4-Ethylphenylboronic acid, identified by CAS No. 63139-21-9, is an aromatic boronic acid used primarily as a building block in organic synthesis. Its molecular formula is commonly represented as C8H11BO2, with a calculated molecular weight of approximately 149.98 g/mol. The molecule contains a phenyl ring, an ethyl substituent in the para position, and a boronic acid group that can participate in palladium-catalyzed cross-coupling reactions. In practical purchasing, buyers should confirm identity, assay, water content, appearance, packaging, and batch-specific analytical documentation before approving the material for production or research.
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4-Ethylphenylboronic acid belongs to the family of arylboronic acids and is also described as 4-(ethyl)phenylboronic acid or para-ethylphenylboronic acid. The CAS number 63139-21-9 distinguishes this compound from other positional isomers, such as 2-ethylphenylboronic acid and 3-ethylphenylboronic acid. Correct positional identity is important because the location of the ethyl group can influence reaction behavior, steric effects, and the properties of the final product.
At room temperature, this material is generally handled as a solid, although exact color, particle form, and physical appearance may vary by supplier and batch. Its boronic acid group is chemically reactive and can interact with diols, water, and other nucleophilic species under suitable conditions. Storage should therefore follow the supplier’s safety data sheet and product specification, with attention to moisture exposure, container closure, temperature, and compatibility with other stored chemicals.
| Parameter | Typical identification or purchasing reference |
|---|---|
| Product name | 4-Ethylphenylboronic acid |
| CAS number | 63139-21-9 |
| Molecular formula | C8H11BO2 |
| Calculated molecular weight | Approximately 149.98 g/mol |
| Functional group | Arylboronic acid |
The main function of 4-ethylphenylboronic acid is to provide a 4-ethylphenyl group in carbon-carbon bond-forming reactions. Its most recognized role is as an aryl partner in Suzuki-Miyaura coupling, where an arylboronic acid reacts with an aryl or vinyl halide in the presence of a suitable catalyst and base. The resulting biaryl or substituted alkene can be used in medicinal chemistry, agrochemical research, materials development, and specialty synthesis.
The para-ethyl substituent can be useful when a target molecule requires additional hydrophobic character or a specific electronic and steric profile. However, the suitability of this reagent depends on the reaction substrate, catalyst system, solvent, base, temperature, and purification strategy. I recommend treating it as a functional intermediate rather than assuming that every coupling protocol will provide the same conversion or selectivity.
Beyond Suzuki coupling, arylboronic acids may be used in method development, sequential synthesis, and exploratory reactions involving boron-containing intermediates. Researchers may also evaluate this compound when designing libraries of substituted aromatic molecules. These applications are usually project-specific, so the appropriate grade and quantity depend on whether the material is intended for screening, process development, analytical reference work, or scale-up.
For commercial development, the most important question is not simply whether the compound is available, but whether its quality profile remains consistent across the required quantity. A material suitable for milligram-scale discovery work may require additional documentation, tighter impurity control, or a different packaging format before it is used in a larger process. Buyers should define the intended application before requesting a quotation.
4-Ethylphenylboronic acid may be offered in different package sizes and quality levels depending on the supplier’s manufacturing and distribution model. Common distinctions include research grade, synthesis grade, and a customer-specific specification for process development. These labels are not always standardized across suppliers, so I advise comparing the actual certificate of analysis rather than relying only on the grade name.
Material options can also include different particle sizes, packaging formats, and documentation packages. A laboratory buyer may require a small bottle with an analytical certificate, while an industrial customer may need larger packaging, lot reservation, production scheduling, and technical support. If the compound is sensitive to moisture or prolonged storage conditions in a specific process, the buyer should discuss packaging and handling requirements before order confirmation.
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A robust purchasing specification should clearly identify the compound and define measurable acceptance criteria. At minimum, I recommend reviewing the CAS number, molecular formula, molecular weight, assay method, assay result, water content where relevant, residual solvents, and impurity profile. The certificate of analysis should be linked to the actual production or packing lot supplied.
| Specification area | What buyers should verify |
|---|---|
| Identity | CAS No. 63139-21-9, chemical name, and analytical identification |
| Assay | Supplier-defined acceptance level, commonly quoted as a percentage on the product specification |
| Appearance | Color, physical form, and any stated limits for visible foreign matter |
| Water and solvents | Limits appropriate for the customer’s reaction and storage requirements |
| Impurities | Known process-related impurities and chromatographic reporting approach |
| Packaging | Container material, net weight, closure, labeling, and transport conditions |
Purity requirements should be connected to the application rather than selected automatically. For example, a discovery screen may prioritize availability and analytical information, whereas a process route may require tighter control of trace impurities that affect catalyst performance or downstream purification. If a buyer needs a defined assay, I can review the requested target with the available manufacturing specification instead of making an unsupported assumption about suitability.
The first selection factor is reliable identity and lot-level quality evidence. Buyers should request a certificate of analysis, a safety data sheet, and, when necessary, representative analytical data such as HPLC, NMR, GC, or water analysis. The exact test package should match the risk of the application and the customer’s internal release procedure.
Availability, minimum order quantity, lead time, packaging, and shelf-life information can materially affect project planning. These details may change according to inventory status, production scheduling, export requirements, and order volume. I recommend asking for a written quotation that separates product price from packaging, documentation, transportation, and any special testing charges.
Before import or distribution, the purchasing team should review applicable chemical inventory, labeling, transport, and workplace requirements in the destination market. A supplier can provide documentation support, but the buyer remains responsible for confirming local compliance for the intended use. This review is especially important when the product will be transferred between laboratories, manufacturing sites, or countries.
At Maison Chemical, we support B2B customers seeking 4-Ethylphenylboronic acid CAS 63139-21-9 for research, development, and commercial sourcing. We can discuss the required quantity, target specification, packaging format, delivery destination, and documentation before preparing a quotation. Our role is to help customers compare the requested quality profile with the available supply route in a clear and practical way.
For a technical inquiry, please provide the expected order quantity, intended application, required assay or impurity limits, preferred packaging, and target delivery date. If you are evaluating the compound for a new synthesis, sharing the reaction stage or downstream requirement can also help us identify relevant documentation and handling information. Product availability, lead time, and commercial terms should be confirmed for each individual order.
4-Ethylphenylboronic acid CAS 63139-21-9 is a specialized aromatic building block most directly associated with Suzuki-Miyaura and related synthetic applications. It may be a suitable choice when a project requires incorporation of a para-ethyl-substituted phenyl group, but final suitability depends on the reaction route, quality requirements, and supply conditions. The next practical step is to define your target specification and quantity, then compare supplier documentation and lead time.
Maison Chemical can help you evaluate the sourcing requirements for this compound and prepare a supply proposal based on your application. Contact our sales team with your desired quantity, purity target, packaging preference, destination, and schedule so we can provide product and commercial information for your review.
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