Regioselective Cellulose Ester Synthesis via Carboxylated Ionic Liquids

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Solution Overview

Problem

The production of cellulose esters in ionic liquids is hindered by the high cost and inefficiency of existing methods, which often result in ionic liquids with residual metals, sulfur, and halides, and the use of halide and sulfur intermediates, making recycling and reuse challenging.

Innovation Solution

A process involving the dissolution of cellulose in a carboxylated ionic liquid, followed by sequential or simultaneous contact with acylating reagents to form a cellulose ester, precipitation, and separation, with the option to recycle the ionic liquid for further cellulose dissolution, reducing residual impurities and enabling regioselective substitution of cellulose esters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional methods are used to produce cellulose esters in ionic liquids, then cellulose esters can be produced, but the ionic liquids contain residual metals, sulfur, and halides making recycling difficult

Engineering Contradiction:

Improvepurity of cellulose esterVSAvoidrecyclability of ionic liquid

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes harmful intermediates (halides and sulfur compounds) from the synthesis pathway by using carboxylated ionic liquids that directly acylate cellulose without requiring these problematic intermediates. This extraction of harmful elements enables both high purity cellulose esters and recyclable ionic liquids

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical parameters of the ionic liquid by using carboxylated variants instead of conventional ionic liquids. This parameter change (adding carboxyl groups) enables the ionic liquid to serve as both solvent and acylating agent, eliminating residual impurities and improving recyclability while maintaining production effectiveness

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If ionic liquids are used as solvents in cellulose ester production, then dissolution and reaction can occur, but the cost is high and recycling methods are insufficient

Engineering Contradiction:

Improvesolubility of celluloseVSAvoidcost of ionic liquid

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The carboxylated ionic liquid performs multiple functions: it acts as the solvent for cellulose dissolution, as the acylating reagent for ester formation, and as a recyclable medium. This multi-functionality reduces the need for additional expensive reagents and simplifies the recycling process, thereby reducing overall manufacturing cost while maintaining high adaptability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The carboxylated ionic liquid provides the acyl groups needed for cellulose esterification from its own structure, eliminating the need for separate acylating agents. This self-service capability reduces material costs and simplifies the process, making the high-cost ionic liquid more economically viable

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If cellulose is converted to cellulose triester and then hydrolyzed to control degree of substitution, then desired DS can be achieved, but random copolymer formation occurs with up to 8 different monomers

Engineering Contradiction:

Improvedegree of substitution controlVSAvoiduniformity of cellulose ester structure

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent performs preliminary acylation directly on dissolved cellulose using carboxylated ionic liquids before any hydrolysis step. This preliminary action allows precise control of the degree of substitution through stoichiometric control of the acylating agent, and the uniform reaction environment prevents random copolymer formation, yielding structurally uniform cellulose esters

Inventive Principle:

Principle #10Preliminary 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 process allows for the production of regioselectively substituted cellulose esters with improved properties, such as controlled degree of substitution and reduced viscosity, facilitating easier processing and potential applications in films, coatings, and drug delivery systems.

Implementation Method 1

dissolving cellulose in a carboxylated ionic liquid to thereby form a cellulose solution

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 2

contacting the cellulose solution with at least two acylating reagents to thereby provide an acylated cellulose solution comprising a cellulose ester

Methodology Applied

Scientific EffectEsterification: Chemical Bonding

Implementation Method 3

contacting the acylated cellulose solution with a non-solvent to cause at least a portion of the cellulose ester to precipitate

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Data Source

PatentUS10174129B2Regioselectively substituted cellulose esters produced in a carboxylated ionic liquid process and products produced therefrom

Publication Date: 2019.01.08 EASTMAN CHEM CO

AI summary

This invention relates to novel compositions comprising regioselectively substituted cellulose esters. One aspect of the invention relates to processes for preparing regioselectively substituted cellulose esters from cellulose dissolved in ionic liquids. Another aspect of the invention relates to the utility of regioselectively substituted cellulose esters in applications such as protective and compensation films for liquid crystalline displays.