Solvent-Free Carboxylic Acid Anhydride Synthesis Using Group 2 Metal Catalysts
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Solution Overview
Problem
Conventional methods for producing carboxylic acid anhydrides and esters are inefficient and costly due to the use of solvents, limited substrate generality, and issues with hygroscopic materials and byproducts, leading to low yields and purification challenges.
Innovation Solution
A method involving the reaction of carboxylic acids with compounds like di-t-butyl dicarbonate in the presence of Group 2 metal compounds with ionic ligands at near room temperature, eliminating the need for solvents and allowing for broader substrate use, thereby enhancing yield and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solvent is added to react di-t-butyl dicarbonate and carboxylic acid, then the reaction progresses, but the cost and efficiency are reduced due to greater solvent amount
Solution Approach 1:
The invention extracts and eliminates the solvent from the reaction system. By using a solid-supported catalyst (magnesium chloride on silica gel or alumina), the reaction can proceed without adding solvent, thus resolving the contradiction between reaction progress and solvent amount.
Solution Approach 2:
The invention introduces a solid-supported catalyst as an intermediary. The magnesium chloride is immobilized on silica gel or alumina, which acts as a mediator to facilitate the reaction between di-t-butyl dicarbonate and carboxylic acid without requiring solvent, thereby improving both reaction reliability and reducing solvent quantity.
2Ease of manufacture
If alkali metal acetate is used as catalyst, then carboxylic acid ester can be produced, but the material handling becomes difficult due to high hygroscopicity
Solution Approach 1:
The invention extracts the problematic hygroscopic alkali metal acetate catalyst from the system and replaces it with a solid-supported magnesium chloride catalyst. This substitution eliminates the handling difficulties associated with hygroscopic materials while maintaining the ability to produce carboxylic acid esters.
Solution Approach 2:
The solid-supported catalyst can be used in stoichiometric or catalytic amounts and does not require special handling precautions for hygroscopicity. The catalyst system is designed to be practical and easy to handle, replacing the problematic alkali metal acetate with a more operationally convenient alternative.
3Productivity
If high reaction temperature (80°C) is used, then reaction rate increases, but the products become colored and byproducts increase
Solution Approach 1:
The invention changes the reaction parameters by using a solid-supported catalyst that enables the reaction to proceed at lower temperatures (room temperature or slightly elevated temperatures). This parameter change maintains adequate reaction rates while preventing the formation of colored products and minimizing byproduct formation, thus resolving the contradiction between productivity and manufacturing precision.
4Manufacturing precision
If conventional purification method is used, then (meth)acrylic acid ester can be extracted, but it is difficult to separate from the ester derived from adduct
Solution Approach 1:
The invention applies beforehand cushioning by preventing the formation of adducts in the first place. By conducting the reaction at lower temperatures and using a solid-supported catalyst, the formation of side products is minimized, which simplifies the purification process and reduces the complexity of separating desired ester from adduct-derived esters.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method produces carboxylic acid anhydrides and esters with high yields and improved cost-effectiveness by operating without solvents and at near room temperature, broadening substrate applicability and reducing byproduct formation.
Implementation Method 1
reacting a carboxylic acid with a compound represented by formula (I) below in the presence of a Group 2 metal compound having an ionic ligand containing an oxygen atom
Implementation Method 2
reacting the carboxylic acid anhydride with alcohol
Data Source
AI summary
Provided is a production method whereby corresponding carboxylic acid anhydrides and carboxylic acid esters can be obtained at high yield from various carboxylic acids even without a solvent and near room temperature. A method for producing a carboxylic acid anhydride represented by formula (II), the method comprising reacting a compound represented by formula (I) and a carboxylic acid in the presence of a Group II metal compound having an ionic ligand containing an oxygen atom. A method for producing a carboxylic acid ester, the method comprising reacting a carboxylic acid anhydride produced by the aforementioned method and an alcohol. In formula (I), R1 represents a C1-20 hydrocarbon group. In formula (II), R2 represents a C1-20 hydrocarbon group.