Meyer-Hartmann reaction

What is Meyer-Hartmann reaction?

The Hartmann and Meyer reaction was first discovered in 1894 and involves the formation of diaryliodonium salt by reacting iodosobenzene (PhIO) and iodoxybenzene (PhIO2) with silver (I) oxide Ag2O, which is also known as the Meyer-Hartmann reaction.

Meyer-Hartmann reaction - general reaction scheme
Meyer-Hartmann reaction

When an equal amount of iodosobenzene and iodoxybenzene is mixed, diphenyliodonium hydroxide is produced in the presence of alkali. The resulting diaryliodonium salt exhibits properties similar to ammonium hydroxide, hence the name.

The presence of moisture or water causes silver (I) oxide to hydrate and become basic, which allows the reaction to occur even with a catalytic amount of silver (I) oxide. The iodine atom in iodosobenzene enters the diphenyliodonium ion, while the iodine atom in iodoxybenzene is oxidized to iodate.

Despite its time-consuming nature, this reaction remains a major method for preparing diaryliodonium salt, which has numerous industrial applications such as in lithography and as a polymerization initiator. A similar reaction for producing p-iodophenyl phenyliodonium bisulfate has also been developed by Meyer and Hartman using concentrated sulfuric acid H2SO4.

References

Hartmann, C. and Meyer, V. (1894), Ueber die Jodoniumbasen. [On the iodonium bases] Ber. Dtsch. Chem. Ges., 27: 502-509. https://doi.org/10.1002/cber.18940270199

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