IODOFORM, a valuable antiseptic discovered by G. S. Serullas in 1822. Iodoform, is formed by the action of iodine and aqueous potassium hydroxide on ethyl alcohol, acetone, acetaldehyde, isopropyl alcohol and most compounds containing the group CH,CO.C—. It crystallizes in yellow hexagonal plates, melting at 119-12o° C, and is readily soluble in alcohol or ether, but insoluble in water. It has a characteristic odour and is volatile in steam. On reduction with hydriodic acid, it yields methylene iodide, Iodoform is also prepared by electrolysis of a solution of potas sium iodide in the presence of alcohol or acetone. A solution of
potassium iodide and sodium carbonate in water with the necessary alcohol is contained in a porous cell fitted with a lead anode, whilst the cathode compartment contains a solution of caustic soda and a nickel electrode. The electrolysis is carried out at a temperature of 70° C, with a current density of one ampere per square deci metre. After three hours the yield is 70% of the calculated quantity.
From its formula it can be seen to be strictly analogous with chloroform, which is trichloromethane, while iodoform is tri-iodomethane.