Hydroiodic acid (or hydriodic acid) is a colorless liquid. It is an aqueous solution of hydrogen iodide with the chemical formula . It is a strong acid, in which hydrogen iodide is completely in an aqueous solution. Concentrated aqueous solutions of hydrogen iodide are usually 48% to 57% HI by mass.
Preparation
Reactions
Hydroiodic acid reacts with
oxygen in air to give
iodine:
Like , hydroiodic acid adds to to give . It can also be used as a reducing agent, for example in the reduction of aromatic nitro compounds to .
Cativa process
The
Cativa process is a major end use of hydroiodic acid, which serves as a
co-catalyst for the production of
acetic acid by the
carbonylation of
methanol.
Illicit uses
Hydroiodic acid is listed as a U.S. Federal DEA List I Chemical, owing to its use as a
reducing agent related to the production of
methamphetamine from
ephedrine or
pseudoephedrine (recovered from nasal decongestant pills).
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