Fluorinated Dioxolane Production with CO2 pH Control
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Solution Overview
Problem
The production of 1,3-dioxolane compounds with a 2-(difluoromethylene) structure is hindered by the formation of HF adducts during thermal decomposition of carboxylic acid salts due to the presence of water, leading to decreased yield and separation difficulties due to similar boiling points.
Innovation Solution
A method involving the reaction of a compound with a base to form a carboxylic acid salt, followed by pH adjustment using carbon dioxide gas to a range of 6.0 to 11.0, and subsequent thermal decomposition to produce the target compound with reduced by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is present during thermal decomposition of carboxylic acid salt, then the reaction can proceed, but HF adducts are formed as by-products reducing yield
Solution Approach 1:
The patent changes the pH parameter of the reaction medium from neutral/acidic to basic (pH > 11.0) by using alkali metal or alkaline earth metal hydroxides, carbonates, or alkoxides. This basic condition prevents the formation of HF adducts during thermal decomposition while maintaining the reaction proceedability, thereby resolving the contradiction between yield and harmful by-product formation
Solution Approach 2:
The patent introduces an intermediary substance (base such as hydroxide, carbonate, or alkoxide) that mediates between the carboxylic acid salt and the thermal decomposition process. This intermediary creates a basic environment that prevents direct reaction between water and the difluoromethylene compound to form HF adducts, while still allowing the decomposition to proceed
2Productivity
If water is present during thermal decomposition, then reaction can occur, but separation of target product from HF adducts becomes difficult
Solution Approach 1:
By changing the pH parameter to basic conditions (pH > 11.0), the patent prevents the formation of HF adducts that would otherwise have similar boiling points to the target compound. This eliminates the separation difficulty while maintaining production capability
3Ease of operation
If inorganic acids are used for pH adjustment, then pH can be controlled, but equipment corrosion occurs
Solution Approach 1:
The patent replaces durable but corrosive inorganic acid equipment with a more durable base system (alkali metal or alkaline earth metal hydroxides, carbonates, or alkoxides) that does not corrode equipment. The base is consumed in the reaction, similar to how acid is consumed, but without the harmful corrosion effect
Solution Approach 2:
The patent converts the potentially harmful effect of strong bases (which could cause other issues) into a beneficial protective effect by using mild bases (hydroxides, carbonates, alkoxides of alkali metals and alkaline earth metals) that provide the necessary pH control without equipment corrosion
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 approach reduces the production of 2-hydro-perfluoromethyl compounds and enables high-purity 1,3-dioxolane production by avoiding the use of inorganic acids and preventing equipment corrosion.
Implementation Method 1
adding carbon dioxide gas to the reaction product obtained in step A, or a liquid obtained by mixing the reaction product with water, to adjust the pH to 6.0 to 11.0
Implementation Method 2
heating the concentrate obtained in step C to thermally decompose the compound represented by formula (3), thereby producing the compound represented by formula (1)
Implementation Method 3
a carbonyl fluoride compound is generally saponified with a base to convert it into a carboxylic acid salt
Data Source
AI summary
An object of the present disclosure is to provide a novel method for producing a 1,3-dioxolane compound having a 2-(difluoromethylene) structure (e.g., 2-(difluoromethylene)-4,4,5-trifluoro-5-(trifluoromethyl)-1,3-dioxolane) from a corresponding carboxylic acid salt, the method suppressing the production of HF adducts (e.g., 2-hydro-perfluoro(2,4-dimethyl-1,3-dioxolane)) as by-products. The present disclosure relates to a method for producing a compound represented by formula (1), the method comprising the following steps A, B, C, and D:step A of reacting a compound represented by formula (2) with at least one base selected from the group consisting of hydroxides, carbonates, and alkoxides of alkali metals and alkaline earth metals to produce a compound represented by formula (3), thereby obtaining a reaction product having a pH range of more than 11.0;step B of adding carbon dioxide gas to the reaction product obtained in step A, or a liquid obtained by mixing the reaction product with water, to adjust the pH to 6.0 to 11.0, thereby obtaining a pH-adjusted liquid;step C of concentrating the pH-adjusted liquid obtained in step B to obtain a concentrate; andstep D of heating the concentrate obtained in step C to thermally decompose the compound represented by formula (3), thereby producing the compound represented by formula (1):wherein R1 to R4 are each independently a fluorine atom or a C1-C7 fluoroalkyl group optionally containing ethereal oxygen, X is a hydroxy group, a fluorine atom, a chlorine atom, or a C1-C3 alkoxy group in which one or more hydrogen atoms are optionally replaced by fluorine atoms, and M is an alkali metal atom or an alkaline earth metal atom.