Polyphenol Disulfide Synthesis via HCl Complexation
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Solution Overview
Problem
Current polyphenol disulfides used as synergists in halogen-free phosphorus-containing flame retardants have unsatisfactory thermal stability and contain a high proportion of low-molecular, highly volatile components, leading to odor issues during polymer processing at elevated temperatures.
Innovation Solution
A process involving the reaction of phenols with S2Cl2 in a solvent that complexes or neutralizes HCl, resulting in polyphenol disulfides with a higher proportion of dimeric and polymeric phenol disulfides, reduced monosulfide and polysulfide units, and lower elemental sulfur content, enhancing thermal stability and minimizing odor development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyphenol disulfides are used as synergists in halogen-free phosphorus-containing flame retardants, then flame retardant properties are improved, but thermal stability is insufficient and odor issues occur during processing
Solution Approach 1:
The patent changes the molecular structure parameters of polyphenol disulfides by controlling the degree of polymerization and sulfur content. The optimized composition (n=1-10, with specific ratios of disulfide, polysulfide, and elemental sulfur) provides enhanced thermal stability while maintaining flame retardant effectiveness, resolving the contradiction between flame retardancy and thermal stability.
2Reliability
If conventional polyphenol disulfides are used, then flame retardant synergy is achieved, but low-molecular volatile components cause odor during polymer processing
Solution Approach 1:
The patent optimizes the molecular weight distribution and compositional parameters of polyphenol disulfides. By controlling the proportions of dimeric, polymeric, and elemental sulfur components within specific ranges, the invention reduces volatile low-molecular fractions that cause odor, while preserving the flame retardant synergistic effects.
3Productivity
If high reaction temperatures are used to produce polyphenol disulfides, then reaction efficiency is improved, but sublimation of unreacted phenol occurs and thermal stability decreases
Solution Approach 1:
The patent optimizes the reaction temperature parameter to a moderate range (20-80°C) and adjusts other parameters including solvent type, molar ratios of phenol to sulfur chloride, and reaction time. This parameter optimization achieves high reaction efficiency without requiring excessive temperature, thereby preventing phenol sublimation and maintaining thermal stability of the product.
4Ease of operation
If conventional solvents are used in the reaction, then ease of operation is maintained, but HCl byproduct causes corrosion and reduces product purity
Solution Approach 1:
The patent introduces an intermediary substance (base or salt) that reacts with the HCl byproduct formed during the reaction. This intermediary neutralizes the corrosive HCl, preventing equipment corrosion and improving product purity, while the reaction system remains easy to operate with standard equipment.
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 produces polyphenol disulfides with improved thermal stability and reduced volatile content, preventing odor issues during polymer processing, while maintaining low chlorine content and allowing for lower reaction temperatures, which is economically and ecologically advantageous.
Implementation Method 1
the solvent L has the property that it complexes and/or neutralizes at least 80 mol% of the HCl formed in the course of the reaction
Implementation Method 2
the solvent L has the property that it complexes and/or neutralizes at least 80 mol% of the HCl formed in the course of the reaction
Data Source
AI summary
Preparing a polyphenoldisulfide compound (Q) comprises reacting phenol compound (Q1) with disulfur dichloride in a solvent, where the solvent has a property that: (a) at least 80 mol.% of hydrochloric acid produced during the reaction in is complexed and/or neutralized and (b) at least 80 mol.% of hydrochloric acid produced during the reaction is insoluble in the solvent. Preparing a polyphenoldisulfide compound (Q) of formula (I) or (Ib) comprises reacting phenol compound (Q1) of formula (II) or (IIa) with disulfur dichloride in a solvent, where the solvent has a property that: (a) at least 80 mol.% of hydrochloric acid produced during the reaction in is complexed and/or neutralized and (b) at least 80 mol.% of hydrochloric acid produced during the reaction is insoluble in the solvent. R1-R4 : 1-18C-alkyl, 2-18C-alkenyl, 2-18C-alkynyl, 6-12C-aryl, 3-10C-cycloalkyl, 6-12C-aryl-1-18C-alkyl, heteroaryl consisting one or more hetero atoms of N, O or S, O-(1-18C)-alkyl, O-(2-18C)-alkenyl, O-(2-18C)-alkynyl, O-(6-12C)-aryl, O-(3-10C)-cycloalkyl, (6-12C)-aryl-(1-18C)-alkyl-O-, -S (1-18C)-alkyl, S-(2-18C)-alkenyl, S-(2-18C)-alkynyl, S-(6-12C)-aryl, S-(3-10C)-cycloalkyl, (6-12C)-aryl-(1-18C)-alkyl-S, OH, F, Cl, Br or H, provided that R4 in (II) is H; R2a : 1-10C-alkyl or 6-12C-aryl; R1a, R3a, R4a : H, provided that R4a in (IIa) is H when n is greater than 0; and n : 1-1000, preferably 3-100 (for (I)) or 0-150 (for (Ib)). Independent claims are included for: (1) the polyphenoldisulfide compound (Q), in which n is >= 1 for (Ib); (2) another polyphenoldisulfide compound of formula (Ic); (3) a diphenoldisulfide compound of formula (XX); (4) a flame retardant system comprising (Q) and at least one halogen-free organic phosphorus compound with a phosphorus content of 0.5-40 wt.%; and (5) a polymer composition comprising one or more polymer and the flame retardant system. R2c, R2d : 6-12C-aryl; R1c, R3c, R4c : 6-12C-aryl or H; n1 : 0-1000; and R1d, R3d, R4d : R1. [Image] [Image] [Image].