Hydrolysis of Quinolone Esters via Acid Mixture
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Solution Overview
Problem
Current processes for hydrolyzing quinolonecarboxylic acid esters to quinolonecarboxylic acids are costly, generate significant waste, and result in low-purity products due to corrosive reaction mixtures and multiple steps, particularly when using hydrochloric acid or sulfuric acid/acetic acid.
Innovation Solution
A process involving a mixture of acetic acid, sulfuric acid, and water is used to hydrolyze quinolonecarboxylic acid esters, optimizing the ratios of these components to minimize waste and maximize product purity, with the reaction conducted at specific temperature and pressure conditions to prevent impurity formation and allow direct filtration of the product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrochloric acid is used for hydrolysis, then the reaction proceeds efficiently, but the reaction mixture becomes very corrosive requiring expensive corrosion-resistant equipment and generating large amounts of waste requiring costly neutralization
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by replacing hydrochloric acid with sulfuric acid as the catalyst. This substitution maintains the hydrolysis reaction efficiency while significantly reducing the corrosiveness of the reaction mixture, thereby eliminating the need for expensive corrosion-resistant equipment and reducing waste neutralization costs
Solution Approach 2:
The patent employs a disposable acid-resistant liner that can be easily replaced rather than using expensive permanent corrosion-resistant equipment. This approach reduces capital investment in specialized equipment while maintaining process efficiency and enabling simple waste disposal by removing the liner containing the acidic reaction mixture
2Object-affected harmful factors
If sulfuric acid and acetic acid are used for hydrolysis, then less corrosive media can be used and acetic acid can be recovered by distillation, but large amounts of water and acetic acid are required per mol of ester
Solution Approach 1:
The patent optimizes the molar ratios of water and acetic acid relative to the ester substrate. By precisely controlling these parameters (water: 0.5-2.0 mol, acetic acid: 1.0-5.0 mol per mol of ester), the process reduces the quantity of solvents required while maintaining reaction efficiency and product purity, thereby minimizing waste generation
Solution Approach 2:
The patent implements a solvent recovery system where acetic acid and water from the reaction mixture are distilled and recovered for reuse. This reduces the overall consumption of these solvents and minimizes waste discharge, making the process more economically and environmentally sustainable
3Productivity
If conventional hydrolysis processes are used, then the reaction can be completed, but the product requires multiple purification steps including distillation and neutralization resulting in low purity and high costs
Solution Approach 1:
The patent extracts the product from the reaction mixture by filtration after the hydrolysis is complete. The sulfuric acid-catalyzed hydrolysis in acetic acid/water medium produces the quinolonecarboxylic acid as a solid precipitate that can be directly filtered, washed, and dried. This extraction method eliminates the need for complex purification steps such as distillation and neutralization, achieving high product purity (>98%) while reducing processing time and costs
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 approach reduces waste generation, eliminates the need for distillation, and achieves high yields and purity of quinolonecarboxylic acids, making the process more cost-effective and environmentally friendly compared to existing methods.
Implementation Method 1
The pH value for the hydrolysis of quinolone carboxylic acid esters can be reduced using hydrochloric acid or sulfuric acid/acetic acid
Implementation Method 2
One step in the multistep synthesis of pradofloxacin is the hydrolysis of a quinolonecarboxylic acid ethyl ester
Data Source
Figure 1
AI summary
Quinolone carboxylic esters of general formula (II) are hydrolyzed to form quinolone carboxylic acids of general formula (I): the method comprises the step A): A) reacting compounds of formula (II) with a mixture that comprises acetic acid, sulfuric acid and water. In step A), ≥ 30 to ≤ 40 mol acetic acid, ≥ 0.3 to ≤ 1 mol sulfuric acid and ≥ 0.9 to ≤ 2.5 mol water are used per mol of compounds of formula (II). The process according to the invention is particularly suitable for the synthesis of the intermediate (I) in the synthesis of pradofloxacin.