Hydroxyl reaction with iodide

Absolute rate constants have been determined for the reaction of the hydroxyl radical with a variety of aromatic compounds in aqueous solution. The rate constants obtained are significantly higher than values previously reported. Rate constants for the reaction of the hydroxyl radical with methyl alcohol and ethyl alcohol have also been determined by competition kinetics using three of these absolute rate constants as reference values. Comparison of our results with the published values from competition kinetics suggests that the rate constants for the reaction of hydroxyl radicals with iodide ion and thiocyanate ion are significantly higher than reported in earlier work. The ultraviolet absorption bands of the various substituted hydroxycyclohexadienyl radicals formed have been observed. 

As inert as the C-25 lactone carbonyl has been during the course of this synthesis, it can serve the role of electrophile in a reaction with a nucleophile. For example, addition of benzyloxymethyl-lithium29 to a cold (-78 °C) solution of 41 in THF, followed by treatment of the intermediate hemiketal with methyl orthoformate under acidic conditions, provides intermediate 42 in 80% overall yield. Reduction of the carbon-bromine bond in 42 with concomitant -elimination of the C-9 ether oxygen is achieved with Zn-Cu couple and sodium iodide at 60 °C in DMF. Under these reaction conditions, it is conceivable that the bromine substituent in 42 is replaced by iodine, after which event reductive elimination occurs. Silylation of the newly formed tertiary hydroxyl group at C-12 with triethylsilyl perchlorate, followed by oxidative cleavage of the olefin with ozone, results in the formation of key intermediate 3 in 85 % yield from 42. 

Chlorosulfate groups can be readily removed to give the corresponding hydroxyl groups, with retention of configuration, by treatment of a solution of the carbohydrate chlorosulfate in methanol with sodium iodide in aqueous methanol24 immediate liberation of iodine and evolution of sulfur dioxide occur.34 A possible mechanism for the dechlorosulfation reaction involves displacement by iodide at the chlorine atom the initially formed iodine monochloride would react with iodide ion to give iodine and chloride ion. Alternatively, an unstable iodosulfate could be formed as an intermediate.35... 

Alumina will also bind Cr03 and stabilize it to 900°C, and it can polymerize ethylene when reduced to Cr(II). High surface area y alumina can be made having the porosity necesssary for good activity. Besides the electronic differences between Si—O—Cr and A1—O—Cr bonds, such alumina catalysts typically have 50-100% more hydroxyl groups than silica at normal calcining temperatures. This is clear in Fig. 21, which shows the hydroxyl populations of three different supports. The hydroxyl concentration was measured by reaction with methylmagnesium iodide. 

Fic,. 21. Hydroxyl population on silica, y alumina, and aluminum phosphate having similar porosity. (Measured by reaction with methylmagnesium iodide.)... 

Carhon monoxide and hydrogen react to form CH in the presence of a nickel catalyst. Methane also is formed by reaction of magnesium methyl iodide in anhydrous ether (Grignard s rcagentl with substances containing the hydroxyl group. See also Grignard Reactions. Methyl iodide (bromide, chloride) is preferably made by reaction of methyl alcohol and phosphorus iodide (bromide, chloride)... 

Epoxides 72 may also act as starting materials for hybrid structures 77 containing an isohexide and a glyceryl moiety, with nitric ester functions at different positions.172 Additional monoethers of isosorbide 2- and 5-nitrate 78 were synthesized by reaction of the free hydroxyl group with any of several alkyl iodides in the presence of freshly prepared silver oxide. The yields were low, as usual.146 Amongst a larger series of different alcohol... 

Garraway, J., Donnovan, J. (1979) Gas phase reaction of hydroxyl radical with alkyl iodides. J. Chem. Soc. Chem. Comm. 23, 1108. Garriga, R., Martinez, S., Perez, P, Gracia, M. (2002) Vapor pressures at several temperatures between 278.15 and 323.15 K and excess functions at T = 298.15 K for 1-bromobutane with 1-butanol or 2-methyl-2-propanol. J. Chem. Eng. Data 47, 322-328. 

The alloy-ethyl chloride reaction rate is quite sensitive to alloy composition, the most reactive alloy being the composition NaPb. The alloy becomes less reactive as the composition is raised in sodium, until reaction almost ceases at the composition NasPb2. With such higher sodium alloys, reaction can be obtained with ethyl bromide or iodide, especially in the presence of amine or hydroxyl compounds 289). With the compound composition NagPb4 catalysts such as ketones, esters, or aldehydes allow good reaction with ethyl chloride. 

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