Arylthionocarboxylic Acid Ester Synthesis via Grignard Reaction
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Solution Overview
Problem
Existing methods for producing arylthionocarboxylic acid esters are inefficient due to low yields, high temperatures, generation of by-products, toxicity of hydrogen sulfide, and complex multi-step processes, making them unsuitable for industrial production as liquid crystal materials.
Innovation Solution
Reacting a halogenated thiocarbonyl compound with a Grignard compound in the presence of trivalent or divalent metal compounds such as iron, copper, nickel, zinc, or cobalt to produce arylthionocarboxylic acid esters under mild conditions, using safe and inexpensive starting materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If methods (4) and (5) are used to produce thionocarboxylic acid esters, then the reaction can proceed, but high temperature (100°C or more) is required and large amounts of by-products are generated
Solution Approach 1:
The invention changes the reaction parameters by using a different chemical pathway that allows the reaction to proceed at lower temperatures (0-100°C, preferably 0-40°C) compared to conventional methods requiring 100°C or more. This parameter change is achieved by using a halogenated thiocarbonyl compound and Grignard reagent system with specific catalysts, fundamentally altering the reaction conditions to reduce both temperature and by-product formation
Solution Approach 2:
The invention introduces a halogenated thiocarbonyl compound as an intermediary substance that enables the formation of thionocarboxylic acid esters through a more efficient pathway. This intermediary reacts with Grignard reagents to form the desired product with fewer by-products, acting as a mediator that improves the overall reaction efficiency and selectivity
2Ease of manufacture
If method (3) or (7) is used, then thionocarboxylic acid esters can be produced, but hydrogen sulfide must be handled which is highly toxic requiring specialized equipment
Solution Approach 1:
The invention eliminates the use of highly toxic hydrogen sulfide gas by replacing it with a safer halogenated thiocarbonyl compound system. This converts the harmful process into a beneficial one by maintaining the ability to produce thionocarboxylic acid esters while removing the toxic hazard, thereby improving process safety and eliminating the need for specialized handling equipment
Solution Approach 2:
The invention uses readily available halogenated thiocarbonyl compounds and Grignard reagents that can be handled under standard laboratory conditions without requiring specialized equipment for toxic gas handling. These reagents serve as safer alternatives that eliminate the need for complex safety infrastructure
3Productivity
If method (9) is used, then thionocarboxylic acid esters can be produced, but a large number of steps are required including synthesizing thioacyl disulfide from dithiocarboxylic acid derivative
Solution Approach 1:
The invention segments the synthesis process into a simple two-component reaction between halogenated thiocarbonyl compound and Grignard reagent, eliminating the need for multi-step synthesis of thioacyl disulfides from dithiocarboxylic acid derivatives. This segmentation reduces the overall process complexity from multiple sequential steps to a single straightforward reaction
Solution Approach 2:
The invention uses pre-prepared halogenated thiocarbonyl compounds as starting materials that are readily available or easily synthesized, eliminating the need for preliminary synthesis steps required by conventional methods. This preliminary preparation of stable, reactive intermediates allows the main reaction to proceed directly without additional synthesis steps
4Productivity
If method (6) is used, then thionocarboxylic acid esters can be produced, but the synthesis yield of starting thionocarboxylic acid chloride is low
Solution Approach 1:
The invention extracts the problematic step of synthesizing thionocarboxylic acid chloride from the overall process by replacing it with a direct reaction using halogenated thiocarbonyl compounds. This extraction removes the low-yield step and replaces it with a high-yield alternative pathway that achieves better overall productivity
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 achieves high yields of arylthionocarboxylic acid esters under mild conditions with safe and inexpensive materials, overcoming the inefficiencies and safety concerns of previous methods.
Implementation Method 1
reacting a halogenated thiocarbonyl compound of formula (1) with a Grignard compound of the formula R-MgY (2) wherein R is as defined above and Y is halogen
Implementation Method 2
in the presence of at least one component selected from trivalent iron compounds, monovalent copper compounds, divalent copper compounds, divalent nickel compounds, divalent zinc compounds, and divalent cobalt compounds
Data Source
AI summary
The present invention provides a process comprising reacting a halogenated thiocarbonyl compound represented by Formula (1): wherein Ar is an optionally substituted aryl group and X is a halogen atom, with an Grignard compound represented by Formula (2): R-MgY wherein R is an optionally substituted aryl group or an optionally substituted cycloalkyl group and Y is a halogen atom. This process can produce the desired arylthionocarboxylic acid ester represented by Formula (3): wherein Ar and R are as defined above, in a high yield under relatively mild reaction conditions.