Transesterification Of Β-keto Esters Research Articles

Prussian Blue as an Efficient Catalyst for Rate Accelerations in the Transesterification of β-Ketoesters

Prussian blue triggered transesterification of ethylacetoacetate with various alcohols underwent efficiently. The reaction is mild, eco-friendly, and selective with good yields. The proposed reaction pathway depicts the formation of an intermediate by the interaction of β-ketoesters with catalytic site of the Prussian blue, followed by nucleophilic attack of the alcohol at the electrophilic center followed by successive elimination of the proton to give the product. Observed longer reaction times under conventional conditions reduced amazingly under sonication and microwave irradiation followed enhanced yield of products.

Preparation of mesoporous graphitic carbon nitride using hexamethylenetetramine as a new precursor and catalytic application in the transesterification of β-keto esters

Hexamethylenetetramine has been utilized as a low-cost and widely available precursor for the synthesis of mesoporous graphitic carbon nitride (CN-H-SBA15) through a nanocasting route. The synthesized CN-H-SBA15 material possesses a high surface area (788 m2 g−1), a large pore volume (0.68 cm3 g−1), and rich N content (N/C = 0.277). The characterization results of transmission electron microscopy and small-angle X-ray scattering illustrated that CN-H-SBA15 successfully replicated the ordered mesostructures of SBA-15. As a heterogeneous base catalyst, CN-H-SBA15 exhibits efficient and stable activity in the transesterification reactions of β-keto esters, affording a maximum conversion of n-butanol of 70% at 110 °C. The catalytically active sites are proposed as the tertiary amine species of CN-H-SBA15, as revealed by Fourier transform infrared and X-ray photoelectron spectroscopy. Furthermore, the catalytic performance in the transesterification reaction was compared with those of other previously reported catalysts; the results show that CN-H-SBA15 can be served as a promising heterogeneous catalyst towards the transesterification of β-keto esters.

A Simple Procedure for the Esterification and Transesterification Using <i>p</i>-Toluene Sulfonic Acid as Catalyst

Esterification of carboxylic acids and transesterification of β-ketoesters with alcohols have been developed by using catalytic amount ofp-toluene sulfonic acid (PTSA) to afford the corresponding esters in good yields.

Microwave-assisted solvent-free lipase catalyzed transesterification of β-ketoesters

Lipase-catalyzed transesterification was used as an efficient tool for the interconversion of β-ketoesters. Catalytic activity of commercial lipase B from Candida antarctica (Novozym 435) was evaluated in systems involving non activated acyl donors, and enhanced using microwave irradiation. Interestingly, the combination of CAL B in microwave irradiation worked excellent in solvent-free conditions, thus assuring a highly competitive and environment-friendly process with high yields (up to 96%) in competitive times (< 2h). The combination of biocatalysis with solvent-free systems and microwave assistance is currently scarcely used, and may represent a powerful synergy for preparative reactions.

An Efficient and Recyclable Silica Based Inorganic–Organic Hybrid Zinc Catalyst for Transesterification of β-Ketoesters

A new silica based inorganic–organic hybrid zinc catalyst was synthesized and its catalytic activity was investigated for transesterification of β-ketoesters. Polymer supported catalyst was characterized by various techniques such as surface area (BET), elemental and thermogravimetric analyses, FTIR, 13C CPMAS spectral studies and atomic absorption spectroscopy (AAS). The reaction proceeded smoothly in the presence of 0.04 mmol of catalyst in toluene at refluxing conditions. The catalyst revealed higher catalytic activity compared to homogeneous catalyst and was reused without appreciable loss in catalytic activity.

Bismuth(III) Chloride‐Catalyzed Highly Efficient Transesterification of β‐Keto Esters

AbstractBismuth(III) chloride was found to be an efficient catalyst for the transesterification of a variety of β‐keto esters with a wide range of alcohols to afford transesterified products in good to high yields in short reaction times (see Table).

ChemInform Abstract: Solvent-Free Microwave-Assisted Organic Reactions. Preparation of β-Keto Esters.

Abstract Microwave technique has been utilised in the preparation of β-keto esters. Two different procedures are described: transesterification of β-keto esters and ring opening of 2,2,6-trimethyl-1,3-dioxin-4-one.

Molecular Iodine in Ionic Liquid: A Green Catalytic System for Esterification and Transesterification

Esterification of carboxylic acids and transesterification of β-ketoesters with alcohols have been developed using a catalytic amount of iodine in polyethylene glycol (PEG) ionic liquid (IL 1000) to afford the corresponding esters in good yields. By simple separation of the ionic-liquid phase containing the iodine, the system of I2/IL 1000 can be reused several times.

