4-Bromoanisole (104-92-7) Physical and Chemical Properties
4-Bromoanisole
A para-brominated anisole serving as an organobromine intermediate for fine chemical and pharmaceutical synthesis, typically used by R&D and process chemistry teams.
| CAS Number | 104-92-7 |
| Family | Halogenated Anisoles |
| Typical Form | Light yellow liquid |
| Common Grades | BP, EP, JP |
4-Bromoanisole is a simple aromatic organobromide belonging to the anisole (methoxybenzene) family with a para-positioned bromine substituent. Structurally it is a monomethoxybenzene (anisole) core bearing an aryl bromide at the 4-position; formal IUPAC name: 1-bromo-4-methoxybenzene. Electronic structure is dominated by the conjugated aromatic ring with a strong electron-donating methoxy group (+M effect) and a halogen that exerts a weak electron-withdrawing inductive effect (−I) while retaining ortho/para directing character via resonance. The combination yields an aromatic system with modestly increased electron density relative to unsubstituted bromobenzene at positions activated by the methoxy group and a relatively stable C–Br bond suitable for common cross-coupling transformations.
In physicochemical terms the molecule is essentially neutral, low in polarity (small topological polar surface area) and moderately lipophilic, consistent with substituted anisoles and aryl bromides. Acid–base behaviour is negligible under normal conditions (no ionizable functional groups), hydrogen-bond donor capacity is zero and hydrogen-bond accepting ability is limited to the methoxy oxygen. Hydrolysis under ambient conditions is not expected; oxidative degradation follows typical patterns for electron-rich aromatics and may occur under strong oxidizing conditions or by radical processes. The aryl bromide functionality makes the compound a standard electrophile in palladium- and nickel-catalysed cross-coupling reactions used in synthetic and manufacturing contexts.
Common commercial grades reported for this substance include: BP, EP, JP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting Point
Experimental description reports a melting point of \(9\text{–}10\,^\circ\mathrm{C}\). The substance is therefore a low-melting aromatic liquid at ambient temperature or a liquid that may solidify near refrigeration temperatures.
Boiling Point
No experimentally established value for this property is available in the current data context.
Vapor Pressure
No experimentally established value for this property is available in the current data context.
Flash Point
No experimentally established value for this property is available in the current data context.
Chemical Properties
Solubility and Phase Behavior
4-Bromoanisole is a low-polarity aromatic liquid with very limited hydrogen-bonding capacity (hydrogen-bond donor count = 0, acceptor count = 1). Solubility will therefore be high in nonpolar and moderately polar organic solvents (ethers, hydrocarbons, chlorinated solvents) and poor in water. The small topological polar surface area and modest molecular polarity predict negligible aqueous solubility and a strong partitioning into organic phases; this is typical for alkoxy-substituted aryl halides.
Reactivity and Stability
As an aryl bromide, the C–Br bond is stable under neutral conditions but is a good leaving group under transition-metal-catalysed cross-coupling and nucleophilic aromatic substitution (when activated). The para-methoxy substituent increases electron density on the ring, facilitating electrophilic aromatic substitution compared with bromobenzene but also stabilizing radical cation intermediates. The compound is chemically stable to mild conditions but can undergo oxidative degradation under strong oxidants or prolonged exposure to light and radical initiators. Standard precautions for handling halogenated aromatics (avoid strong oxidizers, control sources of ignition and light exposure if scaling) are appropriate.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Qualitatively, substituted anisoles and simple aryl bromides exhibit heat capacities and enthalpies of formation in ranges typical of small monocyclic aromatics; thermochemical data for process modelling should be obtained from experimental determinations or validated literature/technical sources before scale-up.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: C7H7BrO
- Molecular weight: \(\,187.03\,\mathrm{g}\,\mathrm{mol}^{-1}\)
LogP and Polarity
- XLogP (computed): 2.8 — indicating moderate lipophilicity consistent with partitioning into organic phases rather than aqueous media.
- Topological Polar Surface Area (TPSA): \(9.2\,\text{Å}^2\) — low polar surface area consistent with limited aqueous solubility.
