Alkanediol Monoacylate Nitration in Continuous Flow for Safer Selectivity
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Solution Overview
Problem
Existing methods for producing ω-nitrooxy-C3-10alkane-1-ols, such as 3-nitrooxypropanol, face challenges in industrial scale production due to poor selectivity, safety concerns with explosive organic nitrates, and increased processing costs in multi-step processes.
Innovation Solution
A three-step process involving acylation, nitrate ester formation, and hydrolysis of α,ω-alkanediols, with continuous nitrate ester formation in a flow-reactor system using inert solvents and controlled reaction conditions to enhance safety and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct nitrate ester formation of α,ω-alkanediols is used, then the production process is simplified, but selectivity deteriorates leading to formation of explosive dinitrated alkanediols
Solution Approach 1:
The patent applies segmentation by using a two-reactor series configuration where the nitration process is divided into two distinct stages. The first reactor performs partial nitration under controlled conditions to form mononitrated intermediates, while the second reactor completes the nitration to form the desired dinitrated product. This segmentation prevents over-nitration and formation of explosive byproducts by controlling the reaction progression through separate stages with intermediate separation and purification steps.
2Reliability
If protection of one alcohol group prior to nitrate ester formation is implemented, then safety and selectivity are improved, but yield decreases and processing cost increases
Solution Approach 1:
The patent applies preliminary action by selectively protecting one hydroxyl group of the α,ω-alkanediol before nitration through acylation or silylation. This preliminary protection step prevents unwanted reactions at the protected position during nitrate ester formation, ensuring high selectivity for mononitrated products. The protecting group is then removed in a final deprotection step, yielding the desired nitrate ester with high purity and safety while maintaining acceptable overall yield through optimized reaction conditions.
3Manufacturing precision
If additional reaction steps for protection and deprotection are added, then selectivity is improved, but processing cost increases
Solution Approach 1:
The patent applies parameter changes by optimizing reaction conditions including temperature, catalyst selection, solvent systems, and stoichiometry ratios for each step of the multi-step process. By carefully controlling these parameters, the patent minimizes side reactions, reduces the need for extensive purification steps, and maximizes product yield at each stage. This parameter optimization significantly reduces processing costs despite the additional reaction steps required for high selectivity.
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 of ω-nitrooxy-C3-10alkane-1-ols while maintaining reaction stability and ensuring process safety, allowing for quantitative recovery of reactants and solvents.
Implementation Method 1
acylation of the corresponding α,ω-alkanediol with an acylating agent
Implementation Method 2
nitrate ester formation of the resulting α,ω-C3-10alkanediol monoacylate with a nitrating agent
Implementation Method 3
hydrolysis of the acyl group to obtain the respective α,ω-C3-10alkanediol mononitrate
Implementation Method 4
removal and recovery of the inert solvent from the reaction mixture by distillation
Data Source
AI summary
The invention relates to a safe and efficient process for the nitrate ester formation of an α,ω-C3-10alkanediol monoacylate. The process is safer to operators and allows to obtain advantageous yields on industrial scale.