Dehydrohalogenation of Halogenated Butenes Using Low-Melting Salts
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Solution Overview
Problem
Existing processes for producing halogenated 1,3-butadienes from halogenated 1-butenes are complex, energy-intensive, and result in difficult-to-separate suspensions, high operational costs, and wastewater treatment challenges due to phase transfer catalysts and increased salt content.
Innovation Solution
A process using an organic base that forms low-melting organic halide salts, preferably ionic liquids, to simplify the reaction and reduce equipment and energy costs, allowing for the recycling of auxiliary materials and minimizing wastewater generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase transfer catalysts are used in the dehydrohalogenation process, then the reaction can proceed in a biphasic system, but the resulting suspension is difficult to separate and requires complex equipment and wastewater treatment
Solution Approach 1:
The patent changes the physical state parameter of the salt product by selecting an organic base that forms low-melting salts (melting point below 100°C, preferably below 50°C). This parameter change transforms the salt from a solid suspension (difficult to separate) into a liquid or low-melting substance that can be easily separated by simple decantation or filtration, eliminating the need for complex separation equipment and wastewater treatment systems.
Solution Approach 2:
The patent utilizes phase transition by designing the salt formation and separation process to occur in the liquid phase. The organic base forms a liquid or low-melting salt with the eliminated hydrohalogenic acid, allowing the salt to remain in the liquid phase during reaction and separation. This phase transition approach enables simple decantation or filtration without requiring complex solid-liquid separation equipment.
2Ease of manufacture
If traditional organic bases are used that form solid salts, then the reaction can proceed, but the salt forms a thick, dense, insoluble slurry that is difficult to handle and remove
Solution Approach 1:
The patent fundamentally changes the melting point parameter of the formed salt by carefully selecting the organic base structure. By choosing bases that form salts with melting points below 100°C (preferably below 50°C), the patent transforms the salt from an insoluble solid slurry into a liquid or easily handleable low-melting substance, dramatically improving ease of operation and removal from the reaction mixture.
Solution Approach 2:
The patent employs an organic base that forms a low-melting salt which can be easily separated and the base recovered. The salt itself acts as a temporary, easily removable component that does not require complex handling or disposal systems, effectively serving as a disposable element in the process that simplifies overall operation.
3Productivity
If the process uses biphasic systems with phase transfer catalysts, then dehydrohalogenation can occur, but operational costs and energy demand increase
Solution Approach 1:
The patent changes the temperature parameter by conducting the reaction and separation process at temperatures below the melting point of the formed salt (or just above for low-melting salts). This temperature control allows the salt to remain liquid or easily separable without requiring high energy input for heating or cooling, thereby reducing energy demand while maintaining productivity.
Solution Approach 2:
The patent extracts the salt phase from the reaction mixture through simple decantation or filtration based on density differences or phase separation. This extraction method eliminates the need for energy-intensive separation processes such as distillation or advanced filtration systems, significantly reducing energy demand while maintaining high monomer production rates.
4Productivity
If phase transfer catalysts and inorganic bases are used, then the reaction proceeds, but wastewater treatment becomes difficult and laborious due to increased salt freight
Solution Approach 1:
The patent changes the solubility parameter of the formed salt by selecting an organic base that creates a low-melting, organic-soluble salt. This parameter change allows the salt to be easily separated from the aqueous phase through liquid-liquid extraction or simple phase separation, preventing salt accumulation in wastewater and eliminating laborious wastewater treatment requirements while maintaining high reaction rates.
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 space-time-yield, reduces operational complexity, and enhances safety by eliminating hazardous materials and manual handling, while optimizing synthesis and minimizing waste.
Implementation Method 1
eliminating hydrohalogenic acid from the halogenated 1-butene to produce the halogenated 1,3-butadiene; and forming a salt of the eliminated hydrohalogenic acid with the organic base
Implementation Method 2
separating the reaction mixture into a product composition containing halogenated 1,3-butadiene; and a salt composition containing salt of the eliminated hydrohalogenic acid with organic base
Implementation Method 3
cleaving the salt to release hydrohalogenic acid from the salt and separating the salt composition into a hydrohalogenic acid composition containing released hydrohalogenic acid; and an organic base composition containing organic base
Data Source
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AI summary
The invention relates to a process for the preparation of a halogenated 1,3-butadiene by dehydrohalogenation of a halogenated 1-butene. Preferably, the process is for the preparation of 2-chloro-1,3-butadiene (CP) from 3,4-dichloro-1-butene (3,4-DBN), or for the preparation of 2,3-dichloro-1,3-butadiene (DCB) from 2,3,4-trichloro-1-butene (TCB). The dehydrohalogenation is performed in the presence of an organic base that forms a salt with eliminated hydrohalogenic acid and provides a low melting halide salt, preferably an organic salt melting below 100 °C, that is an ionic liquid. Preferably, halogenated 1,3-butadiene is separated from the reaction mixture by in-situ distillation. Organic base is recovered from the low melting organic salt by e.g. heating and release of hydrohalogenic acid. After purification, recovered organic base is recycled into the process.