Nitrate Ester Synthesis via Microreactor Segmentation

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Solution Overview

Problem

The preparation of organic nitrate esters, especially those with multiple nitryloxy groups, is challenging due to safety issues related to their explosive nature, the use of corrosive acids, and the management of aqueous nitrate waste, which complicates industrial production and reaction control.

Innovation Solution

A method involving a microreactor system where a solution of a compound with a hydroxyl group and a nitrating agent solution of nitric acid, acetic anhydride, and acetic acid are combined in specific ratios within microtubes, allowing for controlled nitrification to produce nitrate esters with improved yield and purity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional batch reactor is used for preparation of nitrate ester, then reaction can be performed, but local overheating occurs and safety danger arises due to uneven distribution of reactants

Engineering Contradiction:

ImprovesafetyVSAvoidlocal overheating

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent divides the reaction system into multiple microreactors with small channels (0.5-2 mm diameter), creating numerous separate reaction zones. This segmentation ensures uniform heat distribution and prevents local overheating by limiting the volume of reactants in each microreactor, while maintaining overall reaction efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces conventional mechanical stirring and heating systems with a microreactor system that uses controlled fluid flow and heat exchange surfaces integrated into the microreactor structure. This substitution eliminates the need for aggressive mechanical stirring and provides more uniform temperature control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If highly corrosive acids are used for nitrate ester preparation, then nitrification reaction can proceed, but equipment corrosion and waste management difficulty increase

Engineering Contradiction:

Improvereaction efficiencyVSAvoidcorrosive waste

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces acetic acid and acetic anhydride as intermediary substances that facilitate the nitrification reaction. These intermediaries react with nitric acid to form acetyl nitrate, a more stable nitrating agent that reduces the need for highly corrosive conditions while maintaining reaction efficiency. The intermediary system allows for milder acid conditions and easier waste management.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If organic nitrate ester with multiple nitryloxy groups is prepared, then high value product is obtained, but safety issues and handling difficulty increase due to explosive nature

Engineering Contradiction:

Improveproduct valueVSAvoidexplosive sensitivity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent performs the nitrification reaction in multiple separate microreactors rather than a single large reactor. This segmentation allows for controlled, stepwise formation of multiple nitryloxy groups, reducing the concentration of explosive intermediates in any single location and improving safety during handling and processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs continuous flow through the microreactors rather than batch processing. This continuous action allows for immediate removal of heat and reactive intermediates, preventing accumulation of explosive materials and enabling safer handling of the final high-value nitrate ester products.

Inventive Principle:

Principle #20Continuity of useful action

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 enables safe and stable production of nitrate esters with high yield and purity by utilizing a microreactor system, reducing reaction time and avoiding local overheating, while allowing for precise control over the nitrification process.

Implementation Method 1

a nitrating agent solution of nitric acid, acetic anhydride, and acetic acid are combined in specific ratios within microtubes, allowing for controlled nitrification to produce nitrate esters

Methodology Applied

Scientific EffectNitrification: Chemical Bonding

Implementation Method 2

utilizing a microreactor system, reducing reaction time and avoiding local overheating

Methodology Applied

Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentUS10703707B2Method for preparing nitrate ester

Publication Date: 2020.07.07 IND TECH RES INST

AI summary

A method for preparing a nitrate ester is provided. The method includes providing a first solution including a compound (which has at least one hydroxyl group) and a carboxylic acid having 2-5 carbon atoms; providing a second solution including nitric acid, acetic anhydride, and acetic acid; and transferring the first solution and the second solution to a microreactor, obtaining a nitrate ester after a residence time. In particular, the ratio of the weight of nitric acid to the total volume of the acetic anhydride and acetic acid is 1:1 to 1:3.5. The ratio of the molar amount of nitric acid to the hydroxyl group equivalent of the compound is from 1:1 to 15:1.