4-Ethyl-2-methylbenzoic acid - ≥98% , CAS No.190367-29-4

CAS: 190367-29-4 Cat. No.: E991676 Formula: C₁₀H₁₂O₂ Molecular Weight: 164.200

GRADE & PURITY ≥98%

Storage

Room temperature

Specifications

Specifications & Purity

≥98%

Storage

Room temperature

Purity

≥98%

Names and Identifiers

• Canonical Smiles: CCC1=CC(=C(C=C1)C(=O)O)C
• IUPAC Name: 4-ethyl-2-methylbenzoic acid
• InChIKey: JNNUZPKCLVIBMF-UHFFFAOYSA-N
• INCHI: 1S/C10H12O2/c1-3-8-4-5-9(10(11)12)7(2)6-8/h4-6H,3H2,1-2H3,(H,11,12)
• Molecular Weight: 164.200

Taxonomic Classification

Taxonomy Tree

• Kingdom Organic compounds
  • Superclass Benzenoids
    • Class Benzene and substituted derivatives
      • Subclass Benzoic acids and derivatives

• Kingdom: Organic compounds
• Superclass: Benzenoids
• Class: Benzene and substituted derivatives
• Subclass: Benzoic acids and derivatives
• Intermediate Tree Nodes: Not available
• Direct Parent: Benzoic acids
• Alternative Parents: Benzoyl derivatives Toluenes Carboxylic acids Organooxygen compounds Organic oxides Hydrocarbon derivatives
• Molecular Framework: Aromatic homomonocyclic compounds
• Substituents: Benzoic acid - Benzoyl - Toluene - Carboxylic acid - Carboxylic acid derivative - Organic oxygen compound - Organic oxide - Hydrocarbon derivative - Organooxygen compound - Aromatic homomonocyclic compound
• Description: This compound belongs to the class of organic compounds known as benzoic acids. These are organic Compounds containing a benzene ring which bears at least one carboxyl group.
• 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

Chemical and Physical Properties

• Molecular Weight: 164.200 g/mol
• XLogP3: 2.600
• Hydrogen Bond Donor Count: 1
• Hydrogen Bond Acceptor Count: 2
• Rotatable Bond Count: 2
• Exact Mass: 164.084 Da
• Monoisotopic Mass: 164.084 Da
• Topological Polar Surface Area: 37.300 Ų
• Heavy Atom Count: 12
• Formal Charge: 0
• Complexity: 165.000
• 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

No assay or bioanalytical protocols are validated for this SKU. As a chemical building block, typical procedures include:

• Weighing/dissolution in appropriate solvent (e.g., DCM, DMF, EtOAc) for use in coupling or derivatization reactions.
• Preparation of acid chlorides, esters, amides, or redox-active esters as described in the Reaction Conditions tab.

For method-specific, SKU-validated protocols (e.g., chromatography suitability, residual solvents), refer to the product’s CoA/Spec Sheet.

Biological Roles

This substance is a synthetic aromatic carboxylic acid and is not known as a natural metabolite or cofactor.

General considerations (literature):

• Ionization: As a weak acid (benzoic acid class), it exists largely in the neutral form at acidic pH and as the carboxylate above pH ≈ 5. This influences membrane partitioning and extraction behavior, not a biological role.
• Protein/biomolecule interactions: The hydrophobic ring with a single carboxyl function can engage in π–π and hydrophobic interactions, and form ionic/H-bonds when deprotonated; such features are often leveraged in SAR during probe/ligand synthesis.
• Metabolism (analogy to benzoic acid derivatives): Oxidative metabolism on the alkyl substituents and conjugation (e.g., glucuronidation) are typical pathways in vivo; no specific biological activity is attributed here.

Note: No clinical or therapeutic claims are made. This product is provided strictly for research and laboratory use.

Buffer Applications

Not typically used as a standard buffer component due to low aqueous solubility in the neutral pH range.

General information (literature):

• Benzoic acids have pKa values around 4.2–4.7; in principle, a buffer could be formulated near this range (≈ pH 3.5–5.5) using the conjugate base (e.g., sodium salt). However, limited solubility of the neutral acid and hydrophobicity reduce practicality compared with classical buffers (acetate, citrate, MES).
• If preparing analytical standards or extraction phases, the conjugate base can be used to adjust pH, but dedicated buffer systems are recommended for reproducibility.

Recommendation: Use established buffer systems (acetate for pH 3.6–5.6, citrate for pH 3.0–6.2) unless a benzoate matrix effect is specifically required.

Green Alternatives

While the compound itself is a target/building block rather than a solvent, greener choices can be made for its transformations.

