Furan Cycloaddition to Benzene Derivatives via Acid Solvent
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Solution Overview
Problem
Current processes for producing terephthalic acid from renewable sources, such as biomass carbohydrates, suffer from low yields and significant byproduct contamination, making them commercially unattractive.
Innovation Solution
A process involving the cycloaddition reaction of a furan derivative with ethylene in the presence of an acid solvent, specifically a carboxylic acid, under controlled conditions to enhance yield and reduce byproduct formation, utilizing a carboxylic acid as both a solvent and dehydrating agent, and optionally with a desiccating agent to manage water and promote aromatization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Diels Alder reaction is conducted with ethylene pressure of 100-250 psig and temperature of 100-200°C in the presence of water or methanol as solvent, then the reaction can proceed, but the yield of terephthalic acid is very low (0.14 mole%)
Solution Approach 1:
The patent changes the reaction parameters significantly: increases ethylene pressure to 200-2000 psig, raises temperature to 150-250°C, and replaces water/methanol solvents with toluene or xylene. These parameter changes collectively improve the yield from 0.14 mole% to a commercially viable level while maintaining reaction feasibility
Solution Approach 2:
The patent employs a simple, readily available solvent system (toluene or xylene) that can be easily removed, replacing complex aqueous or alcoholic systems. This simplifies the process and improves product recovery, making the overall process more commercially attractive despite the use of higher pressures
2Productivity
If the cycloaddition reaction is conducted over solid catalysts like activated carbon, silica gel, alumina, zirconia, and molecular sieves at 100-300°C with ethylene partial pressure of 10-100 bar, then the yield of benzene derivative is improved, but significant amounts of byproducts are formed
Solution Approach 1:
The patent removes the solid catalyst component from the reaction system entirely, replacing it with a homogeneous acid catalyst in toluene or xylene solvent. This elimination of solid catalysts prevents the formation of byproducts associated with heterogeneous catalysis while maintaining high reaction efficiency
Solution Approach 2:
The patent introduces toluene or xylene as an intermediary solvent that facilitates the reaction between furan derivative and ethylene. This solvent acts as a medium that enables high-yield product formation while suppressing byproduct formation, replacing the need for solid catalysts
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 significantly improves the yield of terephthalic acid production while minimizing byproduct formation, particularly at higher temperatures and pressures, offering a more attractive and efficient route to this valuable chemical from renewable biomass sources.
Implementation Method 1
the reaction of a furan derivative with ethylene is carried out in the presence of an acid solvent... utilizing a carboxylic acid as both a solvent and dehydrating agent
Implementation Method 2
a desiccating agent, which is a water removing agent... The carboxylic acid anhydride is reacted with water to yield the carboxylic acid
Implementation Method 3
the benzene derivative is prepared by a first Diels Alder reaction between the furan derivative of formula (II) with ethylene to form a bicyclic ether, and by a subsequent in situ reaction of this bicyclic ether wherein water is split off and aromatization occurs
Data Source
AI summary
Benzene derivatives of the formula (I); wherein R1 and R2, are the same or different and independently are selected from the group consisting of hydrogen, alkyl, aralkyl, –CHO, -CH2OR3, -CH(OR4 )(OR5 ) and –COOR6, wherein R3, R4 and R5 are the same or different and are selected from hydrogen, alkyl, aryl, alkaryl, aralkyl, alkylcarbonyl or arylcarbonyl, or wherein R4 and R5 together form an alkylene group and wherein R6 is selected from hydrogen, alkyl and aryl, are prepared in a process, which comprises: reacting a furan derivative of formula (II): wherein R1 and R2 have the meanings above, with ethylene under cycloaddition reaction conditions in the presence of an acid solvent to produce the benzene derivative, wherein the acid solvent is a carboxylic acid and is present in a weight ratio acid solvent to furan derivative from 1:1 to 250:1.