Flow Reactor Oxidation of Alcohols Using Acid Anhydride
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Solution Overview
Problem
Current methods for oxidizing primary or secondary alcohol compounds to produce aldehyde or ketone compounds face challenges in achieving high yield and purity, particularly when dealing with compounds containing nucleophilic substituents or vulnerable groups, requiring strict temperature control and leading to the generation of by-products.
Innovation Solution
A method involving a flow-through type reactor process where a primary or secondary alcohol compound with specific groups undergoes sequential reactions with a dialkyl sulfoxide and an acid anhydride, followed by a trialkylamine, at controlled temperatures, to selectively oxidize the target hydroxy group while minimizing by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Swern oxidation is performed at low temperature (-50°C or lower) to prevent by-product formation, then the stability of activated sulfoxide compound and intermediate is improved, but the complexity of temperature control and reaction time increases
Solution Approach 1:
The invention changes the temperature parameter from low temperature (-50°C) to room temperature or higher, fundamentally altering the reaction conditions. This is achieved by modifying the oxidation system to use a different activator (carboxylic acid anhydride instead of oxalyl chloride) that allows stable operation at higher temperatures, thereby eliminating the need for complex low-temperature control equipment while maintaining reaction stability
Solution Approach 2:
The invention uses a readily available carboxylic acid anhydride activator that forms stable intermediates at room temperature, replacing the need for expensive low-temperature control systems and specialized equipment. The reaction can be performed under simple atmospheric conditions without requiring cryogenic equipment
2Productivity
If Swern oxidation is performed on alcohol compounds with nucleophilic substituents, then the oxidation of hydroxy group to carbonyl group is achieved, but the generation of by-products increases due to nucleophilic attack on vulnerable groups
Solution Approach 1:
The invention changes the reaction mechanism by using carboxylic acid anhydride as activator instead of traditional oxalyl chloride, which creates a less aggressive oxidation environment. This parameter change prevents nucleophilic attack on vulnerable groups while maintaining efficient oxidation of the hydroxy group, thereby reducing by-product formation
Solution Approach 2:
The invention introduces a trialkylamine as an intermediary substance that mediates the oxidation process. The amine forms a stable intermediate complex that controls the reactivity, preventing direct nucleophilic attack on vulnerable groups while facilitating the oxidation of the hydroxy group to carbonyl group
3Ease of manufacture
If traditional batch oxidation method is used, then the reaction can be performed with simple equipment, but the reaction time is long and the yield is low due to thermal instability of intermediates
Solution Approach 1:
The invention employs a continuous flow reaction system where the oxidation process occurs continuously through a flow reactor. This eliminates the downtime between batches, maintains optimal reaction conditions throughout the process, and prevents intermediate decomposition by continuously removing products, thereby significantly improving reaction efficiency and yield while using relatively simple 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
This method enables the high-yield, high-purity production of aldehyde or ketone compounds with easy temperature control, even when using alcohol compounds with nucleophilic substituents or vulnerable groups, significantly reducing by-product generation.
Implementation Method 1
a first step including colliding and mixing an acid anhydride having 4 to 10 carbon atoms and a liquid containing the alcohol compound and a dialkyl sulfoxide having 2 to 8 carbon atoms in a flow-through type reactor to cause a reaction
Implementation Method 2
a second step including colliding and mixing, in a flow-through type reactor, a trialkylamine having 3 to 10 carbon atoms and the mixture liquid obtained in the first step to cause a reaction
Data Source
Figure 1
AI summary
A production method for producing an aldehyde compound or a ketone compound by oxidizing a primary or secondary alcohol compound, wherein the alcohol compound has, in the molecule thereof, a group selected from an amino group, an azide group, a hydroxy group and a hydroxy group protected by a protecting group. The method comprises carrying out the reactions of a first step and a second step in succession, wherein the first step comprises collisionally mixing an alcohol compound, a dialkyl sulfoxide having 2 to 8 carbon atoms and an acid anhydride having 4 to 10 carbon atoms with one another in a continuous-flow-type flow reactor to react these components with one another, and the second step comprises collisionally mixing the liquid mixture that has been mixed in the first step with a trialkylamine having 3 to 10 carbon atoms in a continuous-flow-type flow reactor to react these components with each other.