Analytical reference use
Cayman 18709 is supplied as an analytical reference standard for research. [5]
01
THE ESSENTIALS
Phenylacetic Acid in 30 Seconds
The benzene ring makes this an aromatic-containing acid, but the carboxyl carbon is not attached directly to the ring. Its CH₂ side chain has no stereocenter.
Phenylacetic acid has a benzene ring separated from COOH by CH₂. Synthesis-grade bulk material and analytical-standard milligram products serve different purchasing requirements. [1] [3]
Safety at a glance — Merck and Cayman identify serious eye irritation. Protect against contact and dust exposure according to the exact-product SDS. Cayman’s retrieved US OSHA SDS specifies research use rather than human or veterinary diagnosis or therapy. Procurement controls are a separate consideration from these handling hazards. [4] [5] [6] [14]
A condensed structural formula keeps the functional groups visible. [1]
02
GO A LITTLE DEEPER
Understanding Phenylacetic Acid
THE SIMPLE EXPLANATION
The functional groups
The benzene ring makes this an aromatic-containing acid, but the carboxyl carbon is not attached directly to the ring. Its CH₂ side chain has no stereocenter. [1]
A LITTLE DEEPER
What the structure changes
The intervening saturated carbon interrupts direct ring-to-carboxyl conjugation. Forming phenylacetate salts or other derivatives changes chemical form. A chromatographic area assay is not automatically a mass-purity or titration result. [1] [12]
Technical detail Identity, dissociation & specification
The molecular formula specifies the neutral free acid. A commercial solution, salt, ester or anhydride needs its own composition and specification. Quantitative references retain temperature, pressure, product identity and unresolved method qualifiers. [1] [2] [4] [5] [6]
Acid–base reference values describe equilibria under specified conditions. They are not a substitute for a validated formulation or an assay on the purchased lot.
03
MAKE THE CONNECTION
How Phenylacetic Acid Compares
Similar names and functional groups do not mean interchangeable chemicals.
SIDE-BY-SIDE COMPARISON
Phenylacetic Acid vs Benzoic Acid
Aromatic-side-chain monocarboxylic acid
versusAromatic monocarboxylic acid
Fixed comparison for this prototype. Acid selectors are disabled; additional comparisons are coming later.
| Property | Phenylacetic Acid | Benzoic Acid |
|---|---|---|
| Molecular formula | C₈H₈O₂ [1] | C₇H₆O₂ [7] |
| Molecular weight | 136.15 g/mol [1] | 122.12 g/mol [7] |
| Carbon atoms | 8 [1] | 7 [7] |
| Carboxyl groups | 1 [1] | 1 [7] |
| Structure | C₆H₅–CH₂–COOH [1] | C₆H₅–COOH [7] |
| Chemical family | Aromatic-side-chain monocarboxylic acid [1] | Aromatic monocarboxylic acid [7] |
| Identity focus | Free acid [1] | Solid [7] |
Chemical identities are compared here; supplier grades, concentrations, and stereochemical specifications are separate purchasing attributes. pKa values retain their stated conditions; no quantitative solubility ranking is implied.
When Might You Choose One Instead of the Other?
Choose phenylacetic acid when the method requires its benzyl-linked acid residue or a qualified analytical reference. Choose benzoic acid for the directly ring-attached carboxyl identity. Confirm relevant procurement controls before ordering phenylacetic acid. [1] [3] [7]
Specified starting material
Phenylacetic Acid
Match C₆H₅–CH₂–COOH and the method’s required chemical form.
Benzoic Acid
Match C₆H₅–COOH; verify the identity before substituting a related acid.
Before choosing: match the reaction or formulation, then verify the exact form, grade, assay basis, and impurities. These contexts do not establish suitability for an industrial or regulated application.
04
FROM STRUCTURE TO APPLICATION
What Is Phenylacetic Acid Used For?
Analytical reference use
Cayman 18709 is supplied as an analytical reference standard for research. Its milligram format and documentation requirements are distinct from the displayed synthesis-grade products. [5]
Synthesis-intermediate context
Attributed HSDB/Hawley records identify phenylacetic acid as a penicillin G production precursor. This is intermediate use; neither the free acid nor the displayed reagent is itself the antibiotic or an approved medicine. [3]
06
SOURCE WITH CONTEXT
Phenylacetic Acid Suppliers
Compare specific products and package options. Listings are not ranked recommendations.
