessing NAT for selective, catalytic nitrogenation of unfunctionalized organic small molecules.

Simultaneous Harvesting of Multiple Hot Holes via Visible-Light Excitation of Plasmonic Gold Nanospheres for Selective Oxidative Bond Scission of Olefins to Carbonyls

Using visible photoexcitation of gold nanospheres we successfully demonstrate the simultaneous harvesting of plasmon-induced multiple hot holes in the complete oxidative scission of the C=C bond in styrene at room temperature to selectively form benzaldehyde and formaldehyde, which is a reaction that requires activation of multiple substrates. Our results reveal that, while extraction of hot holes becomes efficient for interband excitation, harvesting of multiple hot holes from the excited Au nanospheres becomes prevalent only beyond a threshold light intensity. We show that the alkene oxidation proceeded via a sequence of two consecutive elementary steps; namely, a binding step and a cyclic oxometallate transition state as the rate-determining step. This demonstration of plasmon-excitation-mediated harvesting of multiple hot holes without the use of an extra hole transport media opens exciting possibilities, notably for difficult catalytic transformations involving multielectron oxidation processes.

New iron(iii) complex of bis-bidentate-anchored diacyl resorcinol on a Fe3O4 nanomagnet: C-H bond oxygenation, oxidative cleavage of alkenes and benzoxazole synthesis

We have synthesized a novel, bis-bidentate, covalently anchored, 4,6-diacetyl resorcinol (DAR) ligand on silica-coated magnetic Fe₃O₄ nanoparticles and the corresponding bi-metallic iron(iii) complex (Fe₃O₄@SiO₂-APTESFe₂L^DAR). Both the chemical nature and the structure of the homogeneously heterogenized catalyst were investigated using physico-chemical techniques. The results obtained by XPS, XRD, FT-IR, TGA, VSM, SEM, TEM, EDX, ICP and AAS revealed a magnetic core, a silica layer and the grafting of a binuclear iron complex on the Fe₃O₄@SiO₂-APTES, as well as its thermodynamic stability. Despite many reports of metal complexes on different supports, there are no reports of anchored, bi-metallic complexes. To the best of our knowledge, this is the first report of a bi-active site catalyst covalently attached to a support. This study focuses on the catalytic activity of an as-synthesized, bi-active site catalyst for C-H bond oxygenation, the oxidative cleavage of alkenes, and the multicomponent, one-pot synthesis of benzoxazole derivatives with excellent yields from readily available starting materials. Our results indicated high conversion rates and selectivity under mild reaction conditions and simple separation using a magnetic field. The leaching and recyclability tests of the catalyst were investigated for the above processes, which indicated that all the reactions proceed via a heterogeneous pathway and that the catalyst is recyclable without any tangible loss in catalytic activity for at least 8, 5 and 5 cycles for C-H bond oxygenation, C[double bond, length as m-dash]C bond cleavage and benzoxazole synthesis, respectively.

Detection and Semi-quantification of Lipids on High-Performance Thin-Layer Chromatography Plate using Ceric Ammonium Molybdate Staining

It is desirable to quickly check the composition of lipids in small size samples, but achieving this is challenging using the existing staining methods. Herein, we developed a highly sensitive and semi-quantitative method for analysis of lipid samples with ceric ammonium molybdate (CAM) staining. The CAM detection method was systematically evaluated with a wide range of lipid classes including phospholipids, sphingolipids, glycerolipids, fatty acids (FA) and sterols, demonstrating high sensitivity, stability, and overall efficiency. Additionally, CAM staining provides a clean yellow background in high performance thin-layer chromatography (HPTLC) which facilitates quantification of lipids using image processing software. Lipids can be stained with CAM reagent regardless of their head group types, position of the carbon-carbon double bonds, geometric isomerism and the variation in the length of FA chain, but staining is mostly affected by the degree of unsaturation of the FA backbone. The mechanism of the CAM staining of lipids was proposed on principles of the reduction-oxidation reaction, in which Mo(VI) oxidizes the unsaturated lipids into carbonyl compounds on the HPTLC plate upon heating, while itself being reduced to Mo(IV). This method was applied for the separation, identification, and quantification of lipid extracts from porcine brain.

Photoexcited Nitroarenes for the Oxidative Cleavage of Alkenes

The oxidative cleavage of alkenes is an integral process that converts feedstock materials into high-value synthetic intermediates^1,2,3. The most viable method to achieve this in one chemical step is with ozone^4,5,6,7, which however poses technical and safety challenges owing to the explosive nature of ozonolysis products^8,9. Herein, we disclose an alternative approach to achieve oxidative cleavage of alkenes using nitroarenes and purple light irradiation. We demonstrate that photoexcited nitroarenes are effective ozone surrogates that undergo facile radical [3+2] cycloaddition with alkenes. The resulting "N-doped" ozonides are safe to handle and lead to the corresponding carbonyl products under mild hydrolytic conditions. These features have enabled the controlled cleavage of all types of alkenes in the presence of a broad array of commonly used organic functionalities. Furthermore, by harnessing electronic, steric, and mediated polar effects, the structural and functional diversity of nitroarenes has provided a modular platform to obtain site-selectivity in substrates containing more than one alkene.