Structural Features
The structure is an anisole (methoxy-substituted benzene) with a para-bromine substituent (SMILES: COC1=CC=C(C=C1)Br). The methoxy group is an electron-donating substituent that activates the ring toward electrophilic substitution at ortho/para positions; the bromine atom is a weakly deactivating but ortho/para-directing halogen that is readily employed as a coupling handle in palladium- or nickel-catalysed cross-coupling reactions (e.g., Suzuki, Negishi, Buchwald–Hartwig). Steric hindrance is low (rotatable bond count = 1), and the molecule presents a planar aromatic ring with one substituent bearing lone-pair electrons (oxygen) that can coordinate weakly in catalytic environments.
Additional computed structural parameters: exact mass = 185.96803; monoisotopic mass = 185.96803; heavy atom count = 9; hydrogen-bond donor count = 0; hydrogen-bond acceptor count = 1; rotatable bond count = 1; complexity = 77.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS Registry Number: 104-92-7
- EC (European Community) number: 203-252-1
- UNII: U430F901J9
- ChEBI: CHEBI:47257
- DTXSID: DTXSID2059308
- NSC Number: 8042
- InChI: InChI=1S/C7H7BrO/c1-9-7-4-2-6(8)3-5-7/h2-5H,1H3
- InChIKey: QJPJQTDYNZXKQF-UHFFFAOYSA-N
- SMILES: COC1=CC=C(C=C1)Br
Synonyms and Structural Names
Common synonyms and alternative names reported include:
- 1-bromo-4-methoxybenzene
- p-Bromoanisole
- p-Bromanisole
- 4-Methoxyphenyl bromide
- Anisyl bromide
- p-Anisyl bromide
- 4-Bromoanisol
- 4-methoxy-1-bromobenzene
(Selections above reflect the principal depositor-supplied synonyms available for procurement and indexing.)
Industrial and Commercial Applications
Representative Uses and Industry Sectors
4-Bromoanisole is used primarily as an intermediate in closed process organic synthesis. It is handled and processed in chemical manufacturing settings where substituted aryl bromides serve as building blocks for the production of fine chemicals, advanced intermediates for pharmaceuticals, agrochemical intermediates, and specialty materials. Reported commercial activity levels indicate manufacture and use at industrial scales (aggregated product volumes reported in previous years at scales below 1,000,000 lb).
Role in Synthesis or Formulations
Functionally the compound serves as a readily usable aryl electrophile in metal-catalysed cross-coupling chemistry (e.g., Suzuki–Miyaura, Buchwald-type aminations) to install diverse substituents on an anisole framework. The methoxy substituent can direct further functionalization and can be retained or transformed depending on synthetic strategy. In practice, 4-bromoanisole is selected when a methoxy-substituted aryl bromide is required as a coupling partner or as a precursor to more elaborated aryl derivatives.
Safety and Handling Overview
Acute and Occupational Toxicity
Reported hazard statements in classification listings include: H315 (causes skin irritation), H373 (may cause damage to organs through prolonged or repeated exposure), and H412 (harmful to aquatic life with long lasting effects). Toxicological summaries indicate central nervous system effects consistent with solvent exposure (acute solvent syndrome), and animal inhalation data lists an LC50 (mouse) value of \(\,20\,\mathrm{mg}\,\mathrm{m}^{-3}\). It is described as a skin irritant and harmful by ingestion in toxicology annotations; occupational exposure controls and monitoring are recommended for worker protection.
Storage and Handling Considerations
Handle 4-bromoanisole with standard controls appropriate for low-polarity aromatic organohalides: use adequate local exhaust ventilation or closed systems to limit inhalation exposure, wear appropriate personal protective equipment (chemical-resistant gloves, eye protection and protective clothing), and prevent skin contact and ingestion. Avoid release to the environment; the substance is reported to be harmful to aquatic life and should be stored and disposed of to minimise environmental exposure. Store in a cool, well-ventilated area away from strong oxidizing agents and ignition sources; follow product-specific Safety Data Sheet (SDS) and applicable local regulations for detailed hazard, transport and regulatory requirements.
