What Is (R)-2-(4-Hydroxyphenoxy)propionic Acid (DHPPA) and How Is It Used in Herbicide Synthesis?
Technical Introduction
(R)-2-(4-Hydroxyphenoxy)propionic Acid (abbreviated as DHPPA) is a chiral phenoxypropionic acid derivative with the molecular formula C₉H₁₀O₄.
It is an optically active compound in the R-configuration, making it a key enantioselective intermediate in the synthesis of certain selective herbicides, particularly ACCase (acetyl-CoA carboxylase) inhibitors used in controlling grass weeds in cereal crops.
With 99% purity, DHPPA ensures precise stereochemistry, which is essential for biological activity and regulatory compliance in agrochemical production.
Applications
1. Herbicide Intermediate
Core building block for producing aryloxyphenoxypropionate herbicides such as quizalofop, fluazifop, and haloxyfop.
The R-isomer shows significantly higher herbicidal activity compared to the S-isomer.
2. Chiral Chemical Synthesis
Used in enantioselective synthetic pathways requiring the R-configuration phenoxypropionic acid structure.
3. Agrochemical R&D
Applied in developing next-generation ACCase inhibitors with improved selectivity and reduced environmental impact.
Advantages
High Optical Purity: Ensures consistent bioactivity in herbicide products.
Proven Herbicidal Activity: R-isomer is more potent, allowing lower dosage.
Versatile Reactivity: Can undergo esterification, amidation, and coupling reactions.
High Purity (99%): Meets strict agrochemical manufacturing standards.
Typical Parameters
| Property | Value |
|---|---|
| Chemical Formula | C₉H₁₀O₄ |
| Molecular Weight | 182.17 g/mol |
| CAS Number | 94050-90-5 |
| Purity (%) | ≥99.0 |
| Optical Rotation | Specific to R-isomer |
| Appearance | White to off-white crystalline powder |
| Melting Point (°C) | ~116–118 |
| Solubility | Soluble in organic solvents, slightly soluble in water |
| Storage | Store in cool, dry place, sealed, protected from light |
| Shelf Life | 24 months (sealed) |
FAQs
Q1: Why is the R-isomer preferred over the S-isomer in herbicide production?
A1: The R-isomer has significantly higher herbicidal activity and selectivity, allowing lower application rates and reduced environmental impact.
Q2: Is DHPPA directly used as a herbicide?
A2: No, it is an intermediate used to synthesize ester or amide derivatives with herbicidal properties.
Q3: How is DHPPA typically converted to active herbicides?
A3: It is usually esterified with specific alcohols or coupled with aromatic groups to form the active herbicide structure.
Q4: Does high purity affect herbicide performance?
A4: Yes, impurities and incorrect stereochemistry can reduce potency and cause off-target effects.
Q5: Can DHPPA be synthesized via biocatalysis?
A5: Yes, enzymatic resolution and asymmetric synthesis are used for high enantiomeric excess.
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