This compound belongs to the class of organic compounds known as biphenyls and derivatives. These are organic compounds containing to benzene rings linked together by a C-C bond.
External Descriptors
Not available
1. Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.
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Application Protocols
Not applicable.
No immunoassay or cell-based application protocols are associated with this small-molecule building block. For synthetic procedures using 4‑ethylbiphenyl, see the Reaction Conditions and Synthetic Utility sections for general literature guidance.
Biological Roles
Applicability note
4‑Ethylbiphenyl is an alkylated aromatic hydrocarbon used as a synthetic building block and materials intermediate. It does not have established physiological roles.
Literature perspective (not product-specific)
Environmental/biochemical behavior: Hydrocarbon biphenyls and simple alkylated derivatives are hydrophobic and tend to partition into lipid phases. Biodegradation, when it occurs, typically proceeds via initial aromatic ring oxidation by monooxygenases or benzylic oxidation pathways in microbial systems, followed by ring cleavage. Rates depend strongly on substitution and bioavailability.
Binding and interactions: Aromatic hydrocarbons can exhibit nonspecific hydrophobic interactions with biomembranes and proteins. Specific high-affinity biological targets are not typical for unsubstituted/alkylated biphenyls absent polar functionalities.
Analytical internal standards: Alkylated biphenyls are sometimes employed as retention markers or surrogates in chromatography due to their defined hydrophobicity and UV activity, but selection depends on method requirements.
Research use only
Any biological testing should be conducted under appropriate containment with attention to solvent carriers and dispersants because of low aqueous solubility. No claims are made regarding bioactivity, safety, or suitability for clinical use.
Buffer Applications
Not typically applicable.
4‑Ethylbiphenyl is a hydrophobic organic building block and is not used to prepare aqueous buffer systems. For experiments involving this compound in aqueous settings, use cosolvents (e.g., DMSO at low percentages) or emulsifiers/surfactants and select buffers based on the biological assay requirements rather than on this compound’s properties.
Green Alternatives
Context
4‑Ethylbiphenyl itself is a hydrocarbon building block; “greener alternatives” primarily address solvent choice and reaction conditions used with this substrate rather than replacement of the substrate.
Replace chlorinated solvents (DCM, DCE) with safer ethers or aromatics when feasible (e.g., 2‑MeTHF, CPME, toluene).
For radical benzylic bromination, consider solvent/initiator systems that avoid CCl4 (e.g., MeCN or ethyl acetate with photochemical initiation) and use NBS or NCS judiciously.
For cross-coupling, aqueous micellar catalysis (e.g., TPGS-750-M in water) or bio-derived solvents (2‑MeTHF) can reduce organic solvent load.
Comparison snapshot (general, not product-specific)
DCM vs 2‑MeTHF: Similar solvating power for many EAS/coupling setups; 2‑MeTHF offers higher boiling point, partial water miscibility, bio-based origin; DCM poses higher toxicity and VOC concerns.
THF vs CPME: CPME resists peroxide formation better, has broader liquid range, and easier phase separations; THF is more established and often provides higher solubility for polar reagents.
Toluene/xylene: Good for high-temp catalysis; flammable and VOCs, but non-chlorinated and recyclable at scale.
Process intensification
Flow photochemistry for benzylic functionalization can reduce solvent volumes and improve safety.
Catalytic aerobic oxidations (O2 or air) with TEMPO/metal catalysts can replace stoichiometric oxidants for benzylic oxidation, minimizing waste.
Always validate green substitutions through DoE to balance safety, performance, and quality.
Pharmaceutical Uses
Formulation and process context (no therapeutic claims)
4‑Ethylbiphenyl is not a common excipient and has no recognized pharmacopeial monograph. Its role in pharmaceutical R&D would be as a synthetic intermediate or reference standard for analytical method development where a hydrophobic aromatic is desired.
Considerations for use in process chemistry (literature/guidance)
Impurity profiling: If used as a building block en route to APIs or advanced intermediates, establish impurity fate and purge, including isomeric and polyalkylated byproducts.
Residual levels: Define acceptable carryover based on ICH Q3A/B when used upstream of the final API. Given its hydrophobicity and high boiling point, consider solvent exchanges or crystallization to ensure effective purge.
Analytical methods: GC-FID/GC–MS for volatile/semi-volatile analysis; HPLC-UV for nonvolatile matrices leveraging strong aromatic absorption.
Regulatory note
This product is designated For research use only and is not intended for human or veterinary use, drug substance, or excipient applications without appropriate qualification.
