Oxidative Esterification Of Primary Alcohols Research Articles

Relay Catalysis for Selective Aerobic Oxidative Esterification of Primary Alcohols with Methanol.

Esters are bulk and fine chemicals and ubiquitous in polymers, bioactive compounds, and natural products. Their traditional synthetic approach is the esterification of carboxylic acids or their activated derivatives with alcohols. Herein, a bimetallic relay catalytic protocol was developed for the aerobic esterification of one alcohol in the presence of a slowly oxidizing alcohol, which has been identified as methanol. A concise synthesis of phlomic acid was executed to demonstrate the practicality and potential of this reaction.

Toward biomass-based single-atom catalysts and plastics: Highly active single-atom Co on N-doped carbon for oxidative esterification of primary alcohols

Supported single-atom catalysts (SACs) have attracted much attention as their advantageous performances in heterogenous catalysis. Here, we report a general synthesis approach to produce SACs on nitrogen-doped carbon (M SAs-N@C, where M = Fe, Co, Ni, Cu) by engineering bioinspired metal-lignin coordination complexes. The Co SAs-N@C catalyst shows extraordinary reactivity for the oxidative esterification of primary alcohols via aldehyde intermediates, achieving a high turnover frequency (TOF, 55.6 mol methyl benzoate mol−1Co h−1) for benzyle alcohol, which is approx. 18 times of Co nanoparticles. Experiments and theoretical calculations reveal that the atomically dispersed Co species in Co SAs-N@C are active sites for this reaction. As a proof-of-concept, we demonstrate an integrated biorefinery that lignin-based catalyst enables the effective transformation of carbohydrate-derived furans into building block of plastics and fragrance. Our technique not only provides a facile, low-cost and scalable method to atomically dispersed catalysts but also opens new avenue toward lignin valorization and biomass economy.

Direct oxidative esterification of primary alcohols and oxidation of secondary alcohols over mesoporous spherical silica encapsulated MnO2nanoparticles

In this work, a simple and efficient strategy for the fabrication of novel encapsulated MnO2nanoparticles inside spherical mesoporous silica hollow-nanoparticles was described.

Oxidative esterification of primary alcohols at room temperature under aqueous medium

ABSTRACTOxidative esterification of aliphatic primary alcohols with bromide and bromate couple in aqueous acidic medium at room temperature is reported with a wide range of substrate scope for both aliphatic and cyclic alcohols and obtained excellent yields of products.

Mechanistic Insights into Solution-Phase Oxidative Esterification of Primary Alcohols on Pd(111) from First-Principles Microkinetic Modeling

We present an ab initio microkinetic model for the oxidative esterification of 1-propanol to methyl propionate over Pd(111). The model fully accounts for solvation of solution-phase species and added catalytic base and provides key insights into the factors that limit the activity of unpromoted Pd aerobic oxidation catalysts. In particular, we find that the activity is limited by the large steady-state surface H coverage, which destabilizes other adsorbed intermediates via lateral interactions, and substantial barriers governing the formation of O–H bonds, which is required for the reduction of O2 and removal of H byproducts from the catalyst surface.

Aerobic oxidative esterification of primary alcohols over Pd-Au bimetallic catalysts supported on mesoporous silica nanoparticles

We have prepared a series of mesoporous silica nanoparticle (MSN) supported Pd-Au bimetallic catalysts using a newly developed sequential impregnation method. These catalysts were fully characterized by various techniques including nitrogen sorption, powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and high angle annular dark-field scanning transmission electron microscopy (HADDF-STEM). By using this synthetic approach, we observed metal nanoparticles (NP) with diameters of 1–2nm homogeneously supported on the MSN. The catalytic performance of these MSN supported metal NPs was tested by aerobic oxidative esterification in a tandem reaction where primary alcohols are oxidized to their corresponding aldehydes and to esters in a subsequent reaction. We determined that Pd NPs are very efficient in the first step of oxidation; however, stagnant in the subsequent oxidation. On the contrary, Au NPs show slow reactivity in converting alcohols to aldehydes, but extraordinarily efficient in the oxidation of aldehydes to esters. By fine tuning the metal ratio, the bimetallic catalyst exhibits better reactivity and selectivity toward a variety of primary alcohols than the corresponding monometallic catalysts. In addition, we also found that the bimetallic Pd-Au@MSN catalysts can be recycled three times without a significant loss in activity.

