Hydrogen iodide
Description
Hydrogen iodide (CAS 10034-85-2), commercially supplied as hydroiodic acid, is an inorganic acid used primarily as a reducing agent and iodine source in chemical synthesis. In aqueous solution, it delivers both strong acid activity and iodide ion availability.
This makes it a valued reagent across pharmaceutical manufacturing and specialty chemistry. In pharmaceutical synthesis, it serves as a key reagent for dealkylation reactions, particularly in the production of active pharmaceutical ingredients.
It is frequently used where methyl ether cleavage is required for complex molecules. Food-grade hydroiodic acid is used in limited acidulant and iodine-fortification applications where precise iodide delivery is needed for specific formulations.
In biotechnology and life sciences, it functions as a reagent in nucleotide chemistry and iodination protocols for labeling and analytical workflows. Industrial pH adjustment processes also draw on its strong acid character.
This is particularly useful where iodide co-introduction is acceptable or required for the final product. The chemical is supplied as an aqueous solution, with 47% and 57% w/w concentrations being the most commercially standard.
Reagent-grade and ACS-grade specifications are typical for laboratory and synthesis supply. Pharmaceutical-grade material is also available to meet API manufacturing requirements and rigorous quality control protocols.
Stabilized and unstabilized variants exist for different industrial needs. Stabilized grades include a hypophosphorous acid additive to prevent oxidation and maintain product clarity during long-term storage and transport.
Physical Properties
| Melting Point | -51 °C |
| Boiling Point | -35.5 °C |
| Density | 2.85 g/cm³ (liquid) @ Temp: -5 °C |
| Flash Point | 126-127°C |
| Appearance | Clear liquid, colourless to slightly yellow |
| Color | Colorless to brown |
| Odor | Pungent odor |
| Form | colorless or yellow gas |
| Water Solubility | soluble |
| Vapor Pressure | 721.8kPa at 20℃ |
| pH | 3.01(1 mM solution);2.04(10 mM solution);1.08(100 mM solution) |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 28111990 |
| UN Number | 1787 |
| ADR Class | 8 |
| Packing Group | II |
| Storage Class | 8B - Non-combustible corrosive hazardous materials |
Documentation
Other Names
hydroiodic acid|Hydriodic acid|iodane|Hyriodic acid|Acido yodhidrico|Acide iodhydrique|Hydrogen iodide (HI)|Anhydrous hydriodic acid|HI
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