Halogen-Free Synthesis of N-Hydroxyethylated Hexanediamines
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Solution Overview
Problem
Existing synthesis routes for partially N-hydroxyethylated tertiary 1,6-hexanediamines generate halogenated salts, which are difficult to manage and separate, making them unsuitable for industrial-scale production and not aligned with green chemistry principles.
Innovation Solution
A two-step synthesis process using 1,6-hexanediamine and ethylene oxide, without any halogenated compounds, producing N,N'-dimethyl-N,N'-di(2-hydroxyethyl)-1,6-hexanediamine, where the reactions do not generate salts, only water and light alcohols as co-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If halogenated precursor reagents (1,6-dichlorohexane, 1,6-dibromohexane) are used in condensation reaction, then the synthesis of N,N'-dimethyl-N,N'-di(2-hydroxyethyl)-1,6-hexanediamine can be achieved, but halogenated salts (hydrochloric acid, hydrobromic acid) are generated requiring complex purification and salt management
Solution Approach 1:
The invention extracts and eliminates the halogenated reagents from the synthesis process. Instead of using 1,6-dichlorohexane or 1,6-dibromohexane, the patent employs 1,6-hexanediamine as the starting material, which completely avoids generating halogenated salts during the reaction, thus removing the harmful byproduct generation at the source
Solution Approach 2:
The invention changes the chemical parameters of the starting materials. By switching from halogenated compounds to non-halogenated 1,6-hexanediamine, the reaction pathway is fundamentally altered to produce water and light alcohols instead of halogenated salts, changing the nature of the byproducts from harmful to benign
2Productivity
If conventional synthesis routes using halogenated compounds are employed, then the desired amine product can be obtained, but significant quantity of salts must be separated and eliminated through filtration, centrifugation or washing
Solution Approach 1:
The invention removes the salt generation step entirely by eliminating halogenated reagents from the process. The purification process is simplified because no halogenated salts are formed, eliminating the need for complex separation equipment and operations such as filtration, centrifugation, or extensive washing steps
Solution Approach 2:
The invention changes the byproducts from problematic halogenated salts that must be discarded through complex separation to benign water and light alcohols that can be easily removed by simple distillation or evaporation, making the discarding process much simpler and more efficient
3Productivity
If halogenated reagents and tosyl halides are used in synthesis, then the reaction proceeds efficiently, but the process is not aligned with green chemistry principles and not suitable for industrial-scale production
Solution Approach 1:
The invention fundamentally changes the chemical composition parameters by replacing halogenated reagents and tosyl halides with non-halogenated 1,6-hexanediamine. This parameter change transforms the reaction from one that generates environmentally harmful byproducts to one that produces only water and light alcohols, aligning with green chemistry principles while maintaining industrial scalability
Solution Approach 2:
The invention converts the potential harm of complex purification requirements into a benefit by designing a reaction that naturally produces easily separable byproducts. The water and light alcohols formed are environmentally benign and can be removed by simple processes, turning what would have been a complex waste management problem into a straightforward separation task
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 method allows for the efficient synthesis of partially N-hydroxyethylated tertiary 1,6-hexanediamines without halogenated salts, facilitating industrial development and aligning with sustainable chemistry practices by eliminating the need for salt separation and management.
Implementation Method 1
a first reaction step between 1,6-hexanediamine and ethylene oxide to form at least one intermediate compound chosen from the list comprising N-(2-hydroxyethyl)-1,6-hexanediamine, N-N'-di(2-hydroxyethyl)-1,6-hexanediamine, N,N-di(2-hydroxyethyl)-1,6-hexanediamine, and N-N-N'-tri(2-hydroxyethyl)-1,6-hexanediamine
Implementation Method 2
a second step of methylation of the primary or secondary amine functions of said at least one intermediate compound to form at least the compound according to formula (I 2). The second methylation step is carried out by reaction between said intermediate compound, formaldehyde and hydrogen in the presence of a hydrogenation catalyst
Implementation Method 3
The second methylation step is carried out by reaction between said intermediate compound, formaldehyde and hydrogen in the presence of a hydrogenation catalyst
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for synthesising at least one nitrogen compound belonging to the family of the partially N-hydroxyethylated tertiary 1,6-hexanediamines of the following general formula (I) in which the groups R1, R2 and R3 are each selected, equally, from a methyl group and a hydroxyethyl group, and at least one group from among R1, R2 and R3 is a methyl group, comprising n reaction steps, n ranging from 1 to 3, and comprising at least one first reaction between a first precursor compound free of halogen atoms and a second precursor compound free of halogen atoms. The first precursor compound comprises a carbon backbone formed by a linear chain of six carbon atoms with the four central carbon atoms each bonded to two hydrogen atoms and the carbon atoms in the alpha and omega positions not bonded to a halogen atom, and wherein none of the n reaction steps comprise a halogenated reagent.