Reaction with iodine atoms

In Quest of Friendly Free Radicals Reactions of Iodine Atom Free Radicals with Some Biologically Important Compounds... 

Lithiation and mercuration are directed by the oxygen atom and occur at the 4-position, but thallation, achieved by treatment of dibenzofuran with thallium(III) isobutyrate at 110°C, affords the 2-thallium di(isobutyrate), which may be converted to the 2-iodo compound by reaction with iodine. Mercuration is achieved by treatment of dibenzofuran with mercuryfll) acetate at 150°C, and the resultant 4-mercuric acetate (56%) may also be converted to the iodo compound. ... 

When the activation-limited rate coefficient, feact> is very large by comparison with the diffusion constant, AnRD, the recombination probability is R/r0, which is necessarily < 1. For iodine atoms in carbon tetrachloride, since R/r0 <1 and q 0.75, then the rate coefficient of reaction of iodine atoms at encounter must be at least three times the diffusion rate coefficient [feact > 3(47rRD)] and also R < r0 < 1.3R. While the possible range of values for kac and r0 has been reduced by this, comparison of the experimental results with the time-dependent form of the recombination probability, q( r0, 0), of eqn. (132) does not give very much more aid in defining feact and r0 (see Sect. 3). 

The promoting effect of Reaction 5 should be strongest with chlorine and weakest with iodine atoms since the activation energy of this reaction with respect to the different halogen atoms is (2) ... 

Thomas JK (1967) Pulse radiolysis of aqueous solutions of methyl iodide and methyl bromide. The reactions of iodine atoms and methyl radicals in water. J Phys Chem 71 1919-1925 Tsang W, Hampson RF (1986) Chemical kinetic data base for combustion chemistry, part I. Methane and related compounds. J Phys Chem Ref Data 15 1086-1279 UlanskiP, von Sonntag C (1999) The OFI-radical-induced chain reactions of methanol with hydrogen peroxide and with peroxodisulfate. J Chem Soc Perkin Trans 2 165-168 Ulanski P, Bothe E, Hildenbrand K, von Sonntag C, Rosiak JM (1997) The influence of repulsive electrostatic forces on the lifetimes of polyfacrylic acid) radicals in aqueous solution. Nukleonika 42 425-436... 

Radical cyclization with iodine atom transfer of a highly functionalized propiolic ester 103 using dibenzoyl peroxide as an initiator gave the a-methylene-y-butyrolactone 104 in good yield [95T11257]. The relative stereochemistry at carbon atoms 4 and 5 are established during the reaction. The intermediate 104 has been converted to the anti-tumor agent (-)-methylenolactocin 105. 

But in this case, the weakness of the HI bond means that HI is not readily formed by attack of RH groups, instead the presence of R radicals can lead to combination with iodine atom through the reaction (Equation 4.7) 7... 

The layered oxide ion conductors Srj Bi9 0(27-.t)/2 and BaBigOis show similar intercalation reactions with iodine. The iodine atoms intercalate into the van der Waals gap between adjacent Bi sheets to form stage 1 compounds. The spacing between adjacent Bi layers increases by 3 A corresponding to the intercalation of a monolayer of iodine atoms. Micro-Raman spectroscopy shows that the intercalated iodine species is predominantly I3. Ag-1 intercalated Sri,5Bi7,50i2.75, was synthesized by reaction with iodine and then in a second step with silver metal. Intercalation of lithium iodide into the ferroelectric layered compound Bi4Ti30i2 j has also been reported. ... 

Reactions with sulphur atoms alone give a variety of cyclic products, depending on the conditions [325], but when iodine is also present the potentially aromatic compound... 

It was realized that another reaction, the unimolecular formation of the olefine with elimination of hydrogen iodide would also take place, but it was thought that measurement of the iodine would be a good measure of equation 4.2,4.1. This simple view depends upon the assumption that iodine atoms recombine to give iodine more rapidly than they take part in the reverse of the reaction of equation 4.2,4.1. This seems rather unlikely, because the recombination of iodine atoms requires three body collisions and the recombination of radicals with iodine atoms may well be a bimolecular process. Under these circumstances, it seems more likely that the prevention of complete reformation of the alkyl iodide is due to further reactions of the alkyl radical, such as... 

An intense luminescence has been observed also when I" was present (20, 21), attributed to the reaction of iodine atoms with the reduced dye.] The reductive attack is suppressed by oxygen via Reactions 9 and 10. 

MeOH, Pr OH, or MeO(CHa)aOMe.451e Similarly, the corresponding Br-HaO and Cl-HaO complexes have been observed on laser photolysis of Bra and Cla in water.451" The primary photoprocess following nitrogen-laser irradiation of I37 is (93).462 However, for solutions in various alcohols it has been shown that I47 is produced on laser flash photolysis of Ia/I mixtures.458 This species is formed by reaction of iodine atoms, formed on photolysis of Ia, with I3. I47 has also been observed following y-irradiation of I2 in methyltetrahydrofuran.454... 

A modification of the Hofmann-Loffler-Freytag reaction that avoids the harshly acidic conditions described above has been developed. The A-iodo compound is generated by reaction with iodine and iodobenzene diacetate. Warming or irradiating the reaction mixture promotes the formation of the lutrogen-centred radical and hence subsequent remote hydrogen atom abstraction. The reaction is particularly effective with carboxylic amides, sulfonamides or phosphoramidates, as illustrated in the transannular cyclization to give the indolizidine 20 and in the formation of the bicyclic produet 21 (4.21,4.22). ... 

Bonds to Sulphur or Selenium.— The crystal structure of Bi2ln4S9, recently synthesized by vapour-transport reactions with iodine, indicates that three of the indium atoms are octahedrally co-ordinated by sulphur while the fourth... 

The recoil chemistry of carbon-11 in liquid C5-C7 hydrocarbons has been investigated by Clark The recoil atoms have been produced in the (y,n) reaction. The study of the product yields of ethane, ethylene and acetylene (as well as of methane) from different target molecules has been the main concern in this work. Iodine affected the yields of all the volatile products except acetylene. Acetylene-the principal products in all the hydrocarbons investigated, is produced in hot reactions with naked atoms. Insertion of recoil fragments into C—H and C=C bonds leads to various C-labelled hydrocarbons. 

---