Metal/iodine displacement

Nitrogen Displaces the Metal Phosphorus Displaces the Metal Oxygen Displaces the Metal Sulfur Displaces the Metal Fluorine Displaces the Metal Chlorine Displaces the Metal Bromine Displaces the Metal Iodine Displaces the Metal... 

Iodine is a bluish-black, lustrous solid, volatizing at ordinary temperatures into a blue-violet gas with an irritating odor it forms compounds with many elements, but is less active than the other halogens, which displace it from iodides. Iodine exhibits some metallic-like properties. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide to form beautiful purple solutions. It is only slightly soluble in water. 

The iodides of the alkaU metals and those of the heavier alkaline earths are resistant to oxygen on heating, but most others can be roasted to oxide in air and oxygen. The vapors of the most volatile iodides, such as those of aluminum and titanium(II) actually bum in air. The iodides resemble the sulfides in this respect, with the important difference that the iodine is volatilized, not as an oxide, but as the free element, which can be recovered as such. Chlorine and bromine readily displace iodine from the iodides, converting them to the corresponding chlorides and bromides. 

FIGURE 6.21 (A) Removal of trityl and acetamidomethyl from sulfhydryl by oxidative cleavage by iodine. (B) Cleavage of terf-butylsulfanyl by mercury(II) acetate,88 followed by displacement of the metal ion by hydrogen sulfide. 

Chlorine, added to a solution of bromide or iodide of a metal, displaces the bromine or iodine here the non-ionised chlorine becomes ionised at the expense of the charge on the ionised bromine or iodine, while the latter... 

Immediately upon connecting the cell to a source of direct current, a deposit of gray metallic zinc appears on the surface of the cathode and bubbles of chlorine gas appear at the surface of the anode. A simple chemical test for chlorine may be made by leading this gas into an aqueous sodium iodide solution, whereupon the solution assumes a yellow color caused by displacement of iodine by chlorine. Accordingly, it is concluded that the products of the electrolysis of a zinc chloride solution are elemental zinc and elemental chlorine, and the next problem is that of explaining the mechanism by which these products may be produced. 

From this experiment and the preceding one we should conclude that the non-metallic elements fall in the order F, Cl, Br, 0, I, S (fluorine being strongest) with respect to their activity in aqueous solutions containing free acid. This is approximately the order of the electromotive series for these non-metals. If the solution is made neutral the electromotive potential of oxygen is lowered so that the oxygen is no longer able to displace iodine. 

Cyclization can also occur through halide displacement after initial metalation. For example, acylation of o-lithiofluorobenzenetricarbonylchromium with y-butyrolactone at 25 °C for 24 h is followed by spontaneous fluoride displacement to give complex 36. Oxidation with excess iodine liberates the lactone in 48 % overall yield (Scheme 15) [20]. 

Other synthetic routes reported involve the interactions of trifluoro-phosphine metallates and iodine (method E), displacement of carbon monoxide, alkenes, etc. by PF3 from the corresponding halide complexes (method F), addition of PF3 to dinuclear halogeno-bridged PF3 complexes at low temperatures (method G), and treatment of a metal hydrido- PF3 complex with iodoform (method H). 

Treatment of [Fe(CO)4] with NaNOj or hydroxylamine under mild conditions produced a small yield of the first amino derivative [Fe(CO)j NH2]2 262-265), originally formulated incorrectly as the imino-bridged species 262), but later shown by mass spectrometry 221), and the X-ray crystal structure 158) to have an amino bridged structure (IX). The structure is characterized by a short metal-metal bond and small FeNFe and NFeN angles (Table I). Triphenylphosphine displaced one or two carbonyl groups to form the complexes [Fe2(CO)5(PPhj)(NH2)2] and [Fc2(CO)4 (PPh3)2(NH2)2], the latter undergoing oxidation with iodine to afford... 

Besides substitution by amino, a chloro or bromo substituent may also be replaced by iodo, hydroxy, and alkoxy," though it is not possible to prepare 4-fluoroimidazoles by halogen exchange with metal fluorides on activated bromo- or chloroimidazoles." 4-Fluoroimidazoles are relatively resistant to nucleophiles, but the corresponding 2-fluoro compounds are subject to displacement (via an addition-elimination reaction) under mild conditions (see also Section III,B). Undoubtedly, the intermediate formation of a stable symmetrical 2-fluoroimidazolium cation (120) is responsible for this ease of displacement. (Eq. 28). Iodine at all ring carbons... 

Non-metals also vary in reactivity. In, for example, Group VII of the periodic table (the halogens), chlorine is more reactive than iodine. If you pass chlorine gas.into potassium iodide solution, the solution goes brown because the chlorine displaces iodine from the potassium iodide. Iodine in KI has an oxidation number of — 1 and this rises to 0 in the elemental iodine, so iodine has been oxidised. The opposite occurs with chlorine. 

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