3 suppliers · 3 products · 5 package listingsLatest supplier check: October 3, 2026
Package sizes stay grouped under the supplier product. Assay methods, product forms, and regional markets remain visible. Merck specifies HPLC area% ≥99; Cayman specifies ≥98 with no method; Thermo specifies NaOH titration 98–102%. Milligram standard packages are not mass-normalized against bulk synthesis packages. The Thermo listing is Taiwan-facing with no verified price. US DEA identifies phenylacetic acid, its salts and esters as List I chemicals.
Scroll horizontally if needed. Supplier and package identity stay visible.
| Supplier | Product / Grade | Purity / Assay | Package Size | Public Price | Normalized Price | Documentation | Last Checked | Action |
|---|---|---|---|---|---|---|---|---|
| Sigma-Aldrich / MerckPhenylacetic Acid | For synthesis8209930250 | Minimum 99.0% HPLC area%; not mass purity | 250 g | $37.60USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: Sigma-Aldrich / Merck
| View Product: Sigma-Aldrich / Merck, 8209930250 (opens new tab) | |
| For synthesis8209931000 | Minimum 99.0% HPLC area%; not mass purity | 1 kg | $107.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Sigma-Aldrich / Merck, 8209931000 (opens new tab) | |||
| Cayman ChemicalPhenylacetic Acid | Analytical reference standard; research only18709 · 10 mgStandard-grade milligram packages are not equivalent to synthesis-grade bulk packages. Supplier identifies US List I controls; confirm procurement requirements. | Minimum 98%; method not stated | 10 mg | $36.00USD · US public price | Not comparedGrades, assay bases, or forms differ | Document notes: Cayman Chemical
| View Product: Cayman Chemical, 18709 · 10 mg (opens new tab) | |
| Analytical reference standard; research only18709 · 50 mgStandard-grade milligram packages are not equivalent to synthesis-grade bulk packages. Supplier identifies US List I controls; confirm procurement requirements. | Minimum 98%; method not stated | 50 mg | $77.00USD · US public price | Not comparedGrades, assay bases, or forms differ | View Product: Cayman Chemical, 18709 · 50 mg (opens new tab) | |||
| Thermo Scientific ChemicalsPhenylacetic Acid | Research use only; named grade not stated130285000Taiwan market and 500 g package verified. A titration result over 100% is not chromatographic purity; no US price or availability inferred. | 98.5% headline; NaOH titration specification 98–102% | 500 g | Public price not verified | Not comparedDifferent currency / market | COACheck supplierSDSCheck supplierCOOCheck supplier Document notes: Thermo Scientific Chemicals
| View Product: Thermo Scientific Chemicals, 130285000 (opens new tab) |
Sigma-Aldrich / Merck
Phenylacetic Acid
For synthesis
250 g
8209930250- Public price
- $37.60USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
1 kg
8209931000- Public price
- $107.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: Sigma-Aldrich / Merck
- A product-specific certificate retrieval option was visible; no lot certificate was reviewed. Open the product page and use its certificate section.
- A current regional SDS was not verified in this pass.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
Cayman Chemical
Phenylacetic Acid
Analytical reference standard; research only
Standard-grade milligram packages are not equivalent to synthesis-grade bulk packages. Supplier identifies US List I controls; confirm procurement requirements.
10 mg
18709 · 10 mg- Public price
- $36.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
50 mg
18709 · 50 mg- Public price
- $77.00USD · US public price
- Normalized price
- Not comparedGrades, assay bases, or forms differ
Documentation
Document notes: Cayman Chemical
- A product-specific certificate retrieval option was visible; no lot certificate was reviewed. Open the product page and use its certificate section.
- The linked SDS was retrieved for this product. Read its stated jurisdiction and obtain the applicable current local version.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
Thermo Scientific Chemicals
Phenylacetic Acid
Research use only; named grade not stated
Taiwan market and 500 g package verified. A titration result over 100% is not chromatographic purity; no US price or availability inferred.
500 g
130285000- Public price
- Public price not verified
- Normalized price
- Not comparedDifferent currency / market
Documentation
COACheck supplierSDSCheck supplierCOOCheck supplier
Document notes: Thermo Scientific Chemicals
- COA availability was not verified.
- A current regional SDS was not verified in this pass.
- Origin-document availability was not verified. Country of origin is unverified and is not inferred.
Last checked:
Documentation evidence
COA = Certificate of Analysis · SDS = Safety Data Sheet · COO = Certificate of Origin.
Lookup means a retrieval option was visible, not that a lot certificate was reviewed. Check supplier means availability or the applicable document was not verified.
