1,1,1,2,3-Pentachloropropane Synthesis via Segmented Zones
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Solution Overview
Problem
Current processes for producing high purity chlorinated alkane compounds, such as 1,1,1,2,3-pentachloropropane, face challenges in minimizing impurities and achieving efficient, selective, and reliable industrial-scale synthesis due to issues like impurity formation, catalyst poisoning, and separation difficulties, particularly in continuous operations.
Innovation Solution
A three-step process involving telomerisation, dehydrochlorination, and chlorination, where ethylene reacts with carbon tetrachloride to produce 1,1,1,3-tetrachloropropane, which is then converted to 1,1,3-trichloropropene and further chlorinated to 1,1,1,2,3-pentachloropropane, with controlled molar ratios and treatment steps like distillation and aqueous treatment to manage impurity profiles and enhance purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional multi-step processes are used to produce chlorinated alkane compounds, then industrially acceptable product volumes can be achieved, but cumulative side reactions generate unacceptable impurities
Solution Approach 1:
The synthesis process is divided into three distinct reaction zones (principal alkylation zone, dehydrochlorination zone, chlorination zone) that operate independently with separate catalysts and controlled residence times. This segmentation prevents cumulative impurity formation by isolating side reactions in each zone while maintaining high productivity through continuous operation.
Solution Approach 2:
The process controls the degree of conversion at each reaction stage to prevent excessive formation of unwanted by-products before they accumulate. By managing conversion levels in the alkylation and dehydrochlorination zones, the process preliminarily prevents impurity formation that would otherwise require extensive downstream purification.
2Productivity
If high conversion is achieved in continuous processes, then productivity increases, but impurity formation increases and catalyst life decreases
Solution Approach 1:
Different catalysts are used in each reaction zone, with the principal alkylation zone using a first catalyst, the dehydrochlorination zone using a second catalyst, and the chlorination zone using a third catalyst. This segmentation protects each catalyst from poisoning by impurities generated in other zones, extending catalyst life while maintaining high conversion rates.
Solution Approach 2:
The process uses intermediate purification steps between reaction zones to remove catalyst poisons and impurities that would otherwise accumulate and deactivate catalysts. This intermediary treatment maintains catalyst activity and extends catalyst life in continuous high-conversion operation.
3Manufacturing precision
If distillation steps are used to remove impurities, then product purity improves, but process complexity and difficulty of separation increase
Solution Approach 1:
The process incorporates preliminary removal of catalysts and impurities from reaction zones before subsequent distillation steps. By removing catalysts in the principal alkylation zone and managing impurity profiles in the dehydrochlorination zone, the process reduces the burden on downstream distillation operations, simplifying the overall separation process while achieving high product purity.
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 achieves high purity 1,1,1,2,3-pentachloropropane with improved selectivity and yield, reducing impurity formation and extending catalyst life, enabling continuous industrial manufacture with enhanced product quality.
Implementation Method 1
providing a reaction mixture comprising ethylene, carbon tetrachloride and a catalyst in a principal alkylation zone to produce 1,1,1,3-tetrachloropropane
Implementation Method 2
contacting the 1,1,1,3-tetrachloropropane feedstock with a catalyst in a dehydrochlorination zone to produce a reaction mixture comprising 1,1,1,3-tetrachloropropane and 1,1,3-trichloropropene
Implementation Method 3
contacting the 1,1,3-trichloropropene feedstock with chlorine in a reaction zone to produce a reaction mixture containing 1,1,1,2,3-pentachloropropane
Implementation Method 4
treating the reaction mixture obtained in step 3-a) by extracting to obtain the 1,1,1,2,3-pentachloropropane product
Data Source
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AI summary
Disclosed is a process for preparing a highly pure 1,1,1,2,3-pentachloropropane product, comprising 1-a) providing a reaction mixture comprising ethylene, carbon tetrachloride and a catalyst in a principal alkylation zone to produce 1,1,1,3- tetrachloropropane in the reaction mixture, and 1- b) treating the reaction mixture obtained in step 1-a) to obtain a 1,1,1,3-tetrachloropropane feedstock; 2- a) contacting the 1,1,1,3-tetrachloropropane feedstock with a catalyst in a dehydrochlorination zone to produce a reaction mixture comprising 1,1,1,3-tetrachloropropane and 1,1,3-trichloropropene, and 2- b) treating the reaction mixture obtained in step 2-a) to obtain a 1,1,3-trichloropropene feedstock; 3- a) contacting the 1,1,3-trichloropropene feedstock with chlorine in a reaction zone to produce a reaction mixture containing 1,1,1,2,3-pentachloropropane and 1,1,3-trichloropropene, the reaction zone being different from the dehydrochlorination zone, and 3-b) treating the reaction mixture obtained in step 3-a) to obtain the highly pure 1,1,1,2,3-pentachloropropane product.