Triiodophenol Iodination in Aqueous Medium Without Chlorinated By-Products
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for the iodination of phenol derivatives to produce 2,4,6-triiodophenol suffer from low yields, formation of chlorinated by-products, and require harsh conditions, making them inefficient and unsafe for industrial applications.
Innovation Solution
A process using an iodinating system comprising silver or copper with phosphoric or carbonic acid in an aqueous medium at room temperature, avoiding the use of corrosive reagents like ICI and achieving high yields and complete conversion of phenol to 2,4,6-triiodophenol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ICI or its analogues are used for iodination, then the iodination reaction can proceed, but corrosive acids are generated requiring neutralization, increasing operation time and waste volumes
Solution Approach 1:
The patent extracts and removes the problematic corrosive acid component (HCl) from the traditional ICI-based iodination system. By using I2 with Ag2O or CuSO4 in aqueous medium, the reaction generates only mild by-products that do not require extensive neutralization, thereby reducing operation time and waste treatment requirements while maintaining effective iodination capability
Solution Approach 2:
The patent changes the chemical parameters of the iodinating system from strong acid-based (ICI in concentrated HCl) to mild aqueous-based (I2 with Ag2O/CuSO4 at pH 7.0-9.0). This parameter change eliminates the need for time-consuming neutralization steps and reduces waste volumes, while the reaction remains effective in producing 2,4,6-triiodophenol derivatives
2Productivity
If ICI or its analogues are used for iodination, then the reaction can proceed, but chlorine gas is generated that reacts with phenol substrate to form chlorinated by-products
Solution Approach 1:
The patent converts the potentially harmful chlorine gas by-product of traditional ICI iodination into a beneficial outcome by completely eliminating chlorine generation. The alternative system using I2 with Ag2O or CuSO4 produces only harmless by-products (water, CO2, or mild salts), preventing chlorinated by-product formation and improving final product purity without sacrificing reaction efficiency
Solution Approach 2:
The patent introduces Ag2O or CuSO4 as intermediary substances that facilitate the iodination reaction without generating harmful chlorine gas. These intermediaries enable the release of iodine from I2 in a controlled manner that selectively iodinates the phenol substrate at positions 2, 4, and 6 without competing chlorination reactions, thereby ensuring high product purity
3Speed
If heating to 60°C or higher is used for in-situ generation of iodinating species, then the reaction proceeds faster, but hydrolysation of amide moieties occurs reducing yield
Solution Approach 1:
The patent changes the temperature parameter from elevated (60°C or higher) to ambient (room temperature). This parameter change prevents thermal hydrolysis of amide moieties in substrates like iomeprol intermediates, maintaining high overall yield. The use of Ag2O or CuSO4 as catalysts compensates for the lower temperature, ensuring the reaction proceeds at a practical rate without requiring heating that would cause decomposition
4Manufacturing precision
If electrochemical triioduration or heating at reflux is used, then complete conversion can be achieved, but reaction times exceed 2 hours
Solution Approach 1:
The patent changes multiple parameters simultaneously: uses aqueous medium at pH 7.0-9.0, employs Ag2O or CuSO4 as catalysts, and conducts reaction at room temperature. This combination of parameter changes achieves complete conversion of the phenol substrate to 2,4,6-triiodophenol in significantly shorter times than electrochemical methods or reflux heating, eliminating the need for prolonged reaction periods while maintaining complete conversion
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 process achieves high yields (>90%) and complete conversion of phenol to 2,4,6-triiodophenol in short reaction times, reducing the formation of side-products and improving safety and cost-effectiveness.
Implementation Method 1
reacting said phenol of step a) and said iodinating system of step b) in an aqueous medium having a pH comprised in the range of 7.0 to 9.0, to obtain the 2,4,6-triiodophenol of formula (II)
Data Source
Figure 1
AI summary
The invention relates to a process for the preparation of a 2,4,6-triiodo-phenol derivative of formula (II), which is useful as an intermediate for the synthesis of conventional X-ray contrast agents, said process comprising the tri-iodination of the correspondent phenol derivative of said 2,4,6-triiodo-phenol derivative by means of an iodinating system comprising I2 and an oxide or a salt of an element of group 11 of the periodic table.