Discovery of Multicomponent Heterogeneous Catalysts via Admixture Screening: PdBiTe Catalysts for Aerobic Oxidative Esterification of Primary Alcohols.

In the present study, we demonstrate the utility of "admixture screening" for the discovery of new multicomponent heterogeneous Pd catalyst compositions that are highly effective for aerobic oxidative methyl esterification of primary alcohols. The identification of possible catalysts for this reaction was initiated by the screening of simple binary and ternary admixtures of Pd/charcoal in combination with one or two metal and/or metalloid components as the catalyst. This approach permitted rapid evaluation of over 400 admixture combinations for the oxidative methyl esterification of 1-octanol at 60 °C in methanol. Product yields from these reactions varied widely, ranging from 2% to 88%. The highest yields were observed with Bi-, Te-, and Pb-based additives, and particularly from those containing both Bi and Te. Validation of the results was achieved by preparing specific PdBiTe catalyst formulations via a wet-impregnation method, followed by application of response surface methodology to identify the optimal Pd-Bi-Te catalyst stoichiometry. This approach revealed two very effective catalyst compositions: PdBi0.47Te0.09/C (PBT-1) and PdBi0.35Te0.23/C (PBT-2). The former catalyst was used in batch aerobic oxidation reactions with different primary alcohols and shown to be compatible with substrates bearing heterocycle and halide substituents. The methyl ester products were obtained in >90% yield in nearly all cases. Implementation of the PBT-2 catalyst in a continuous-flow packed-bed reactor achieved nearly 60 000 turnovers with no apparent loss of catalytic activity.

ChemInform Abstract: Sequential Alcohol Oxidation/putative Homo Claisen—Tishchenko‐Type Reaction to Give Esters: A Key Process in Accessing Novel Biologically Active Lactone Macrocycles.

We report an efficient methodology for the direct oxidative esterification of primary alcohols to diether-esters using pyridinium chlorochromate (PCC). Numerous studies were carried out to probe the reaction mechanism and at the same time optimize the reaction conditions. The reaction could be conducted with 1 equivalent of PCC and 1 equivalent of BF3·OEt2. Indications based on literature precedent were that the reaction may proceed via a sequential alcohol oxidation to the aldehyde followed by a putative Cr or boron catalyzed Claisen–Tishchenko-type reaction. Using this efficient methodology, we synthesized a family of novel diether-esters in very good yields; some of these molecules were subsequently tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In addition, we also disclose a new synthetic strategy for the synthesis of lactam macrocycles with potential biological activity. This methodology included the regioselective borylation of the ester substrate and a subsequent Suzuki–Miyaura coupling to obtain the desired lactam macrocycle.

ChemInform Abstract: Oxidative Esterification of Primary Alcohols with TEMPO/CaCl2/Oxone under Hydrous Conditions.

Abstract Symmetric esters are important compounds in the chemical industry, which creates demand for simple and efficient synthetic routes. Oxidative esterification is a promising method to achieve these aims. Here, we show that TEMPO/CaCl2/Oxone forms a convenient catalytic system for the synthesis of the aforementioned symmetric esters from primary alcohols in a biphasic dichloromethane–water solvent mixture. The substrate scope of the reaction method is complementary to those previously published and the terminal oxidant appears to play an important role. In addition, the method is shown to oxidize thiols preferentially over alcohol functional groups to give disulfide-bridged compounds.

Oxidative esterification of primary alcohols with TEMPO/CaCl2/Oxone under hydrous conditions

Symmetric esters are important compounds in the chemical industry, which creates demand for simple and efficient synthetic routes. Oxidative esterification is a promising method to achieve these aims. Here, we show that TEMPO/CaCl2/Oxone forms a convenient catalytic system for the synthesis of the aforementioned symmetric esters from primary alcohols in a biphasic dichloromethane–water solvent mixture. The substrate scope of the reaction method is complementary to those previously published and the terminal oxidant appears to play an important role. In addition, the method is shown to oxidize thiols preferentially over alcohol functional groups to give disulfide-bridged compounds.

