3-Isobutylglutaric Acid Monoamide Synthesis via Liquid-Liquid Reaction
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Solution Overview
Problem
The existing methods for preparing pregabalin intermediate 3-isobutylglutaric acid monoamide face challenges such as high stirring resistance, safety hazards, urea crystallization causing clogging, low urea utilization, and low yield due to solvent-free and solid-liquid reaction processes.
Innovation Solution
A method involving the use of 3-isobutylglutaric acid and urea in a first organic solvent, followed by heating, cooling, pH adjustment with ion-exchange membrane caustic soda solution, separation, and extraction with a second organic solvent to achieve a liquid-liquid reaction system, reducing crystallization and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-free high-temperature reaction is employed, then the reaction can proceed without additional solvents, but the viscosity of the reaction system becomes too large causing large stirring resistance and safety hazards
Solution Approach 1:
The patent introduces an organic solvent as an intermediary substance to mediate between the reactants (3-isobutylglutaric acid and urea). This solvent acts as a medium that reduces the viscosity and stirring resistance of the reaction system, while still allowing the reaction to proceed efficiently. The solvent serves as a bridge that enables better mixing and heat transfer without being consumed in the reaction.
Solution Approach 2:
The patent changes the physical state parameters of the reaction system by introducing a solvent, which fundamentally alters the viscosity and flow characteristics of the reaction mixture. This parameter change transforms the system from a high-viscosity solvent-free state to a more manageable liquid state with appropriate stirring characteristics, thereby resolving the stirring resistance issue.
2Device complexity
If solvent-free reaction is used, then the process is simpler, but urea crystallizes on the reactor wall causing clogging of distillation outlet and exhaust gas line
Solution Approach 1:
The organic solvent acts as an intermediary that prevents urea crystallization on the reactor walls. By providing a liquid medium, the solvent ensures that urea remains dissolved or suspended during the reaction, preventing it from depositing and clogging the distillation outlet and exhaust gas lines. The solvent mediates between the reactants and the equipment, preventing harmful interactions.
Solution Approach 2:
The introduction of solvent changes the temperature-concentration profile of the reaction system, preventing urea from reaching its crystallization point on the reactor walls. The solvent acts as a thermal buffer and concentration diluent, maintaining parameters that prevent crystallization and subsequent clogging throughout the reaction and distillation process.
3Productivity
If solid-liquid reaction process is employed, then the reaction can proceed, but urea utilization rate is low and reaction is incomplete
Solution Approach 1:
The patent changes the reaction medium from solid-liquid to liquid-liquid by introducing an organic solvent. This parameter change improves the contact between urea and 3-isobutylglutaric acid, ensuring that urea remains in solution and is fully utilized in the reaction. The solvent creates a homogeneous reaction environment that eliminates the limitations of solid-liquid interfaces, thereby improving both reaction completion and urea utilization rate.
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 simplifies the reaction process, prevents clogging, increases urea utilization, and significantly enhances the yield of 3-isobutylglutaric acid monoamide, making it safer and more efficient.
Implementation Method 1
adding 3-isobutylglutaric acid and urea to a first organic solvent
Implementation Method 2
heating to a temperature of 100-140° C., and refluxing while maintaining the temperature
Implementation Method 3
cooling a mixture obtained in step 2) to 70-90° C., then adding water
Implementation Method 4
adding ion-exchange membrane caustic soda solution to adjust the pH value to 11.0-14.0
Implementation Method 5
adding an acid into an aqueous layer to adjust the pH value to 1.0-3.0
Implementation Method 6
extracting the solution obtained in step 6) with a second organic solvent
Implementation Method 7
distilling an organic layer obtained by extraction under reduced pressure to remove 0.5-0.6 V of organic solvent
Implementation Method 8
cooling to 0-15° C. and crystallizing to obtain 3-isobutylglutaric acid monoamide
Data Source
AI summary
Provided is a method for preparing a pregabalin intermediate 3-isobutylglutaric acid monoamide. The method comprises: 1) adding 3-isobutylglutaric acid and urea into a first organic solvent; 2) keeping warm and refluxing when heated to 100-140° C.; 3) adding water when cooled to 70-90° C.; 4) adding an ion membrane alkaline when cooled to 40-60° C., adjusting the pH to 11.0-14.0, then keeping warm at 40-60° C.; 5) when finished keeping warm, removing an organic layer; 6) adding an acid into the water layer to adjust the pH to 1.0-3.0; 7) extracting the solution acquired in step 6) by using a second organic solvent of a total volume of V, vacuum distilling 0.5-0.6 V of the organic solvent from an organic layer acquired by extraction; and 8) cooling to 0-15° C. and crystallizing to acquire 3-isobutylglutaric acid monoamide.