Al(H2PO4)3: An Efficient and Effective Solid Acid Catalyst for Transesterification of β-keto Esters Under Solvent Free Condition

Al(H2PO4)3 is an efficient, cheap and reusable heterogeneous catalyst for transesterification of β-ketoesters with a variety of alcohols in moderate to good yields within a short reaction time under solvent free condition.

A Simple and Efficient Method for Transesterification of β-Keto Esters Catalyzed by Cesium Fluoride

Cesium fluoride is found to be an efficient and reusable catalyst for the transesterification of β-keto esters with various alcohols in good to high yields.

Transesterification of β-ketoesters catalyzed by hybrid materials based on silica sol–gel

This work shows an alternative process for β-ketoester transesterification using new silica-based hybrid materials as heterogeneous catalysts. The catalysts were synthesized using silica and 3-aminopropyltriethoxysilane or 1,1,1,3,3,3-hexamethyldisilazane as functionalizating agents. β-Ketoesters and alcohols were transesterified in refluxing toluene with reaction times between 4 h and 14 h. Different ketoesters with good performance were obtained. The influence of the catalysts and starting materials on the reaction rate was studied. In all cases, coproduct formation was not observed; the catalysts were recovered and reused without loss of catalytic activity.

Hexamethylenetetramine-Mediated Transesterification of β-Keto Esters

Treatment of methyl or ethyl p-keto esters with primary, secondary, or tertiary alcohols in the presence of a catalytic amount ofhexamethylenetetramine results in good to high yields of the corresponding esters.

Sustainable Transesterification of β‐Ketoesters Catalyzed by Amine Grafted on Silica Gel.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Transesterification over various zeolites under liquid-phase conditions

Abstract Transesterification of β-keto esters with a variety of alcohols to the corresponding β-keto esters has been carried out efficiently over aluminosilicates simply by refluxing in toluene under liquid-phase conditions. Aliphatic β-keto esters exhibit the higher reactivity than the aromatic and/or cyclic β-keto esters, whereas other esters such as α-keto esters, α,β-unsaturated esters, normal esters, and α-halo esters fail to undergo the transesterification. The reaction proceeds smoothly with primary alcohols than the tertiary-, cyclic-, and allylic alcohols. The large-pore zeolites such as Y, mordenite, and β show higher activity than the medium-pore ZSM-5 and the partial removal of framework aluminum from the large-pore zeolites by dealumination increases their activity. The aluminum containing mesoporous MCM-41 shows poor activity. Among the different solvents used toluene leads to the highest activity and the optimum catalyst concentration found was ca. 20 wt.% of the substrate. The activity increases with increasing reaction temperature. The reaction pathway consists of formation of acyl ketene intermediate by the interaction of β-keto esters with Bronsted acid sites of the catalyst, followed by nucleophilic attack of the alcohol at the electrophilic center and successive elimination of the proton to give the product.

Sodium Borohydride Reductionand Selective Transesterification of β-Keto Esters in aOne-pot Reaction under Mild Conditions

An efficient and simple one-pot method of preparing β-hydroxy esters by sodium borohydride reduction cum selective transesterification of β-keto esters under mild conditions is described.

Transesterification of β-ketoesters with alcohols catalyzed by montmorillonite K-10

Montmorillonite K-10 is an efficient reusable catalyst for the transesterification of ethyl/methyl β-ketoesters with various alcohols in good yields. The main advantages of the catalyst are easy operation in the workup and a more economical and environmentally benign procedure.

Solvent-Free Microwave-Assisted Organic Reactions Preparation of β-Keto Esters

Microwave technique has been utilised in the preparation of β-keto esters. Two different procedures are described: transesterification of β-keto esters and ring opening of 2,2,6-trimethyl-1,3-dioxin-4-one.

Synthesis of new baccatin III derivatives through transesterification of β-keto esters with a protected 10-deacetylbaccatin III

Synthesis of a new array of baccatin III derivatives bearing a β-keto ester appendage on C-13 is successfully achieved through transesterification of a wide range of β-keto esters with a protected baccatin III.

Simple and high yielding syntheses of β-keto esters catalysed by zeolites

Simple and high yielding syntheses of several β-keto esters, catalysed by zeolite Hβ are reported. The methods developed include condensation of aldehydes with ethyl diazoacetate and transesterification of β-keto esters with primary, secondary, allylic and benzylic alcohols etc., all catalysed by Hβ. It was further observed that under microwave irradiation the yields of many aromatic β-keto esters were enhanced appreciably.