Dialkyl Carbonate Purification via Alkoxy Alkanol Conversion
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Solution Overview
Problem
The presence of alkoxy alkanol impurities in dialkyl carbonate streams interferes with subsequent production processes, leading to product loss and separation issues, particularly when attempting to produce diphenyl carbonate or polycarbonate, as these impurities react with phenol or act as 'poisons' in polymerization, necessitating a method to efficiently remove them without significantly decreasing the overall yield of dialkyl carbonate.
Innovation Solution
A process involving the use of a catalyst to convert alkoxy alkanol impurities into carbonate ethers, which can be easily separated from dialkyl carbonate, followed by recycling streams to distillation columns to recover pure dialkyl carbonate and alkanediol, thereby preventing yield reduction and facilitating further purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If specific distillation techniques are used to remove alkoxy alkanol impurities, then purity of dialkyl carbonate is improved, but device complexity and processing time increase
Solution Approach 1:
The patent changes the chemical state of the impurity by converting alkoxy alkanol into a different compound through reaction with dialkyl carbonate. This parameter change (chemical transformation) enables easier separation through standard distillation, avoiding the need for complex specialized distillation techniques while maintaining high purity standards.
Solution Approach 2:
The patent introduces an intermediary reaction step where alkoxy alkanol reacts with dialkyl carbonate to form a new compound. This intermediary transformation converts the difficult-to-separate impurity into a form that can be readily removed by conventional distillation, simplifying the overall separation process.
2Manufacturing precision
If multiple distillation steps are used to separate alkoxy alkanol from dialkyl carbonate, then purity is improved, but productivity decreases
Solution Approach 1:
The patent performs a preliminary chemical conversion of the impurity before the main separation operation. By converting alkoxy alkanol to a different compound in advance, the subsequent distillation becomes a single-step process rather than requiring multiple sequential separations, thereby maintaining purity while improving production rate.
Solution Approach 2:
The patent extracts the separation problem by transforming the impurity into a different chemical form that can be more easily removed. This extraction approach converts a complex multi-step separation challenge into a simpler single-step distillation process, enhancing productivity.
3Object-generated harmful factors
If alkoxy alkanol impurity is removed by specific distillation techniques, then harmful factors are reduced, but loss of substance increases
Solution Approach 1:
The patent converts the harmful impurity (alkoxy alkanol) into a beneficial outcome by reacting it with dialkyl carbonate to form a new compound that can be easily separated. This transformation eliminates the harmful effect of the impurity while allowing recovery of most dialkyl carbonate, thus reducing substance loss compared to direct distillation methods.
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 effectively removes alkoxy alkanol impurities, preventing interference in downstream processes and maintaining high dialkyl carbonate yields by converting them into separable carbonate ethers, allowing for the recovery of pure dialkyl carbonate and alkanediol, thus enhancing the overall efficiency of the production process.
Implementation Method 1
A process involving the use of a catalyst to convert alkoxy alkanol impurities into carbonate ethers
Implementation Method 2
recycling streams to distillation columns to recover pure dialkyl carbonate and alkanediol
Data Source
AI summary
The invention relates to a process for the preparation of an alkanediol and a dialkyl carbonate comprising:reacting an alkylene carbonate and an alkanol in the presence of a transesterification catalyst to obtain a reaction mixture comprising dialkyl carbonate, unconverted alkanol, alkanediol, unconverted alkylene carbonate and an alkoxy alkanol impurity; andsubjecting the reaction mixture to distillation in a series of steps.