2-(2-Chlorophenyl)oxazole: Handling, Storage & Use Protocol

2-(2-Chlorophenyl)oxazole is a halogenated aryl-oxazole heterocyclic building block widely employed in medicinal chemistry and materials science as a versatile intermediate for C–H functionalization, cross-coupling, and scaffold diversification reactions.

Chemical Name

2-(2-Chlorophenyl)oxazole

SKU

C185659

Molecular Formula

C₉H₆ClNO

Molecular Weight

179.60 g/mol

Core Heterocycle

1,3-Oxazole (five-membered O,N-containing ring)

Key Functional Handle

Aryl C–Cl bond suitable for cross-coupling (Suzuki, Negishi, Buchwald–Hartwig)

Recommended Storage

Cool, dry, well-ventilated area; away from light and moisture

Safety & Pre-Use Assessment

Before working with 2-(2-Chlorophenyl)oxazole (SKU C185659), consult the current Safety Data Sheet (SDS) supplied by Aladdin Scientific. As an aryl chloride–containing heterocycle, the compound should be treated as a potential irritant to skin, eyes, and respiratory tract.

Required personal protective equipment (PPE):

• Chemical-splash safety goggles
• Nitrile or neoprene gloves (minimum 0.3 mm thickness recommended)
• Laboratory coat and closed-toe shoes
• Work inside a certified fume hood whenever weighing or dissolving the solid

Waste disposal: Collect all waste solutions and contaminated materials in clearly labelled solvent-waste containers and dispose of according to your institution's chemical-waste regulations. Do not pour chlorinated-compound waste into aqueous drains.

Storage & Stability Guidelines

2-(2-Chlorophenyl)oxazole should be stored under the following conditions to maintain purity and ensure reagent integrity over time:

• Temperature: Store at room temperature (15–25 °C) in a cool, dry location away from heat sources. Refrigerated storage (2–8 °C) may extend shelf life; allow the container to equilibrate to room temperature before opening to prevent moisture condensation.
• Light: Keep in the original amber or opaque container, or wrap in aluminium foil, to minimize photodegradation of the oxazole ring system.
• Moisture: Store tightly sealed. Silica gel desiccant sachets may be placed in the storage cabinet as a precaution.
• Incompatibilities: Keep away from strong oxidising agents, strong bases, and reactive metals. The aryl C–Cl bond may be activated under forcing conditions.

Check the certificate of analysis (CoA) for lot-specific purity data and retest dates. If discolouration or unusual odour is observed upon opening, do not use and contact Aladdin Scientific technical support.

Solution Preparation Protocol

Follow this general procedure to prepare stock solutions of 2-(2-Chlorophenyl)oxazole for synthetic or analytical use:

1. Select an appropriate solvent. The compound is soluble in common organic solvents including dichloromethane (DCM), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), ethyl acetate, and acetonitrile. Verify compatibility with your downstream reaction conditions before selecting a solvent.
2. Calculate the required mass. Use the molecular weight of 179.60 g/mol to determine the quantity needed for your target concentration (e.g., for a 0.1 M stock in 10 mL THF: 179.60 mg × 0.1 × 10 = 179.60 mg).
3. Weigh accurately. Tare a clean, dry vial on an analytical balance. Transfer the compound quickly to minimise atmospheric exposure. Record the exact mass.
4. Dissolve. Add the calculated volume of dry solvent. Cap and vortex or stir gently until completely dissolved. For poorly soluble preparations, mild warming (≤40 °C) in a water bath may assist dissolution.
5. Verify by TLC or UV. Confirm compound integrity by thin-layer chromatography (silica gel, UV 254 nm) or UV-Vis spectroscopy where applicable.
6. Label and store. Label clearly with compound name, SKU, concentration, solvent, date, and preparer's initials. Store under inert atmosphere (N₂ or Ar) if prolonged storage is required.

Typical Research Applications & Reaction Guidance

2-(2-Chlorophenyl)oxazole serves as a multifunctional building block in several synthetic contexts:

1. Palladium-Catalysed Cross-Coupling

The aryl C–Cl bond is a competent electrophile for Pd(0)/Pd(II) catalytic cycles. Use bulky, electron-rich phosphine ligands (e.g., SPhos, RuPhos, XPhos) to activate the less-reactive aryl chloride. Typical base: Cs₂CO₃ or K₃PO₄; typical solvent: toluene, dioxane, or DMF at 80–110 °C. Suzuki–Miyaura coupling with aryl- or heteroaryl boronic acids can install diverse biaryl motifs.

