6-Chlorodibenzo[d,f][1,3,2]dioxaphosphepin Synthesis via Inverted Addition
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Solution Overview
Problem
Existing methods for preparing 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin result in low yields and high energy or time requirements due to the formation of undesirable by-products, and involve energy-intensive thermal equilibration, vacuum distillation, or the use of corrosive and expensive filtration processes.
Innovation Solution
A process involving the suspension of 2,2′-dihydroxybiphenyl in an inert solvent with an excess of phosphorus trichloride under inert gas, followed by neutralization, removal of excess reagents, and isolation of 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin without the need for energy-intensive cooling or distillation, base addition, or use of tetrahydrofuran.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphorus trichloride is added dropwise to 2,2′-dihydroxybiphenyl, then the reaction can be controlled, but phosphitic by-products are formed requiring energy-intensive thermal equilibration
Solution Approach 1:
Instead of adding phosphorus trichloride to 2,2′-dihydroxybiphenyl as in conventional methods, the patent inverts the addition sequence by adding 2,2′-dihydroxybiphenyl to phosphorus trichloride. This reversal prevents phosphitic by-product formation and eliminates the need for energy-intensive thermal equilibration, while maintaining reaction control through the specified addition rate of 0.05-0.2 mol/min.
2Manufacturing precision
If vacuum distillation is performed at very high temperatures or low pressures, then product purification is achieved, but the process requires expensive equipment and is difficult to realize industrially
Solution Approach 1:
The patent changes the purification parameters by performing distillation at atmospheric pressure (1013 hPa) rather than vacuum conditions, and at a moderate temperature of 80-90°C instead of very high temperatures. This parameter change eliminates the need for expensive vacuum distillation equipment while achieving sufficient product purification for industrial implementation.
3Manufacturing precision
If the reaction mixture is cooled to 0° C. to obtain sufficient selectivity, then by-product formation is reduced, but energy-intensive cooling and expensive corrosion-resistant filtration apparatus are required
Solution Approach 1:
The patent employs the solvent toluene as a self-cooling medium through its reflux capability. The exothermic reaction heat is utilized to maintain the reaction temperature through natural reflux, eliminating the need for energy-intensive external cooling to 0°C. This self-regulating system maintains good selectivity without requiring expensive corrosion-resistant filtration apparatus.
4Productivity
If conventional methods are used to prepare 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin, then the reaction can proceed, but yields are reduced due to formation of undesirable by-products
Solution Approach 1:
The patent performs preliminary action by adding 2,2′-dihydroxybiphenyl to phosphorus trichloride before any by-products can form. This preliminary addition sequence, combined with controlled addition rate (0.05-0.2 mol/min) and immediate stirring, prevents phosphitic by-product formation from the outset, achieving yields of 85-95% without requiring subsequent by-product removal steps.
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 achieves high yield and purity of 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin with minimal by-products at ambient temperature, ensuring safe industrial-scale operation and avoiding costly filtration and distillation processes.
Implementation Method 1
phosphorus trichloride is reacted with 2,2′-dihydroxybiphenyl to form compound 1
Data Source
AI summary
The invention relates to a method for producing 6-chlorodibenzo[d,f][1,3,2]-dioxaphosphepin (formula 1), comprising the following steps: a) addition of 2,2′-dihydroxybiphenyl, which is suspended in an inert solvant. into a reactor to an excess of phosphorous trichloride under inert gas and stirring; b) discharge and neutralization of the resulting gases from the reaction mixture; c) separation of the excess phosphorous trichloride and the solvant; d) obtention of 6-chlorodibenzo[d,f][1,3,2]-dioxaphosphepin.