Deacylation of X-ray Contrast Agent Intermediates
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Solution Overview
Problem
The industrial production of non-ionic X-ray contrast agents like lodixanol and lohexol involves significant impurity formation during the acylation and deacylation steps, particularly the generation of Compound 1, which is difficult to remove and affects yield and purity.
Innovation Solution
The process involves adding the over-acylated intermediate Compound B2 to an aqueous solution of a deacylating agent, such as sodium hydroxide, under milder conditions to reduce the formation of impurities like Compound 1, thereby optimizing the deacylation step and improving yield and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deacylation process is used to remove acylated hydroxyl groups, then deacylation is achieved, but significant impurity (Compound 1) is generated which is difficult to remove
Solution Approach 1:
The patent changes the concentration parameter of the deacylation process by performing it in a diluted aqueous solution (0.1-10% w/v base concentration) rather than concentrated conditions. This parameter change suppresses the formation of impurity Compound 1 while maintaining effective deacylation, achieving purity >99.5% without requiring additional purification steps.
2Productivity
If acylation step is performed to produce Compound A from Compound B, then N-acetylated compound is formed, but O-acetylated intermediate (Compound B2) is generated which requires deacylation
Solution Approach 1:
The patent performs deacylation during the acylation process itself by adding aqueous base to the acylation mixture, rather than as a separate subsequent step. This preliminary action removes O-acetyl groups from Compound B2 in-situ, preventing impurity accumulation and eliminating the need for a distinct deacylation workup step, thereby maintaining high productivity.
3Manufacturing precision
If deacylation is performed to remove O-acetyl groups, then purity is improved, but heat is generated during the process
Solution Approach 1:
The patent changes the concentration parameter by performing deacylation in diluted aqueous solution (0.1-10% w/v base concentration) rather than concentrated conditions. This dilution reduces the exothermic heat generation during deacylation while maintaining effective removal of O-acetyl groups, enabling safer large-scale production with minimal temperature control 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
This approach significantly reduces the generation of impurity Compound 1, leading to higher purity (>99.5%) and improved yield, with minimal heat generation, making the process more efficient and cost-effective for large-scale production.
Implementation Method 1
a process for deacylation of the acylated hydroxyl groups of an intermediate of these compounds
Data Source
AI summary
The present invention relates to a process for the preparation of iodinated X-ray contrast agents and in particular to key intermediates thereof. It particularly relates to an improved process for preparation of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (Compound A) or N,N'-bis(2,3-dihydroxypropyl)-5-formamido-2,4,6-triiodoisophthalamide (Compound C), which are intermediates in the industrial preparation of non-ionic X-ray contrast agents. More particularly the invention provides a process for deacylation of the acylated hydroxyl groups of an intermediate compound of Compound A and Compound C.