Nitration of Alkanediols Using Dilute Nitric Acid
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Solution Overview
Problem
Current methods for the nitration of α,ω-C 3-10 alkanediols, such as 1,3-propanediol, face challenges including poor selectivity, high salt loads, use of explosive reagents, and requirements for organic solvents and low temperatures, making them inefficient and unsafe for industrial-scale production of ω-nitrooxy-C 3-10 alkane-1-ols like 3-nitrooxypropanol.
Innovation Solution
A solvent-free, one-pot batch process using a mixture of 50-75 wt.% nitric acid in water as the nitration agent, with nitric acid amounts ranging from 0.5 to 5 mol equivalents, and conducted at elevated temperatures (65-100°C), in the absence of organic solvents and explosive reagents, to efficiently produce ω-nitrooxy-C 3-10 alkane-1-ols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional nitration methods using acetyl nitrate or stabilized nitric acid are used, then nitration efficiency is improved, but process safety deteriorates due to explosive reagents
Solution Approach 1:
The patent changes the concentration parameter of nitric acid from highly concentrated (83-85% or fuming) to a safer range (50-75%), and changes the temperature parameter from low temperature (≤0°C) to elevated temperature (65-100°C). This parameter transformation maintains nitration efficiency while dramatically improving process safety by eliminating explosive conditions
Solution Approach 2:
The patent replaces expensive and hazardous reagents (acetyl nitrate, stabilized nitric acid requiring special handling) with a simpler, safer nitric acid solution that can be handled more easily. The process uses readily available nitric acid at moderate concentration, eliminating the need for specialized explosive reagent handling infrastructure
2Manufacturing precision
If chlorinated organic solvents are used for nitration, then reaction selectivity is improved, but environmental harm and process complexity increase
Solution Approach 1:
The patent extracts and eliminates the harmful chlorinated organic solvent component from the reaction system. By removing this harmful element entirely and replacing it with water as the sole solvent, the process achieves the same nitration selectivity without environmental contamination or safety concerns associated with chlorinated solvents
Solution Approach 2:
The patent creates a homogeneous aqueous reaction system where nitric acid, water, and alkanediol mix completely. This homogeneous aqueous environment provides sufficient reaction selectivity without requiring the phase-separated chlorinated solvent systems, simplifying the process and eliminating environmental harm
3Manufacturing precision
If low temperatures (≤0°C) are used for nitration, then by-product formation is reduced, but energy consumption and process complexity increase
Solution Approach 1:
The patent inverts the conventional temperature approach by using elevated temperature (65-100°C) instead of low temperature (≤0°C). This counterintuitive approach, combined with the optimized nitric acid concentration (50-75%), achieves better by-product control while significantly reducing energy consumption for cooling and simplifying process equipment requirements
4Productivity
If high amounts of nitric acid equivalents are used, then nitration completeness is improved, but salt load and waste treatment complexity increase
Solution Approach 1:
The patent optimizes the nitric acid concentration parameter to 50-75% and uses a moderate amount (0.5-5 mol equivalents), which is sufficient to achieve complete nitration. This optimized parameter combination ensures reaction completeness while minimizing excess acid usage and subsequent salt load, simplifying waste treatment
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 process allows for the economical and safe production of ω-nitrooxy-C 3-10 alkane-1-ols with reduced nitric acid equivalents, minimizing by-products and enabling scale-up, while avoiding the use of hazardous solvents and low temperatures, thus enhancing process safety and efficiency.
Implementation Method 1
the nitration of an α,ω-C 3-10 alkanediol with a nitration agent, characterized in that the nitration agent is a mixture consisting of 50 to 75 wt.-% of nitric acid in water
Data Source
AI summary
The invention relates to a process for the preparation of ω-nitroxyC3-1 0 alkane-1-ols comprising the nitration of an α,ω-C 3-10 alkanediol with a nitration agent, optionally in the presence of a nitrite trapping agent, characterized in that the nitration agent is a mixture consisting of 50 to 75 wt.-% of nitric acid in water wherein the nitric acid is used in an amount selected in the range from 0.5 to 5 mol equivalents based on the α,ω--C3-10alkanediols, and wherein the nitration is carried out at a temperature selected in the range from 65 - 100°C.