6-Chlorodibenzo[d,f][1,3,2]dioxaphosphepin Synthesis via Catalytic Nitrogen Base
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Solution Overview
Problem
Current processes for preparing phosphochloridites, such as 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin, face challenges including high excess usage of toxic and corrosive PCl3, inefficient use of starting materials, and safety concerns due to uncontrollable reactions and excessive HCl production.
Innovation Solution
A process involving the reaction of an aromatic diol with PCl3 in the presence of a catalytic amount of an acid salt of a nitrogen base, without external organic solvents, allowing for a small excess of PCl3 and minimizing PCl3 vaporization, using a catalytic amount of an acid salt like N-methylimidazolium hydrochloride, and conducting the reaction in the absence of free nitrogen bases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large excess of PCl3 is used in the reaction with aromatic diol, then the reaction proceeds to completion and high yields are achieved, but the handling of toxic and corrosive PCl3 streams increases and safety risks are elevated
Solution Approach 1:
The patent changes the reaction parameters by introducing a catalytic amount of nitrogen base (0.01-5 mol%) and conducting the reaction at elevated temperatures (80-150°C) to achieve high conversion with minimal excess PCl3 (1.05-1.5 equivalents), thereby reducing the harmful PCl3 streams while maintaining high productivity
Solution Approach 2:
The patent introduces a nitrogen base (such as pyridine, triethylamine, or imidazole) as an intermediary catalyst that facilitates the reaction between PCl3 and aromatic diol, enabling the reaction to proceed efficiently with stoichiometric or near-stoichiometric amounts of PCl3, thus reducing the excess reagent required and the associated harmful effects
2Reliability
If PCl3 is used in excess to ensure complete reaction, then conversion is improved, but PCl3 vaporization and loss increase
Solution Approach 1:
The patent performs preliminary action by adding the nitrogen base catalyst before introducing PCl3, and by pre-heating the reaction mixture to the desired temperature range (80-150°C) before PCl3 addition. This ensures immediate catalysis upon PCl3 introduction, promoting rapid reaction and minimizing vaporization losses through controlled, efficient conversion
3Productivity
If free nitrogen bases are used in the reaction, then catalytic activity is enhanced, but formation of hydrohalic acid salts and by-products increases complicating purification
Solution Approach 1:
The patent optimizes the parameter of nitrogen base quantity to a catalytic range (0.01-5 mol%), which is sufficient to enhance reaction rate but insufficient to form excessive amounts of hydrohalic acid salts. This parameter optimization maintains high productivity while minimizing purification complexity
Solution Approach 2:
The patent converts the potentially harmful effect of nitrogen base into a beneficial catalytic effect by using sub-stoichiometric amounts. The nitrogen base catalyzes the reaction without forming significant amounts of salts that would complicate purification, thus turning what could be a source of complexity into a source of rate enhancement
4Stability of the object's composition
If external organic solvents are used in the reaction, then solubility and reaction homogeneity are improved, but combustion risks and safety concerns increase
Solution Approach 1:
The patent extracts or removes the external organic solvent from the reaction system entirely, conducting the reaction in neat conditions (without added solvent). This eliminates the combustion risk associated with organic solvents while maintaining reaction homogeneity through the use of catalytic nitrogen base and controlled temperature conditions
Solution Approach 2:
The patent creates an inert environment by eliminating flammable organic solvents from the system. The reaction is conducted in a solvent-free or water-based environment that does not present combustion risks, while still achieving good reaction homogeneity through efficient mixing and catalysis
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 achieves high yields and purity of 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin with reduced PCl3 usage, minimizing toxic and corrosive substance handling, and avoiding volatile organic solvent combustion and complex purification steps.
Implementation Method 1
reacting an aromatic diol with PCl3 in the presence of a catalytic amount of an acid salt of a nitrogen base
Data Source
AI summary
The present invention relates to a process for preparing 6-chlorodibenzo[d,f][1,3,2]dioxaphosphepin (I)which comprises reacting 2,2′-dihydroxybiphenyl with PCl3 in the presence of a catalytic amount of an acid salt of a nitrogen base, wherein the reaction is carried out in the absence of external organic solvents.