Physical Properties
Item-specific specifications
Not specified for this item; refer to CoA/Spec Sheet for any tested physicochemical attributes (e.g., assay, GC purity, residual solvents, metals, water content, UV cutoffs).
Literature/Computed (general guidance for 4‑ethylbiphenyl; not product specifications)
Phase at ambient conditions: Typically a low-melting aromatic solid or high-boiling liquid depending on isomeric purity and crystallinity; hydrophobic
Solubility: Practically insoluble in water; soluble in nonpolar and moderately polar organic solvents (e.g., hexanes, toluene, ether, dichloromethane) (literature)
Density: Expected near that of substituted aromatics (~0.95–1.03 g/mL if liquid; literature range)
Volatility: Low vapor pressure relative to lower MW aromatics; high boiling point typical of biphenyl derivatives (literature)
Partitioning: High logP expected due to fully hydrocarbon character (literature)
UV characteristics: Strong aromatic π–π* absorption in UV region; may show bands near 200–280 nm typical of biphenyls (literature)
Practical implications
Handling and work-up generally rely on organic solvents; aqueous washes remove inorganic residues but do not dissolve the product appreciably.
Flash chromatography typically uses hexanes or hexanes/ethyl acetate gradients due to the nonpolar nature.
Thermal stability is generally good for unsubstituted/alkylated biaryls under neutral conditions; avoid prolonged heating with strong oxidants.
Quality and Grades
Item-specific information
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
General guidance on quality for synthetic building blocks (literature/practice)
Typical quality controls: Identity by NMR/GC-MS/HRMS; purity by GC or HPLC; residual solvent by GC; water content by Karl Fischer (not applicable if solid and anhydrous, yet sometimes reported); and inorganic residue/metal screening if relevant to synthesis history.
Impact on performance: Trace peroxides are not a concern for this hydrocarbon; however, residual halogenated solvents or Lewis acid catalysts from alkylation could affect sensitive downstream steps (e.g., strong-base metalations). Low UV background is usually adequate for photophysical work because of defined aromatic absorptions, but for analytical use, confirm UV cutoffs and extinction in your solvent system.
Stabilizers: None are typically required for alkylated biphenyls. If a stabilizer or antioxidant is present, it will be declared on the CoA; absence here means “Not specified for this item.”
Batch-to-batch consistency: For chromatography-grade or synthesis-grade materials, consistent isomeric purity (para vs ortho/meta) and low levels of polyalkylated byproducts are often more critical than absolute assay percentage.
Documentation
For regulatory or critical applications, request the lot-specific CoA and, if needed, a detailed specification sheet covering analytical methods and acceptance criteria.
Reaction and Applications
Research-use context
This product is supplied for research and laboratory synthesis only.
Representative application spaces (literature; not product-specific)
Electrophilic aromatic substitution (EAS): The ethyl group is a strong ortho/para director and activator, enabling regioselective nitration, sulfonation, halogenation, and Friedel–Crafts acylation on the ethyl-bearing ring (preferentially at the 2- and 4-positions relative to the ethyl; the biaryl bond occupies the 1-position).
Benzylic transformations: The benzylic CH2 of the ethyl substituent can undergo radical bromination (NBS/AIBN, hv) or oxidation (e.g., KMnO4, RuO4, or catalytic aerobic oxidations) to yield benzyl bromides, alcohols, or acids, providing handles for further diversification.
Cross-coupling strategies: After installing a halogen (e.g., para- or ortho-bromination relative to the ethyl substituent), Suzuki–Miyaura, Negishi, Kumada, or Buchwald–Hartwig reactions can elaborate the framework. The biphenyl core is robust to many Pd-catalyzed conditions.
Directed metalation: Strong bases (sBuLi, tBuLi) in the presence of ligands (TMEDA) can effect ring metalation on biphenyl systems, permitting formylation or borylation after quench, though substitution patterns and temperature control are critical.
Materials/ligands: Alkylated biphenyls serve as hydrophobic scaffolds in liquid crystal research, polymer additives, and as calibration or retention markers in chromatographic method development (due to their defined hydrophobicity and aromaticity).
Practical tips
Ensure anhydrous, oxygen-minimized conditions for organometallic steps; dry glassware and degassed solvents improve reproducibility.
Control exotherms carefully during EAS with Lewis acids; aromatic solvents can aid heat management.
Purify by low-polarity chromatography; monitor by GC or TLC under UV.