Sequential alcohol oxidation/putative homo Claisen–Tishchenko-type reaction to give esters: a key process in accessing novel biologically active lactone macrocycles

We report an efficient methodology for the direct oxidative esterification of primary alcohols to diether-esters using pyridinium chlorochromate (PCC).

Silver nanoparticles embedded over mesoporous organic polymer as highly efficient and reusable nanocatalyst for the reduction of nitroarenes and aerobic oxidative esterification of alcohols

Silver nanoparticles (Ag-NPs) have been finely dispersed at the mesoporous organic polymer via post-synthetic chemical grafting over mesoporous poly-triallylamine (MPTA-1). The resulting Ag-MPTA-1 nanomaterial has been characterized by elemental analysis, powder x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA), EPR spectroscopy and AAS elemental analysis. The Ag-MPTA-1 acts as an efficient heterogeneous nanocatalyst in the reduction of substituted nitrobenzenes via transfer hydrogenation. The material also showed excellent catalytic activity in one-step catalytic oxidative esterification of primary alcohols using molecular oxygen as a green oxidant. The catalyst is air-stable, inexpensive, easy to prepare and reused several times without significant decrease in activity and selectivity.

Oxidative Esterification of Primary Alcohols with a Pd/Bi/Te Catalyst

Oxidative Esterification of Primary Alcohols with a Pd/Bi/Te Catalyst

Oxidant controlled Pd-catalysed selective oxidation of primary alcohols

The oxidant controlled palladium catalysed selective oxidation of primary alcohols to aldehydes or esters was investigated. The electronic properties of the benzylic alcohols and the structure of the oxidant are both important factors in controlling the selectivity between aldehydes and esters. A covalent benzyl ligand derived from BnCl provides η(3) coordination to the Pd centre. This covalent ligand is the key to the selective oxidative esterification of primary alcohols.

Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticles

Methyl esters were prepared by the clean, one-step catalytic esterification of primary alcohols using molecular oxygen as a green oxidant and a newly developed SiO2-supported gold nanoparticle catalyst. The catalyst was highly active and selective in a broad range of pressure and temperature. At 3 atm O2 and 130 °C benzyl alcohol was converted to methyl benzoate with 100% conversion and 100% selectivity in 4 h of reaction. This catalytic process is much “greener” than the conventional reaction routes because it avoids the use of stoichiometric environmentally unfriendly oxidants, usually required for alcohol oxidation, and the use of strong acids or excess of reactants or constant removal of products required to shift the equilibrium to the desired esterification product.

Facile and Efficient Oxidative Transformation of Primary Alcohols to Methyl Esters in Water Using Hypervalent Iodine(III) Reagents.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Facile and Efficient OxidativeTransformation of Primary Alcohols to Methyl Esters in Water UsingHypervalent Iodine(III) Reagents

A facile and direct oxidative esterification of primary alcohols in water using a combination of the hypervalent iodine(III) reagent, iodosobenzene (PhIO), and KBr has been developed. This methodology is expected to be environmentally benign since it uses a recyclable polymer-supported iodine(III) reagent in water.

ChemInform Abstract: Oxidative Esterification of Primary Alcohols by NaBrO3/NaHSO3 Reagent in Aqueous Medium.

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Oxidative Esterification of Primary Alcohols by NaBrO3/NaHSO3 Reagent in Aqueous Medium

Abstract NaBrO3 combined with NaHSO3 was found to be an efficent reagent for the oxidative esterification of primary alcohols. Thus, a variety of esters was prepared from primary alcohols, aldehydes, and acetals in aqueous medium under mild conditions. Treatment of α,ω-diols with NaBrO3/NaHSO3 reagent afforded the corresponding lactones and/or dicarboxylic acids in fair yields.