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
No manufacturer-validated biological assay protocols are provided for this small-molecule reagent. For synthetic applications, see Reaction Conditions for generalized procedures (Sonogashira coupling, CuAAC, Glaser coupling). Any application-specific protocol should be developed and validated by the end user based on their substrate set and analytical methods.
Biological Roles
This product is a synthetic aromatic hydrocarbon intended for chemical research and materials synthesis; it does not have an established physiological role.
General, literature-based context (no clinical claims):
Hydrophobic probes/scaffolds: Terminal alkynes can serve as bioorthogonal handles for post‑synthetic tagging (e.g., CuAAC to install fluorophores/affinity tags) when the compound is incorporated into larger constructs such as polymers, surfaces, or small‑molecule libraries. Any biological use must be designed and validated by the researcher.
Membrane affinity: The biphenyl–propyl motif is strongly lipophilic and can increase membrane association when appended to biomolecules or amphiphiles; this is sometimes exploited in probe design for model membranes or lipid assemblies.
Metabolic stability (conceptual): Aryl–alkynes are generally metabolically robust; however, oxidative metabolism of the biphenyl core (e.g., aromatic hydroxylation) can occur in biological systems. These considerations are relevant only for in vitro assay design and not indicative of suitability in vivo.
Important: No item-specific bioactivity, pharmacology, or toxicity data are provided. Use strictly for laboratory research. Any biological experimentation should adhere to institutional safety guidelines, and copper catalysts used in azide–alkyne ligations require careful control to avoid unintended biological effects.
Buffer Applications
Not typically applicable. 4‑Ethynyl‑4'‑propylbiphenyl is a highly hydrophobic, nonionic aromatic compound with negligible aqueous solubility and does not function as a buffering agent. For aqueous work, see Solvent Selection for guidance on cosolvent systems if dispersion in water-based media is required (e.g., t‑BuOH/H2O or DMF/H2O for CuAAC chemistry).
Green Alternatives
Sustainability considerations focus on solvent/catalyst choices rather than replacing the substrate itself.
Greener choices (literature/general guidance):
Solvents for Sonogashira/CuAAC:
Prefer 2‑MeTHF or CPME over THF/diethyl ether (renewable origin, better safety) and anisole or propylene carbonate over chlorinated solvents for aromatic dissolution.
Use ethanol/water or t‑BuOH/water mixtures for CuAAC when solubility allows; these reduce VOC impact.
Catalysis and bases:
Employ Pd catalysts at ppm levels (ligand-enabled) or heterogeneous Pd/C for easier recovery; copper-free Sonogashira variants avoid Cu waste and Glaser byproducts.
Minimize silica usage via crystallization or solvent‑switch precipitation when product crystallinity allows.
Comparison snapshot (general):
Conventional vs greener
THF or toluene for coupling vs 2‑MeTHF/anisole: similar performance; greener options have higher flash points and lower peroxide concerns (for 2‑MeTHF vs THF, monitor peroxides still).
DCM/CHCl3 in chromatography vs cyclohexane/EtOAc or heptane/MTBE: reduces halogenated waste.
Tradeoffs:
Greener solvents may alter solubility and rates; modest temperature increases or ligand optimization may be needed.
Water-rich media can decrease solubility for this hydrophobic substrate; use co‑solvents or surfactants (e.g., micellar catalysis) as a compromise.
Pharmaceutical Uses
No pharmacopeial/excipient status or formulation grade is provided for this item. It is offered solely for research and laboratory synthesis.
General, non-clinical context (literature-based):
Medicinal chemistry building block: The terminal alkyne enables rapid diversification via Sonogashira coupling or CuAAC for SAR exploration in hydrophobic series.
Materials in drug-delivery research: Biphenyl–alkyl motifs may be used to tune hydrophobic core properties in polymeric carriers or model membranes; the terminal alkyne offers a conjugation handle to attach the motif to polymers or lipids.
No therapeutic claims are made or implied. If use in any regulated context is contemplated, obtain full characterization (purity, residual metals/solvents, stability) and verify compliance with relevant standards. Item-specific excipient/compendial compliance: Not specified for this item; refer to CoA/Spec Sheet.
Physical Properties
Item-specific specifications are not provided in the Product Data. Consult the CoA/Spec Sheet for definitive values.
General/literature expectations for this structure (informational only, not item specifications):
Phase/appearance: Aromatic biphenyl derivatives around 220 g/mol often occur as low‑melting solids or viscous oils; actual appearance for this item: Not specified for this item; refer to CoA/Spec Sheet.
