4-Ethylquinoline - ≥97% , CAS No.19020-26-9

CAS: 19020-26-9 Cat. No.: E1361737 Summenformel: C₁₁H₁₁N Molekulargewicht: 157.21 EG-Nummer: 871-613-6

GRADE & PURITY ≥97%

Storage

Room temperature

Shipped In

Normal

Specifications

Spezifikationen & Reinheit

≥97%

Storage

Room temperature

Verschickt in

Normal

Reinheit

≥97%

Namen und Kennungen

Kanonisches Lächeln

CCC1=CC=NC2=CC=CC=C12

IUPAC Name

4-ethylquinoline

InChIKey

UOYJBGYNFMPCLV-UHFFFAOYSA-N

INCHI

1S/C11H11N/c1-2-9-7-8-12-11-6-4-3-5-10(9)11/h3-8H,2H2,1H3

Molekulargewicht

157.21

Taxonomic Classification

Taxonomy Tree

• Kingdom Organic compounds
  • Superclass Organoheterocyclic compounds
    • Klasse Quinolines and derivatives

• Kingdom: Organic compounds
• Superclass: Organoheterocyclic compounds
• Klasse: Quinolines and derivatives
• Subclass: Not available
• Intermediate Tree Nodes: Not available
• Direct Parent: Quinolines and derivatives
• Alternative Parents: Pyridines and derivatives Benzenoids Heteroaromatic compounds Azacyclic compounds Organopnictogen compounds Organonitrogen compounds Hydrocarbon derivatives
• Molecular Framework: Aromatic heteropolycyclic compounds
• Substituents: Quinoline - Benzenoid - Pyridine - Heteroaromatic compound - Azacycle - Organic nitrogen compound - Organopnictogen compound - Hydrocarbon derivative - Organonitrogen compound - Aromatic heteropolycyclic compound
• Beschreibung: This compound belongs to the class of organic compounds known as quinolines and derivatives. These are compounds containing a quinoline moiety, which consists of a benzene ring fused to a pyrimidine ring to form benzo[b]azabenzene.
• External Descriptors: Not available

Data sources

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.

DOI: 10.1186/s13321-016-0174-y

Chemische und physikalische Eigenschaften

• Molekulargewicht: 157.210 g/mol
• XLogP3: 3.000
• Hydrogen Bond Donor Count: 0
• Hydrogen Bond Acceptor Count: 1
• Rotatable Bond Count: 1
• Exact Mass: 157.089 Da
• Monoisotopic Mass: 157.089 Da
• Topological Polar Surface Area: 12.900 Ų
• Heavy Atom Count: 12
• Formal Charge: 0
• Complexity: 144.000
• Isotope Atom Count: 0
• Defined Atom Stereocenter Count: 0
• Undefined Atom Stereocenter Count: 0
• Defined Bond Stereocenter Count: 0
• Undefined Bond Stereocenter Count: 0
• The total count of all stereochemical bonds: 0
• Covalently-Bonded Unit Count: 1

Application Protocols

Not applicable. No validated bioassay or immunoassay protocols (WB, IHC, IF, FC) are associated with this small‑molecule building block. For chemical applications, see Reaction & Applications, Synthetic Utility, and Reaction Conditions sections.

Biological Roles

This product is intended strictly for research use. The following notes describe general properties of quinoline scaffolds; no biological/clinical claims are made for this item.

• Quinoline as a chemotype (literature/general)
  • Aromatic nitrogen heterocycles like quinolines are prevalent scaffolds in chemical biology and medicinal chemistry due to tunable basicity and planarity.
  • The ring nitrogen (pyridine‑like) can engage in hydrogen bonding and metal coordination, affecting binding to proteins or metalloenzymes in probe development.
• Physicochemical profile
  • Weakly basic (quinolinium pKa ~5), moderately lipophilic (estimated logP ~3 for 4‑ethylquinoline), and poor aqueous solubility at neutral pH—features that influence permeability and formulation strategies for probes.
• Derivatization for probes
  • N‑oxide formation modulates electron density and can alter fluorescence; benzylic functionalization enables installation of reporter groups or linkers.
  • Quinolinium salts are more water‑soluble and can serve as cationic probes or precursors to N‑ylides for bioconjugation chemistry under controlled conditions.

Item-specific bioassay data, targets, or activities: Not specified for this item; refer to primary literature if needed for structure‑based design hypotheses.

