N-Vinyl Carboxylic Acid Amide Purification by Two-Stage Crystallization
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Solution Overview
Problem
Existing methods for producing N-vinyl carboxylic acid amide monomers face challenges in efficiently purifying and achieving high polymerizability, leading to low productivity and poor polymerization results due to the presence of impurities and inefficient purification techniques.
Innovation Solution
A method combining cooling crystallization with solvent crystallization using methyl ethyl ketone and an aliphatic hydrocarbon with 6 to 7 carbon atoms, including steps of melting, precipitation, and subsequent dissolution in a mixed solvent for effective purification of N-vinyl carboxylic acid amide monomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure crystallization is used to purify N-vinyl carboxylic acid amide, then high polymerizability is achieved, but equipment investment is large and productivity is poor unless large-scale production is carried out
Solution Approach 1:
The invention changes the purification parameters by using a specific solvent system (carboxylic acid amide and water in a weight ratio of 95:5 to 50:50) and controlling crystallization temperature (0°C to 40°C), replacing the need for expensive pressure crystallization equipment while achieving high purity monomer with excellent polymerizability
Solution Approach 2:
The invention introduces a solvent system comprising carboxylic acid amide and water as an intermediary medium to facilitate purification through controlled crystallization, avoiding the need for complex pressure crystallization equipment while achieving the desired purification effect
2Manufacturing precision
If solvent crystallization using alcohol and aliphatic hydrocarbon is used to purify N-vinyl carboxylic acid amide, then purification is achieved, but the amount of poor solvent used is large and volumetric efficiency is low
Solution Approach 1:
The invention optimizes the solvent composition parameters by using carboxylic acid amide and water in a specific weight ratio range (95:5 to 50:50), which improves purification efficiency while reducing the volume of solvents required compared to traditional alcohol-hydrocarbon systems
Solution Approach 2:
The invention uses a composite solvent system comprising carboxylic acid amide and water, which combines the advantages of both solvents to achieve effective purification with reduced solvent volume, improving volumetric efficiency while maintaining high purity
3Productivity
If conventional purification methods are used, then N-vinyl carboxylic acid amide is obtained, but impurities such as unreacted N-(1-alkoxyethyl)carboxylic acid amide and carboxylic acid amide remain, making distillation difficult
Solution Approach 1:
The invention converts the similarity in physical properties between the monomer and impurities (which makes distillation difficult) into an advantage by using a solvent system where the monomer and impurities exhibit different solubilities and crystallization behaviors, enabling effective purification through crystallization rather than distillation
Solution Approach 2:
The invention utilizes phase transition (crystallization) to purify the monomer by controlling the temperature and solvent composition, causing the pure monomer to crystallize while impurities remain in the mother liquid, achieving high purity without requiring distillation
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
The method produces a highly polymerizable N-vinyl carboxylic acid amide monomer with high purity and improved productivity, enabling efficient polymerization and utilization in various applications.
Implementation Method 1
a step of melting a crude N-vinyl carboxylic acid amide monomer comprising 50 to 88 mass % of an N-vinyl carboxylic acid amide monomer by heating
Implementation Method 2
followed by cooling for precipitation (cooling crystallization)
Implementation Method 3
a step of further dissolving the N-vinyl carboxylic acid amide monomer crystals separated in the step (A) in a mixed solvent of methyl ethyl ketone and an aliphatic hydrocarbon having 6 to 7 carbon atoms
Implementation Method 4
then performing crystallization (solvent crystallization)
Data Source
AI summary
A method for producing a highly polymerizable N-vinyl carboxylic acid amide monomer includes (A) melting a crude N-vinyl carboxylic acid amide monomer including 50 to 88 mass % of an N-vinyl carboxylic acid amide monomer by heating, followed by cooling for precipitation, and subjecting precipitated N-vinyl carboxylic acid amide monomer crystals to solid-liquid separation, and (B) further dissolving the N-vinyl carboxylic acid amide monomer crystals separated in step (A) in a mixed solvent of methyl ethyl ketone and an aliphatic hydrocarbon having 6 to 7 carbon atoms, then performing crystallization, performing solid-liquid separation, and recovering an N-vinyl carboxylic acid amide monomer purified product, wherein a mass ratio of methyl ethyl ketone/N-vinyl carboxylic acid amide monomer crystal in step (B) is 0.01 to 0.5, and a mass ratio of aliphatic hydrocarbon having 6 to 7 carbon atoms/N-vinyl carboxylic acid amide monomer crystal in step (B) is 0.5 to 3.0.