Product Description
Imidazole (molecular formula C₃H₄N₂) is an organic diazole compound. It is a five‑membered aromatic heterocycle containing two non‑adjacent nitrogen atoms. The lone electron pair on the N‑1 nitrogen participates in ring conjugation, lowering its electron density and making the bonded hydrogen easy to dissociate as a proton.
It is amphoteric, behaving as both an acid and a base, and can form salts with strong bases. Its chemical properties combine features of pyridine and pyrrole. The imidazole ring is the core functional group of histidine in organisms; it participates in acyl transfer and lipid hydrolysis, and delivers catalytic effects in enzymatic reactions. Imidazole derivatives are broadly found in biological systems and are more widely studied and applied than imidazole itself, such as substances related to DNA and hemoglobin.
Chemical Properties
| Melting point | 88-91 °C(lit.) |
| Boiling point | 256 °C(lit.) |
| density | 1.01 g/mL at 20 °C |
| vapor pressure | <1 mm Hg ( 20 °C) |
| refractive index | 1.4801 |
| Fp | 293 °F |
| storage temp. | Store below +30°C. |
| solubility | H2O: 0.1 M at 20 °C, clear, colorless |
| pka | 6.953(at 25℃) |
| form | crystalline |
| color | white |
| Specific Gravity | 1.03 |
| Odor | Amine like |
| PH Range | 9.5 - 11 |
| PH | 9.5-11.0 (25℃, 50mg/mL in H2O) |
| Water Solubility | 633 g/L (20 ºC) |
| Sensitive | Hygroscopic |
| λmax | λ: 260 nm Amax: 0.10 |
| λ: 280 nm Amax: 0.10 | |
| Merck | 144912 |
| BRN | 103853 |
| Dielectric constant | 23.0（Ambient） |
| Stability: | Stable. Incompatible with acids, strong oxidizing agents. Protect from moisture. |
| InChIKey | RAXXELZNTBOGNW-UHFFFAOYSA-N |
| LogP | -0.02 at 25℃ |
| CAS DataBase Reference | 288-32-4(CAS DataBase Reference) |
| NIST Chemistry Reference | 1H-Imidazole(288-32-4) |
| EPA Substance Registry System | Imidazole (288-32-4) |
| Hazard Codes | C,Xi,T |
| Risk Statements | 36/38-63-34-22-20/21/22-61 |
| Safety Statements | 26-36/37/39-45-22-36-27-53 |
| RIDADR | UN 2923 8/PG 3 |
| WGK Germany | 1 |
| RTECS | NI3325000 |
| Autoignition Temperature | 480 °C |
| TSCA | Yes |
| HazardClass | 8 |
| PackingGroup | III |
| HS Code | 29332990 |
| Hazardous Substances Data | 288-32-4(Hazardous Substances Data) |
| Toxicity | LD50 in mice (mg/kg): 610 i.p.; 1880 orally (Nishie) |
Product Application
Imidazole is a weakly basic heterocyclic compound with stronger basicity than pyrazole. It readily reacts with acids to form stable salts, such as picrates and nitrates. One of its important applications is the purification of histidine-tagged (His-tagged) proteins through immobilized metal affinity chromatography (IMAC).
In this process, His-tagged proteins bind selectively to nickel ions attached to the chromatography resin. An imidazole-containing buffer is then introduced to compete with the histidine residues for nickel-binding sites, allowing the target proteins to detach from the resin and be collected. This method is widely used in protein purification due to its efficiency and selectivity.
