3-Mercaptopropionic Acid Synthesis via Segmented Reaction
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Solution Overview
Problem
Existing methods for preparing 3-mercaptopropionic acid are complex, result in low yields, and involve high-temperature treatments that lead to product degradation and increased production costs, particularly in the synthesis of thiourethane-based optical lenses.
Innovation Solution
A method involving the reaction of acrylonitrile with sodium hydrosulfide to form 2-sodium cyanoethanethiolate, followed by neutralization and acid addition, with subsequent reflux and distillation under reduced pressure using organic solvents like n-butyl acetate to enhance yield and purity while reducing temperature and distillation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods (adding H2S to acrylic acid or using thiodipropionitrile) are used to prepare 3-mercaptopropionic acid, then the reaction can proceed, but the process becomes very complicated with multiple steps and low yield
Solution Approach 1:
The patent segments the synthesis process into distinct stages: first forming thiodipropionitrile dimer as an intermediate, then converting it to 3-mercaptopropionitrile, and finally hydrolyzing to 3-mercaptopropionic acid. This segmentation allows optimization of each step independently, achieving high overall yield despite multiple steps.
Solution Approach 2:
The method performs preliminary formation of thiodipropionitrile dimer which then serves as a stable intermediate for subsequent conversion. This preliminary action allows better control over the reaction pathway and improves overall process efficiency and yield.
2Productivity
If strong acid and iron are used to convert thiodipropionic acid into 3-mercaptopropionate, then the conversion can occur, but undesired composition of products and by-products occur
Solution Approach 1:
The patent changes the reaction parameters by using milder conditions (aqueous NaOH instead of strong acid and iron) for the conversion of thiodipropionic acid to 3-mercaptopropionate. This parameter change eliminates the formation of by-products while maintaining high conversion efficiency.
Solution Approach 2:
The method uses readily available, inexpensive reagents like aqueous sodium hydroxide instead of expensive or hazardous catalysts like iron and strong acids. This substitution maintains effectiveness while eliminating harmful by-products.
3Productivity
If thiodipropionitrile is converted to 3-mercaptopropionic acid through reflux with strong acid, then the nitrile converts to carboxylic group, but the process is complicated and yield is low due to unreacted nitrile remaining
Solution Approach 1:
The patent changes the hydrolysis conditions from strong acid reflux to milder basic conditions with aqueous NaOH. This parameter change significantly reduces reaction time and eliminates the problem of unreacted nitrile remaining, thereby increasing both yield and efficiency.
Solution Approach 2:
The method substitutes the mechanical/thermal intensive process of prolonged reflux with a chemical approach using aqueous base that proceeds under milder conditions. This substitution reduces energy consumption and process time while improving yield.
4Productivity
If high-temperature treatment is applied in the process of obtaining 3-mercaptopropionitrile and converting to acid, then the reactions proceed, but yield loss and degradation of products occur
Solution Approach 1:
The patent changes the temperature parameter by conducting reactions at moderate temperatures rather than high temperatures. The use of aqueous NaOH allows the conversion to proceed efficiently at lower temperatures, preventing product degradation while maintaining good reaction rates.
Solution Approach 2:
The method uses simple, readily available reagents like aqueous sodium hydroxide that enable reactions to proceed under milder temperature conditions, eliminating the need for high-temperature equipment and preventing thermal degradation of the product.
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 significantly increases the yield of 3-mercaptopropionic acid to 10% or higher, reduces production costs, and produces a compound with excellent purity and color, enabling the production of high-quality, low-cost carboxylic acid ester compounds and thiourethane-based optical lenses with improved optical properties.
Implementation Method 1
reacting acrylonitrile with sodium hydrosulfide to obtain 2-sodium cyanoethanethiolate
Implementation Method 2
neutralizing the 2-sodium cyanoethanethiolate with an acid to obtain 3-mercaptopropionitrile
Implementation Method 3
adding an acid to the 3-mercaptopropionitrile, refluxing the resulting mixture to convert the 3-mercaptopropionitrile into 3-mercaptopropionic acid
Implementation Method 4
distilling the resulting reaction solution under reduced pressure to obtain 3-mercaptopropionic acid
Data Source
AI summary
A method for producing 3-mercaptopropionic acid and methods using same for producing a carbonic acid ester compound having a mercapto group and a thiourethane-based optical material. The present invention improves a process during the production of 3-mercaptopropionic acid, significantly increases yield, and reduces the temperature and time during vacuum distillation, thereby preventing the destruction of a product and significantly increasing productivity. The present invention allows high-purity 3-mercaptopropionic acid having an excellent color to be finally yielded; accordingly, by using same, a high-purity carbonic acid ester compound having an excellent color and a mercapto group can be inexpensively obtained. A thiourethane-based polymeric composition and a thiourethane-based optical material obtained by polymerizing same can likewise be inexpensively obtained by using said carbonic acid ester compound. Such carbonic acid ester compound can be used for the production of inexpensive thiourethane optical lenses; consequently, inexpensive optical lenses having an excellent color can be obtained.