2. Directed C–H Functionalization

The oxazole nitrogen and the ortho-chlorophenyl geometry can cooperate to direct transition-metal-catalysed C–H activation at specific ring positions, enabling C–H arylation, alkylation, or halogenation without pre-functionalisation.

3. Nucleophilic Aromatic Substitution (SNAr)

Under sufficiently activated conditions (electron-withdrawing groups, polar aprotic solvents), the aryl chloride may undergo SNAr with nitrogen, oxygen, or sulfur nucleophiles to produce N-, O-, or S-aryl products.

4. Medicinal Chemistry Scaffold Decoration

Oxazole-containing motifs are prevalent in bioactive molecules. 2-(2-Chlorophenyl)oxazole provides a handle for rapid analogue synthesis in drug-discovery programmes targeting kinases, GPCRs, and antimicrobial targets (literature precedent; specific biological data not confirmed for this compound — see review flags).

Note: Optimise reaction conditions on small scale before scale-up. Monitor reactions by TLC or HPLC and quench appropriately.

Quality Control & Troubleshooting

Purity verification: Confirm reagent purity by ¹H NMR (expected signals: aromatic protons in the δ 7.3–8.1 ppm region; oxazole C4-H and C5-H in the δ 7.5–8.0 ppm region) and/or HPLC (C18 reverse-phase column, UV 254 nm detection). Lot-specific CoA from Aladdin Scientific provides reference purity values.

Common issues and solutions:

Issue	Probable Cause	Recommended Action
Low coupling yield	Insufficient ligand loading or catalyst poisoning	Increase Pd loading; switch to a more active ligand (e.g., XPhos Pd G3 precatalyst); degas solvent thoroughly
Unreacted starting material	Aryl chloride less reactive than bromide/iodide	Raise temperature; use microwave assistance; switch to more nucleophilic base
Compound discolouration in solution	Moisture ingress or light exposure	Prepare fresh solutions; use dry, degassed solvents; store in dark
Poor solubility	Solvent mismatch	Switch to DMSO or DMF for stock preparation; dilute into reaction solvent

Frequently asked questions

What solvents are recommended for dissolving 2-(2-Chlorophenyl)oxazole?

2-(2-Chlorophenyl)oxazole is soluble in common polar aprotic and chlorinated organic solvents including DCM, THF, DMSO, DMF, ethyl acetate, and acetonitrile. DMSO or DMF are preferred for preparing concentrated stock solutions due to their high solvating power. Always verify solvent compatibility with your target reaction before use.

Can 2-(2-Chlorophenyl)oxazole be used directly in Suzuki–Miyaura cross-coupling reactions?

Yes, the aryl C–Cl bond in 2-(2-Chlorophenyl)oxazole is a viable electrophile for Suzuki–Miyaura coupling, though aryl chlorides are generally less reactive than the corresponding bromides or iodides. To achieve good yields, use a second-generation or third-generation palladium precatalyst with a bulky biarylphosphine ligand (e.g., SPhos or XPhos), a carbonate or phosphate base, and a polar solvent such as dioxane or toluene/water mixtures at elevated temperature (80–110 °C).

How should I confirm the identity and purity of 2-(2-Chlorophenyl)oxazole upon receipt?

Upon receipt, check the Aladdin Scientific Certificate of Analysis (CoA) for the lot number, purity, and analytical data. Identity can be confirmed by ¹H NMR in CDCl₃ or DMSO-d₆, comparing characteristic aromatic and oxazole proton signals with reference spectra. Purity can be independently assessed by HPLC using a C18 reverse-phase column with UV detection at 254 nm. Any discrepancy should be reported to Aladdin Scientific customer support promptly.

Is 2-(2-Chlorophenyl)oxazole air- and moisture-sensitive?

As an aryl chloride heterocycle, 2-(2-Chlorophenyl)oxazole is not highly air- or moisture-sensitive under normal storage conditions; however, prolonged exposure to atmospheric moisture may lead to gradual degradation. For long-term storage or when preparing dilute solutions for sensitive reactions, use dry, degassed solvents and store under an inert atmosphere (N₂ or Ar) with the container tightly sealed.

References

1. Aladdin Scientific. Certificate of Analysis and Safety Data Sheet for 2-(2-Chlorophenyl)oxazole, SKU C185659. Aladdin Scientific, Shanghai.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. Chapter on heterocyclic chemistry and cross-coupling reactions.
3. Johansson Seechurn, C. C. C.; Kitching, M. O.; Colacot, T. J.; Snieckus, V. Palladium-Catalyzed Cross-Coupling: A Historical Contextual Perspective to the 2010 Nobel Prize. Angew. Chem. Int. Ed. 2012, 51, 5062–5085. doi:10.1002/anie.201107017

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