Boiling point: Likely high due to biphenyl core; many C17 aromatic hydrocarbons boil >300 °C at 1 atm (literature trend). Not specified for this item; refer to CoA/Spec Sheet.
Melting point: Dependent on crystal packing; para‑disubstituted biphenyls can be crystalline. Not specified for this item; refer to CoA/Spec Sheet.
Density: Aromatic hydrocarbons typically ~0.95–1.05 g/mL (literature range). Not specified for this item; refer to CoA/Spec Sheet.
Solubility: Expected very low in water; freely soluble in common organic solvents (toluene, THF, DCM, chloroform, ethyl acetate, hexanes) due to hydrophobicity (literature expectation).
LogP: Large hydrophobic surface; logP likely >4 (literature expectation for biphenyls with n‑propyl). Not specified for this item; refer to CoA/Spec Sheet.
pKa (terminal alkyne C–H): ~25 (literature, in DMSO), allowing deprotonation by strong bases.
UV/Vis: Conjugated aryl–alkynyl chromophore typically absorbs in the near‑UV; specific cutoff/ε: Not specified for this item; refer to CoA/Spec Sheet.
Refractive index (if liquid) and other analytical indices: Not specified for this item; refer to CoA/Spec Sheet.
Quality & Grades
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Guidance on interpreting grades (general, for planning):
Research/technical grade: Suitable for most synthetic applications and material studies when ultra–low impurity levels are not critical.
High-purity/assay ≥98–99%: Preferred for materials research (e.g., optical/electronic property measurements, liquid‑crystal formulation) to minimize impurity effects on phase behavior and device performance.
Stabilizers/inhibitors: Not specified for this item; refer to CoA/Spec Sheet. Terminal alkyne reagents are typically sold without stabilizers; if present, confirm compatibility with downstream reactions (e.g., Pd-catalyzed couplings are sensitive to certain additives).
What to check on receipt (best practices):
Confirm identity by 1H/13C NMR (look for characteristic terminal alkyne proton ~δ 3.0 ppm and C≡C carbons ~δ 80–90/120–130 ppm, literature), and biphenyl aromatic pattern; HRMS for molecular ion ~m/z 220.1 (literature calc for C17H16).
Purity by HPLC/GC as applicable; assess residual solvents and metal content if the material is intended for catalysis/materials studies. If UV transparency is important, request UV cutoff data.
Particle form (crystalline vs oil) may vary with lot; if crystallinity is critical (e.g., for mesophase studies), note lot-to-lot differences.
Reaction & Applications
With a terminal alkyne on an aryl scaffold, 4‑ethynyl‑4'‑propylbiphenyl is a versatile building block for C–C and C–N bond formations and for constructing extended π‑systems.
Key reaction families (literature/general):
Sonogashira coupling (Pd/Cu or Pd-only): Couples the terminal alkyne with aryl/vinyl halides or triflates to afford aryl–ethynyl–aryl motifs, extending conjugation for optoelectronic materials. Typical catalysts: Pd(PPh3)2Cl2 + CuI; bases: Et3N, iPr2NEt, or Cs2CO3; solvents: THF, toluene, DMF.
CuAAC “click” chemistry: The terminal alkyne undergoes copper(I)-catalyzed azide–alkyne cycloaddition to yield 1,4‑disubstituted 1,2,3‑triazoles, enabling attachment to azide‑functional polymers, surfaces, or biomolecules (when appropriate linkers are used).
Glaser–Hay oxidative coupling: Dimerization to form symmetrical diynes under Cu(I)/O2, useful for rigid‑rod materials; control conditions to avoid unwanted oligomerization.
Hydrofunctionalizations: Hydroboration of the terminal alkyne (e.g., catecholborane, 9‑BBN) followed by oxidation gives aryl aldehydes (anti‑Markovnikov hydration pathway); hydrostannylation, hydrosilylation, and hydroamination expand diversification routes.
Deprotonation/alkylation: Strong bases (e.g., n‑BuLi, LDA, NaNH2 under rigorously anhydrous conditions) generate the acetylide anion for nucleophilic substitutions with suitable electrophiles.
Application spaces (literature/general):
Liquid‑crystal and organic electronic materials: The propyl‑substituted biphenyl core is a classic mesogenic motif; ethynylation enables tuning of mesophase, dipole alignment, and transition temperatures.
Conjugated polymers/oligomers: Aryl–ethynyl linkages impart rigidity and high optical anisotropy.
Practical tips:
Exclude oxygen/copper during non‑oxidative transformations to prevent inadvertent Glaser coupling.
For Pd couplings, degas solvents and consider amine-free bases to minimize side reactions.
