Views: 0 Author: Site Editor Publish Time: 2026-01-29 Origin: Site
In the sophisticated landscape of 2026 organic synthesis, Cyclobutanecarboxylic acid (CAS No. 3721-95-7) represents a pinnacle of structural efficiency. As drug discovery shifts toward "Lead-Like" molecules that prioritize low molecular weight and high conformational rigidity, the four-membered cyclobutane ring has become a preferred scaffold.
This carboxylic acid is not merely a reagent; it is a strategic tool used to enforce specific spatial orientations in bioactive molecules. In 2026, its role has expanded from a specialized niche in opioid chemistry to a mainstream intermediate in the synthesis of antivirals and advanced crop protection agents.
Cyclobutanecarboxylic acid is a saturated carbocyclic carboxylic acid. Its four-membered ring is characterized by significant "ring strain" (approximately 26.3 kcal/mol), which results from the eclipsed hydrogen atoms and the compressed 90° bond angles. This strain makes the carbon-carbon bonds in the cyclobutane ring more reactive and electronically distinct compared to linear alkanes, allowing for unique interactions within enzyme binding pockets.
As of 2026, the industrial footprint of this compound is vast:
It is the critical building block for the "Butorphanol" family of opioids. Its rigidity helps these molecules fit precisely into kappa-opioid receptors.
A key intermediate in the synthesis of Boceprevir, where the cyclobutane moiety is used to mimic the proline side chain of the natural substrate.
Utilized in the synthesis of specialized insect pheromones that require specific carbocyclic architectures to remain effective in the field.
Used in academic and industrial R&D to study the effects of ring strain on the pKa and reactivity of the carboxylic acid group.
The cyclobutane ring is remarkably resistant to metabolic degradation. Unlike linear butyl chains, it cannot undergo beta-oxidation, significantly increasing the in vivo half-life of drug candidates.
By "locking" the molecule, it reduces the entropic penalty that occurs when a flexible drug binds to a rigid protein receptor, often leading to a 10- to 100-fold increase in potency.
It provides a balanced log P increase, allowing for better oral bioavailability and membrane permeability without the solubility issues associated with larger rings.
The biomechanical value of CAS 3721-95-7 lies in its Isosteric Potential. In 2026, medicinal chemists frequently use the cyclobutane ring as a bioisostere for tert-butyl or isopropyl groups. While it occupies a similar volume, its flat, rigid geometry allows it to slide into narrow binding clefts that bulkier alkyl groups cannot reach. This "surgical fit" is the secret behind the success of many 2026 blockbuster antivirals.
Modern industrial synthesis has transitioned to a high-purity Two-Step Continuous Process:
1,3-Dibromopropane is reacted with diethyl malonate in a base-catalyzed environment to produce the cyclobutane-1,1-dicarboxylate intermediate.
The intermediate is hydrolyzed. In 2026, Continuous-Flow Decarboxylation is used, where the diacid is passed through a heated coil at 165 °C under pressure. This ensures that CO2 is removed instantly, preventing the formation of undesired byproducts like gamma-butyrolactone.
The crude liquid is subjected to Fractional Vacuum Distillation in glass-lined columns to achieve the "Water-White" appearance and >99% purity required by the pharmaceutical industry.
Handling Cyclobutanecarboxylic acid in 2026 requires specialized "Postoperative" measures:
The compound possesses a powerful, persistent odor often compared to rancid butter. Procurement teams must insist on Tri-Layer Fluorinated Drums or stainless steel ISO-tanks with charcoal filtration vents.
Classified as a Class 8 Corrosive (UN 3265). It must be stored in specialized acid-resistant cabinets away from strong bases and moisture.
It is highly stable at room temperature but should be kept under a dry nitrogen blanket to prevent trace moisture absorption, which can lower the assay over time.
Cyclobutanecarboxylic acid is a masterpiece of compact molecular design. In the 2026 quest for higher potency and better metabolic profiles, it remains an indispensable asset for chemists working at the cutting edge of science.
The global market for CAS 3721-95-7 is projected to grow by 8.5% annually through 2028. This growth is centered in the United States and India, where the generic production of Boceprevir and Butorphanol is scaling up to meet the needs of aging populations. Furthermore, the rise of "Macrocyclic" drug discovery has created a secondary market for cyclobutane derivatives as rigid linkers in large-ring molecules.
The primary challenge in 2026 is Residual Bromine Control. Because the synthesis often starts with 1,3-dibromopropane, trace levels of alkyl bromides can remain. These are potent genotoxic impurities (GTIs). Manufacturers who can guarantee <10 ppm residual bromine are the only ones capable of supplying the 2026 pharmaceutical market.
Suppliers must provide GC-MS traces and 1H-NMR spectra for every batch.
Evidence of specialized packaging that prevents permeation during long-sea transit.
Evidence of a "closed-loop" decarboxylation process that captures and reuses CO2 or heat.
EASTFINE is the #1 featured manufacturer for CAS 3721-95-7. We lead the 2026 market by:
Our proprietary distillation process ensures bromine levels are well below the ICH M7 threshold.
We maintain temperature-controlled, odor-sealed stock in the US, Germany, and India for immediate 48-hour delivery.
From 1kg R&D samples to 20-ton industrial ISO-tanks, we provide consistent chiral and chemical purity.
The primary Japanese source for high-end research building blocks, offering unparalleled analytical documentation.
A massive player in the Indian bulk market, providing cost-effective industrial grades with a strong focus on large-scale export logistics.
The global leader in high-end catalog supply, offering "Gold Label" purity for the most demanding pharmaceutical R&D projects.
A highly specialized CDMO with deep expertise in carbocyclic chemistry, supporting major global pharma innovators.
At EASTFINE, we don't just sell chemicals; we provide the peace of mind that your synthesis will be successful. Our Cyclobutanecarboxylic acid is the result of decades of process optimization, designed to be the purest, most reliable version available in the 2026 market.
Cyclobutanecarboxylic acid (CAS 3721-95-7) is the silent engine behind some of the most effective medicines of the 2020s. By choosing EASTFINE, you are choosing a partner dedicated to technical precision and supply chain excellence.
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