Continuous Flow Synthesis of Methylene Bis-(Dialkylamino-dithioformate
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Solution Overview
Problem
Conventional processes for synthesizing methylene bis-(dialkylamino-dithioformate are inefficient due to long reaction times, high viscosity, and complex operations, leading to low yields and poor product quality, with existing methods requiring multiple steps and solvents that complicate temperature control and increase side reactions.
Innovation Solution
A one-step process using a continuous flow tubular reactor where dialkylamine, carbon disulfide, and sodium hydroxide are simultaneously supplied, with dichloromethane added, allowing for rapid mixing and heat removal, reducing side reactions and improving yield and product quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-step process is used to prepare methylene bis-(dialkylamino-dithioformate), then the reaction can be completed with proper temperature control, but the reaction time is prolonged and productivity is reduced
Solution Approach 1:
The patent combines two separate reaction steps into a single continuous process. The first step (reaction of dialkylamine with carbon disulfide in sodium hydroxide solution) and the second step (alkylation with dichloromethane) are merged into one continuous flow reactor system, eliminating the intermediate isolation step and reducing total reaction time while maintaining temperature control through continuous operation
Solution Approach 2:
The patent implements continuous flow processing where reactants are continuously fed into the reactor, reaction occurs continuously, and products are continuously removed. This continuous operation eliminates idle time between batches and maintains optimal reaction conditions throughout the process, significantly improving productivity compared to discontinuous batch processing
2Stability of the object's composition
If solvents like toluene and isopropanol are added to reduce viscosity, then mixing homogeneity is improved, but the yield decreases and additional solvent recovery operations are required
Solution Approach 1:
The patent removes the harmful element (additional solvents like toluene and isopropanol) from the reaction system. By using continuous flow processing, the reaction achieves adequate mixing without requiring large amounts of diluent solvents, thereby eliminating the need for solvent recovery operations and avoiding yield loss associated with solvent removal
Solution Approach 2:
The patent changes the operating parameters of the reaction system by implementing continuous flow processing with controlled residence time and continuous stirring. This parameter change allows the reaction to proceed with improved mixing homogeneity without adding excess solvents, thus maintaining high yield while achieving uniform composition
3Ease of operation
If the reaction temperature is increased to reduce viscosity, then mixing is improved, but side reactions increase and product quality deteriorates
Solution Approach 1:
The patent implements dynamic control of reaction conditions through continuous flow processing. The system maintains optimal mixing through continuous agitation and controlled flow rates, while the reaction temperature is dynamically maintained within the optimal range (0-50°C) to prevent side reactions. The continuous removal of heat of reaction prevents localized overheating that would lead to poor product quality
Solution Approach 2:
The continuous flow system provides inherent feedback control where the continuous monitoring and adjustment of flow rates and temperature maintain optimal reaction conditions. The system automatically responds to maintain stable operation, preventing the temperature excursions that would cause side reactions and quality deterioration
4Reliability
If multiple vacuum distillation operations are performed to improve product color, then product quality is enhanced, but the number of operations increases and complexity rises
Solution Approach 1:
The patent combines multiple purification steps into a single integrated continuous process. The continuous flow reactor system performs reaction and purification in one operation, eliminating the need for separate repeated vacuum distillation steps. The continuous operation inherently provides better product quality with fewer discrete operations, reducing overall process complexity
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 process significantly shortens reaction time, increases yield, and enhances product quality by achieving homogeneous mixing and precise temperature control, resulting in a more efficient and cost-effective synthesis of methylene bis-(dialkylamino-dithioformate with improved color and reduced impurities.
Implementation Method 1
Because the reaction releases a great amount of heat, CS2 is added dropwise; furthermore, the dropping time is comparatively long, and a relatively low temperature should be maintained for the reaction
Implementation Method 2
After completion of the reaction, the mixture is slowly heated to not higher than 65° C. to expel unreacted carbon disulfide
Data Source
AI summary
A process for preparing methylene bis-(dialkylamino-dithioformate) in one step includes: simultaneously feeding all or part of four raw materials: dialkylamine, an aqueous solution of sodium hydroxide, dichloromethane and carbon disulfide through a constant-flow pump into a continuous flow reactor; performing the reactions in the continuous flow reactor under a temperature of 10 to 100° C. and with a residence time of 10 to 100 s; simply separating of the obtained reaction products to give the final product. The process synthesizes the product in one step by using the continuous flow reactor. The rapid mass transfer and heat transfer in the continuous flow reactor promote the main reaction, reduce side reactions, improve the product color, and shorten the operation time. Moreover, the yield is relatively high and the quality of the final product meets the requirements.