3,3,3-Trifluoropropyne Synthesis via Non-Aqueous Base Dehydrohalogenation
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Solution Overview
Problem
Current industrial processes lack efficient methods for producing 3,3,3-trifluoropropyne in commercial quantities due to low yields and complexity, particularly when dealing with trans isomers of chlorofluoroolefins, which are needed as alternatives to ozone-depleting chlorofluorocarbons.
Innovation Solution
The process involves treating 1-chloro-3,3,3-trifluoropropene with potassium tert-butoxide or mixing 1,3,3-tetrafluoropropene with sodium amide in tetrahydrofuran, followed by hydrochloric acid addition, to achieve high yields of 3,3,3-trifluoropropyne, utilizing commercially available starting materials and recyclable solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dehydrohalogenation of trans-1-chloro-3,3,3-trifluoropropene is performed with aqueous KOH, then the reaction can proceed, but the yield is quite low due to the acidic proton in TFP
Solution Approach 1:
The patent changes the base from aqueous KOH to non-aqueous bases (potassium tert-butoxide in THF, sodium amide in liquid ammonia) to alter the reaction conditions. This parameter change allows the dehydrohalogenation to proceed with high yield by avoiding the protonation issue that occurs with aqueous bases, directly resolving the contradiction between reaction proceedability and yield.
Solution Approach 2:
The patent uses non-aqueous bases as intermediaries to facilitate the dehydrohalogenation reaction. These bases act as mediators that can remove the acidic proton from TFP without causing the side reactions that occur with aqueous KOH, thereby improving both yield and reaction efficiency simultaneously.
2Productivity
If multistep synthesis of 1,1,2-trichloro-3,3,3-trifluoropropene is used, then TFP can be produced, but the process complexity increases and commercial availability in large quantities is limited
Solution Approach 1:
The patent extracts and utilizes readily available starting materials (cis-1-chloro-3,3,3-trifluoropropene and trans-1-chloro-3,3,3-trifluoropropene) that can be obtained through simple processes, avoiding the need for complex multistep syntheses. By starting from these easily available compounds and using direct dehydrohalogenation, the patent reduces process complexity while maintaining high productivity.
3Productivity
If cis-1-chloro-3,3,3-trifluoropropene is treated with aqueous KOH, then dehydrochlorination occurs, but the reaction conditions are not suitable for producing TFP in good yield
Solution Approach 1:
The patent changes the reaction parameters by using non-aqueous bases (potassium tert-butoxide in THF, sodium amide in liquid ammonia) instead of aqueous KOH. This parameter change makes the reaction conditions suitable for producing TFP in good yield from cis-1-chloro-3,3,3-trifluoropropene, resolving the contradiction between productivity and ease of manufacture.
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 enables the production of 3,3,3-trifluoropropyne with improved yields and versatility, allowing for the use of both cis and trans isomers, thus overcoming previous limitations and enabling its commercial-scale production.
Implementation Method 1
a solution of 1-chloro-3,3,3-trifluoropropene in tetrahydrofuran is provided, and potassium tert-butoxide is added to the solution to yield TFP
Implementation Method 2
a compound selected from the group consisting of 1,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, and 1,1,1,3,3-pentafluoropropane is mixed with a solvent, sodium amide is added to the mixture, and then hydrochloric acid is added to yield TFP
Implementation Method 3
This TFP lithium salt may also be obtained by deprotonating CF3CH2CHF2 (245fa) with n-butyl lithium (Organomet. 2003, 5534) in ether
Data Source
AI summary
In accordance with the present invention, processes of synthesizing 3,3,3-trifluoropropyne from 1,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene, and/or 1,1,1,3,3-pentafluoropropane are provided.