Alternative Dimerisation Reagents for Iodixanol Synthesis
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Solution Overview
Problem
The traditional industrial synthesis of iodixanol relies solely on epichlorohydrin as a dimerization agent, necessitating the development of alternative reagents to ensure an acceptable yield in converting 5-acetamido-N,N′-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide to iodixanol.
Innovation Solution
The use of alternative dimerization agents such as 1,3-dichloropropanol, 1,3-dibromopropanol, 1,3-diiodopropanol, and their protected derivatives, along with specific reaction conditions like alkaline pH between 10 and 12, to facilitate the conversion of Compound A to iodixanol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If epichlorohydrin is used as the dimerisation agent, then the conversion of Compound A to iodixanol can be achieved, but the method lacks flexibility in reaction conditions and produces impurities
Solution Approach 1:
The patent applies parameter changes by systematically varying the dimerisation agent (using different halogenated propanols with varying halogen types and protected derivatives) and reaction conditions (pH 10-12, temperature 5-50°C) to optimize both the conversion efficiency and purity of iodixanol, resolving the contradiction between method flexibility and product purity
Solution Approach 2:
The patent employs readily available and inexpensive dimerisation agents such as 1,3-dichloropropanol, 1,3-dibromopropanol, and their protected derivatives as disposable reagents that can be easily replaced, providing flexible reaction conditions while maintaining acceptable yield and purity
2Productivity
If alternative dimerisation agents are used, then reaction flexibility and yield acceptability are improved, but the reaction time and temperature control become more variable
Solution Approach 1:
The patent applies dynamics by allowing variable reaction times from a few hours to several days depending on the specific dimerisation agent and desired conversion level, with temperature control between 5-50°C, enabling optimization of yield while accommodating different production needs and tolerances
3Ease of manufacture
If the dimerisation reaction is performed under alkaline conditions with pH between 10 and 12, then the conversion to iodixanol is facilitated, but the reaction may produce O-alkylated compounds and trimers
Solution Approach 1:
The patent applies local quality by selecting specific dimerisation agents with particular chemical properties (different halogen types, protected derivatives) that are better suited for the alkaline condition environment, thereby optimizing the local reaction characteristics to minimize harmful side reactions while maintaining ease of manufacture
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 allows for varying reaction times and temperatures, achieving full or partial conversion while maintaining selectivity and reducing impurities like trimers and O-alkylated compounds, thus providing a viable alternative to the conventional method.
Implementation Method 1
The traditional industrial synthesis of iodixanol involves dimerisation of intermediate 5-acetamido-N,N′-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide ('Compound A') as the final synthetic step
Data Source
AI summary
This invention relates generally to non-ionic X-ray contrast agents. It further relates to the synthesis of iodixanol. In particular, it relates to alternative dimerisation reagents in the conversion of 5-acetamido-N,N′-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (“Compound A”) to iodixanol.