Buffer Applications

4‑Ethylquinoline is not a buffering agent and is not typically used to prepare biochemical buffers or electrophoresis running solutions. If handling in aqueous systems is required, salts of the conjugate acid (e.g., hydrochloride) can increase water solubility for stock solutions, but these do not confer significant buffering capacity. For pH control, select established buffers (e.g., phosphate, HEPES, acetate) appropriate to your target pH.

Green Alternatives

Because 4‑ethylquinoline is a heteroaromatic building block (not a process solvent), “green alternatives” focus on greener transformations and media used with it.

• Greener media and reagents (literature/general)
  • Replace chlorinated solvents (DCM) with ethyl acetate or 2‑MeTHF where feasible; consider CPME or toluene for higher‑temperature steps.
  • For benzylic oxidations to carbonyls, avoid stoichiometric Cr(VI)/Mn(VII) where possible:
    • Use catalytic TEMPO/NaOCl (pH‑controlled biphasic) or oxoammonium salts.
    • Employ Cu/TEMPO/O2 or Co/Mn/O2 aerobic oxidations in acetonitrile or greener solvents.
  • N‑oxide formation with H2O2/AcOH or H2O2/urea adduct (urea–hydrogen peroxide) can replace peracids; monitor to suppress over‑oxidation.
  • Cross‑coupling: ligand‑tuned Pd catalysis in aqueous micellar media (TPGS‑750‑M) or ethanol/water mixtures can reduce solvent impact.
• Energy and safety considerations
  • Favor flow or continuous aerobic oxidations to improve mass/heat transfer and minimize peroxide inventories.
  • Use lower‑loading catalysts and room‑temperature photoredox for benzylic functionalizations where applicable.

Item-specific green certifications or solvent-residue limits: Not specified for this item; refer to CoA/Spec Sheet.

Summary comparison (general)

• Conventional: DCM, stoichiometric metal oxidants, high‑boiling polar aprotics.
• Greener: 2‑MeTHF/EtOAc/CPME, catalytic aerobic oxidations, aqueous micellar couplings.

Pharmaceutical Uses

No excipient or pharmacopeial status is specified for this item; it is sold for research use only.

• Role in development (literature/general)
  • 4‑Ethylquinoline is a heteroaromatic building block useful for discovery chemistry and intermediate preparation. Its benzylic position (within the ethyl group) and the quinoline ring can be diversified to produce libraries for structure–property exploration.
  • Quinolinium salts derived from 4‑ethylquinoline can serve as intermediates in the synthesis of ionic liquids or as phase‑transfer auxiliaries in process development research.
• Formulation considerations (general)
  • Poor aqueous solubility at neutral pH suggests use of cosolvents (DMSO, EtOH) or conversion to acid salts for aqueous handling during screening assays.

Item-specific regulatory listings (USP/Ph.Eur.), residual solvent limits, or impurity profiles: Not specified for this item; refer to CoA/Spec Sheet.

Physical Properties

The following values are provided as literature/general references for 4‑ethylquinoline, not as specifications for this particular catalog item.

• State/appearance at ambient conditions (literature): typically a colorless to pale yellow liquid at room temperature.
• Boiling point (literature): ~265–270 °C at 1 atm.
• Melting point (literature): below ambient; remains liquid at room temperature.
• Density (literature): on the order of ~1.0–1.06 g/mL at 20–25 °C.
• Refractive index (literature): commonly around nD20 ~1.60–1.62 for alkylated quinolines.
• Solubility (literature):
  • Water: very low (sparingly soluble)
  • Organic solvents: miscible/soluble in common organics such as ethanol, acetone, ether, dichloromethane, toluene, and acetonitrile.
• Acid–base properties (literature):
  • Conjugate acid pKa (quinolinium) typically ~4.9–5.2; 4‑ethyl substitution slightly increases basicity vs quinoline.
  • As a weak base, forms water‑soluble salts with strong acids (e.g., HCl) and can be extracted accordingly.
• Partitioning (computed/literature estimates):
  • logP (octanol/water): expected in the ~3.0 range due to added ethyl substituent vs quinoline (~2.7).
• Vapor pressure (literature): very low at ambient temperature, consistent with high boiling point.

Item-specific specs for this SKU (bp, mp, density, refractive index, water/peroxide/metal content, UV cutoff): Not specified for this item; refer to CoA/Spec Sheet.

