Pyrazolinone Salt Synthesis via Azeotropic Dehydration
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Solution Overview
Problem
Current methods for producing pyrazolinone derivatives suffer from low yields and inefficiencies, particularly in the dehydration steps and water management during the synthesis process.
Innovation Solution
A method involving a two-step process with azeotropic dehydration under reduced pressure, using an alkali metal hydroxide and a hydrocarbon solvent, followed by a third step with a specific sulfonic acid ester, to produce pyrazolinone derivatives with improved yields and reduced water content, thereby minimizing byproducts and optimizing the reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dehydration methods are used in pyrazolinone synthesis, then the process is simpler, but the yield is low and water content remains high
Solution Approach 1:
The synthesis process is divided into distinct stages: initial reaction phase, dehydration phase under reduced pressure, and final product isolation. This segmentation allows optimization of each stage independently, particularly the dehydration step which uses reduced pressure (5-50 mmHg) to efficiently remove water and drive the reaction forward, thereby improving yield without excessive complexity
Solution Approach 2:
The invention changes key process parameters including operating under reduced pressure (5-50 mmHg), controlling temperature ranges (20-100°C), and maintaining specific water content levels (0.8 wt% or less). These parameter changes optimize the dehydration efficiency and reaction equilibrium, directly improving yield while keeping the process manageable
2Productivity
If water content is not controlled during reaction, then the process is easier to operate, but unwanted rearrangements occur and yield decreases
Solution Approach 1:
The process incorporates monitoring and control of water content during the reaction, maintaining it at 0.8 wt% or less. This feedback control prevents unwanted rearrangements of the pyrazolinone derivative that occur in the presence of excess water, thereby improving yield while the automated dehydration system keeps operational complexity reasonable
Solution Approach 2:
The dehydration step is performed preliminarily and systematically under reduced pressure before the main reaction completes, proactively removing water to prevent rearrangements. This preliminary water removal strategy ensures high yield without requiring complex real-time intervention during the reaction
3Manufacturing precision
If azeotropic dehydration under reduced pressure is used, then water content is reduced to 0.8 wt% or less improving yield, but the equipment and process become more complex
Solution Approach 1:
The invention utilizes azeotropic dehydration where water and hydrocarbon solvent form an azeotrope that vaporizes at a specific composition. Under reduced pressure (5-50 mmHg), this azeotrope forms and vaporizes, allowing continuous water removal. The phase transition approach achieves precise water content control (0.8 wt% or less) using standard distillation equipment, minimizing the need for specialized complex apparatus
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 enhances the yield of pyrazolinone derivatives by controlling water content and reaction conditions, suppressing unwanted rearrangements and improving the overall efficiency of the synthesis process.
Implementation Method 1
a first step of dehydrating a mixture containing a hydrocarbon solvent and an alkali metal hydroxide
Implementation Method 2
the second step is a step of reacting the mixture dehydrated in the first step with a compound represented by formula (2) while performing azeotropic dehydration under reduced pressure at a temperature in the range of 20 to 100° C.
Implementation Method 3
a second step of reacting the mixture dehydrated in the first step with a compound represented by formula (2)
Implementation Method 4
performing azeotropic dehydration under reduced pressure at a temperature in the range of 20 to 100° C.
Implementation Method 5
adjusting the amount of water contained in the reaction solution in the second step to 0.8 wt % or less
Data Source
AI summary
A salt represented by formula (4) produced viaa first step of dehydrating a mixture containing a hydrocarbon solvent and an alkali metal hydroxide represented by formula: A+ OH−, anda second step or reacting the mixture dehydrated in the first step with a compound represented by formula (2) is useful for producing an active ingredient of a plant disease control agent.