Oxidative Cleavage of Vicinal Diols via pH Control
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Solution Overview
Problem
Existing processes for oxidative cleavage of vicinal diols in the production of carboxylic acids face challenges with catalyst recycling, leading to pH reduction, slowed reaction rates, and reduced yield due to the acidic nature of the aqueous phase.
Innovation Solution
Maintaining a pH value between 4 and 7 during the oxidative cleavage reaction allows for the reuse of the catalytic solution, maintaining reaction time and improving yield, even with partial or complete substitution of fresh catalyst, by adding a base to the recycled aqueous phase before reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the aqueous phase containing catalyst is reused in the oxidative cleavage reaction, then economic and environmental benefits are achieved through catalyst recovery, but the pH of the aqueous phase decreases during the reaction, causing slowing of reaction rate and reduction in yield
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the recycled aqueous phase back to the initial range of 4-7 before reuse. This parameter adjustment restores the optimal reaction conditions, allowing the recycled catalyst to maintain high reaction rates and yields comparable to fresh catalyst, thus resolving the contradiction between catalyst reuse benefits and reaction performance degradation
Solution Approach 2:
The patent implements a feedback mechanism where the pH of the recycled aqueous phase is monitored and adjusted back to the optimal range before being fed into the next reaction cycle. This feedback control ensures that the recycled catalyst consistently delivers high reaction rates and yields, eliminating the performance degradation that would otherwise occur with repeated reuse
2Productivity
If multiple catalysts are used for the two-step oxidation process, then the oxidative cleavage reaction can be completed, but the complexity of the process increases due to catalyst separation and management
Solution Approach 1:
The patent merges the two oxidation steps into a single continuous process where the first catalyst remains in the aqueous phase and the second catalyst is added directly to the same reactor. The aqueous phase containing the first catalyst serves as the reaction medium for the second step, eliminating the need for separate separation units and reducing overall process complexity while maintaining high productivity
Solution Approach 2:
The aqueous phase containing the first catalyst serves multiple functions: it acts as the reaction medium for the first oxidation step, provides a continuous catalyst source for ongoing reactions, and serves as the base solution for adding the second catalyst in the oxidative cleavage step. This multi-functionality reduces the number of separate process units needed
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 efficient recycling of the catalytic solution, maintaining reaction time and significantly increasing the yield of monocarboxylic and dicarboxylic acids, with repeated reuse showing comparable results to fresh catalyst usage.
Implementation Method 1
at least a part of the said aqueous phase separated out in step c) and comprising the catalyst and at least one base are fed to step b) so that the mixture of the intermediate compound of step a) with the said part of aqueous phase and the said base has a pH value of between 4 and 7
Implementation Method 2
reacting the said intermediate compound, oxygen or compound containing oxygen, and a catalyst capable of catalysing the oxidation reaction of vicinal diols to carboxylic acid groups
Implementation Method 3
reacting at least one unsaturated carboxylic acid or a derivative thereof, an oxidising compound and a catalyst capable of catalysing the oxidation reaction of the olefin double bond, in order to obtain an intermediate compound containing vicinal diols
Data Source
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AI summary
This invention relates to a process for obtaining monocarboxylic and dicarboxylic acids from unsaturated carboxylic acids and/or their derivatives. The said process comprises an oxidative cleavage reaction of vicinal diols into which are fed at least some of the aqueous phase separated out at the end of the reaction itself and at least one base so that the pH of the aqueous solution at the start of the oxidative cleavage reaction is between 4 and 7.