Quality and Grades

• Item-specific grade/purity for SKU E1361737: Not specified for this item; refer to CoA/Spec Sheet.
• Interpreting common grades (general guidance)
  • Research/technical grade: suitable for most synthetic transformations; impurity profile may not be optimized for trace analyses.
  • High-purity/analytical grades (e.g., ≥98–99%): preferable for structure–activity studies, catalysis screening, or spectroscopic measurements where background signals matter.
  • HPLC grade (solvents) vs synthetic building blocks: For non‑solvent organics like 4‑ethylquinoline, "HPLC grade" is uncommon; low UV absorbance at analytical wavelengths is not generally specified.
• Stabilizers
  • Not typically stabilized. If provided with inhibitors or stated antioxidants, assess impact on intended reactions (e.g., oxidative couplings) and remove by basic/acidic washes or short silica passes if necessary.
• Verification and release
  • For heteroaromatics, QC often includes 1H/13C NMR, GC/LC purity, HRMS, and, when relevant, water content by Karl Fischer. Request the current CoA for this lot’s purity, residual solvents, and identification.
• Fit for purpose
  • For photophysical or mechanistic studies, consider further purification (distillation under reduced pressure or column chromatography) to remove trace oxidized species (e.g., N‑oxides) that can bias reactivity or spectra.

Reaction and Applications

As a substituted quinoline, 4‑ethylquinoline serves as a versatile heteroaromatic scaffold and synthon in research chemistry.

• Representative applications (literature/general)
  • Scaffold for medicinal chemistry libraries: installation of functional groups at the benzylic (4‑ethyl’s methylene) or on the aromatic ring after pre‑functionalization (e.g., halogenation) enables rapid SAR exploration across the quinoline chemotype.
  • Benzylic transformations: oxidation to 4‑acetylquinoline (via alcohol/aldehyde intermediates), bromination/chlorination to 4‑(haloethyl)quinolines, or radical functionalization (e.g., Giese additions after conversion to suitable precursors).
  • N‑oxidation: forms the N‑oxide, useful for tuning electronics, as an intermediate to rearrangements (e.g., Boekelheide on appropriately substituted systems) or as a directing group for C–H functionalization.
  • Quaternization: alkylation at N affords quinolinium salts, relevant as phase‑transfer auxiliaries, ionic liquids, or intermediates to N‑ylides.
  • Hydrogenation: catalytic reduction to tetrahydro analogs modifies basicity and conformational properties for further derivatization.
  • Cross‑coupling sequences: after electrophilic pre‑functionalization (e.g., bromination at C5/C8), Pd‑catalyzed Suzuki/Negishi/Sonogashira couplings introduce aryl/alkenyl substituents.
  • Directed ortho metalation (DoM)/lithiation: the ring nitrogen can direct lithiation at C2 under strong base at low temperature, enabling formylation/acylation/halogenation.
• Practical tips
  • Remove trace N‑oxides by passing through neutral/basic alumina or reducing with PCl3 before sensitive reactions.
  • For benzylic oxidations, manganese or chromium reagents are effective; greener variants include TEMPO/bleach or catalytic Cu with O2 for aerobic oxidation (see Green Alternatives).
  • Control regioselectivity by leveraging N‑oxide directing effects or pre‑installed halogens.

Reaction Conditions

The following are representative literature/general conditions for transformations involving 4‑ethylquinoline or closely related quinolines. They are not specifications for this item.

