Iodoform

The compound iodoform is CHI₃. A pale yellow, crystalline, volatile substance, it has a penetrating odor (in older chemistry texts, the smell is sometimes referred to as the smell of hospitals) and, analogous to chloroform, sweetish taste. It is slightly soluble in glycerol, petroleum ether or alcohol (78 g/l at 25 °C), averagely soluble in chloroform, acetic acid and ether (136 g/l at 25 °C) and easily soluble in benzene and acetone (120 g/l at 25 °C).

Its entalphy of sublimation is 69.9 kJ.mol^-1 at range of temperatures 35 – 92 °C.

Iodoform molecule parameters are: d(C-I) = 2.12 ± 0.04 Å, d(I-I) = 3.535 ± 0.01 Å and I-C-I = 113°. Dipole moment is 1 D. Its space group is P6₃ and lattice constants are a = 6.83 Å, c = 7.52 Å.

It has critical point at 584.85 °C, 5.63 MPa. Refractive index is 1.786 (D, 20 °C).

It was first prepared by Georges Serrulas in 1822 and its molecular formula was identified by Jean-Baptiste Dumas in 1834.

Iodoform can be synthesized in the haloform reaction by the reaction of iodine and sodium hydroxide with any one of these four kinds of organic compounds:

• a methyl ketone: CH₃COR, where R is an organic side chain.
• acetaldehyde: CH₃CHO
• ethanol: CH₃CH₂OH
• secondary alcohols: CH₃CHROH, where R is an alkyl or aryl group.

These reactions are so reliable that it is called the iodoform test, signalled by the precipitation of pale yellow crystals.

Some reagents (e.g. hydroiodic acid) can convert iodoform to diiodomethane.

Also conversion to carbon dioxide is possible. Iodoform reacts with silver nitrate producing carbon monoxide, which is oxidized by mixture of sulfuric acid and iodine pentaoxide.

It was used in medicine as a healing and antiseptic dressing for wounds and sores around the beginning of the 20th century, though this use is now superseded by better antiseptics.

• Merck Index, 12 Edition, 5054.

• Haloalkane
• Halomethane
• Trihalomethane
• Iodomethane
• Diiodomethane
• Carbon tetraiodide (Tetraiodomethane)
• Fluoroform
• Chloroform
• Bromoform
• Iodoform reaction

• Template:PGCH
• MSDS at Oxford University
• MSDS at Science Lab
• A Method for the Specific Conversion of Iodoform to Carbon Dioxide
• Article at 1911 Encyclopaedia Britannica
• Preparation

Template:Medicated dressings

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