Chemical Identity and Key Properties

3-Aminobenzeneboronic acid pinacol ester hydrochloride (SKU: A187008) is an arylboronic acid pinacol ester in which the boronic acid –B(OH)₂ group is protected as the pinacol cyclic ester, and the meta-amino group is stabilized as the hydrochloride salt. This dual-protection strategy serves two important functions: the pinacol ester prevents premature protodeboronation and oxidative degradation of the reactive boronate, while the HCl salt form of the amine suppresses undesired intramolecular coordination between the nitrogen lone pair and the Lewis-acidic boron center, thereby enhancing the compound's shelf stability and ease of handling.

The compound presents as a white to off-white crystalline solid. It is soluble in polar protic solvents such as water, methanol, and ethanol, and moderately soluble in dimethyl sulfoxide (DMSO). Solubility in non-polar organic solvents is limited. The pinacol ester can be hydrolyzed to the free boronic acid under aqueous acidic or basic conditions, releasing the active boronic acid species in situ when required for coupling reactions.

Note: Exact physicochemical data (melting point, specific optical rotation, purity) should be confirmed against the batch-specific Certificate of Analysis (CoA) supplied with the product.

Storage, Handling, and Safety Guidelines

Storage: Store at 2–8 °C in a tightly sealed container under an inert atmosphere (nitrogen or argon). Protect from moisture, light, and air. Long-term storage under these conditions is expected to maintain compound integrity; always verify by checking the expiry date on the product label and CoA.

Handling precautions:

• Work in a well-ventilated fume hood when weighing or dissolving.
• Wear appropriate personal protective equipment (PPE): nitrile gloves, safety glasses, and a lab coat.
• Avoid inhalation of dust or aerosols generated during weighing.
• As a hydrochloride salt, the compound is mildly acidic in aqueous solution; avoid contact with eyes, skin, and mucous membranes.
• Boronic acid esters may be mildly irritating; treat all fine powders as potential respiratory irritants.

Disposal: Dispose of waste in accordance with local regulations and your institutional chemical waste management policies. Do not discharge into drains or waterways.

Emergency procedures: In case of skin or eye contact, flush immediately with copious amounts of water for at least 15 minutes and seek medical advice. Refer to the product Safety Data Sheet (SDS) for comprehensive hazard information.

Review flag: Specific GHS hazard classifications and R/S or H/P statements should be verified against the current SDS for A187008 before use.

Solution Preparation and Dissolution Protocol

Follow this stepwise protocol to prepare stock solutions of 3-Aminobenzeneboronic acid pinacol ester hydrochloride:

1. Equilibrate to room temperature: Allow the sealed vial to warm to room temperature before opening to prevent moisture condensation on the solid.
2. Weigh accurately: Tare a clean, dry microbalance vessel and transfer the required mass of compound using a spatula inside a fume hood.
3. Select appropriate solvent: For aqueous applications, dissolve in water, phosphate-buffered saline (PBS), or aqueous methanol. For organic synthesis, DMSO or methanol are preferred. Avoid prolonged exposure to strongly alkaline aqueous conditions, which may accelerate hydrolysis of the pinacol ester.
4. Add solvent gradually: Add the chosen solvent in small aliquots with gentle vortex mixing or sonication (brief, low-power) until complete dissolution is achieved. Do not heat above 40 °C unless validated for your specific application.
5. Verify clarity: Inspect the solution for complete dissolution. If particulates remain, filter through a 0.2 µm syringe filter.
6. Aliquot and store: Divide stock solutions into single-use aliquots under inert atmosphere to minimize freeze–thaw cycles and oxidative degradation. Store aliquots at –20 °C for short-term use or –80 °C for longer storage.
7. Record: Document the lot number, concentration, solvent, preparation date, and storage location in your laboratory notebook.

Note: Recommended working concentrations will depend on the specific assay or reaction; consult the relevant literature or your experimental design for guidance.

Applications in Organic Synthesis and Research

3-Aminobenzeneboronic acid pinacol ester hydrochloride is a versatile bifunctional building block used across multiple research domains:

1. Suzuki–Miyaura Cross-Coupling: The pinacol boronate ester serves as a competent coupling partner for palladium-catalyzed Suzuki–Miyaura reactions with aryl or vinyl halides and pseudohalides. The amine functionality (after free-basing) can be used as a handle for downstream functionalization, enabling rapid construction of aminobiaryl scaffolds relevant to pharmaceutical lead optimization.

2. Medicinal Chemistry and Drug Discovery: The meta-amino and boronate ester groups together provide orthogonal reactivity. The free amine (liberated by treatment with base) can be acylated, sulfonylated, or reductively alkylated. Boronic acids and esters are also pharmacophores in their own right, found in proteasome inhibitors, serine protease inhibitors, and antibacterial agents, so this compound may serve as a direct pharmacophore component or as a precursor to boronic acid drugs.

3. Materials Science and Functional Polymers: Arylboronic acid pinacol esters are employed in the synthesis of conjugated polymers, covalent organic frameworks (COFs), and sensor materials. The amino group enables further condensation chemistry (e.g., imine or amide bond formation) for building porous or stimuli-responsive materials.

4. Bioconjugation and Chemical Biology: After hydrolysis to the free boronic acid, the compound can engage in reversible covalent bonding with cis-diols (sugars, catecholamines), offering utility in biosensing, targeted drug delivery, and affinity-based separation of glycoproteins.

Review flag: Specific literature citations for each application should be added before publication. The claims above reflect well-established textbook-level knowledge of arylboronic acid chemistry.

Quality, Purity, and Regulatory Considerations

Purity and QC: Each lot of A187008 is accompanied by a Certificate of Analysis (CoA) documenting purity (typically assessed by HPLC and/or NMR), identity confirmation (e.g., ¹H NMR, ¹³C NMR, MS), and physical characterization data. Users should request and review the CoA for their specific lot prior to use.

Research-grade use: This compound is supplied for research use only and is not intended for diagnostic, therapeutic, or human/veterinary medicinal use. Researchers should ensure compliance with all applicable institutional, national, and international regulations governing the use of chemicals in research.

Regulatory export/import: While 3-Aminobenzeneboronic acid pinacol ester hydrochloride is a standard research chemical, users in certain jurisdictions should verify whether import or export permits are required under local chemical control regulations.

GMP status: Unless explicitly stated on the product page, this material is not manufactured under GMP conditions. Contact Aladdin Scientific directly if GMP-grade material is required for your application.

Batch-to-batch consistency: Contact Aladdin Scientific's technical support team to obtain multiple-lot data or to discuss custom synthesis requirements if large-scale or lot-matched supply is needed.