Sucrose-6-Ester Synthesis via Continuous Counter-Current Dehydration
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Solution Overview
Problem
Existing methods for synthesizing sucrose-6-esters are hindered by slow dehydration reactions, leading to the production of decomposed carbohydrates and significant amounts of unreacted sucrose, which reduces yield and results in undesirable chlorinated compounds during the synthesis of sucralose.
Innovation Solution
A continuous counter-current process involving a reaction mixture of sucrose, a polar aprotic solvent, and an organotin-based acylation promoter, where water is removed using gas or solvent vapors, allowing for faster reaction times and higher selectivity of sucrose-6-ester production through reactive distillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional batch dehydration methods are used, then water removal is achieved, but reaction time is excessively long (60 minutes or more)
Solution Approach 1:
The patent implements continuous counter-current contact between the reaction mixture and gas/solvent vapour phases, replacing conventional batch dehydration. This continuous operation maintains constant driving force for water removal throughout the process, achieving complete dehydration in 3-8 minutes versus 60+ minutes in batch methods, thereby dramatically improving productivity while reducing time loss.
Solution Approach 2:
The patent employs gas or solvent vapour phases to remove water from the reaction mixture through counter-current contact. This pneumatic approach uses vapor-phase mass transfer to achieve rapid dehydration, replacing liquid-based batch methods and enabling the reaction to reach completion in minutes rather than hours, thus resolving the time-productivity contradiction.
2Quantity of substance
If prolonged dehydration reaction is performed, then water is removed, but decomposed carbohydrates are produced
Solution Approach 1:
The continuous counter-current dehydration process maintains optimal water removal rate throughout the reaction, preventing water accumulation that would otherwise require prolonged reaction times. This ensures complete water removal (achieving 26-60% water removal in 3-8 minutes) while minimizing residence time, thereby eliminating the condition for carbohydrate decomposition and reducing harmful by-products.
Solution Approach 2:
The patent rapidly accelerates the dehydration step through counter-current vapor contact, completing water removal in 3-8 minutes versus 60+ minutes conventionally. This 'rushing through' the dehydration phase prevents the extended reaction time that causes carbohydrate decomposition, thus achieving complete water removal without generating harmful decomposed carbohydrates.
3Quantity of substance
If extended reaction time is used, then dehydration is complete, but unreacted sucrose remains in the product
Solution Approach 1:
The continuous counter-current dehydration maintains constant water removal efficiency throughout the process, achieving complete dehydration (26-60% water removal) in just 3-8 minutes. This prevents the extended reaction time that leads to sucrose degradation and residual unreacted sucrose, thereby achieving both dehydration completeness and high product purity (95-98%) simultaneously.
Solution Approach 2:
The patent rapidly completes the dehydration step through vapor-phase counter-current contact, achieving full water removal in 3-8 minutes versus 60+ minutes conventionally. This rapid completion prevents sucrose degradation and minimizes unreacted sucrose in the final product, resolving the contradiction between dehydration completeness and product purity.
4Temperature
If slow dehydration reaction occurs, then reaction conditions are mild, but yield of sucrose-6-ester is reduced
Solution Approach 1:
The patent uses gas or solvent vapour phases to remove water from the reaction mixture through counter-current contact. This pneumatic dehydration method achieves rapid water removal at mild temperatures (30-100°C) in just 3-8 minutes, compared to prolonged heating required in batch methods. The vapor-phase mass transfer enables complete dehydration under mild conditions, achieving 95-98% yield without thermal degradation.
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 significantly reduces reaction time, minimizes the production of decomposed carbohydrates, and achieves high selectivity of sucrose-6-ester, thereby improving the yield and reducing the formation of undesirable by-products.
Implementation Method 1
removal of water from said first reaction mixture by contacting, in a continuous counter-current manner, with gas or solvent vapour capable of removing water
Implementation Method 2
forming a first reaction mixture comprising sucrose, a polar aprotic solvent, and an organotin-based acylation promoter
Data Source
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AI summary
The present application discloses a process for the synthesis of a sucrose-6-ester comprising: (a) forming a first reaction mixture comprising sucrose, a polar aprotic solvent, and an organotin-based acylation promoter; (b) removal of water from said first reaction mixture by contacting, in a continuous counter-current manner, with gas or solvent vapour capable of removing water at a temperature, pressure and residence time sufficient to afford a second reaction mixture which is substantially free from water; followed by (c) adding a carboxylic anhydride to said second reaction mixture to afford a third reaction mixture, and maintaining said third reaction mixture at a temperature and for a period of time sufficient to produce a sucrose-6-ester. The sucrose-6-ester can be used to make sucralose.