Iodine acetate

Iodine acetate also has been proposed331 as the electrophile in the peroxyacetic catalysed-iodination of benzene in acetic acid at 50 °C, which obeys the kinetic equation... 

Iodine acetate would seem to be unambiguously present in the iodination of pentamethylbenzene in acetic acid by iodine and mercuric acetate, since the latter components form an equilibrium mixture of iodine acetate and acetoxy-mercuric iodide and mercuric acetate speeds up the iodination332. Second-order rate coefficients of 0.078 (25 °C) and 0.299 (45 °C) were obtained, and these values are intermediate between those obtained for the reaction of bromine acetate with benzene (2.5 xlO-3) and toluene (1.2) at 25 °C, indicating that bromine acetate is the stronger electrophile. 

Significant amounts of the bicyclo[3.3.1]nonane adduct and of the octahydropental-enes were isolated also from the reaction of 3 with preformed iodine acetate and iodine acetate thallium (equation 75)94 whereas only the monocyclic 1,2-adducts were obtained from treatment of 3 with iodine azide, iodine isocyanate or iodine nitrate95. The different propensity to give transannular products with these latter reagents has been related to the different positive charge density on carbons in the corresponding iodonium ion intermediates. 

Alkyl iodines from alkyl iodines, acetic acid AgY (SiOy/AlyOy = 10) with zirconia or silica binder [243]... 

Iodine-acetic acid oxidation of (376) gave the lactone (377) which, when treated with chloromethyl benzyl ether, produced (378) in which phenylthiomethyl groups have been inserted at the 5- and 15-positions, but not at 10-. The lack of reactivity at the last position... 

Wijs Solution Dissolve 13 g of resublimed iodine in 1000 mL of glacial acetic acid. Pipet 10.0 mL of this solution into a 250-mL flask, add 20 mL of potassium iodide TS and 100 mL of water, and titrate with 0.1 N sodium thiosulfate, adding starch TS near the endpoint. Record the volume required as A. Set aside about 100 mL of the iodine-acetic acid solution for future use. Pass chlorine gas, washed and dried with sulfuric acid, through the remainder of the solution until a 10.0-mL portion requires not quite twice the volume of 0.1 N sodium thiosulfate consumed in the titration of the original iodine solution. A characteristic color change occurs when the desired amount of chlorine has been added. Alternatively, Wijs Solution may be prepared by dissolving 16.5 g of iodine monochloride, IC1, in 1000 mL of glacial acetic acid. Store the solution in amber bottles sealed with paraffin until ready for use, and use within 30 days. 

As noted at several points in previous sections, iodine-based reagents can act as Lewis acids. This has been known for many years, and has been exploited in the formation54 and cleavage55 of isopropylidene acetals of carbohydrates. In recent work, we have shown56 that iodine-acetic anhydride is an effective combination for the acetylation or partial acetylation of sugars this represents a practical alternative to the commonly used pyridine-acetic anhydride combination. The potential of iodine-based reagents to activate oxygen as well as sulfur centers is clear. 

A wide variety of dehydrating agents have been employed. In addition to those already mentioned are sulfuric acid, potassium bisulfate, formic acid, thionyl chloride, iodine, acetic anhydride, phosphorus oxychloride, and phosphorus pent-oxide. It should be noted that the free olefinic acids are sometimes decatboxylated under conditions similar to those described for certain of these dehydrations (cf. method 27). 

Acetyl hypoiodite (iodine acetate), CH3COOI, is prepared by treatment of silver acetate in acetic acid with iodine at room temperature [779, 780], The reagent cleaves vicinal diols to dicarbonyl compounds [779] and degrades tertiary alcohols to ketones [780], Acetyl hypoiodite is also an intermediate in the reaction of alkenes with the so-called Simonini complex, an addition product of iodine with 2 mol of silver acetate [781, 782, 783],... 

T etra-0-acetyl-/S-D-glucosyl fluoride silver carbonate, Anhydrone, and iodine acetate) 40 73... 

The experimenter separates heterooligomers before cleaving them into subunits. Then she denatures the purified subunit and reduces possible disulfide bridges. A carboxymethylation with iodoacetic acid protects against the reoxidation of the cysteines (Lind and Baker 1982). This reaction requires a sure instinct, in that other amino acids such as methionine, lysine, and histidine also react at high concentrations of iodine acetate or at the wrong pH. If you just need a few partial sequences, you can skip the carboxymethylation. 

Phosphorus/iodine acetic acid Mercaptans from sulfonic acid dilorides... 

Coumarin-fused 4H-pyrans can be achieved through the tandem reaction of 4-hydroxycoumarins with chalcones mediated by iodine/acetic acid... 

Use of other nucleophiles in the presence of an oxidant can install other functionality (Scheme 3.55). While N-halosuccinimides are very effective, other systems, such as iodosobenzene diacetate-halide mixtures, or copper(II) halide salts can be employed. The powerful oxidant oxone can also be used in combination with alcohols, to give ethers (Scheme 3.56). Iodine acetate has been used for C-H activation directed by carboxylic acids (Scheme 3.57). The heteroatom may also be supplied intramolecularly (Scheme 3.58). The use of palladium catalysis can also override the inherent regioselectivity of an arene substrate (Scheme 3.59). 

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