Greener solvent and reagent substitutions (literature/green chemistry guidance):

• Solvents:
  • Replace DCM with EtOAc, 2-MeTHF, CPME, or toluene where feasible (workup and reaction performance permitting).
  • For amide/ester couplings, consider MeCN, EtOAc, or 2-MeTHF instead of DMF/CH2Cl2 when compatible.
• Coupling reagents:
  • Prefer water-soluble EDC (with OxymaPure) or CDI in greener solvents; minimize use of DCC (generates DCU waste).
  • Explore catalytic amidation strategies (e.g., boronic acid-catalyzed amidation) where substrate scope allows.
• Energy efficiency:
  • Use microwave or flow platforms to shorten times and reduce energy input.
• Workup/waste:
  • Employ solvent recycling and minimal-chromatography workflows (crystallization, aqueous washes) to reduce waste.

Comparison snapshot (general):

• DCM vs 2-MeTHF: 2-MeTHF is bio-based, higher boiling, and less volatile; may change selectivity/solubility profile.
• DMF vs MeCN/EtOAc: MeCN/EtOAc offer easier removal and lower hazard classification in many jurisdictions but can affect coupling efficiency.

Trade-offs should be balanced against yield, selectivity, and substrate stability.

Pharmaceutical Uses

No pharmacopeial/excipient designation is provided for this item.

Context (general, non-clinical):

• Aromatic carboxylic acids like this are commonly employed as synthetic intermediates en route to esters and amides used in discovery chemistry and process development.
• The hydrophobic 2-methyl-4-ethylphenyl motif can be valuable in modifying lipophilicity, metabolic stability, and binding interactions in small-molecule libraries.

Notes:

• This product is for research use only. No therapeutic or clinical uses are claimed or implied.
• Any discussion pertains to its role as a chemical intermediate in formulation/process R&D, not as an active ingredient or excipient.

Physical Properties

Item-specific specifications (this SKU):

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.

Literature/computed values and general expectations for 4-ethyl-2-methylbenzoic acid:

• Molecular weight: 164.20 g/mol (calculated from C10H12O2; literature)
• Physical state: typically a crystalline solid (literature, typical for alkylbenzoic acids)
• Acidity (pKa): benzoic acids typically pKa ≈ 4.2; electron-donating alkyl groups modestly raise pKa (expected ≈ 4.4–4.7) (literature/analogy)
• Aqueous solubility: low at neutral pH; solubility increases in basic media (carboxylate salt) (literature trend)
• Organic solubility: good in common organic solvents (EtOAc, THF, DCM, toluene, MeOH) (literature/general)
• Partitioning: logP for dialkyl-substituted benzoic acids commonly in the 2.5–3.5 range (literature analogy)
• UV: aromatic π–π* absorption around 200–280 nm typical of benzoic acid derivatives (literature)

Notes:

• Exact numerical MP/BP/density/refractive index for this specific isomer are not specified for this item; refer to CoA/Spec Sheet. Do not apply thermal operations until verified by SDS/CoA.

Quality & Grades

• Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.

Guidance on interpreting grades (general):

• Research grade: Suitable for most synthetic and analytical applications where ultra-trace impurities are not critical.
• AR/ACS grade (if specified): Tight impurity limits for common inorganics/organics; suitable for analytical work.
• HPLC grade (for solvents; not typically applicable here): Low UV absorbance and particulate load for chromatography.
• Stabilizers/inhibitors: Not typically used for aromatic carboxylic acids; if any stabilizer or residual reagent is present, it will be declared on the CoA.

Batch quality control (general expectations):

• Identity confirmation by NMR/IR/MS and compliance with assay/impurity limits as listed on the CoA.
• Water content (KF), residual solvents, and trace metals: Not specified for this item; refer to CoA/Spec Sheet.

Recommendation: For moisture/trace-metal sensitive transformations, review the CoA for assay, water, and metals data; pre-dry the material if necessary and perform a small-scale test to verify suitability.

Reaction & Applications

This aryl carboxylic acid serves as a versatile building block for constructing hydrophobic aromatic motifs.

