Labile Esters for Agrochemical Controlled Release
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Solution Overview
Problem
Carboxylic acid agrochemicals face challenges in achieving controlled release due to rapid hydrolysis and water solubility, leading to reduced residual activity and increased off-site movement, particularly for auxin-mimic herbicides like dicamba and 2,4-D, which can cause crop damage and environmental contamination.
Innovation Solution
Development of esters of carboxylic acid agrochemicals with photolabile or hydrolytically labile protecting groups, such as nitrophenyl and phenacylmethyl esters, that undergo controlled cleavage to regenerate the active agrochemical upon exposure to light or moisture, reducing volatility and aqueous solubility, thereby enhancing residual activity and controlled release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If carboxylic acid agrochemicals are applied directly, then immediate herbicidal activity is achieved, but rapid leaching and off-site movement occur reducing residual activity
Solution Approach 1:
The patent employs an ester prodrug as an intermediary form of the carboxylic acid agrochemical. The ester group acts as a protecting group that masks the polar carboxylic acid functionality, reducing water solubility and preventing premature leaching. Upon application to the plant, enzymatic hydrolysis by esterases releases the active carboxylic acid form, providing sustained herbicidal activity while minimizing off-site movement during the transport phase.
Solution Approach 2:
The patent modifies the physicochemical parameters of the agrochemical by converting the carboxylic acid to an ester derivative. This parameter change reduces water solubility and increases lipophilicity, allowing the compound to remain on or near the application site longer. The ester prodrug maintains stability during transport but undergoes controlled conversion to the active form at the target, extending duration of action while reducing loss through leaching.
2Loss of substance
If alkyl esters are used to reduce water solubility, then off-site movement is reduced, but rapid hydrolysis increases susceptibility to microbial degradation
Solution Approach 1:
The patent applies local quality by using specific ester substituents (nitrophenyl, phenacylmethyl) at the ester position rather than simple alkyl groups. These specially designed ester groups provide localized chemical properties that balance hydrolytic stability with controlled release. The nitrophenyl and phenacylmethyl groups create steric and electronic effects that protect against premature hydrolysis and microbial degradation during transport, while still allowing enzymatic conversion at the target plant.
Solution Approach 2:
The ester prodrug acts as a temporary, disposable protective form that serves its purpose during transport and application, then is intentionally degraded at the target site. The ester group is designed to be labile and hydrolyzable under specific biological conditions (esterase enzymes in plants), converting the protected prodrug into the active agrochemical. This disposable protecting group approach allows controlled release while minimizing premature degradation during storage and transport.
3Duration of action of moving object
If hindered aromatic esters are used for controlled release, then hydrolysis rate is reduced, but release is too slow to be practical
Solution Approach 1:
The patent employs dynamic control of the hydrolysis rate through enzyme-specific design. The ester prodrugs are engineered with specific molecular structures (nitrophenyl, phenacylmethyl groups) that create differential reactivity: stable against non-specific hydrolysis and microbial degradation during transport, but highly susceptible to enzymatic hydrolysis by plant esterases at the target. This dynamic behavior allows slow, controlled release during storage/transport while enabling rapid activation upon contact with the target plant, balancing both controlled release and practical 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
The use of labile esters results in improved residual activity and reduced off-site movement of agrochemicals, providing effective and sustained weed control while minimizing environmental impact.
Implementation Method 1
Some of these esters undergo photo-induced cleavage to form the agronomically active carboxylic acid when exposed to natural or artificial light
Implementation Method 2
Others of these esters undergo hydrolytic conversion to the agronomically active acid when exposed to moisture in the environment
Data Source
AI summary
The present invention relates to esters of carboxylic acid agrochemicals comprising a labile protecting group and having formula (I). Certain of the esters of carboxylic acid agrochemicals do not undergo hydrolysis to a significant degree in the dark, but are cleaved to regenerate the parent carboxylic acid agrochemical when exposed to light. Others of the esters of carboxylic acid agrochemicals undergo hydrolysis under both light and dark conditions. The present invention further relates to methods for the controlled release of a carboxylic acid agrochemicals, and to methods of controlling unwanted plants comprising applying to the unwanted plants an ester of a carboxylic acid agrochemical.