From tandem to catalysis – organic solvent nanofiltration for catalyst separation in the homogeneously W-catalyzed oxidative cleavage of renewable methyl 9,10-dihydroxystearate

Phosphotungstic acid is applied as a homogeneous catalyst for oxidative cleavage of methyl 9,10-dihydroxystearate, allowing for retention of the catalyst via organic solvent nanofiltration.

Catalyst and reactor design considerations for selective production of acids by oxidative cleavage of alkenes and unsaturated fatty acids with H2O2

Mechanistic insight and measurements of apparent kinetics for productive and non-productive reaction pathways guide the development of semi-batch reactors and conditions for stable production of carboxylic acids and diacids over supported tungstate catalysts.

Visible-Light-Driven Oxidative Cleavage of Alkenes Using Water-Soluble CdSe Quantum Dots

The oxidative cleavage of C=C bonds is an important chemical reaction, which is a popular reaction in the photocatalytic field. However, high catalyst-loading and low turnover number (TON) are general shortcomings in reported visible-light-driven reactions. Herein, the direct oxidative cleavage of C=C bonds through water-soluble CdSe quantum dots (QDs) is described under visible-light irradiation at room temperature with high TON (up to 3.7×10⁴ ). Under the same conditions, water-soluble CdSe QDs could also oxidize sulfides to sulfoxides with 51-84 % yields and TONs up to 3.4×10⁴ . The key features of this photocatalytic protocol include high TONs, wide substrates scope, low catalyst loadings, simple and mild reaction conditions, and molecular O₂ as the oxidant.

1,2-Dibutoxyethane-Promoted Oxidative Cleavage of Olefins into Carboxylic Acids Using O2 Under Clean Conditions

Herein, we report the first example of an effective and green approach for the oxidative cleavage of olefins to carboxylic acids using a 1,2-dibutoxyethane/O₂ system under clean conditions. This novel oxidation system also has excellent functional-group tolerance and is applicable for large-scale synthesis. The target products were prepared in good to excellent yields by a one-pot sequential transformation without an external initiator, catalyst, and additive.

Fatty Acids and their Derivatives as Renewable Platform Molecules for the Chemical Industry

Oils and fats of vegetable and animal origin remain an important renewable feedstock for the chemical industry. Their industrial use has increased during the last 10 years from 31 to 51 million tonnes annually. Remarkable achievements made in the field of oleochemistry in this timeframe are summarized herein, including the reduction of fatty esters to ethers, the selective oxidation and oxidative cleavage of C-C double bonds, the synthesis of alkyl-branched fatty compounds, the isomerizing hydroformylation and alkoxycarbonylation, and olefin metathesis. The use of oleochemicals for the synthesis of a great variety of polymeric materials has increased tremendously, too. In addition to lipases and phospholipases, other enzymes have found their way into biocatalytic oleochemistry. Important achievements have also generated new oil qualities in existing crop plants or by using microorganisms optimized by metabolic engineering.

Oxidative Cleavage of Alkenes by O2 with a Non-Heme Manganese Catalyst

The oxidative cleavage of C=C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O₂ and oxidatively cleave C=C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O₂, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O₂. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn–oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O₂ activation that leads to the formation of the oxo species.

The Oxidative Cleavage of 9,10-Dihydroxystearic Triglyceride with Oxygen and Cu Oxide-based Heterogeneous Catalysts

This paper deals with a new heterogeneous catalyst for the second step in the two-step oxidative cleavage of unsaturated fatty acids triglycerides derived from vegetable oil, a reaction aimed at the synthesis of azelaic and pelargonic acids. The former compound is a bio-monomer for the synthesis of polyesters; the latter, after esterification, is used in cosmetics and agrochemicals. The reaction studied offers an alternative to the currently used ozonization process, which has severe drawbacks in terms of safety and energy consumption. The cleavage was carried out with oxygen, starting from the glycol (dihydroxystearic acid triglyceride), the latter obtained by the dihydroxylation of oleic acid triglyceride. The catalysts used were based on Cu²⁺ , in the form of either an alumina-supported oxide or a mixed, spinel-type oxide. The CuO/Al₂ O₃ catalyst could be recovered, regenerated, and recycled, yielding promising results for further industrial exploitation.

