Views: 0 Author: Site Editor Publish Time: 2026-02-26 Origin: Site
In the high-precision chemical landscape of 2026, 5-Methyl-4-isoxazolecarboxylic acid (CAS No. 42831-50-5) has solidified its role as an indispensable building block. Within the industry, it is recognized as a "high-utility heterocyclic scaffold," serving as the essential intermediate for the synthesis of immunomodulatory drugs such as Leflunomide and Teriflunomide, as well as next-generation agrochemical active ingredients.
For EASTFINE, this compound represents our core competency in heterocyclic chemistry. We understand that in the pharmaceutical and agrochemical sectors, an intermediate is only as good as its purity profile. By leveraging advanced synthetic technologies, we provide the global market with a high-purity crystalline form that ensures seamless downstream integration, reducing the need for costly purification steps in the final stages of API (Active Pharmaceutical Ingredient) production.
This compound is a five-membered heterocyclic carboxylic acid with the molecular formula C5H5NO3. Its molecular architecture features an isoxazole ring—a five-membered ring containing one nitrogen and one oxygen atom—substituted with a methyl group at the 5-position and a carboxylic acid group at the 4-position. This specific substitution pattern is the fundamental key to its biological activity and chemical reactivity, providing the necessary electron density for selective bonding in pharmaceutical applications.
It is the primary, non-negotiable intermediate for the production of Leflunomide (used in Rheumatoid Arthritis) and Teriflunomide (used in Multiple Sclerosis). It forms the rigid scaffold that binds to human enzymes.
Increasingly utilized in 2026 for the synthesis of specialized isoxazole-based herbicides and fungicides. These products are favored for their ability to target resistant weed strains while maintaining low environmental persistence.
Acts as a versatile building block for creating libraries of bioactive compounds, particularly in the development of novel kinase inhibitors and anti-inflammatory lead compounds.
The carboxylic acid group at the 4-position acts as a ready-made "chemical handle," allowing for rapid transformation into amides, esters, or acid chlorides without requiring complex activation of the ring.
Professional manufacturing protocols at EASTFINE ensure that the problematic 3-methyl isomer is strictly controlled, preventing the formation of toxic or inactive drug analogs.
As a stable crystalline solid, it offers excellent shelf-life and predictable flow characteristics for large-scale industrial charging, far surpassing liquid-phase alternatives in reliability.
In its 2026 standardized industrial form, the compound appears as a white to off-white crystalline powder with a sharp melting point of 145°C – 149°C. It exhibits high solubility in polar organic solvents like ethanol and methanol, while remaining chemically stable under dry, ambient storage conditions. The aromaticity of the isoxazole ring provides a unique electronic profile that enhances the binding affinity and metabolic stability of final active ingredients.
EASTFINE utilizes a high-efficiency, closed-loop process designed for 2026 environmental standards:
Ethyl acetoacetate is reacted with triethyl orthoformate and acetic anhydride to produce an ethoxymethylene intermediate.
The intermediate is treated with hydroxylamine hydrochloride under strictly controlled temperatures to construct the isoxazole ring.
Precise pH-controlled hydrolysis of the ethyl ester precursor yields the target carboxylic acid.
Multi-stage recrystallization using specialized solvent systems removes trace process impurities like CATA (Cyanuric Acid Triethyl Amide) to reach pharma-grade purity.
The product must be kept in a cool (15°C – 25°C), dry, and well-ventilated warehouse, away from strong oxidizing agents.
Handlers must wear standard personal protective equipment (PPE), including nitrile gloves, safety goggles, and N95 dust masks to prevent respiratory and skin irritation.
EASTFINE typically supplies this in 25kg fiber drums with double-layer anti-static PE liners to ensure moisture protection and structural integrity during international transit.
5-Methyl-4-isoxazolecarboxylic acid is a strategic asset in the 2026 fine chemical supply chain. Its quality is the direct foundation upon which the effectiveness of life-saving medicines and high-efficacy crop protection products is built. At EASTFINE, we ensure that foundation is unbreakable.
The 2026 market for heterocyclic intermediates is experiencing a robust 7.2% CAGR. This growth is driven largely by the global expansion of the autoimmune therapy sector and the urgent development of "green" agrochemicals with higher target specificity. As global pharmaceutical hubs shift toward more complex molecules, the demand for "API-ready" intermediates like CAS 42831-50-5—those requiring minimal pre-processing—has reached a decade high.
The primary industrial challenge in 2026 remains regioselective isomer control. During the cyclization step, 3-methyl-isoxazole-4-carboxylic acid often forms as a difficult-to-separate byproduct. Even trace amounts of this isomer can compromise the safety profile and regulatory compliance of the final drug. EASTFINE has mastered a proprietary catalytic pathway that keeps this 3-methyl isomer below 0.1%, solving a critical quality bottleneck for our global partners.
Mandatory verification that the 3-methyl isomer content is ＜ 0.2% via validated HPLC methods.
Every batch must be accompanied by full analytical characterization, including HPLC, NMR, and trace metal analysis.
The supplier must demonstrate the capacity for multi-ton production and maintain a stable inventory to ensure global supply chain security.
EASTFINE is the premier manufacturer for CAS 42831-50-5, offering:
Consistently delivering ≥ 99.5% assay for the most sensitive API production lines.
Deep-rooted knowledge in pharmaceutical and agrochemical intermediate synthesis.
Strategic logistics hubs in China, India, and Europe for rapid, localized fulfillment.
A leading manufacturer specializing in bulk drug intermediates, serving as a vital link in the Indian generic medication market.
A premium supplier focused on high-end custom synthesis and specialty chemicals for the stringent EU pharmaceutical sector.
The global gold standard for laboratory-scale research quantities and analytical standards with exhaustive documentation.
A major supplier of specialty reagents and heterocyclic building blocks, primarily serving the APAC research and development region.
Choosing EASTFINE means choosing technical resilience and professional integrity. As a specialist in both pharmaceutical and agrochemical intermediates, we understand that our products are the starting point for your success. We don't just supply chemicals; we provide the compliance and quality standards that protect your brand and your customers. Our 5-Methyl-4-isoxazolecarboxylic acid is the most stable and reliable foundation for your next-generation product.
Contact our technical team today for a comprehensive CAS 42831-50-5 technical package, including 2026 Stability Data and sample request forms!
In 2026, the success of a pharmaceutical or agrochemical product begins with the quality of its intermediate. At EASTFINE, we take pride in being the professional, honest, and collaborative partner that provides the building blocks for a healthier and more sustainable world.
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