HFSI Synthesis Using HF Reflux for High-Yield Purity
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Solution Overview
Problem
Existing methods for producing hydrogen bis(fluorosulfonyl)imide (HFSI) suffer from low yields, toxicity issues, and impurities, particularly when using hydrogen fluoride (HF), making large-scale commercial production challenging.
Innovation Solution
A method involving the reaction of hydrogen bis(halosulfonyl)imide (HXSI) with hydrogen fluoride (HF) under refluxing conditions, where HF is condensed back into the reaction mixture to selectively remove by-products, achieving high yields of HFSI up to 99% by adjusting condensation temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HCSI is reacted with excess anhydrous HF at high temperature to produce HFSI, then the reaction proceeds, but the yield is poor (55% at 130°C) and the process is not satisfactory
Solution Approach 1:
The patent changes the reaction parameters by using a different temperature range (0-50°C instead of 130°C), different HF equivalents (1-5 instead of excess), and different reaction times (1-48 hours instead of 2 hours), achieving yields of 80-99% compared to the previous 55% yield
Solution Approach 2:
The patent follows the basic reaction pathway of HCSI + HF → HFSI + HX from previous methods but copies it with modified conditions: lower temperature, controlled HF equivalents, and extended reaction time, transforming an unsatisfactory process into a highly effective one
2Productivity
If fluorosulfonic acid is used to synthesize HFSI from urea, then the reaction can proceed, but the acid is toxic and corrosive and the reaction is difficult to control due to local overheating
Solution Approach 1:
The patent replaces the toxic and corrosive fluorosulfonic acid with hydrogen fluoride, which is less hazardous and can be handled more safely, while still achieving the desired HFSI product through the fluorination of HCSI
Solution Approach 2:
The patent uses HCSI as an intermediary compound that can be fluorinated by HF to produce HFSI, avoiding the need to directly handle and use fluorosulfonic acid in the synthesis process
3Productivity
If HCSI is fluorinated with arsenic trifluoride to produce HFSI, then the reaction can proceed, but arsenic trifluoride is toxic and has high vapor pressure making it difficult to handle on industrial scale
Solution Approach 1:
The patent replaces arsenic trifluoride with hydrogen fluoride, which is less toxic and easier to handle on an industrial scale, while still achieving the fluorination of HCSI to produce HFSI
4Productivity
If HCSI is fluorinated with antimony trifluoride to produce HFSI, then the reaction can proceed, but the byproduct antimony trichloride has high solubility in HFSI and similar boiling point making separation very difficult
Solution Approach 1:
The patent replaces antimony trifluoride with hydrogen fluoride, which produces gaseous HCl as a byproduct that can be easily removed from the reaction mixture, avoiding the separation difficulties associated with antimony trichloride
Solution Approach 2:
The patent removes the problematic byproduct HCl from the reaction system through gas evolution and venting, preventing it from contaminating the HFSI product and eliminating the need for complex separation processes
5Productivity
If HCSI is reacted with HF in an autoclave, then the reaction can proceed under pressure, but the process requires pressurized reaction vessels and subsequent evaporation and distillation steps
Solution Approach 1:
The patent changes the pressure parameter from high pressure (autoclave conditions) to atmospheric or near-atmospheric pressure, simplifying the reactor design and eliminating the need for pressurized vessels and complex evaporation/distillation steps
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 enables high-yield production of HFSI with minimal impurities, overcoming the limitations of previous methods by achieving yields of at least 80%, typically 95%, and often 99%, using a continuous stirred-tank reactor (CSTR) or plug flow reactor (PFR) systems.
Implementation Method 1
reacting HXSI with HF under HF refluxing conditions that selectively remove HX that is produced in the reaction
Implementation Method 2
refluxing conditions are those that allow condensing back the HF into the reaction mixture by using a condenser at an appropriate temperature
Data Source
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AI summary
The invention provides a method for producing hydrogen bis(fluorosulfonyl)imide (HFSI) by reacting hydrogen bis(halosulfonyl)imide (HXSI) with hydrogen fluoride, where each X is independently a nonfluoro-halide, such as CI, Br, or I.