Purifying Dialkyl Sulfides via Oxidative Impurity Removal
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Solution Overview
Problem
Current methods for purifying dialkyl sulfides, such as dimethyl sulfide, are inadequate in removing malodorous impurities like carbon disulfide, hydrogen sulfide, and thiols, which persist even at low concentrations, causing unpleasant odors and are not suitable for producing high-purity dialkyl sulfide borane complexes for pharmaceutical applications.
Innovation Solution
A process involving the use of bases and alkali or alkaline earth metals, specifically metal alcoholates and alkali metals, to selectively remove malodorous impurities from dialkyl sulfides, followed by reaction with electrophiles to form stable derivatives that can be separated, resulting in low-odor dialkyl sulfides and high-purity dialkyl sulfide borane complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If absorption methods using activated alumina treated with alkali metals are used to remove impurities from dialkyl sulfides, then some sulfur-containing impurities are removed, but the process is reversible and cannot completely remove all impurities
Solution Approach 1:
The patent employs strong oxidizing agents (sodium hypochlorite, potassium permanganate, or ozone) to irreversibly oxidize sulfur-containing impurities (thiols, disulfides, carbon disulfide) into water-soluble or removable forms. This oxidation step converts the reversible absorption process into an irreversible removal process, completely eliminating malodorous impurities that conventional absorption cannot remove.
2Manufacturing precision
If steam distillation is used to purify dialkyl sulfides, then water is removed from the dialkyl sulfide, but residual water remains and the method is inappropriate for dialkyl sulfide borane complex preparation
Solution Approach 1:
The oxidation process with strong oxidizing agents converts residual water into a removable form and simultaneously eliminates all sulfur-containing impurities. This provides a more complete drying and purification effect than steam distillation, making the dialkyl sulfide suitable for sensitive applications like borane complex preparation where even trace water and sulfur impurities are unacceptable.
3Object-affected harmful factors
If odor-masking compounds are added to dialkyl sulfides, then the unpleasant odor is masked, but the compounds react with borane and cannot be used in dialkyl sulfide borane complex preparation
Solution Approach 1:
Instead of masking the odor with compounds that interfere with borane reactivity, the patent converts the harmful sulfur-containing impurities (the source of odor) into beneficial water-soluble oxidation products through strong oxidation. This eliminates the odor at its source without introducing any compounds that would react with borane, making the purified dialkyl sulfide ideal for borane complex preparation.
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 effectively reduces impurities like carbon disulfide and dimethyldisulfide to below 0.01% in dialkyl sulfides, producing low-odor products and high-purity dialkyl sulfide borane complexes that enhance enantioselective reductions, meeting pharmaceutical standards for enantiomeric excess.
Implementation Method 1
A process involving the use of bases and alkali or alkaline earth metals, specifically metal alcoholates and alkali metals, to selectively remove malodorous impurities from dialkyl sulfides
Implementation Method 2
The process effectively reduces impurities like carbon disulfide and dimethyldisulfide to below 0.01% in dialkyl sulfides, producing low-odor products and high-purity dialkyl sulfide borane complexes
Data Source
AI summary
The invention relates to new processes to prepare low odor dialkyl sulfides, the low odor dialkyl sulfides obtainable by these processes and to methods of using these low odor dialkyl sulfides. Moreover, the invention relates to a process to prepare dialkyl sulfide borane complexes of high purity, the dialkyl sulfide borane complexes obtainable by this process and to a process for enantioselective reductions employing these dialkyl sulfide borane complexes of high purity as reducing agent.