Reaction Conditions
The following are general literature conditions for common transformations of terminal aryl‑alkynes; they are guidance, not item-specific specifications.
Sonogashira coupling (to aryl/vinyl halides):
Catalyst: Pd(PPh3)2Cl2 (1–3 mol%) + CuI (2–5 mol%) or Pd-only systems (e.g., Pd2(dba)3 + dialkylbiaryl phosphine ligand).
Base: Et3N, iPr2NEt, or Cs2CO3 (1.5–2.5 equiv).
Solvent: THF, toluene, dioxane, DMF, MeCN.
Temp/time: 25–80 °C, 1–12 h. Typical isolated yields: 70–95% with aryl iodides/bromides.
Notes: Degas; exclude O2 to avoid Glaser coupling; copper-free variants help with sensitive substrates.
Solvent: t‑BuOH/H2O (1:1) or DMF/H2O; adjust with EtOH/MeOH if needed for solubility.
Temp/time: RT to 50 °C, 1–6 h; often quantitative conversion by LC/MS.
Notes: Use chelators or ligand-accelerated conditions for hydrophobic substrates; remove residual copper with scavengers.
Glaser–Hay homocoupling:
Catalyst: CuCl/CuI (5–10 mol%) + TMEDA; O2 or air as oxidant.
Solvent: Pyridine, toluene, or DMF; 20–60 °C.
Notes: Monitor closely to mitigate over‑oxidation/polymerization.
Hydroboration–oxidation of terminal alkyne:
Reagents: 9‑BBN or dicyclohexylborane; then H2O2/NaOH.
Outcome: Anti‑Markovnikov hydration to aryl aldehyde (literature pathway via enol/tautomerization).
General workup: Dilute with organic solvent, wash with aq. NH4Cl or EDTA (if Cu used), dry, and purify by silica gel using hexanes-rich eluents.
Safety & Handling
Item-specific GHS/HS codes are not provided. Always consult the SDS for authoritative safety information.
General hazards and handling guidance for aryl–alkynes/biphenyls (informational, not a substitute for SDS):
GHS classification/Pictograms: Not specified for this item; refer to SDS.
Flammability: Aromatic hydrocarbons and terminal alkynes are combustible; keep away from ignition sources. Vapors from organic solutions may form flammable mixtures with air.
Health hazards: Hydrophobic aromatics can cause irritation on skin/eyes and CNS depression upon inhalation of solvent vapors. Avoid breathing dust/vapors and prolonged contact.
PPE: Use chemical-resistant gloves (e.g., nitrile), safety goggles, lab coat. Handle in a fume hood to avoid inhalation of solvent vapors/aerosols.
Storage incompatibilities: Avoid strong oxidizers (risk of exotherm), strong bases in presence of protic media (may deprotonate the terminal alkyne with gas evolution), and halogenating agents. Copper salts plus oxygen can promote Glaser coupling (unintended dimerization) if the terminal alkyne is in solution.
First aid (overview):
Inhalation: Move to fresh air; seek medical attention if symptoms persist.
Skin/eye contact: Rinse with copious water; remove contaminated clothing; seek medical advice if irritation persists.
Ingestion: Rinse mouth; do not induce vomiting; get medical care.
Waste: Collect as halogen-free organic waste unless solutions contain halogenated solvents; follow local regulations.
Special risks: Terminal alkynes can form copper acetylides with Cu(I), which are moisture/air sensitive; avoid copper contamination when unintended.
Solvent Selection
4-Ethynyl-4'-propylbiphenyl is a highly hydrophobic, weakly polar aromatic hydrocarbon with a terminal alkyne. Solvent choice is driven by solubility, reaction compatibility (e.g., Pd/Cu catalysis), and downstream purification.
Polarity/miscibility (general):
Poorly soluble in water; readily soluble in nonpolar and moderately polar aprotic solvents (hexanes/heptane, toluene, xylene, CH2Cl2, CHCl3, THF, EtOAc). Solubility increases with temperature and aromaticity of the medium.
Typical use scenarios:
Pd-catalyzed couplings (Sonogashira): THF, toluene, dioxane, DMF, acetonitrile; bases such as Et3N, iPr2NEt, or amine–solvent dual roles.
CuAAC “click” with azides: t‑BuOH/H2O or DMF/H2O mixtures to balance organic solubility with catalyst turnover; use cosolvents if aqueous miscibility is low.
Materials processing and thin films: Toluene, chlorobenzene, anisole, or cyclohexanone for spin coating or solution casting; select higher‑boiling aromatics for slow evaporation.
