Iodine monochloride basicity basicities

Organoborane intermediates can also be used to synthesize alkyl halides. Replacement of boron by iodine is rapid in the presence of base.150 The best yields are obtained with sodium methoxide in methanol.151 If less basic conditions are desirable, the use of iodine monochloride and sodium acetate gives good yields.152 As is the case in hydroboration-oxidation, the regioselectivity of hydroboration-halogenation is opposite to that observed for direct ionic addition of hydrogen halides to alkenes. Terminal alkenes give primary halides. 

Elementary chlorine, bromine, and iodine dissolve in many organic solvents, and the variations in the colors among the iodine solutions in various solvents have been a matter of interest to many workers. (Both bromine solutions and solutions of iodine monochloride show analogous variations, but the effect for iodine is by far the most striking.) In completely nonbasic solvents (for example, CCU and CS2) iodine appears violet, the same color as its vapor but as the basicity of the solvent increases, the iodine color shifts toward orange or brown, presumably because the electronic excitation responsible for the iodine color is made more difficult by approach of electron-rich reagents. As the basicity of the solvent increases, the iodine-to-iodine bond weakens in the organic base, pyridine (reaction c, below), many of the I—I bonds are broken, wrhereas... 

The reactions of the interhalogen compounds are not greatly different from those of the halogens themselves. Hydrolysis of compounds in basic solution yield the halide ion derived from the smaller halogen and an oxy-halogen anion derived from the larger halogen thus, hydrolysis of BrF yields a 5 1 mixture of fluoride and bromate, Iodine monochloride... 

As discussed already, some of the functional groups cannot tolerate the basic conditions employed in the reaction. This difficulty, however, can be obviated also by the use of iodine monochloride and methanolic sodium acetate, as illustrated in Eq. 114 176). 

Iodine Monochloride This precursor is generated by the exchange IGl/Na I, which corresponds to an oxidation of iodide by cold iodine. It can also be obtained by oxidation with elemental GI2. Depending on the reaction conditions, pH, and solvent, the reagent is either IO or IOH and lOHj, respectively, in basic and acidic media. 

The oxidation can be carried out in acidic, neutral, or basic media. Iodide will be oxidized to iodine in basic and neutral media and to iodine monochloride in acidic medium (HCl). In aqueous solution, chloramine T forms hypochlorous acid (HOCl), which is thought to be the actual oxidizing species. The oxidation can be controlled by the depletion of chloramine T, as the fimiting reagent or by the addition of a reducing agent (sodium bisulfite) to stop it (Robles et al, 2001). 

The explanation of this effect can be conceived as follows. Phenol has a fairly high dipole moment and has no low-energy acceptor orbitals, whereas iodine has no dipole moment hence interactions with iodine may be expected to have more covalent character than the analogous reactions with phenol. Accordingly, iodine will react more readily with the better polarizable reaction partners possessing lower ionization potentials. Similar considerations may be employed to interpret, for example, the sequence of basic strengths of primary, secondary and tertiary amines [Dr 63], and the sequence of acid strengths of iodine monochloride, elemental bromine, elemental iodine, phenol and sulphur dioxide [Dr 62]. 

Iodine bromide and arsenic(III) bromide resemble closely as solvents iodine monochloride and arsenic(III) chloride respectively, and stable acids have not been isolated in the bromo-systems. Molten mercury(II) bromide is an excellent solvent for various classes of compounds. Alkali metal bromides form solvated anionic species which appear to contain the ions [IBr2] , [AsBr4] and [HgBr3] respectively and phosphorus(V) bromide gives PBr4+IBr2 in iodine bromide where it behaves as a base. Other basic substances are nitrogenous bases such as pyridine. 

Studies of the X—Y stretching vibration in complexes of XY with different Lewis bases reveal a characteristic decrease in frequency as the strength of the base increases [35, 36]. Hence spectroscopic scales of halogen-bond basicity can be built [37] in the manner described in Chapter 4 for the O—H stretching vibration in hydrogen-bonded complexes. Spectroscopic scales based on the shifts of the v(I—I) band of diiodine at 211 cm , the u(I—Cl) band of iodine monochloride at 376 cm and the v(I—CN) band of iodine cyanide at 485 cm will be presented and compared with thermodynamic basicity and/or affinity scales. 

Lamsabhi, M.A., Bouab, W., Esseffar, M. et al. (2001) Basicity of some carbonyl compounds towards iodine monochloride experimental and theoretical study. New J. Chem., 25,509-517. 

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