Dialkyl Carbonate Purification via Cyclic Ether Control
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Solution Overview
Problem
Conventional methods for producing dialkyl carbonate and diol from cyclic carbonate and aliphatic monohydric alcohol result in high levels of carbonate ether impurities, which hinder the production of high-purity dialkyl carbonate and colorless, high molecular weight aromatic polycarbonate.
Innovation Solution
A method involving a transesterification reaction between a cyclic carbonate with reduced cyclic ether content and an aliphatic monohydric alcohol, followed by separation of dialkyl carbonate and diol, where the cyclic carbonate contains 0.1 to 3,000 ppm cyclic ether and the dialkyl carbonate contains no more than 10,000 ppm carbonate ether, to minimize carbonate ether content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transesterification methods are used to produce dialkyl carbonate, then production efficiency is maintained, but carbonate ether impurity content increases to unacceptable levels
Solution Approach 1:
The patent applies preliminary action by pre-purifying the cyclic carbonate raw material to reduce cyclic ether content before the transesterification reaction. This preliminary purification step prevents the formation of excessive carbonate ether impurities during reaction, thereby improving product purity without requiring complex post-reaction treatment that would reduce productivity.
Solution Approach 2:
The patent employs extraction by removing the harmful cyclic ether component from the cyclic carbonate raw material through purification processes before reaction. By extracting this impurity in advance, the subsequent transesterification produces dialkyl carbonate with significantly reduced carbonate ether content, resolving the contradiction between purity and efficiency.
2Manufacturing precision
If high-purity dialkyl carbonate is produced by reducing cyclic ether content in raw materials, then product quality improves, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by implementing purification of cyclic carbonate to reduce cyclic ether content before the transesterification reaction. This advance preparation ensures high purity dialkyl carbonate product while using relatively simple and conventional purification techniques, avoiding the need for complex multi-stage purification systems that would increase device complexity.
3Manufacturing precision
If cyclic carbonate with low cyclic ether content is used, then carbonate ether impurity in product is reduced, but raw material cost and processing difficulty increase
Solution Approach 1:
The patent applies preliminary action by purifying cyclic carbonate to reduce cyclic ether content before reaction. This preliminary treatment, while adding a processing step, uses straightforward purification methods that do not significantly increase manufacturing difficulty, while effectively controlling the carbonate ether content in the final product.
Solution Approach 2:
The patent applies parameter changes by controlling the cyclic ether content parameter in the cyclic carbonate raw material to a specific range. By adjusting and controlling this key parameter through purification, the process achieves low carbonate ether content in the product while maintaining reasonable ease of manufacture through parameter optimization rather than complex process changes.
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 effectively reduces carbonate ether content in dialkyl carbonate, enabling its use in producing high-purity transesterification aromatic carbonate for creating colorless, high molecular weight aromatic polycarbonate.
Implementation Method 1
effecting a transesterification reaction between a cyclic carbonate and an aliphatic monohydric alcohol in the presence of a transesterification catalyst
Implementation Method 2
separation of the dialkyl carbonate from the dialkyl carbonate-containing liquid
Implementation Method 3
separation of the diol from the diol-containing liquid
Data Source
AI summary
A method for producing a dialkyl carbonate and a diol, comprising: (a) effecting a transesterification reaction between a cyclic carbonate and an aliphatic monohydric alcohol in the presence of a transesterification catalyst, thereby obtaining a reaction mixture containing a product dialkyl carbonate and a product diol, (b) withdrawing a dialkyl carbonate-containing liquid from the reaction mixture, followed by separation of the dialkyl carbonate from the dialkyl carbonate-containing liquid, and (c) withdrawing a diol-containing liquid from the reaction mixture, followed by separation of the diol from the diol-containing liquid, wherein the cyclic carbonate contains a cyclic ether in an amount of from 0.1 to 3,000 ppm by weight, and the product dialkyl carbonate contains a carbonate ether of not more than 10,000 ppm by weight.