Typical applications (literature/general):

• Ester formation:
  • Fischer esterification in ROH with catalytic H2SO4/p-TsOH; azeotropic water removal for higher-boiling systems.
  • Steglich esterification (DCC/DMAP) in DCM for acid-sensitive substrates.
• Amide synthesis:
  • Coupling with amines using EDC·HCl/HOBt, DIC/HOAt, HATU, or PyBOP in DMF/DCM. DMAP or DIPEA as base where applicable.
  • Via acid chloride (SOCl2 or oxalyl chloride, catalytic DMF) followed by aminolysis in DCM/THF with base (Et3N).
• Anhydride and mixed anhydride formation for acyl transfer chemistry (e.g., with isobutyl chloroformate) enabling peptide couplings.
• Decarboxylative transformations:
  • Photoredox/Ni dual catalysis enabling decarboxylative arylation or alkylation via redox-active esters (RAEs; NHP esters) prepared from the acid (literature).
  • Hunsdiecker-type variants less common for aryls, but single-electron techniques via RAEs are established.
• Electrophilic aromatic substitution (EAS) on the ring is deactivated by the –CO2H meta-directing group; however, pre-functionalization strategies (e.g., halogenation before oxidation to acid) are often preferred.
• Directed ortho-metalation (DoM) adjacent to the acid is generally not practical; use protected derivatives (esters, amides) as directing groups.

Use cases:

• Preparation of hydrophobic esters/amides for materials, ligand fragments, and SAR exploration where a 2-methyl-4-ethyl phenyl motif is desired.

Reaction Conditions

General conditions reported in the literature for benzoic-acid derivatives; optimize for your substrate and scale.

• Acid chloride formation:
  • Reagents: SOCl2 (3–5 eq) or (COCl)2 (2–3 eq) with 0.05 eq DMF.
  • Solvent: DCM or toluene; 0–25 °C to reflux as required.
  • Time: 1–4 h; monitor by IR (loss of broad OH, appearance of acyl chloride band ~1800 cm−1).
• Amide coupling (carbodiimide):
  • EDC·HCl (1.1–1.5 eq) + HOBt/Oxyma (1.1–1.5 eq), amine (1.1–1.5 eq), base (DIPEA 2–3 eq).
  • Solvent: DMF, DCM, or MeCN; 0–25 °C.
  • Typical times: 2–16 h; yields commonly 70–95% (literature range for benign substrates).
• Steglich esterification:
  • DCC (1.1–1.2 eq), catalytic DMAP (0.05–0.1 eq), alcohol (2–5 eq).
  • Solvent: DCM; 0 °C to rt; 4–24 h. Filter DCU byproduct.
• NHP ester formation (for decarboxylation):
  • DIC (1.1 eq) + N-hydroxyphthalimide (1.1–1.2 eq), catalytic DMAP.
  • Solvent: DCM/DMF; rt 2–6 h.
  • Follow with photoredox/Ni coupling in MeCN/DMF with blue LEDs.
• Salt formation/extraction:
  • Dissolve in aqueous NaHCO3/Na2CO3; extract neutral impurities with organic solvent. Re-acidify (pH < 2) and extract the acid into EtOAc.

All parameters are general literature guidance for substituted benzoic acids; confirm on small scale before scale-up.

Safety & Handling

Product-specific hazard details:

• Signal word: Not specified for this item; refer to SDS.
• H-statements / GHS Classification / Pictograms: Not specified for this item; refer to SDS.

General safety guidance for aromatic carboxylic acids (literature/industry practice):

• Expected hazards: May cause skin/eye irritation; dust may cause respiratory irritation. Avoid inhalation of particulates and contact with skin/eyes.
• PPE: Safety glasses, lab coat, and chemical-resistant gloves (nitrile recommended). Use a fume hood when weighing/handling powders.
• Storage incompatibilities: Avoid strong oxidizers (risk of exotherm), strong bases (forms carboxylate salts), and reactive acid chlorinating agents unless used intentionally under controlled conditions.
• Handling tips: Minimize dust; use antistatic measures when transferring powders. For solution handling, ensure containers are clearly labeled with solvent identity and concentration.
• First aid (overview; defer to SDS): Rinse eyes/skin with water for several minutes; remove contaminated clothing. If inhaled, move to fresh air. If ingested, rinse mouth and seek medical attention.
• Fire behavior: Organic solid; combustible. Suitable extinguishing media: CO2, dry chemical, foam. Avoid high-temperature decomposition; combustion may produce COx.
• Environmental: Prevent release to drains in significant quantities. Collect spills with inert absorbent.

Always consult the Aladdin SDS for authoritative, SKU-specific hazard and response information.

Solvent Selection

Compound type: hydrophobic aromatic carboxylic acid (weak acid; largely nonionic in neutral media, ionic as carboxylate in base).