Prices may vary by quantity, account, contract, geography, and availability. These products have different grades, assay bases, or forms; no normalized comparison is shown. Foreign-market prices are reference listings only. No currency conversion, mass-to-volume conversion, or ranking is applied. Confirm equivalent specifications and a current quote before comparison. [4] [5] [6]
Verification limits & placement policy
pKa: OMITTED. Compiled 4.31 lacked a sufficiently matched temperature/solvent/method context in retrieved records. Water solubility: CONFLICT UNRESOLVED. HSDB gives 17.3 g/L at 25 °C and 16.6 g/L at 20 °C; Merck gives 1.58 g/L without temperature. Cause of the lower supplier value not established; no numeric solubility comparison promoted. Melting / density: CONDITION-DEPENDENT. Melting ranges retain product specifications. Molten density at 97 °C is not substituted for powder or solid density.
Only the displayed identity, specification, packages, public prices and stated documentation evidence were reviewed. Current stock, lead times, shipping eligibility, contract pricing, lot certificates, and regulatory suitability are unverified.
There are no paid placements. Future paid listings will show “Sponsored” in both views; payment will not determine chemistry interpretation or imply a ranking.
07
PLAN A LARGER ORDER
Need Phenylacetic Acid in Bulk?
Turn your requirements into a clear supplier brief.
Bulk RFQ feature — coming soon. Prototype form: submissions are not currently sent to suppliers. Use sample details to prepare an on-screen brief.
Prepare a bulk request Prototype form
08
A BUYER’S CHECKLIST
Before You Buy Phenylacetic Acid
Selections remain only while this page is open.
09
FOR YOUR REFERENCE
Phenylacetic Acid Technical Reference
Identity, product reference properties, and handling context.
Identification Names, formula & identifiers
- Principal CAS
- 103-82-2
- Identity focus
- Free acid
- Formula
- C₈H₈O₂
- Molecular weight
- 136.15 g/mol
- IUPAC name
- 2-phenylacetic acid
- Connectivity SMILES
- C1=CC=C(C=C1)CC(=O)O
- Identity SMILES
- C1=CC=C(C=C1)CC(=O)O
- InChI
- InChI=1S/C8H8O2/c9-8(10)6-7-4-2-1-3-5-7/h1-5H,6H2,(H,9,10)
- PubChem CID
- 999
Connectivity SMILES describes connectivity; it is not an independent stereochemical assignment. CAS and product-form distinctions are supported by the supplier listings. [1] [4] [5] [6]
Physical Properties Product references & conditions
Solid in the supplier products. Density values measured above the melting region describe molten material, not room-temperature powder. [13] [4] [5]
- Melting specification
- Merck 820993: 74–77 °C; Thermo: 75–78 °C specification [4]
- Boiling reference
- Merck 820993: 265 °C at 1013 hPa [4]
- Molten density reference
- Merck 820993: 1.091 g/cm³ at 97 °C; not bulk powder density [4]
Hydrate, concentration, stereoisomer, and temperature can change the relevant specification. Product reference data are not a reviewed lot certificate.
Acid/Base Properties Verified values & missing data
A numeric pKa was not verified for the selected identity in this review; no value is inferred. [2]
pKa: OMITTED. Compiled 4.31 lacked a sufficiently matched temperature/solvent/method context in retrieved records. Water solubility: CONFLICT UNRESOLVED. HSDB gives 17.3 g/L at 25 °C and 16.6 g/L at 20 °C; Merck gives 1.58 g/L without temperature. Cause of the lower supplier value not established; no numeric solubility comparison promoted. Melting / density: CONDITION-DEPENDENT. Melting ranges retain product specifications. Molten density at 97 °C is not substituted for powder or solid density.
Temperature, ionic strength, and the use of activities versus concentrations matter in quantitative work. These reference values are not buffer recipes.
Safety at a Glance Product-specific hazards
Merck and Cayman identify serious eye irritation. Protect against contact and dust exposure according to the exact-product SDS. Cayman’s retrieved US OSHA SDS specifies research use rather than human or veterinary diagnosis or therapy. Procurement controls are a separate consideration from these handling hazards. [4] [5] [6] [14]
Hazard classifications can vary by concentration, product, supplier and jurisdiction. Review the SDS for the exact product before handling. This summary does not replace the SDS.
Supplier safety information and SDS retrieval (opens new tab) · Cayman Chemical SDS PDF · exact product (opens new tab)
A product-page safety classification is not verification of every regional SDS. Confirm product code, chemical form and current local document.
