Ionic Liquid Synthesis of Chalcogenones
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Solution Overview
Problem
Existing methods for producing heterocyclic chalcogenones, such as imidazole-2-thiones, require the use of external bases and solvents, leading to the formation of inorganic by-products and increased costs, as well as additional process steps.
Innovation Solution
A process involving the reaction of ionic liquids or salts with elemental chalcogens in the absence of additional bases, utilizing nitrogen-containing heterocyclic cations and anions as conjugate bases of weak acids, which eliminates the need for external bases and solvents, allowing for the formation of heterocyclic chalcogenones in a solvent-free, single-step process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external bases and solvents are used in the preparation of heterocyclic chalcogenones, then the reaction can proceed, but inorganic by-products are formed and process complexity increases
Solution Approach 1:
The ionic liquid serves dual functions: as the reaction medium and as the base reagent. The basic anion in the ionic liquid directly deprotonates the heterocyclic cation to form the carbene intermediate, eliminating the need for separate external base addition and subsequent by-product formation.
Solution Approach 2:
The patent combines the solvent function and base function into a single ionic liquid component. The ionic liquid both dissolves the reactants and provides the basic anion necessary for carbene formation, integrating multiple reagents into one substance.
2Reliability
If external bases are used in the preparation of heterocyclic chalcogenones, then the reaction can proceed, but additional process steps are required for separation
Solution Approach 1:
The ionic liquid's basic anion performs the deprotonation function internally, and the resulting conjugate acid by-product remains in the ionic liquid phase, allowing the carbene intermediate to be extracted into organic solvent without requiring separate base separation steps.
Solution Approach 2:
The ionic liquid acts as an intermediary system that facilitates the reaction and then allows for simple phase separation. The conjugate acid by-product stays in the ionic liquid phase while the neutral carbene intermediate moves to the organic phase, enabling clean separation.
3Reliability
If organic solvents are used in the preparation of heterocyclic chalcogenones, then the reaction can proceed, but cost and hazard increase
Solution Approach 1:
The ionic liquid serves as its own solvent, eliminating the need for separate organic solvent addition. This reduces both the cost of multiple reagents and the hazard associated with handling multiple flammable substances.
Solution Approach 2:
The patent merges the solvent and base functions into the ionic liquid, reducing the total number of chemical substances that need to be handled, stored, and disposed of, thereby reducing overall hazard and cost.
4Reliability
If stoichiometric quantities of inorganic salt by-products are formed, then the reaction can proceed, but separation steps are required
Solution Approach 1:
The ionic liquid acts as an intermediary phase that selectively retains the charged conjugate acid by-product through ionic interactions, while allowing the neutral carbene intermediate to be extracted into organic solvent, enabling efficient separation without requiring extensive purification.
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 approach reduces costs, minimizes hazardous by-products, and simplifies the production process by eliminating the need for additional solvents and external bases, while achieving high conversion rates of the starting materials to chalcogenones.
Implementation Method 1
reacting an elemental chalcogen selected from elemental sulfur, elemental selenium and elemental tellurium with an ionic liquid or salt having the formula: [Cat+][X−]
Data Source
AI summary
The present invention is a novel process for the preparation of chalcogenone compounds by conversion of ionic liquids and salts comprising nitrogen-containing heterocyclic cations and basic anions to the corresponding nitrogen-containing heterocyclic chalcogenones by reaction with elemental chalcogens.