Organic Diphosphite Purification via Precipitation and Extraction
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Solution Overview
Problem
The existing methods for purifying organic diphosphite compounds are inefficient in removing impurities, particularly secondary organophosphites and halide ions, which can act as catalyst poisons and affect the stability and performance of rhodium complex catalysts in hydroformylation processes, leading to operational malfunctions and product quality issues.
Innovation Solution
A method involving the precipitation of crude organic diphosphites using a second solvent in which they are sparingly soluble, such as linear C1-C4 alcohols or ethylene glycol di(C1-C4) ethers, to effectively remove impurities and achieve high purity levels, allowing for the production of organic diphosphites suitable for use as ligands in continuous industrial processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods are used, then the purification process is simple, but the removal of impurities (secondary organophosphites and halide ions) is insufficient
Solution Approach 1:
The patent introduces an auxiliary base (such as triethylamine, pyridine, or imidazole derivatives) as an intermediary substance that mediates the purification process. The auxiliary base reacts with hydrogen halides to form soluble salts, which then partition into the aqueous phase during liquid-liquid extraction, effectively removing halide impurities without requiring complex purification equipment
Solution Approach 2:
The patent changes the physical and chemical parameters of the system by adjusting the pH through auxiliary base addition, changing the solubility characteristics of impurities, and controlling the partition coefficients during liquid-liquid extraction. These parameter changes enable selective removal of secondary organophosphites and halide ions while maintaining the diphosphite compound in the organic phase
2Object-generated harmful factors
If base is used to remove hydrogen halides, then the acid salts can be removed, but the base salts cannot be recycled and must be disposed of, increasing costs
Solution Approach 1:
The auxiliary base serves as a sacrificial intermediary that temporarily binds hydrogen halides during the reaction, forming water-soluble salts that partition into the aqueous phase. This intermediary approach allows for complete removal of halide impurities while the auxiliary base itself is consumed in the process, converting the problem of base salt disposal into a controlled liquid-liquid extraction process where the salts are efficiently separated
Solution Approach 2:
The patent utilizes phase transition and partitioning principles by performing liquid-liquid extraction between organic and aqueous phases. The base salts formed during hydrogen halide removal exhibit different solubility characteristics in the two phases, allowing them to automatically partition into the aqueous phase and be separated from the organic phase containing the purified diphosphite compound
3Productivity
If impurities are not removed, then the process is simpler, but catalyst poisons (acetonitrile, chloride ions) affect rhodium complex catalysts, leading to operational malfunctions
Solution Approach 1:
The auxiliary base acts as a mediator that specifically targets and removes catalyst-poisoning impurities (hydrogen halides, secondary organophosphites) through chemical reaction and phase partitioning. This intermediary approach ensures high purity of the diphosphite ligand, preventing catalyst deactivation and maintaining high productivity in subsequent catalytic processes without requiring overly complex purification equipment
Solution Approach 2:
The patent employs parameter changes including pH adjustment through auxiliary base addition, temperature control during extraction, and solvent selection to optimize the partitioning of impurities into the aqueous phase. These parameter changes enable selective removal of catalyst poisons while maintaining simplicity in the overall process design
Data Source
AI summary
A method of purifying an organic diphosphite of general formula (I)The method comprises providing a crude organic diphosphite of general formula (I) that is at least partly dissolved in a first solvent (L1), wherein (L1) is selected from the group consisting of alkylbenzenes, aryl alkyl ethers, chlorobenzene, and mixtures thereof, and precipitating by admixing with a second solvent (L2) selected from the group consisting of linear C1-C4-alkanols, ethylene glycol di(C1-C4-alkyl) ethers, and mixtures thereof, and separating off the precipitated organic diphosphite from the solvents.