Review supplier documentation10
COMMON QUESTIONS
Phenylacetic Acid FAQ
What distinguishes Phenylacetic Acid?
The benzene ring makes this an aromatic-containing acid, but the carboxyl carbon is not attached directly to the ring. Its CH₂ side chain has no stereocenter. [1]
How does it differ from Benzoic Acid?
Benzoic acid attaches COOH directly to the ring; phenylacetic acid inserts CH₂. The extra carbon changes the residue and electronic connection. A reference-standard purpose is separate from buying an acid as a synthetic precursor. [7]
What must a buyer specify?
Merck specifies HPLC area% ≥99; Cayman specifies ≥98 with no method; Thermo specifies NaOH titration 98–102%. Milligram standard packages are not mass-normalized against bulk synthesis packages. The Thermo listing is Taiwan-facing with no verified price. US DEA identifies phenylacetic acid, its salts and esters as List I chemicals. [4]
Are the listed products directly price-comparable?
No. The table retains differing grades, assay bases, forms, and markets. No normalized ranking or currency conversion is applied. [5]
What reference data still need checking?
pKa: OMITTED. Compiled 4.31 lacked a sufficiently matched temperature/solvent/method context in retrieved records. Water solubility: CONFLICT UNRESOLVED. HSDB gives 17.3 g/L at 25 °C and 16.6 g/L at 20 °C; Merck gives 1.58 g/L without temperature. Cause of the lower supplier value not established; no numeric solubility comparison promoted. Melting / density: CONDITION-DEPENDENT. Melting ranges retain product specifications. Molten density at 97 °C is not substituted for powder or solid density.
Can I request a bulk quote here?
The RFQ is a prototype that prepares an on-screen brief. Nothing is sent to suppliers. Confirm actual bulk terms directly with the supplier.
11
TRACE THE INFORMATION
Sources & Editorial Notes
Identity and compiled reference values are separated from supplier-specific specifications. Structural comparisons and buyer guidance are editorial interpretation. Sources were checked October 3, 2026; supplier information can change.
- PubChem · chemical identity (opens new tab)
Neutral molecular identity verified independently through PUG REST; CAS also checked on all selected supplier products.
- PubChem / HSDB · dissociation references (opens new tab)
No numeric field promoted: insufficient conditions or unresolved conflicting records.
- PubChem / HSDB · application references (opens new tab)
Attributed application records reviewed claim by claim. Free acid, intermediate, derivative and biological context are distinguished.
- Sigma-Aldrich / Merck · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- Cayman Chemical · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- Thermo Scientific Chemicals · commercial product (opens new tab)
Direct product checked October 3, 2026. Identity, listed assay methods, packages, market, prices and documentation interfaces inspected. Lot certificates and stock are not verified.
- Benzoic Acid · identity (opens new tab)
Primary structural comparison. Practical interpretation does not establish suitability.
- Mandelic Acid · identity (opens new tab)
Related identity and structural relationship.
- Cinnamic Acid · identity (opens new tab)
Related identity and structural relationship.
- Acetic Acid · identity (opens new tab)
Related identity and structural relationship.
- Benzoic Acid · dissociation references (opens new tab)
Only independently reviewed values are promoted into the comparison; no condition-free acidity ranking.
- OpenStax · Carboxylic-acid structure and properties (opens new tab)
General carboxylate resonance, acidity and structural interpretation; not authority for this acid’s quantitative constants.
- PubChem / HSDB · attributed physical references (opens new tab)
Attributed references reviewed; product, phase, pH and method gaps stated rather than inferred.
- Cayman · exact-product US OSHA SDS (opens new tab)
July 29, 2025; article 18709/CAS confirmed and eye-irritation classification reviewed.
- DEA · regulated chemicals list (opens new tab)
August 27, 2026 list identifies phenylacetic acid, esters and salts as List I, code 8791. No transaction-threshold advice inferred.
Review limits
pKa: OMITTED. Compiled 4.31 lacked a sufficiently matched temperature/solvent/method context in retrieved records. Water solubility: CONFLICT UNRESOLVED. HSDB gives 17.3 g/L at 25 °C and 16.6 g/L at 20 °C; Merck gives 1.58 g/L without temperature. Cause of the lower supplier value not established; no numeric solubility comparison promoted. Melting / density: CONDITION-DEPENDENT. Melting ranges retain product specifications. Molten density at 97 °C is not substituted for powder or solid density.
This informational prototype is not a supplier, quotation service, or endorsement of a product’s fitness for an application. Buyers should verify the applicable specification, certification, and regulatory requirements for their intended use.