Iodoform

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Iodoform
Names
IUPAC name
Triiodomethane
Preferred IUPAC name
Triiodomethane
Other names
Carbon triiodide
Properties
CHI3
Molar mass 393.73 g/mol
Appearance Yellowish powder
Odor Saffron-like
"Hospital"-like
Density 4.008 g/cm3
Melting point 119 °C (246 °F; 392 K)
Boiling point 218 °C (424 °F; 491 K)
0.1 g/L
Solubility Soluble in glacial acetic acid, benzene, carbon disulfide, chloroform
Slightly soluble in glycerol, olive oil, petroleum ether
Solubility in diethyl ether 136 g/L
Solubility in acetone 120 g/L
Solubility in ethanol 78 g/L
Thermochemistry
180.1–182.1 kJ·mol−1
Hazards
Safety data sheet AcrosOrganics
Flash point 204 °C
Lethal dose or concentration (LD, LC):
355 mg/kg (oral, rat)
1180 mg/kg (dermal, rat)
1.6 mmol/kg (s.c., mouse)
Related compounds
Related compounds
Chloroform
Bromoform
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Iodoform is a yellowish organoiodine compound with the formula CHI3.

Properties

Chemical

Iodoform reacts with silver nitrate to yield carbon monoxide.

AgNO3 + CHI3 → AgI + CO + I2 + ½ N2 + O2 + ½ H2

Iodoform can be reduced with hydrogen iodide to diiodomethane:

CHI3 + HI → CH2I2 + I2

Physical

Triiodomethane is a pale yellow, crystalline, volatile substance, with a very strong penetrating and distinctive odor, reminiscent of hospitals, due to its use as a desinfectant. It is practically insoluble in water, but soluble in organic solvents such as acetone, benzene, chloroform, diethyl ether.

Availability

Iodoform is sold in pharmacies, either as a powder or as ether solution. Vet shops also carry it.

Iodoform in pure form can be bought from lab suppliers or online.

Angel's bonnets naturally produce a small amount of iodoform, which gives their characteristic smell, but extracting it may not be practical, as you will need lots of them.

Preparation

Iodoform can be prepared very easy via the haloform reaction, by reacting iodine, sodium hydroxide with a ketone, such as acetone. As iodoform is practically insoluble in water, the suspension is filtered and then air dried.

A less known route involves passing iodine vapors with steam over red hot coals. The resulting product is purified via distillation, though if the coal used impurities, many other side products will also be produced.[1]

Reacting chloroform with calcium iodide at 100 °C yields iodoform.[2]

Projects

  • Antiseptic
  • Make diiodomethane
  • Strong smelling compound collecting

Handling

Safety

Iodoform is irritant and should be handled with care. Most people find its strong odor obnoxious, so work must be done in well ventilated areas, and never indoors as the odor is quite persistent.

Since CHI3 is used as an antiseptic in medicine, proper protection like gloves and coat should be worn when handling the compound.

Storage

CHI3 must be kept in amber glass bottles, bottles with a PTFE seal are recommended to limit its escape, preferably away from light and if possible, air. Do not use plastic, as iodoform will will irreversible stain it, especially if in contact with air (elemental iodine is formed) and absolutely never in metal containers.

Disposal

Can be neutralized with a strong base. This gives sodium iodide which can be recycled, as it's a source of iodine.

References

  1. http://gallica.bnf.fr/ark:/12148/bpt6k6137757n/f2.image
  2. Spindler; Justus Liebigs Annalen der Chemie; vol. 231; (1885); p. 272

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