• Benzylic oxidation (ethyl → acetyl/acid)
  • Reagents: KMnO4 (acetone/water, reflux) to acid; or MnO2 (DCM/PhMe, rt–reflux) to aldehyde/ketone; TEMPO/NaOCl (pH ~9, 0–25 °C) for selective oxidation to aldehyde; Cu/TEMPO/O2 (MeCN, rt–60 °C) as greener aerobic option.
  • Typical times: 1–12 h depending on reagent and temperature; monitor by GC or TLC (UV active).
• N‑oxidation
  • mCPBA (DCM, 0 °C to rt, 1–3 h) or H2O2/AcOH (rt–50 °C) to give the quinoline N‑oxide. Control equivalents (1.1–1.5) to minimize over‑oxidation.
• Quaternization (N‑alkylation)
  • Alkyl halide or dimethyl sulfate (MeCN or acetone, rt–reflux, 2–24 h) to form quinolinium salts; base workup or ion exchange to desired counterion.
• Directed lithiation at C2
  • Base: s‑BuLi or t‑BuLi (1.1–1.5 equiv) with TMEDA in dry THF at −78 to −40 °C under N2/Ar; quench with electrophiles (CO2 → carboxylate, DMF → aldehyde, MeI → methyl).
• Aromatic halogenation (for subsequent coupling)
  • NBS/NCS in PhMe/AcOH, catalytic acids, or electrophilic bromination at 5/8‑positions; then Suzuki–Miyaura (Pd(PPh3)4, K2CO3, dioxane/H2O, 80–100 °C) to install aryl groups.
• Hydrogenation
  • Catalyst: Pd/C or PtO2; solvent EtOH/EtOAc; 1–5 bar H2, rt–50 °C to tetrahydro derivatives; monitor to prevent over‑reduction of aromatic ring if not desired.

Typical isolated yields for well‑optimized steps: 60–90% depending on substitution and step; always confirm on small scale before scale‑up.

Safety and Handling

• GHS/SDS
  • Signal word, hazard classes, H‑statements, and pictograms: Not specified for this item; refer to the product SDS for authoritative classification.
• General hazards (literature/good practice for alkylated quinolines)
  • May cause irritation to skin, eyes, and respiratory tract; avoid inhalation of vapors and contact with skin/eyes.
  • Combustible organic liquid; keep away from ignition sources and hot surfaces.
  • Harmful if swallowed; toxicological profile not fully characterized—handle as a substance of unknown toxicity.
• PPE and engineering controls
  • Use in a fume hood with appropriate local exhaust.
  • Wear lab coat, nitrile gloves (change regularly), splash goggles; use face shield for large transfers.
• Handling guidance
  • Avoid aerosol generation; use closed transfer when feasible.
  • For acid–base workups, note formation of water‑soluble quinolinium salts in acidic media; neutralize cautiously to prevent exotherms and vigorous CO2 evolution if carbonates are used.
• Incompatibilities (general)
  • Strong oxidizing agents (risk of exothermic reaction/oxidation to N‑oxide); strong acids form salts (benign unless dehydrating/oxidizing conditions are present); strong bases may induce benzylic lithiation under anhydrous, low‑temperature conditions.
• First aid (overview; defer to SDS)
  • Inhalation: move to fresh air; seek medical attention if symptoms persist.
  • Skin/eye contact: rinse with water for at least 15 minutes; remove contaminated clothing.
  • Ingestion: rinse mouth; do not induce vomiting; seek medical attention.
• Fire safety
  • Use dry chemical, CO2, or alcohol‑resistant foam; cool containers with water spray.

Solvent Selection

This product is a heteroaromatic building block, not primarily used as a laboratory solvent. Therefore, solvent selection pertains to media in which 4‑ethylquinoline is dissolved or reacted.

• Polarity and miscibility (literature)
  • Moderately nonpolar/basic aromatic; highly soluble in most organic solvents (DCM, toluene, THF, EtOAc, MeCN, EtOH). Sparingly soluble in water; soluble upon protonation with strong acids.
• Choosing media by transformation type (general guidance)
  • Electrophilic substitution and metalation: Use inert, anhydrous solvents (toluene, THF, diethyl ether) under N2/Ar; for directed ortho‑metalation near the ring nitrogen, THF at low temperature is typical.
  • Cross‑coupling (after prior halogenation): Polar aprotic solvents (DMF, dioxane, toluene, MeCN) often with aqueous base.
  • Oxidations to N‑oxides: Acetonitrile, DCM, or MeOH with mCPBA or H2O2 systems.
  • Quaternization to quinolinium salts: Polar solvents (MeCN, acetone, MeOH) with alkyl halides/sulfates.
• Comparison note
  • Versus parent quinoline, the ethyl substituent raises hydrophobicity and boiling point; solubility in nonpolar media (e.g., hexanes/toluene) is enhanced.

Item-specific solvent impurity limits or UV cutoff: Not specified for this item; refer to CoA/Spec Sheet.

