Iodoform structure

The high pressure phases, electronic structure, and optical properties of iodoform at zero temperature have been investigated by first-principles pseudopotential plane-wave calculations based on the density-functional theory. A new high pressure polar monoclinic structure with space group Cc, denoted as β phase, has been observed after a series of simulated annealing and geometry optimizations. Our calculated enthalpies showed that the transition from α to β phase occurs at 40.1 GPa. Electronic structure calculated results showed that the insulator–metal transition in α phase due to band overlap is found at about 32 GPa. In addition, the calculated absorption spectra of iodoform are consistent with the experimental results.

The structures of CHI 3 and of its adduct with quinoline have been analyzed using X-ray single crystal diffraction at low (106K, CHI 3) and room temperature (adduct CHI 3⋅3(C 9H 7N)). The disorder of the molecule is removed at low temperature and the non centrosymmetric structure in P6 3 space group allows a deep examination of the halogen bondings in the crystal. The iodine atom clearly shows in the both compounds its electrophilic and nucleophilic behavior. It is noteworthy that when iodoform forms adducts involving the three iodine atoms with Lewis bases, it gives raise to non centrosymmetric crystals, and it is a good candidate for obtaining new materials. Introduction Non linear optics, optoelectronic transducers, ferro-, piezo- and pyro-electric materials are required for applications in chemistry, physics, material sciences and for important technological and industrial applications. Materials used for these purposes require polar molecules in polar crystals for necessary chemical and physical properties. Iodoform (CHI 3) is a molecule with a permanent (and small) dipole moment and is part of the family of CHX 3(X=F, Cl, Br, I) compounds that exhibit an interesting range of crystallographic structures and polymorphic phase transitions at different temperatures [1]. In the past there has been a continuing interest in the solid state of iodoform (CHI 3). Crystalline iodoform has been studied by X-ray [2] and neutron diffraction [3], Raman and IR spectroscopy [4], [5],...

triiodomethane (iodoform) reaction with aldehydes and ketones THE TRIIODOMETHANE (IODOFORM) REACTION WITH ALDEHYDES AND KETONES This page looks at how the triiodomethane (iodoform) reaction can be used to identify the presence of a CH 3CO group in aldehydes and ketones. Note: This reaction can also be used in testing for the CH 3CH(OH) group in alcohols. You will find a link to this at the bottom of the page. Doing the triiodomethane (iodoform) reaction There are two apparently quite different mixtures of reagents that can be used to do this reaction. They are, in fact, chemically equivalent. Note: It would be silly to learn both of these methods. Use whichever one your examiners want - find out by looking at past papers and mark schemes. If you haven't got these, go to the Use the BACK button on your browser to return to this page. Using iodine and sodium hydroxide solution This is chemically the more obvious method. Iodine solution is added to a small amount of aldehyde or ketone, followed by just enough sodium hydroxide solution to remove the colour of the iodine. If nothing happens in the cold, it may be necessary to warm the mixture very gently. A positive result is the appearance of a very pale yellow precipitate of triiodomethane (previously known as iodoform) - CHI 3. Apart from its colour, this can be recognised by its faintly "medical" smell. It is used as an antiseptic on the sort of sticky plasters you put on minor cuts, for example. Using potassium iodide and ...