- Formula
- C₇H₆O₃
- CAS
- 99-06-9
- Carbon atoms
- 7
- COOH groups
- 1
- Profile form
- Neutral free acid; water and derivatives specified separately
- pKa and conditions
- See compound referenceNo number repeated here.
COOH defines ring position 1 and OH occupies position 3. There is one carboxyl group, not two; the phenolic proton is a separate acid-base site. The neutral structure is achiral.
TCI reports HPLC area% and neutralization titration separately; Sigma’s 99% method is unstated; Thermo’s 99% headline has a minimum 98.5% HPLC specification. None is a verified pharma or cosmetic ingredient grade. Positional identity is independent of total acid assay.
Identity source (opens new tab) · Technical reference
- Formula
- C₇H₆O₃
- CAS
- 99-96-7
- Carbon atoms
- 7
- COOH groups
- 1
- Profile form
- Neutral free acid; water and derivatives specified separately
- pKa and conditions
- See compound referenceNo number repeated here.
OH and COOH occupy opposite ring positions, 1 and 4. The phenolic hydroxyl does not make this a dicarboxylic acid, and the molecule has no stereocenter.
The Wako 100 mg qNMR/HPLC standard is not equivalent to TCI or Sigma bulk reagents. Food analysis is not food-ingredient grade. Keep positional identity, assay method and ester identity distinct.
Identity source (opens new tab) · Technical reference
- Formula
- C₇H₆O₂
- CAS
- 65-85-0
- Carbon atoms
- 7
- COOH groups
- 1
- Profile form
- Solid
- pKa and conditions
- See compound referenceNo number repeated here.
A carboxyl group attached directly to a benzene ring.
Distinguish the free acid from benzoate salts and a certified reference standard.
Identity source (opens new tab) · Technical reference
- Formula
- C₉H₈O₂
- CAS
- 140-10-3
- Carbon atoms
- 9
- COOH groups
- 1
- Profile form
- E (trans) free acid
- pKa and conditions
- See compound referenceNo number repeated here.
A CH=CH unit connects the phenyl ring to COOH. E describes the opposite-side arrangement of the higher-priority substituents across that double bond. This structure has no phenolic hydroxyl group.
All three products state trans identity, but their 97%, 98% and 99.5% assays have different stated or unstated methods. A trans name is not a measured isomer-purity percentage. Separate MALDI, food and reference-standard products do not transfer their grades to these listings.
Identity source (opens new tab) · Technical reference
- Formula
- C₇H₆O₅
- CAS
- 149-91-7
- Carbon atoms
- 7
- COOH groups
- 1
- Profile form
- Neutral free acid; water and derivatives specified separately
- pKa and conditions
- See compound referenceNo number repeated here.
OH groups occupy ring positions 3, 4 and 5. The neutral free acid is achiral; its formula excludes any crystal water. Three phenolic OH groups do not mean three COOH groups.
TCI G0011 now labels the free acid and treats moisture as impurity, with up to 10% drying loss and titration after drying. Sigma titration spans 97.5–102.5%. Santa Cruz’s SAMPLE UHPLC result is not a current lot certificate. Fixed monohydrate CAS 5995-86-8 / 188.13 g/mol is excluded from this price table.
Identity source (opens new tab) · Technical reference
- Formula
- C₈H₆O₄
- CAS
- 121-91-5
- Carbon atoms
- 8
- COOH groups
- 2
- Profile form
- Free acid
- pKa and conditions
- See compound referenceNo number repeated here.
One ring carbon lies between the two COOH-bearing carbons along the shorter ring path. This positional arrangement differs from both neighboring ortho groups and opposite para groups; the neutral identity is achiral.
Wako’s 95% capillary-GC 1st Grade is not equivalent to the 99% TCI or Sigma products. Neutralization titration does not itself prove positional identity. A clear solution in NaOH is not the solubility of neutral acid in water.
Identity source (opens new tab) · Technical reference
- Formula
- C₈H₈O₃
- CAS
- 90-64-2
- Carbon atoms
- 8
- COOH groups
- 1
- Profile form
- Solid · DL identity
- pKa and conditions
- See compound referenceNo number repeated here.
A phenyl-bearing alpha-hydroxy acid; this profile uses DL identity.
Specify DL, R, or S form and optical-purity requirements separately from chemical assay.
Identity source (opens new tab) · Technical reference
- Formula
- C₈H₈O₂
- CAS
- 103-82-2
- Carbon atoms
- 8
- COOH groups
- 1
- Profile form
- Free acid
- pKa and conditions
- See compound referenceNo number repeated here.
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.
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.
Identity source (opens new tab) · Technical reference
- Formula
- C₈H₆O₄
- CAS
- 88-99-3
- Carbon atoms
- 8
- COOH groups
- 2
- Profile form
- Free acid
- pKa and conditions
- See compound referenceNo number repeated here.
Two neighboring ring carbons carry COOH groups. Their adjacent arrangement is positional isomerism, not a cis/trans alkene designation. The neutral acid is achiral.
TCI uses GC and titration, Wako uses capillary GC and Sigma’s ACS reagent assay method is unstated. Positional identity, water and anhydride impurity need their own controls. ACS or JP test-reagent terminology does not establish pharmaceutical-ingredient suitability.
Identity source (opens new tab) · Technical reference
- Formula
- C₇H₆O₃
- CAS
- 69-72-7
- Carbon atoms
- 7
- COOH groups
- 1
- Profile form
- Solid
An aromatic acid with a neighboring phenolic hydroxyl.
Require the appropriate impurity profile and formulation specification; distinguish titration from HPLC assay.
Identity source (opens new tab) · Technical reference
- Formula
- C₈H₆O₄
- CAS
- 100-21-0
- Carbon atoms
- 8
- COOH groups
- 2
- Profile form
- Neutral free acid; water and derivatives specified separately
- pKa and conditions
- See compound referenceNo number repeated here.
The 1,4, or para, arrangement is a molecular-connectivity identity. It is distinct from 1,2 phthalic acid and 1,3 isophthalic acid despite sharing their formula and molecular weight.
Laboratory GC, titration and method-unspecified products are not automatically purified terephthalic acid qualified for an industrial polymer line. Wako 95% capillary GC differs from the 98–99% entries. Confirm para identity and process-specific impurities.
Identity source (opens new tab) · Technical reference
Numerical pKa values are repeated here only for the six independently reviewed profiles, with their reference conditions. Other values remain in the individual technical references. Compare matched identities and conditions; no acidity ratio or solubility ranking is inferred.