Dehalogenation of Halofluorinated Compounds via Biphasic Solvent Segmentation
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Solution Overview
Problem
Existing dehalogenation processes of halofluorinated compounds suffer from low yield and high formation of hydrogenated by-products, making it difficult to obtain high-purity dehalogenated compounds, especially when dealing with aromatic rings, due to the formation of complexes with transition metal salts and secondary reactions.
Innovation Solution
A biphasic system of immiscible solvents, comprising a (per)fluorinated solvent and a dipolar aprotic or protic solvent, is used for dehalogenation, with a specific ratio of co-solvent to halofluorinated compound, allowing for improved selectivity and reduced hydrogenated by-products, using transition metals like zinc, manganese, or copper at controlled temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dehalogenation is carried out using heterogeneous systems with transition metals and solvents (protic or dipolar aprotic), then the reaction can proceed, but complexes form with the halogenated salt of the transition metal making solvent recovery difficult
Solution Approach 1:
The system is divided into two immiscible phases: an organic phase containing the halofluorinated compound and transition metal, and a fluorinated solvent phase. This segmentation prevents complex formation between the dipolar aprotic solvent and transition metal salt, enabling easy phase separation and solvent recovery without complex treatment.
Solution Approach 2:
The fluorinated solvent acts as an intermediary medium that facilitates the dehalogenation reaction while remaining immiscible with the organic phase. It allows the reaction to proceed without forming complexes with the transition metal salt, and its immiscibility enables simple phase separation for solvent recovery.
2Productivity
If dehalogenation reactions use dipolar aprotic solvents to increase yields, then hydrogenated by-products are reduced, but complexes form with transition metal salts making solvent recovery difficult
Solution Approach 1:
The reaction system is segmented into immiscible phases, allowing the use of dipolar aprotic solvents in the organic phase to achieve high yields while the fluorinated solvent phase remains separate for easy recovery, avoiding complex formation issues.
Solution Approach 2:
The system changes the physical state parameters by using immiscible phases. The fluorinated solvent operates in a different phase from the dipolar aprotic solvent, changing the interaction parameters and preventing complex formation while maintaining the beneficial yield-enhancing effects of dipolar aprotic solvents.
3Productivity
If the dehalogenated product remains in contact with the solvent for prolonged periods, then the reaction completes, but secondary reactions occur reducing yields
Solution Approach 1:
The dehalogenated product is continuously extracted from the reaction zone into the fluorinated solvent phase or removed by phase separation. This takes the product out of the reaction environment, preventing secondary reactions while allowing the main dehalogenation reaction to complete.
Solution Approach 2:
The reaction process is designed to rush through the dehalogenation step quickly, minimizing the time the product remains in contact with the reaction medium. The immiscible phase system enables rapid separation, skipping the prolonged contact period that would lead to secondary reactions.
4Object-generated harmful factors
If distillation is used to remove the dehalogenated product, then secondary reactions are reduced, but it is difficult to remove the product when the starting material contains aromatic rings due to high boiling point
Solution Approach 1:
Instead of relying on volatility differences for distillation, the system uses liquid-liquid phase transition and immiscibility. The dehalogenated product partitions into or is removed with the fluorinated solvent phase, enabling separation based on phase behavior rather than boiling point differences.
Solution Approach 2:
The fluorinated solvent acts as an intermediary phase that selectively interacts with or facilitates the removal of the dehalogenated product. This intermediary phase enables product removal without requiring distillation, overcoming the high boiling point issue of aromatic compounds.
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 process achieves higher selectivity and yield of vinyl compounds with reduced hydrogenated by-products, facilitating easier purification and avoiding secondary reactions, thus enhancing the purity and efficiency of the dehalogenation process.
Implementation Method 1
operating in a biphasic system of solvents immiscible among each other, formed of a (per)fluorinated solvent and a dipolar aprotic solvent
Implementation Method 2
the halofluorinated compounds are dehalogenated in the presence of a transition metal
Implementation Method 3
complexes are formed with the halogenated salt of the transition metal which forms in the reaction itself
Implementation Method 4
process for obtaining vinyl compounds with aromatic substituents, by dehalogenation of halofluorinated compounds
Data Source
AI summary
A process for obtaining vinyl compounds by dehalogenation of halofluorinated compounds with aromatic substituents, having formula:T-Ar—(O)y—CFX′—CF2X″ (I)wherein:X′=F, Cl, Br, I;X″=Cl, Br, I;y=0,1; when y=0 X′≠F;T=H, —(O)y—CFX′—CF2X″, wherein y, X′ and X″ are as above;Ar is a monocyclic, bicyclic or tricyclic bivalent aromatic radical from 6 to 14 carbon atoms, optionally containing heteroatoms, or Ar is formed of two aromatic rings linked by a bivalent radical;said process characterized in that the halofluorinated compounds are dehalogenated in the presence of a transition metal, by operating in a biphasic system of solvents immiscible among each other, formed of a (per)fluorinated solvent and a dipolar aprotic or protic solvent (co-solvent), wherein the ratio moles co-solvent/equivalents of the halofluorinated compound with aromatic substituents ranges from 0.5 to 10.