• Polarity/miscibility profile (literature/general):
  • Low water solubility at neutral pH; highly soluble as its sodium/potassium salt in aqueous base (pH > 7).
  • Good solubility in moderately polar organic solvents (EtOAc, acetone, MeOH/EtOH, THF, DMSO) and in nonpolar aromatics (toluene) when warmed.
• Choosing solvents by task:
  • Acid chlorination (e.g., SOCl2, oxalyl chloride): Use DCM, toluene, or neat reagent with catalytic DMF; exclude moisture.
  • Esterification (Fischer): Alcohol solvent (MeOH/EtOH/iPrOH) with acid catalyst; remove water (Dean–Stark in toluene/ROH mixtures for higher-boiling systems).
  • Amide coupling: Polar aprotic solvents (DMF, NMP, DCM, MeCN) with carbodiimide/phosphonium/uronium reagents.
  • Metalation/cross-coupling after derivatization (e.g., acid → acid chloride or anhydride): Use dry THF/Et2O/toluene as appropriate.
• Solubility enhancement options:
  • Convert to the carboxylate salt in aqueous systems; back-extract upon acidification.
  • Add co-solvents (DMSO up to 5–10% in water) for analytical sample prep.

Comparison (literature guidance):

• Versus unsubstituted benzoic acid: Higher hydrophobicity and lower water solubility; improved solubility in nonpolar organics.

Storage & Reconstitution

• Storage conditions: Room temperature (Product Data). Store tightly closed in a dry, well-ventilated area. Protect from moisture and strong oxidizers.
• Container: Use amber glass with PTFE-lined cap for long-term storage of the solid; minimize headspace humidity.
• Stability: Aromatic carboxylic acids are generally stable solids under ambient conditions. Avoid prolonged exposure to high heat; do not store near strong bases/acylating agents.
• Reconstitution/preparation:
  • For solution stock: Dissolve in a suitable dry solvent (e.g., DCM, EtOAc, THF, MeOH, DMF, DMSO) to the desired concentration. Filter if particulate is present.
  • For aqueous work: Dissolve by forming the sodium/potassium salt (add equimolar NaHCO3/NaOH), then adjust pH as needed; re-acidify to isolate the free acid.
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet. Prepare fresh reactive derivatives (acid chlorides, RAEs) immediately before use.
• Shipping: Not specified for this item; refer to CoA/Spec Sheet.

Research use only: Not for human or veterinary use.

Structure & Identity

A substituted benzoic acid building block featuring one methyl (ortho) and one ethyl (para) group relative to the carboxyl group; useful as a hydrophobic, weakly acidic aryl synthon.

• Product name: 4-Ethyl-2-methylbenzoic acid (synonym: 2-methyl-4-ethylbenzoic acid)
• CAS: 190367-29-4 (Product Data)
• CID: 10535017 (Product Data)
• InChIKey: 165191 (Product Data)
• SMILES: O=C(O)c1ccc(CC)c(C)c1 (literature)
• Molecular formula: C10H12O2 (literature)
• Molecular weight: 164.20 g/mol (literature, calculated from formula)

Structural features (descriptive):

• Aromatic ring with three substituents: one carboxylic acid (–CO2H), one methyl (–CH3) ortho to the acid (2-position), and one ethyl (–CH2CH3) para to the acid (4-position).
• Functional groups: carboxylic acid (acidic, H-bond donor/acceptor), alkyl substituents (methyl, ethyl) that increase hydrophobicity and reduce ring electrophilicity relative to benzoic acid.
• Stereochemistry: none (achiral).

Synthetic Utility

Key reactive handle: the carboxylic acid.

Transformations (literature/general):

• Protection/activation of the acid:
  • Convert to acid chlorides (SOCl2/DMF cat.) or mixed anhydrides (iBuOCOCl) for efficient acylations.
  • Transform to N-hydroxyphthalimide (NHP) esters to enable decarboxylative cross-couplings under photoredox/Ni catalysis (C–C, C–N, C–S formations).
• Formation of derivatives:
  • Esters (Fischer, Steglich, Mitsunobu variants) to tune lipophilicity and as protecting groups for further chemistry.
  • Amides/ureas via carbodiimide or uronium/phosphonium reagents; useful for probe and fragment libraries.
• Retrosynthetic leverage:
  • The acid can be traced back to oxidation of corresponding alkyl toluenes or via carboxylation strategies (e.g., metalation followed by CO2 quench on appropriately substituted arenes).
• Ring functionalization strategy:
  • The –CO2H group is meta-directing and deactivating for EAS; further ring substitution typically proceeds via prefunctionalized precursors (aryl halides) followed by cross-coupling (Suzuki, Negishi, Kumada) conducted prior to oxidation to the acid or on protected derivatives (esters).

Practical notes:

• Drying the acid (60–80 °C under vacuum) prior to coupling can improve reproducibility.
• Monitor for anhydride formation under dehydrating conditions; add base or catalytic DMAP as needed to control selectivity.

Target Specificity

Not applicable. This product is a small-molecule building block, not an antibody, enzyme, or targeted biological reagent. No antigen/epitope or species reactivity data apply.