Mixed Polyol Ester Synthesis via Reactivity-Ordered Anhydride Addition
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Solution Overview
Problem
Existing processes for producing polyol esters face limitations in flexibility and controllability, particularly in achieving high conversion rates and specific compositions, especially when esterifying monocarboxylic acids with different reactivities, leading to inefficient reaction times and unsatisfactory control over ester compositions.
Innovation Solution
A two-stage process where monocarboxylic acids are reacted with polyols in the order of their reactivity, with the less reactive acids initially used as anhydrides and the more reactive acids added later as acids, allowing for precise control over the composition and reaction time of mixed polyol-carboxylic acid esters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If monocarboxylic acids with different reactivities are reacted simultaneously with polyol, then the reaction proceeds faster, but the composition of the ester mixture becomes difficult to control
Solution Approach 1:
The patent divides the esterification process into multiple sequential stages, where monocarboxylic acids with different reactivities are introduced at different times. Less reactive acids are reacted first, followed by more reactive acids in subsequent stages. This segmentation allows independent control of each acid's esterification, achieving both high overall reaction rate and precise composition control.
Solution Approach 2:
The patent applies preliminary action by pre-reacting less reactive monocarboxylic acids with the polyol before introducing more reactive acids. This ensures that less reactive acids, which would otherwise be outcompeted, are partially esterified in advance, allowing precise control over the final ester composition while maintaining efficient overall reaction progression.
2Productivity
If less reactive monocarboxylic acids are used as anhydrides, then the reaction efficiency increases, but the process complexity increases
Solution Approach 1:
The patent changes the chemical form parameter of less reactive monocarboxylic acids by using them as anhydrides instead of free acids. This parameter change significantly increases esterification efficiency and reaction rate for these acids, while the added process complexity is managed through the structured multi-stage reaction protocol.
Solution Approach 2:
The patent uses acid anhydrides as intermediary compounds to facilitate the esterification of less reactive monocarboxylic acids. The anhydride form acts as a more reactive intermediate that enables efficient esterification, which would be difficult to achieve with the free acid form, thereby resolving the efficiency-complexity trade-off.
3Manufacturing precision
If reaction time is extended to achieve high conversion, then the composition control deteriorates due to transesterification, but shortening reaction time reduces conversion
Solution Approach 1:
The patent segments the overall esterification into multiple shorter stages, each targeting specific acids. This prevents prolonged exposure that would lead to transesterification and composition drift, while still achieving high overall conversion through the cumulative effect of sequential stages.
Solution Approach 2:
By performing preliminary esterification of less reactive acids before introducing more reactive ones, the patent achieves high conversion of each acid type in controlled time windows. This preliminary action prevents the need for extended overall reaction times that would trigger unwanted transesterification reactions.
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 approach enables the production of mixed polyol esters with controlled compositions and reduced reaction times, overcoming the limitations of previous methods by allowing for a wide range of compositions and efficient esterification, particularly suitable for small polyols with multiple hydroxyl groups.
Implementation Method 1
a polyol is reacted in an at least two-stage reaction with different monocarboxylic acids in the form of monocarboxylic acids or of monocarboxylic acid anhydrides
Data Source
AI summary
The present invention relates to a process for the preparation of mixed polyol-carboxylic acid esters having a molecular weight of greater than or equal to 200 g/mol and less than or equal to 1000 g/mol, wherein a polyol is reacted in an at least two-step reaction with different monocarboxylic acids in the form of monocarboxylic acids or of monocarboxylic acid anhydrides, wherein the different monocarboxylic acids are reacted with the polyol in the order of their reactivity in the esterification reaction, starting with the lowest reactivity, wherein the monocarboxylic acids with the lower reactivity are reacted at least partly as monocarboxylic acid anhydride and the monocarboxylic acid with the highest reactivity is reacted thereafter as monocarboxylic acid with the polyol. Furthermore, the present invention relates to the use of the process for the preparation of mixed polyol esters.