Bifunctional Catalyst for Phosgene-Free Isocyanate Synthesis

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Solution Overview

Problem

Current phosgene-free isocyanate production methods, particularly carbamate cleavage, face challenges in achieving high selectivity and efficiency without undesirable side reactions, necessitating the development of effective catalysts that accelerate the reaction while minimizing side products.

Innovation Solution

A process utilizing catalysts with both proton donor and proton acceptor functions, specifically compounds of the formula (X)(Y)(Z-H), where Z represents O, S, or N, and X and Y are connected via a bridge, facilitating the cleavage of carbamates or thiolcarbamates to form isocyanates at elevated temperatures, thereby enhancing reaction efficiency and selectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If thermal carbamate cleavage is performed without catalyst, then high temperature (above 180°C) is required, but this leads to increased energy consumption and potential side reactions

Engineering Contradiction:
Improvereaction temperatureVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent changes the chemical parameter by introducing a catalyst with specific functional groups (carboxylic acid, phenol, sulfonic acid, or phosphoric acid) that lowers the activation energy of the carbamate cleavage reaction, enabling it to proceed at reduced temperatures (150-200°C) while maintaining high conversion efficiency and minimizing side reactions

Inventive Principle:
Principle #35Parameter changes

2Productivity

If conventional catalysts are used for carbamate cleavage, then reaction rate is improved, but selectivity decreases due to undesirable side reactions

Engineering Contradiction:
Improvereaction rateVSAvoidreaction selectivity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by designing catalysts with specific functional groups (carboxylic acid, phenol, sulfonic acid, or phosphoric acid) that provide localized active sites for carbamate cleavage. These catalysts exhibit high selectivity (90-95% isocyanate selectivity) by facilitating the desired reaction pathway while minimizing side reactions, thus achieving both high productivity and manufacturing precision

Inventive Principle:
Principle #3Local quality

3Productivity

If metal-containing catalysts are used, then catalytic activity is achieved, but environmental friendliness and cost-effectiveness are reduced

Engineering Contradiction:
Improvecatalytic activityVSAvoidenvironmental impact
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent employs cheap, environmentally benign organic acids (carboxylic, phenolic, sulfonic, or phosphoric acids) as catalysts that can be used in small amounts and do not require expensive metal components. These catalysts provide sufficient catalytic activity for carbamate cleavage while being environmentally friendly and cost-effective, eliminating the need for metal-containing catalysts

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 proposed process significantly accelerates the formation of isocyanates with high selectivity, reducing side reactions and improving the overall efficiency of phosgene-free isocyanate production, while eliminating the need for metal-containing catalysts, thus being more environmentally friendly and cost-effective.

Implementation Method 1

A process utilizing catalysts with both proton donor and proton acceptor functions, specifically compounds of the formula (X)(Y)(Z-H), where Z represents O, S, or N, and X and Y are connected via a bridge, facilitating the cleavage of carbamates or thiolcarbamates to form isocyanates at elevated temperatures

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

catalysts with both proton donor and proton acceptor functions, specifically compounds of the formula (X)(Y)(Z-H)

Methodology Applied
Scientific EffectProton transfer:

Implementation Method 3

facilitating the cleavage of carbamates or thiolcarbamates to form isocyanates at elevated temperatures

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3679013B1Method for making isocyanates
Publication Date: 2023.11.29 COVESTRO INTELLECTUAL PROPERTY GMBH & CO KG
  • EP3679013B1 patent drawing
  • EP3679013B1 patent drawing
  • EP3679013B1 patent drawing

AI summary

The invention relates to a method for producing an isocyanate, wherein a carbamate or thiolcarbamate is converted, in the presence of a catalyst, with separation of an alcohol or thioalcohol, at a temperature of at least 150 °C, to the corresponding isocyanate, wherein a compound of the general formula (X)(Y)(Z-H) is used as a catalyst, in particular characterized in that the compound has both a proton donator function and a proton acceptor function. In the catalysts according to the invention, a separable proton is bound to a heteroatom, which is more electronegative than carbon. Said heteroatom is either identical to Z or a component thereof. In the catalysts according to the invention, there is additionally a proton acceptor function which is either identical to X or a component thereof. According to the invention, the proton donator and proton acceptor function are connected to each other by the bridge Y.