Product Description of Citric Acid CAS#77-92-9
Citric acid is a weak organic acid appearing as white crystals. It exists naturally in most plants and numerous animal organisms, acting as a key intermediate in cellular respiration. Possessing three carboxyl functional groups, it is categorized as a tricarboxylic acid. The word “citrus” originates from the Greek term kedromelon, which translates to “apple of melon” and refers to the citron (Citrus medica). Historically, the citron has been documented as an oblong fruit borne on a shrubby tree. Lemons and limes contain notably high concentrations of citric acid, accounting for up to 8% of their dry mass.
As a weak acid, citric acid dissociates hydrogen ions from its three carboxyl groups (COOH) when dissolved, generating citrate anions (C₃H₅O(COO)₃³⁻). Partial dissociation can also take place, creating intermediate ionic species upon the release of one or two hydrogen atoms. Citrate ions readily coordinate with metal cations to form salts, among which calcium citrate is the most prevalent. Citric acid is also capable of undergoing esterification to yield an array of citrate derivatives including trimethyl citrate and triethyl citrate.
Citric Acid Chemical Properties
| Melting point | 153-159 °C (lit.) |
| Boiling point | 248.08°C (rough estimate) |
| density | 1.67 g/cm3 at 20 °C |
| vapor density | 7.26 (vs air) |
| vapor pressure | <0.1 hPa (20 °C) |
| refractive index | 1.493~1.509 |
| FEMA | 2306 | CITRIC ACID |
| Fp | 100 °C |
| storage temp. | 2-8°C |
| solubility | Citric acid also dissolves in absolute (anhydrous) ethanol (76 parts of citric acid per 100 parts of ethanol) at 15 °C. |
| form | grit |
| pka | 3.14(at 20℃) |
| color | White |
| PH | 3.24(1 mM solution);2.62(10 mM solution);2.08(100 mM solution); |
| Odor | Odorless |
| Odor Type | odorless |
| explosive limit | 8%, 65°F |
| Water Solubility | soluble in Water (1174g/L at 10°C, 1809g/L at 30°C, 3825g/L at 80°C). |
| Sensitive | Hygroscopic |
| λmax | λ: 260 nm Amax: 0.20 λ: 280 nm Amax: 0.10 |
| Merck | 14,2326 |
| JECFA Number | 218 |
| BRN | 782061 |
| Stability: | Stable. Incompatible with bases, strong oxidizing agents, reducing agents, metal nitrates. |
| InChIKey | KRKNYBCHXYNGOX-UHFFFAOYSA-N |
| LogP | -1.64 |
| CAS DataBase Reference | 77-92-9(CAS DataBase Reference) |
| NIST Chemistry Reference | 1,2,3-Propanetricarboxylic acid, 2-hydroxy-(77-92-9) |
| EPA Substance Registry System | Citric acid (77-92-9) |
Safety Information
| Hazard Codes | Xi,C,T |
| Risk Statements | 41-36/37/38-36/38-37/38-34-36-35-61-60 |
| Safety Statements | 26-39-37/39-24/25-36/37/39-45-36-53 |
| RIDADR | UN 1789 8/PG 3 |
| WGK Germany | 1 |
| RTECS | GE7350000 |
| F | 9 |
| TSCA | Yes |
| HS Code | 2918 14 00 |
| Hazardous Substances Data | 77-92-9(Hazardous Substances Data) |
| Toxicity | LD50 in mice, rats (mmol/kg): 5.0, 4.6 i.p. (Gruber, Halbeisen) |
Product Application of Citric Acid CAS#77-92-9
Citric acid acts as an acidulant and antioxidant. It can be manufactured via mould fermentation of sugar solutions, or extracted from lemon juice, lime juice and pineapple canning waste residues. It constitutes the main acid component in oranges, lemons and limes. Citric acid exists in anhydrous and monohydrate crystalline variants: anhydrous citric acid crystallises from hot solutions, whereas the monohydrate form precipitates from cold solutions below 36.5°C.
At 20°C, the solubility of anhydrous citric acid reaches 146 g per 100 mL of distilled water; the monohydrate offers a solubility of 175 g within the same volume. A 1% aqueous solution registers a pH value of 2.3 at 25°C. The material is hygroscopic and carries a pronounced tart flavour.
Citric acid is widely applied as an acidulant at dosage rates of 0.25–0.40% in fruit beverages and carbonated soft drinks, 3–4% in cheese, and also in jelly products. By chelating metal ions to inhibit deterioration, it serves as an antioxidant in instant mashed potatoes, wheat crisps and potato sticks. Moreover, it is blended with other antioxidants during the processing of fresh frozen fruits to suppress browning and discoloration.