Workup/purification:
Normal-phase silica gel chromatography with hexanes/EtOAc or hexanes/DCM gradients is typical; aromatic eluents (toluene) can improve band shape for sticky aromatics.
Comparison notes:
Versus highly polar solvents (MeOH, H2O): poor solubility; employ biphasic or cosolvent systems.
Versus greener ethers (2‑MeTHF) or CPME: often good compromise between solubility and sustainability for couplings.
Practical tips:
Warm slightly (30–50 °C) or use sonication to dissolve in less polar media.
Avoid prolonged exposure to basic aqueous media if preserving the terminal alkyne proton is important.
Storage & Reconstitution
Storage (per Product Data): Store at room temperature.
Shipped in: Not specified for this item; refer to CoA/Spec Sheet.
Appearance/physical form: Not specified for this item; refer to CoA/Spec Sheet.
General guidance (literature/practice):
Keep container tightly closed in a dry, well‑ventilated place. Protect from strong light and prolonged air exposure if long-term purity of the terminal alkyne is critical.
If frequent openings are expected, consider storing under inert gas (N2/Ar) to limit adventitious oxidation of solutions and to avoid inadvertent copper contamination that could trigger Glaser coupling in solution.
For solution storage (user-prepared): Use dry, oxygen‑free solvents (e.g., toluene, THF, DCM). Store at 2–8 °C for medium‑term stability; bring to ambient and mix before use. Do not freeze aqueous cosolvent mixtures.
Freeze–thaw cycles: Not applicable unless storing solutions; in that case, aliquot to avoid repeated freeze–thaw that can introduce moisture/oxygen.
Stability testing: Confirm integrity by 1H NMR (terminal alkyne proton signal) and LC/MS after extended storage.
Reconstitution: Not typically required. If solid or viscous, dissolve with gentle warming and sonication in a compatible organic solvent (e.g., toluene, THF, CH2Cl2) to the desired concentration.
Structure & Identity
4-Ethynyl-4'-propylbiphenyl is a para/para-disubstituted biphenyl bearing a terminal alkyne and an n-propyl group on opposite rings.
Item-specific identifiers (from Product Data):
CAS: 360768-57-6
SKU: E404412
InChIKey: 452731 (as provided; truncated/format-short — consult CoA/SDS for the complete key)
Storage condition: Room temperature (per Product Data)
Structural features: two phenyl rings connected at C1–C1′; one ring bears a para ethynyl substituent, the other a para n‑propyl. The terminal alkyne proton is acidic (sp C–H), enabling deprotonation/coupling. The n‑propyl group increases lipophilicity and can tune mesogenic behavior.
2D description in words: A biphenyl scaffold with a linear –C≡CH group para to the inter-ring bond on one ring and a straight n‑propyl chain para to the inter‑ring bond on the other ring; overall linear, rigid, and highly hydrophobic.
Synthetic Utility
Functional group inventory and reactivity (literature/general):
Terminal alkyne (–C≡CH):
Nucleophilicity upon deprotonation (pKa ~25 in DMSO) enables C–C bond formation with alkyl halides, aldehydes/ketones (e.g., Corey–Fuchs derived transformations), and acyl equivalents.
Transition‑metal couplings: Sonogashira to aryl/vinyl halides; Glaser/Eglinton oxidative homocoupling to diynes; C–H alkynylation variants under Pd/Cu.
Cycloadditions: CuAAC with organoazides to give triazoles; [2+2+2] cycloadditions under Co/Rh to polycyclic aromatics.
Biphenyl core with para‑n‑propyl: Rigid, conjugated arene platform that enhances solubility in nonpolar media and modulates packing; useful in liquid‑crystal design and organic electronics. The aryl C–H positions ortho/meta to substituents can be leveraged in directed C–H functionalization if appropriate directing groups are introduced downstream.
Retrosynthetic value:
This building block sits at the “alkynyl‑aryl” node of many modular syntheses. Convergent assembly via coupling the terminal alkyne with diverse aryl/vinyl partners streamlines library generation. Conversely, it can be advanced to internal alkynes, enynes, or triazoles while preserving the propyl‑biphenyl backbone.
Practical notes:
Protect the alkyne (e.g., TMS) if strongly basic or metalating steps are planned elsewhere in the molecule; deprotect with K2CO3/MeOH or TBAF under mild conditions.
Avoid copper/oxygen exposure unless Glaser coupling is intended.
Target Specificity
Not applicable. This product is a small-molecule reagent, not a biological targeting agent. No antigen/epitope, clone, isotype, or species reactivity information applies.
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