Monokaryotic Pleurotus sapidus Strains with Intraspecific Variability of an Alkene Cleaving DyP-Type Peroxidase Activity as a Result of Gene Mutation and Differential Gene Expression

The basidiomycete Pleurotus sapidus produced a dye-decolorizing peroxidase (PsaPOX) with alkene cleavage activity, implying potential as a biocatalyst for the fragrance and flavor industry. To increase the activity, a daughter-generation of 101 basidiospore-derived monokaryons (MK) was used. After a pre-selection according to the growth rate, the activity analysis revealed a stable intraspecific variability of the strains regarding peroxidase and alkene cleavage activity of PsaPOX. Ten monokaryons reached activities up to 2.6-fold higher than the dikaryon, with MK16 showing the highest activity. Analysis of the PsaPOX gene identified three different enzyme variants. These were co-responsible for the observed differences in activities between strains as verified by heterologous expression in Komagataella phaffii. The mutation S371H in enzyme variant PsaPOX_high caused an activity increase alongside a higher protein stability, while the eleven mutations in variant PsaPOX_low resulted in an activity decrease, which was partially based on a shift of the pH optimum from 3.5 to 3.0. Transcriptional analysis revealed the increased expression of PsaPOX in MK16 as reason for the higher PsaPOX activity in comparison to other strains producing the same PsaPOX variant. Thus, different expression profiles, as well as enzyme variants, were identified as crucial factors for the intraspecific variability of the PsaPOX activity in the monokaryons.

Oxidative cleavage of cycloalkenes using hydrogen peroxide and a tungsten-based catalyst: towards a complete mechanistic investigation

The identification of intermediates and by-products issuing from the oxidative cleavage of cycloolefins allows proposing of a reaction mechanism.

Aerobic oxidative CC bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst

High-valency iron-containing perovskite catalyst BaFeO_3−δ could efficiently promote the additive-free oxidative CC bond cleavage of various aromatic alkenes using O₂ as the sole oxidant.

Highly efficient oxidative cleavage of olefins with O2 under catalyst-, initiator- and additive-free conditions

Without employing any external catalyst, initiator and additives, an efficient and eco-friendly protocol has been developed for the synthesis of carbonyl compound via 1,4-dioxane- promoted oxidation of olefins with atmospheric O₂ as the sole oxidant.

Oxidation of Long-Chain α-Olefins Using Environmentally-Friendly Oxidants

Studies on the oxidation of α-olefins via the two-stage method are presented. The new method consisted of oxidizing C30+ α-olefins with hydrogen peroxide (2 equiv.) and subsequent oxidation with oxygen. Products with high acid numbers (29–82 mgKOH/g) and saponification numbers (64–140 mgKOH/g) were obtained and compared with products obtained using only hydrogen peroxide or oxygen. It was demonstrated that H₂O₂ can be partially replaced by oxygen in the oxidative cleavage reaction of α-olefins. N-hydroxyphthalimide in combination with Co(acac)₂ demonstrated high activity in the oxidation stage using oxygen.

A DyP-Type Peroxidase of Pleurotus sapidus with Alkene Cleaving Activity

Alkene cleavage is a possibility to generate aldehydes with olfactory properties for the fragrance and flavor industry. A dye-decolorizing peroxidase (DyP) of the basidiomycete Pleurotus sapidus (PsaPOX) cleaved the aryl alkene trans-anethole. The PsaPOX was semi-purified from the mycelium via FPLC, and the corresponding gene was identified. The amino acid sequence as well as the predicted tertiary structure showed typical characteristics of DyPs as well as a non-canonical Mn²⁺-oxidation site on its surface. The gene was expressed in Komagataella pfaffii GS115 yielding activities up to 142 U/L using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) as substrate. PsaPOX exhibited optima at pH 3.5 and 40 °C and showed highest peroxidase activity in the presence of 100 µM H₂O₂ and 25 mM Mn²⁺. PsaPOX lacked the typical activity of DyPs towards anthraquinone dyes, but oxidized Mn²⁺ to Mn³⁺. In addition, bleaching of β-carotene and annatto was observed. Biotransformation experiments verified the alkene cleavage activity towards the aryl alkenes (E)-methyl isoeugenol, α-methylstyrene, and trans-anethole, which was increased almost twofold in the presence of Mn²⁺. The resultant aldehydes are olfactants used in the fragrance and flavor industry. PsaPOX is the first described DyP with alkene cleavage activity towards aryl alkenes and showed potential as biocatalyst for flavor production.

Synthesis and Liver Microsomal Metabolic Stability Studies of a Fluorine-Substituted δ-Tocotrienol Derivative

A fluoro-substituted δ-tocotrienol derivative, DT3-F2, was synthesized. This compound was designed to stabilize the metabolically labile terminal methyl groups of δ-tocotrienol by replacing one C-H bond on each of the two methyl groups with a C-F bond. However, in vitro metabolic stability studies using mouse liver microsomes revealed an unexpected rapid enzymatic C-F bond hydrolysis of DT3-F2. To the best of our knowledge, this is the first report of an unusual metabolic hydrolysis of allylic C-F bonds.

