Synthesis of 1-(3,5-dichlorophenyl)-2,2,2-trifluoroethanone via Segmented Chlorination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing processes for preparing halo-substituted 1-aryl-2,2,2-trifluoro-ethanones are inefficient due to a large number of reaction steps, low yields, and high production costs, with significant waste generation and atom economy issues.
Innovation Solution
A process involving three key reaction steps: nitration of compounds, chlorination using trichloroisocyanuric acid in the presence of sulfuric acid, and substitution of aromatic nitro groups with chlorine gas at high temperatures, reducing the number of steps and improving yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multistep procedures (4-6 steps) are used to prepare bromo derivatives and final products, then the synthesis can be completed, but the overall yield is low and production cost is high
Solution Approach 1:
The patent segments the synthesis into three distinct reaction steps: (a) nitration of compound of formula II to give compound of formula III, (b) reaction of compound III with trichloroisocyanuric acid in sulfuric acid to give compound of formula IV, and (c) chlorination of compound IV with chlorine gas to give final product of formula I. This segmentation allows each step to be optimized independently, improving overall yield while reducing complexity compared to the prior art's 4-6 steps.
Solution Approach 2:
The patent performs preliminary nitration and chlorination reactions to create highly reactive intermediates (compounds of formula III and IV) that can be readily converted to the final product in a single chlorination step. This preliminary action prepares the substrate in advance to facilitate the final transformation, reducing the total number of steps required.
2Loss of substance
If multistep procedures are used for synthesis, then the reaction can proceed, but large quantities of waste are generated and atom economy is low
Solution Approach 1:
The patent changes the reaction parameters by using trichloroisocyanuric acid as a chlorinating agent in sulfuric acid medium, which provides better atom economy compared to traditional methods. The reaction conditions are optimized to minimize waste generation while maintaining high conversion efficiency, directly addressing the atom economy problem.
Solution Approach 2:
The patent employs reaction conditions and reagents that minimize waste generation, and the process is designed to be economically viable by reducing the need for extensive purification steps and material recovery, thereby improving atom economy and reducing loss of substance.
3Ease of manufacture
If traditional Friedel-Crafts method is used to prepare compound of formula II with R1=fluoro, then only expensive acylating agents work, but this increases production cost
Solution Approach 1:
The patent uses trifluoroacetyl chloride, a cheap and readily available acylating agent, instead of expensive alternatives like 1-(trifluoroacetyl)-4-(dimethylamino)pyridinium trifluoroacetate. This substitution with a more economical reagent directly reduces production cost while maintaining the ability to synthesize compound of formula II with R1=fluoro.
Solution Approach 2:
The patent changes the reaction parameters by using aluminum chloride as a Lewis acid catalyst under specific conditions that enable the use of trifluoroacetyl chloride as an effective acylating agent. This parameter change makes the process economically viable by allowing the use of cheaper reagents.
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 significantly reduces production costs and increases yields by simplifying the synthesis pathway, minimizing waste, and enhancing atom economy, making the preparation of halo-substituted 1-aryl-2,2,2-trifluoro-ethanones more efficient and cost-effective.
Implementation Method 1
fluorobenzene is reacted with trifluoroacetyl chloride in the presence of aluminium chloride
Implementation Method 2
reacting a compound of formula II with a nitration agent to the compound of formula III
Implementation Method 3
reacting the compound of formula III with trichloroisocyanuric acid in the presence of sulfuric acid or fuming sulfuric acid to the compound of formula IV
Implementation Method 4
reacting the compound of formula IV with chlorine gas at a temperature from 180°C to 250°C to the compound of formula I
Data Source
AI summary
The present invention relates to a process for the preparation of a compound of formula I wherein R1 is hydrogen, fluoro or chloro; which process comprises a) reacting a compound of formula II wherein R1 is hydrogen, fluoro or chloro; with a nitration agent to the compound of formula III wherein R1 is hydrogen, fluoro or chloro; b) reacting the compound of formula III with a chlorinating agent to the compound of formula IV wherein R1 is hydrogen, fluoro or chloro; and c) reacting the compound of formula III with chlorine gas at a temperature from 180°C to 250°C to the compound of formula I.