Slurry Bisphosphite Synthesis with Low HCl Solubility Solvent
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Solution Overview
Problem
Current methods for synthesizing phosphoromonochloridites in the production of organopolyphosphites face inefficiencies due to the need for excessive phosphorus trichloride (PCl3) handling, generation of undesirable by-products, and challenges in removing hydrogen chloride (HCl), which complicates the process and reduces yield.
Innovation Solution
A novel process involving the contact of phosphorus trichloride with aromatic diols in a slurry containing an organic solvent with low HCl solubility, followed by removal of excess PCl3 and subsequent reaction with a nitrogen base to produce bisphosphites, optimizing the molar ratios and reaction conditions to minimize by-products and enhance yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a nitrogen base is used to neutralize HCl in the condensation reaction, then HCl removal is achieved, but the process generates chloride and nitrogen-containing wastes that increase cost and require filtration
Solution Approach 1:
The patent extracts HCl from the reaction system by sparging with inert gas (nitrogen or argon) to physically remove it as it forms, rather than chemically neutralizing it with a base. This extraction approach eliminates the need for filtration and waste removal steps associated with base neutralization.
Solution Approach 2:
The patent introduces an intermediary inert gas phase that acts as a mediator to transfer HCl from the liquid reaction phase to the gas phase for removal. This intermediary approach allows HCl removal without direct chemical interaction between the base and reaction mixture, avoiding salt formation.
2Object-generated harmful factors
If a large excess amount of PCl3 is used to drive off HCl by reflux, then HCl removal is achieved, but the process requires handling and removal of large excess PCl3 which reacts exothermically with moisture and increases safety considerations
Solution Approach 1:
The patent employs continuous sparging with inert gas throughout the condensation reaction to continuously remove HCl as it forms. This continuous removal approach maintains low HCl concentration without requiring large excess PCl3, enabling the reaction to proceed with near-stoichiometric amounts and eliminating the need to handle and remove large volumes of excess reagent.
3Productivity
If the condensation reaction is conducted to achieve high conversion of alcohol, then product yield is improved, but HCl accumulation occurs which requires removal to prevent side reactions and maintain product quality
Solution Approach 1:
The patent implements a feedback mechanism where HCl removal is continuously monitored and adjusted by controlling the sparging rate. As HCl accumulates during high conversion, the sparging intensity is maintained or increased to prevent HCl from reaching concentrations that would cause side reactions, allowing sustained high conversion with product quality maintenance.
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 process significantly improves the yield of phosphoromonochloridites and bisphosphites by reducing excess PCl3 usage and minimizing by-product formation, leading to a more efficient and cost-effective synthesis of organopolyphosphites.
Implementation Method 1
contacting phosphorus trichloride with a first aromatic diol in a slurry, which slurry comprises portions of the first aromatic diol in solid forms and comprises a solution phase comprising the remaining portions of the first aromatic diol dissolved in an organic solvent
Implementation Method 2
a slurry, which slurry comprises portions of the first aromatic diol in solid forms and comprises a solution phase comprising the remaining portions of the first aromatic diol dissolved in an organic solvent
Data Source
AI summary
The present invention provides a step-wise process for preparation of a bisphosphite. In step (a) the process prepares a phosphoromonochloridite in high yield, by contacting phosphorus trichloride with an aromatic diol in a slurry under reaction conditions and in the presence of a second aromatic diol to produce a mixture comprising the phosphoromonochloridite, the second aromatic diol, and excess PC13. The slurry comprises less than 5 mole percent of a nitrogen base, and the organic solvent is selected for its low hydrogen chloride solubility. After removing the excess PC13, a nitrogen base is added to effect condensation of the phosphoromonochloridite with the second aromatic diol to yield the bisphosphite. The invention particularly provides a process for preparing 6, 6' - (3,3',5,5' -tetra-tert-butylbiphenyl-2, 2' -diyl)bis (oxy) didibenzo [d, f ] [1,3,2] dioxaphosphepine by the above route.