Reaction Conditions
General conditions (literature examples; not product specifications)
Electrophilic aromatic substitution (EAS):
Bromination: Br2 (1.05–1.2 equiv) with catalytic FeBr3 in DCM or acetic acid at 0–25 °C, 0.5–4 h; regioselectivity favors ortho/para to ethyl. Workup with aqueous sodium bisulfite.
Nitration: HNO3/H2SO4 (mixed acid) at 0–5 °C to control overreaction; short reaction times (minutes) favored for mono-nitration on activated ring.
Benzylic radical bromination:
NBS (1.1–1.5 equiv), AIBN (5–10 mol%), CCl4, C6H6, or MeCN, reflux or hv (365 nm), 2–8 h to give benzyl bromide; monitor by GC/TLC.
Benzylic oxidation:
KMnO4 (excess) in tBuOH/H2O with phase transfer or NaOH(aq) at reflux; or catalytic Co/Mn/Br with O2 in acetic acid; 50–100 °C, several hours to acids.
Cross-coupling (after aryl bromination):
Suzuki–Miyaura: Aryl–Br (1.0 equiv), Ar–B(OH)2 (1.2–1.5 equiv), Pd(PPh3)4 (1–3 mol%), K2CO3 (2–3 equiv), dioxane/H2O or toluene/H2O, 80–110 °C, 2–16 h.
Buchwald–Hartwig amination: Aryl–Br, amine (1.2–2.0 equiv), Pd2(dba)3 (1–2 mol%) with XPhos/BippyPhos, NaOtBu or Cs2CO3, toluene or dioxane, 90–110 °C.
Directed metalation/borylation:
sBuLi (1.1–1.5 equiv) with TMEDA in THF at −78 to −40 °C, then B(OMe)3 quench; oxidative workup to aryl boronic acid/ester.
Tips
Control regioselectivity through temperature and stoichiometry; the ethyl group biases EAS on its ring.
Degas solvents for Pd-catalyzed reactions; employ inert atmosphere (N2/Ar).
Use nonpolar eluents for purification; high-boiling products may benefit from Kugelrohr distillation if liquid.
Safety and Handling
Item-specific hazard data
GHS classification, signal word, pictograms, and H-statements: Not specified for this item; refer to the SDS for authoritative safety information.
General safety considerations for alkylated biphenyls (literature; not product-specific)
Likely hazards: Combustible organic; may cause skin/eye irritation on contact and respiratory irritation if aerosolized. Avoid inhalation of vapors/mists and prolonged skin contact.
PPE: Wear lab coat, safety glasses or chemical splash goggles, and appropriate chemical-resistant gloves (e.g., nitrile). Use in a fume hood to minimize exposure to vapors and solvent co-contaminants.
Incompatibilities: Strong oxidizers (risk of exothermic reaction/oxidation), strong electrophiles under Friedel–Crafts conditions, and very strong bases that may effect benzylic deprotonation or ring lithiation.
Fire safety: Treat as a combustible aromatic hydrocarbon. Use CO2, dry chemical, or foam for small fires. Keep away from ignition sources and hot surfaces.
First aid (overview):
Inhalation: Move to fresh air; consult medical attention if symptoms persist.
Skin: Wash with soap and water; remove contaminated clothing.
Eyes: Rinse cautiously with water for several minutes; remove contact lenses if present and easy to do.
Ingestion: Rinse mouth; seek medical advice; do not induce vomiting unless directed by medical personnel.
Environmental: Avoid release to the environment; collect spills with inert absorbent and dispose according to local regulations.
Always consult the SDS supplied with the batch for definitive, product-specific hazard and response information.
Solvent Selection
Applicability note
4‑Ethylbiphenyl is a hydrophobic aromatic building block rather than a solvent. This section discusses solvent choices for dissolving, reacting, or purifying this compound.
General miscibility and polarity (literature)
Polarity class: Nonpolar/aromatic. Freely soluble in hydrocarbon and chlorinated organic solvents (hexanes, heptane, toluene, xylene, dichloromethane, chloroform) and in ethers (diethyl ether, MTBE, THF). Practically insoluble in water and highly polar protic media.
Use-case-driven selection
Reaction medium:
Electrophilic aromatic substitution (EAS): Often performed in chlorinated solvents (DCM, DCE) or aromatics (chlorobenzene, nitrobenzene) under Lewis/Brønsted acid catalysis.
Benzylic functionalization (e.g., NBS bromination): CCl4, DCM, or refluxing CCl4 alternatives (e.g., MeCN with radical initiator) as greener options.