Iron(III)/O2-Mediated Regioselective Oxidative Cleavage of 1-Arylbutadienes to Cinnamaldehydes

A simple, efficient, and environmentally benevolent regioselective oxidative cleavage of 1-arylbutadienes to cinnamaldehydes mediated by iron(III) sulfate/O₂ has been developed. The reaction offered good yields and excellent regioselectivity and showed good functional group tolerance (31 examples). The method is important, as few reports with limited substrate scope are available for such excellent oxidative cleavage of conjugated dienes.

Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation

A one‐pot multi‐step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis‐dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2‐diol. Carbon–carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon–carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions.

Iron-Catalyzed Nitrene Transfer Reaction of 4-Hydroxystilbenes with Aryl Azides: Synthesis of Imines via C═C Bond Cleavage

C═C bond breaking to access the C═N bond remains an underdeveloped area. A new protocol for C═C bond cleavage of alkenes under nonoxidative conditions to produce imines via an iron-catalyzed nitrene transfer reaction of 4-hydroxystilbenes with aryl azides is reported. The success of various sequential one-pot reactions reveals that the good compatibility of this method makes it very attractive for synthetic applications. On the basis of experimental observations, a plausible reaction mechanism is also proposed.

From Alkenes to Isoxazolines via Copper-Mediated Alkene Cleavage and Dipolar Cycloaddition

An unprecedented copper-mediated anion transformation is reported, along with selective C═C double bond cleavage and dipolar cycloaddition reaction from simple alkenes and inexpensive copper nitrate. Various transformations demonstrate the generality of this method. Further mechanistic investigation indicates a novel ionic pathway for alkene cleavage and highlights the coeffect of iodide and boric acid as additives on the inhibition of well-documented competitive nitration byproducts.

Titania-Catalyzed H2O2 Thermal Oxidation of Styrenes to Aldehydes

We investigated the selective oxidation of styrenes to benzaldehydes by using a non-irradiated TiO₂–H₂O₂ catalytic system. The oxidation promotes multi-step reactions from styrenes, including the cleavage of a C=C double bond and the addition of an oxygen atom selectively and stepwise to provide the corresponding benzaldehydes in good yields (up to 72%). These reaction processes were spectroscopically shown by fluorescent measurements under the presence of competitive scavengers. The absence of the signal from OH radicals indicates the participation of other oxidants such as hydroperoxy radicals (•OOH) and superoxide radicals (•O₂⁻) into the selective oxidation from styrene to benzaldehyde.

Iron(ii) tetrafluoroborate complexes of new tetradentate C-scorpionates as catalysts for the oxidative cleavage of trans-stilbene with H2O2

Iron(ii) complexes of two new tetradentate C-scorpionate ligands are characterized. Both catalyze stilbene cleavage using either H₂O₂ or a O₂/photocatalyst oxidant.

Cleavage of carbon–carbon bonds by radical reactions

This review provides insights into the in situ generated radicals triggered carbon–carbon bond cleavage reactions.

Room-temperature production of bio-based aldehydes from vegetable oil-derived epoxide via H2WO4@Al-MCM-41 as recyclable catalyst

The oxidative cleavage of vegetable oils and their derivatives to produce bio-based aldehydes is a potentially useful process, although the aldehyde products are readily oxidized to carboxylic acids and thus seldom obtained in high yields. The present study developed a room-temperature method for the synthesis of bio-aldehydes via the oxidative cleavage of vegetable oil-derived epoxides, using H₂WO₄ as the catalyst, H₂O₂ as the oxidant, and t-BuOH as the solvent. Reactions were carried out at temperatures ranging from 25 to 35 °C for 3.5–10.5 h, and provided >99% conversion and >90% aldehyde yield. In particular, an approximately 97% yield was obtained at 25 °C after 10.5 h. As the reaction proceeded, the H₂WO₄ dissolved to form a W-containing anion. Several mesoporous Al-MCM-41 materials having different Si/Al ratios were hydrothermally synthesized and used as adsorbents to recover the catalyst by adsorbing these anions. The adsorption capacity of the Al-MCM-41 was found to increase with decreases in the Si/Al ratio. The Al-MCM-41 had little effect on the oxidative cleavage reaction at 25 °C, and thus could be directly added to the reaction system. The excellent anion adsorption performance of the Al-MCM-41 greatly improved the reusability of the H₂WO₄ catalyst. When using the Al-MCM-41 with the best adsorption performance, there was no significant decrease in the activity of the catalyst following five reuses.

>90% bio-aldehydes yield was obtained from H₂WO₄-catalyzed epoxy vegetable oil at room-temperature; Al-MCM-41 was added to recover catalyst via adsorption.