| 3-Hydroxybenzoic AcidC₇H₆O₃ · CAS 99-06-9 | 7 carbons
1 COOH | Neutral free acid; water and derivatives specified separately | 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 |
| 4-Hydroxybenzoic AcidC₇H₆O₃ · CAS 99-96-7 | 7 carbons
1 COOH | Neutral free acid; water and derivatives specified separately | 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 |
| Citric AcidC₆H₈O₇ · CAS 77-92-9 | 6 carbons
3 COOH | Solid · anhydrous identity | 3.128 / 4.761 / 6.396 (25 °C, water, zero ionic strength)Reference & conditions (opens new tab) | Three carboxyl groups and one additional hydroxyl group.Specify anhydrous or monohydrate, assay basis, and the required application specification.Identity source (opens new tab) · Technical reference |
| Gallic AcidC₇H₆O₅ · CAS 149-91-7 | 7 carbons
1 COOH | Neutral free acid; water and derivatives specified separately | 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 |
| Gluconic AcidC₆H₁₂O₇ · CAS 526-95-4 | 6 carbons
1 COOH | D neutral acid identity; displayed aqueous acid/lactone products | See compound referenceNo number repeated here. | Four CHOH centers carry the stereochemistry of this D identity. The terminal CH₂OH supplies the fifth non-carboxylic hydroxyl. A condensed formula does not encode the four configurations; the IUPAC name and InChI do.All three listings are solutions priced by solution mass. TCI explicitly contains gluconolactone and reports 45–50% w/w titration; Sigma reports 49–53 wt.% without a method; Wako reports 47–53% titration and its SDS confirms weight-% composition. None establishes chemical or optical purity.Identity source (opens new tab) · Technical reference |
| Glycolic AcidC₂H₄O₃ · CAS 79-14-1 | 2 carbons
1 COOH | Free acid | See compound referenceNo number repeated here. | The hydroxyl-bearing carbon is CH₂, so it has no stereocenter. The non-carboxylic OH makes this a hydroxy acid; it does not add a second carboxyl group.All three priced entries are solids. Sigma separately lists technical 70 wt.% aqueous glycolic acid; Wako separately lists a 67–73% solution assay without a retrieved explicit mass basis. Neither is treated as 70% chemical purity. A clear-solution test at 50 mg/mL is not saturation solubility.Identity source (opens new tab) · Technical reference |
| Lactic AcidC₃H₆O₃ · CAS 50-21-5 | 3 carbons
1 COOH | Commercial liquids / aqueous solutions | 3.86 (20 °C, in water)Reference & conditions (opens new tab) | A three-carbon alpha-hydroxy acid; L, D and DL forms matter.Specify concentration, chemical assay and method, L/D/DL form, optical specification, water content, and package mass or volume separately.Identity source (opens new tab) · Technical reference |
| Malic AcidC₄H₆O₅ · CAS 6915-15-7 | 4 carbons
2 COOH | Solid · DL identity | See compound referenceNo number repeated here. | A hydroxy diacid with one stereocenter; this profile uses DL identity.Specify DL, L, or D form and require stereochemical evidence when relevant.Identity source (opens new tab) · Technical reference |
| Mandelic AcidC₈H₈O₃ · CAS 90-64-2 | 8 carbons
1 COOH | Solid · DL identity | 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 |
| Salicylic AcidC₇H₆O₃ · CAS 69-72-7 | 7 carbons
1 COOH | Solid | 2.98 (carboxyl, 20 °C)Reference & conditions (opens new tab) | 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 |
| Tartaric AcidC₄H₆O₆ · CAS 87-69-4 | 4 carbons
2 COOH | Solid · L-(+) identity | 3.036 / 4.366 (25 °C, water, zero ionic strength; L-(+) form)Reference & conditions (opens new tab) | A hydroxy diacid with two stereocenters; this profile uses L-(+).Require L-(+) identity, stereochemical specification, and separate chemical and optical assay.Identity source (opens new tab) · Technical reference |