Metalation/cross-coupling after halogenation: Polar aprotics (THF, CPME, 2‑MeTHF, dioxane), or toluene for high-temp Pd-catalyzed couplings.
Workup and purification:
Nonpolar eluents (hexanes) or hexanes/ethyl acetate gradients are typically effective in flash chromatography.
Crystallization may be achieved from ethanol or isopropanol/hexanes mixtures for suitably crystalline derivatives; the parent compound may oil out depending on isomeric purity.
Comparison tip
When high solubility and fast mass transfer are needed, toluene or THF are good starting points. For greener workflows, consider 2‑MeTHF or CPME, balancing safety and process constraints.
Storage and Reconstitution
Item-specific (from Product Data)
Storage conditions: Room temperature
Shipped in: Normal conditions
General guidance (literature/practice; not product-specific)
Container: Store in a tightly closed amber glass bottle to minimize photochemical degradation and solvent loss (if liquid). For solids, protect from moisture ingress; although hydrophobic, powders can adsorb organics.
Atmosphere: Ambient atmosphere is typically acceptable; inert gas blanket is optional for long-term storage, especially if repeatedly heated for melting.
Stability: Alkylated biphenyls are generally stable under neutral, dry conditions. Avoid strong oxidizers and prolonged exposure to strong UV.
Reconstitution/dissolution: If supplied as a solid, dissolve directly in an appropriate organic solvent (e.g., hexanes, toluene, THF, DCM) to the desired concentration. Gentle warming and sonication can accelerate dissolution. Filter if necessary through PTFE membranes (0.45 µm) to remove particulates.
Freeze–thaw: Not applicable; store at ambient unless otherwise directed by the CoA. Do not freeze solutions in glass without headspace to prevent breakage.
Always refer to the lot-specific CoA/Spec Sheet for definitive instructions on storage, handling, and solution stability.
Structure and Identity
Item-specific (from Product Data)
SKU: E115520
Product name: 4-Ethylbiphenyl
CAS: 5707-44-8
CID: 79786
InChIKey: 343564 (as provided)
Storage: Room temperature; shipped under normal conditions
Literature/General identity information (for the chemical name “4‑ethylbiphenyl”; not a product specification)
Structural class: Alkylated polycyclic aromatic hydrocarbon; biphenyl core bearing a para-ethyl substituent on one ring
Functional groups: Aromatic rings (biaryl), alkyl (ethyl) substituent; no heteroatoms
2D structural description: Two phenyl rings linked by a C–C bond (biphenyl). On one ring, the ethyl group (–CH2–CH3) is located para to the biaryl bond, giving a symmetric substitution pattern on that ring and an unsubstituted partner ring.
Representation: Commonly depicted as a biphenyl scaffold with an ethyl at the 4-position of one ring (para to the inter-ring bond).
Notes
SMILES and a standardized InChIKey are not specified for this item; refer to CoA/Spec Sheet. Representative strings can be found in public databases for the compound name (literature).
Synthetic Utility
Reactivity features (literature)
Activating alkyl substituent: The ethyl group is ortho/para-directing and ring-activating toward electrophilic aromatic substitution on the substituted ring.
Benzylic handle: The CH2 of the ethyl substituent provides a site for radical halogenation, oxidation, or deprotonation under strong base to access benzyl derivatives.
Robust biaryl core: The unsubstituted ring can be selectively functionalized after halogenation or metalation, enabling divergent synthesis.
Transformations and strategies
Halogenation (Br2/FeBr3, NBS under radical conditions) to set up cross-couplings (Suzuki–Miyaura, Kumada, Negishi, Stille) for rapid scaffold diversification.
Friedel–Crafts acylations on the activated ring to build diaryl ketones; subsequent reductions or rearrangements expand chemical space.
Benzylic oxidation to 4‑(biphenyl-4-yl)acetic acid derivatives via KMnO4 or catalytic aerobic methods; acids can be converted to amides, esters, or used in cross-coupling as redox-active esters.
Lithiation/borylation sequences: Strong base metalation followed by electrophile quench (B(OR)3) affords aryl boronates, valuable for iterative couplings.
Retrosynthetic value
4‑Ethylbiphenyl serves as a convergence point for biphenyl frameworks with an alkyl substituent; it can be traced back to biphenyl via Friedel–Crafts alkylation or to aryl–aryl coupling of an ethyl-substituted aryl with a haloarene.
Target Specificity
Not applicable.
This product is a small-molecule aromatic building block, not a biological targeting reagent (e.g., antibody, ligand with defined biological target). No antigen, epitope, clone, or species reactivity data apply.
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