Sorbic Anhydride Phosgenation Purity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing sorbic anhydride result in rapid isomerization of sorbyl chloride, leading to impurities and inefficiencies, particularly in the production of substantially isomerically pure all-E-sorbic anhydride, which is essential for its preservative properties.
Innovation Solution
Phosgenation of alkali metal or alkaline earth metal salts of sorbic acid in inert solvents at controlled temperatures and stoichiometries, achieving high yields and purity levels of all-E-sorbic anhydride with minimal isomerization and byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosgene-based production of sorbyl chloride is used, then sorbic anhydride can be produced, but rapid isomerization occurs leading to impurities and reduced purity of all-E-sorbic anhydride
Solution Approach 1:
The patent changes the reaction parameters by using controlled phosgenation conditions with specific temperature ranges and stoichiometries to prevent isomerization. It also changes the approach from producing sorbyl chloride as an intermediate to directly producing sorbic anhydride through phosgenation of sorbic acid salts, thereby eliminating the isomerization step that occurs during sorbyl chloride formation and subsequent hydrolysis.
Solution Approach 2:
The patent extracts the problematic intermediate step (sorbyl chloride formation) from the synthesis pathway. Instead of going through sorbyl chloride which undergoes rapid isomerization, the method directly converts sorbic acid salts to sorbic anhydride through phosgenation, removing the source of isomerization impurities from the process.
2Ease of manufacture
If chlorination of sorbic acid using thionyl chloride or oxalyl chloride is used, then sorbyl chloride can be produced, but isomerization problems occur similar to phosgene-based methods
Solution Approach 1:
The patent changes the reagent system from thionyl chloride or oxalyl chloride to phosgene, and more importantly, changes the reaction approach from forming the chloride intermediate to direct anhydride formation. This parameter change eliminates the isomerization problem while maintaining ease of manufacture through a straightforward phosgenation process.
3Quantity of substance
If polyester cleavage method is used, then sorbic acid can be produced, but the method is tightly bound to special production conditions and not universally practicable
Solution Approach 1:
Instead of producing sorbic acid through polyester cleavage and then converting it to sorbic anhydride, the patent inverts the approach by directly converting sorbic acid salts to sorbic anhydride through phosgenation. This inversion eliminates the need for polyester production and cleavage steps, making the method more versatile and independently applicable without being bound to special polyester production conditions.
4Manufacturing precision
If triethylammonium salt phosgenation is used, then sorbic anhydride can be produced, but large amounts of triethylammonium chloride are produced requiring separation and disposal
Solution Approach 1:
The patent extracts the problematic auxiliary base (triethylammonium) from the reaction system. By using alkali metal or alkaline earth metal salts of sorbic acid directly as reactants with phosgene, the method eliminates the need for auxiliary bases that generate ammonium chloride waste. This extraction of the harmful component simplifies the process and eliminates waste separation requirements.
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 method produces all-E-sorbic anhydride with >90% yield and >95% purity, reducing isomerization and byproduct issues, and enhances its preservative effectiveness, making it suitable for food preservation with minimal environmental impact.
Implementation Method 1
the phosgenation of alkali metal or alkaline earth metal salts of sorbic acid (in particular potassium sorbate) in inert solvents succeeds readily and in high yields at suitable temperatures in a one-step synthesis
Data Source
AI summary
A method is described for the production of sorbic anhydride, in which alkali metal or alkaline earth metal salts of sorbic acid are reacted with phosgene in an inert organic solvent. In addition, use thereof as a preservative in foods, in particular drinks, is described.