2-Chloro-3-Trifluoromethylpyridine Separation via Distillation and Crystallization
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Solution Overview
Problem
Existing methods for producing 2-chloro-3-trifluoromethylpyridine result in low yields of this compound, making it costly to produce in sufficient quantities while producing 2,5-chloro-trifluoromethylpyridine in high yields.
Innovation Solution
A method involving the reaction of β-methylpyridine or β-trifluoromethylpyridine with chlorine and anhydrous hydrogen fluoride in the presence of a catalyst and inert diluent, followed by distillation and crystallization to separate and purify 2-chloro-3-trifluoromethylpyridine, allowing for high yield and cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods (PD-1 to PD-5) are used to produce chloro-β-trifluoromethylpyridine compounds, then 2,5-CTF is obtained in high yield, but 2,3-CTF is obtained only in slight amounts
Solution Approach 1:
The patent divides the production process into two independent stages: (1) a chlorination reaction stage that produces a mixture of 2,5-CTF and 2,3-CTF, and (2) a separation stage that isolates 2,3-CTF from the reaction mixture through distillation and crystallization. This segmentation allows the reaction to proceed with high overall productivity while enabling sufficient recovery of 2,3-CTF that would otherwise be lost.
Solution Approach 2:
The patent extracts 2,3-CTF from the reaction mixture by taking advantage of its specific physical properties (boiling point and crystallization behavior). Through fractional distillation and selective crystallization, 2,3-CTF is separated and recovered from the mixture where it co-exists with 2,5-CTF, thereby increasing the quantity of 2,3-CTF obtained without affecting the main production of 2,5-CTF.
2Quantity of substance
If alternative production methods are adopted to increase 2,3-CTF yield, then 2,3-CTF production improves, but production cost increases
Solution Approach 1:
The patent employs self-service by utilizing the inherent physical properties of 2,3-CTF (its boiling point and crystallization characteristics) to achieve separation and purification. The process uses simple distillation and crystallization operations that rely on the compound's own properties rather than requiring expensive specialized equipment or complex multi-step synthesis routes, thereby maintaining cost-effectiveness while increasing 2,3-CTF recovery.
Solution Approach 2:
The patent changes physical parameters (temperature and pressure conditions during distillation and crystallization) to optimize the separation of 2,3-CTF. By carefully controlling these parameters, the process achieves high recovery of 2,3-CTF using conventional, cost-effective equipment rather than requiring expensive alternative production methods.
3Ease of manufacture
If simple separation methods are used, then production cost is reduced, but separation precision of 2,3-CTF from reaction mixture is insufficient
Solution Approach 1:
The patent applies preliminary action by performing fractional distillation first to concentrate 2,3-CTF in a specific fraction, followed by crystallization to achieve final purification. This two-step preliminary separation approach ensures high purity of 2,3-CTF while using simple, cost-effective operations that can be easily implemented in conventional manufacturing settings.
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 enables the production of 2-chloro-3-trifluoromethylpyridine in high yield and purity, suitable for use as an intermediate in medicines and agrochemicals, with improved cost efficiency.
Implementation Method 1
reacting a β-methylpyridine compound (I) with chlorine and anhydrous HF in a vapor phase in the presence of a catalyst and an inert diluent
Implementation Method 2
purifying 2,3-CTF from a distillation product fractionated in a distillation process
Implementation Method 3
allowing for high yield and cost-effective production
Data Source
AI summary
A method for separating and purifying 2-chloro-3-trifluoromethylpyridine useful as an intermediate for medicines, agrochemicals, and the like, said method including: (1 ) producing chloro β-trifluoromethylpyridine compounds by allowing a β-methylpyridine compound to react with chlorine and hydrogen fluoride in a reaction apparatus, allowing a β-trifluoromethylpyridine compound to react with chlorine in a reaction apparatus, or allowing a chloro β-trichloromethylpyridine compound to react with hydrogen fluoride in a reaction apparatus, ( 2) fractionating a liquid mixture containing chloro β-trifluoromethylpyridine compounds from the reaction apparatus, and ( 3) separating and purifying 2-chloro-3-trifluoromethylpyridine from the liquid mixture.