Storage and Reconstitution

• Storage (item-specific from Product Data)
  • Store at room temperature.
  • Shipped under normal conditions.
• General storage guidance (heteroaromatic liquids/solids)
  • Keep tightly closed in an inert atmosphere (nitrogen/argon) when feasible to minimize slow aerial oxidation to N‑oxide, especially over extended storage.
  • Protect from strong light and heat; store in amber glass if long‑term.
  • Segregate from oxidizers and strong acids/bases.
• Stability
  • Typically stable at ambient conditions; low volatility due to high boiling point reduces evaporative loss.
• Reconstitution/handling
  • Neat liquids: use as supplied; if solidified at low temperature, warm gently to room temperature before dispensing.
  • Stock solutions: prepare in dry organic solvents (e.g., DMSO, MeCN, EtOH, DCM, toluene) as needed; for aqueous applications, convert to a salt (e.g., hydrochloride) or use cosolvents. Filter if particulate is observed.

Appearance, stabilizers, and item-specific limits (water, peroxides, metals, UV cutoff): Not specified for this item; refer to CoA/Spec Sheet.

Research Use Note: For research use only.

Structure and Identity

Brief description: 4‑Ethylquinoline is an ethyl-substituted quinoline (bicyclic benzannulated pyridine) bearing an ethyl group at the 4‑position of the quinoline ring system.

• Item-specific identifiers (from Product Data)
  • CAS: 19020-26-9
  • CID (PubChem): 87900
  • InChIKey: Not specified for this item; refer to CoA/Spec Sheet. (Product Data lists a nonstandard placeholder.)
  • SMILES: Not specified for this item; refer to CoA/Spec Sheet.
• Names
  • Preferred name: 4‑Ethylquinoline
  • Synonym (literature): Quinoline, 4‑ethyl-
• Structural features (general/literature)
  • Core: Quinoline (fused benzene–pyridine system) with the ring nitrogen at position 1 (pyridine-type).
  • Substitution pattern: Ethyl (–CH2CH3) at C4 of the quinoline nucleus (on the pyridine ring portion), para to the ring nitrogen across the C2–C4 axis.
  • Functional groups: Aromatic heterocycle (weakly basic tertiary ring nitrogen); benzylic methylene within the ethyl substituent.
  • Stereochemistry: None (achiral).
• Empirical data (general/literature, not item-specific)
  • Molecular formula (literature): C11H11N
  • Molecular weight (literature): ~157.21 g/mol

2D description in words: A bicyclic aromatic scaffold consisting of a six‑membered benzene ring fused to a six‑membered pyridine ring (nitrogen at position 1). At the carbon four positions away from the ring nitrogen (C4), an ethyl group projects from the ring, introducing a benzylic CH2 adjacent to the heteroaromatic system.

Synthetic Utility

• Functional handles intrinsic to 4‑ethylquinoline (literature/general)
  • Ring nitrogen: amenable to N‑oxidation, quaternization, coordination to metals (as a weak ligand), and acts as a directing group for C–H activation.
  • Benzylic CH2 (in the ethyl substituent): susceptible to oxidation (to aldehyde/acid/ketone depending on conditions), halogenation, and radical functionalization; can be converted to handles (e.g., bromide, azide) for further elaboration.
• Typical transformations
  • Electrophilic aromatic substitution: occurs preferentially on the benzene portion (e.g., nitration/sulfonation at C5/C8 after controlling conditions).
  • Directed ortho metalation and lithiation: strong bases (sec‑/tert‑butyllithium) at low temperature in THF enable functionalization at C2 (adjacent to N) followed by quench with electrophiles (CO2, DMF, I2).
  • Cross‑coupling cascades: pre‑halogenation (NBS/NCS or Sandmeyer alternatives) allows Suzuki–Miyaura, Negishi, or Buchwald–Hartwig reactions to install diverse substituents.
  • Oxidation to N‑oxide: provides a handle for Minisci‑type radical additions or rearrangements on suitably substituted systems.
  • Hydrogenation: conversion to partially saturated tetrahydroquinolines for further chemistry.
• Retrosynthetic value
  • 4‑Ethylquinoline can be traced back to Friedländer or Doebner–Miller quinoline syntheses using 4‑ethyl‑substituted anilines or appropriate aldehyde/ketone precursors, making it a convenient node in heteroaromatic synthesis routes.

Target Specificity

Not applicable. This product is a small‑molecule heteroaromatic building block and is not an antibody, protein, or targeted biological reagent. No antigen/epitope, species reactivity, clone, or isotype information applies.