Iodine reaction with carboxylic acids

Iodine is a very good electrophile for effecting intramolecular nucleophilic addition to alkenes, as exemplified by the iodolactonization reaction71 Reaction of iodine with carboxylic acids having carbon-carbon double bonds placed to permit intramolecular reaction results in formation of iodolactones. The reaction shows a preference for formation of five- over six-membered72 rings and is a stereospecific anti addition when carried out under basic conditions. 

SAFETY PROFILE Poison by ingestion and inhalation. A corrosive irritant to skin, eyes (at 2 ppm), and mucous membranes. Potentially explosive reaction with chlorobenzene + sodium, dimethyl sulfoxide, molten sodium, chromyl chloride, nitric acid, sodium peroxide, oxygen (above 100°C), tetravinyl lead. Reacts with carboxylic acids (e.g., acetic acid) to form violently unstable products. Violent reaction or ignition with Al, chromium pentafluoride, diallyl phosphite + allyl alcohol, F2, hexafluoroisopropylideneaminolithium, hydroxylamine, iodine chloride, PbOa, HNO2, organic matter, potassium, selenium dioxide, sulfur acids (e.g., sulfuric acid. 

Many organic compounds react with carboxylic acids, acyl halides, or anhydrides in the presence of certain metallic halides, metallic oxides, iodine, or inorganic acids to form carbonyl compounds. The reaction is generally applicable to aromatic hydrocarbons. Benzene, alkylbenzenes, biphenyl, fluorene, naphthalene, anthracene, acenaphthene, phenanthrene, higher aromatic ring systems, and many derivatives undergo the reaction. 

Organoacyloxysilanes are also produced by reaction of oiganosilanes with carboxylic acids in the presence of strong mineral acids, eg, sulfuric and hydroiodic acids. Trialkylacyloxysilanes have been obtained in 81—87% yield from monocarboxylic acids in the presence of aluminum and iodine. 

The reaction of carboxylic acids with the PhI(OAc)2-iodine system may result in a decarboxylation ieading to the intermediate formation of a carbon-centered radical, which can be further oxidized to a carbocation and trapped by a nucleophile. This process has been utilized in several syntheses [97, 615,616, 617]. In a typical example, the oxidative decarboxylation of uronic acid derivatives 568 in acetonitrile under mild conditions affords acetates 569 in good yields (Scheme 3.225) [615]. A similar oxidative decarboxylation has been be used for the synthesis of 2-substituted pyrrolidines 571 from the cyclic amino acid derivatives 570 [616,617]. 

So, maleic anhydride Diels-Alder addition products to (conjugated) linoleic acid (CLA, Figure 3B.16, a.) may be prepared both with and without catalytical amounts of iodine, clay, or silica at a reaction temperature generally from about 100°C to about 230 °C. Similarly, the Diels-Alder addition of acrylic acid yields a C21-diacid (Figure 3B.16, b.). Under somewhat more vigorous conditions, the monounsaturated oleic/elaidic acids react with maleic anhydride at 215 °C to about 250 °C to form an ene-adduct (Figure 3B.16, c.). Diels-Alder and ene reaction products ofTOFA form polyfunctional carboxylic acids that can further be sulfonated by reaction with sulfuric acid and/or can undergo esterification or amidation reactions. - ... 

Iodine triacylates (29) are readily obtained by ozonization of solutions of iodine in aliphatic carboxylic acid anhydrides thermolysis with mercuric oxide affords the symmetrical esters (30) in good yield. Mercuric iodate can perform the same transformation by direct reaction with the anhydride. 

Methylaziridine is shown to react with carbon dioxide in the presence of iodine to give 4-methyl-2-oxazolidone in 80% yield (Scheme 134). Acyl hydrazones gave 2-substituted 4-acyl-l,3,4-oxadiazolines when treated with carboxylic acid anhydrides in pyridine (Scheme 135), whereas, in a somewhat analogous reaction. 

The reaction of lithio derivatives with appropriate electrophiles has been utilized in the preparation of alkyl, aryl, acyl and carboxylic acid derivatives. Representative examples of these conversions are given in Scheme 79. Noteworthy is the two-step method of alkylation involving reaction with trialkylborane followed by treatment with iodine (78JOC4684). 

In the photolysis of difiuorodiazirine (218) a singlet carbene was also observed (65JA758). Reactions of the difiuorocarbene were especially studied with partners which are too reactive to be used in the presence of conventional carbene precursors, such as molecular chlorine and iodine, dinitrogen tetroxide, nitryl chloride, carboxylic acids and sulfonic acids. Thus chlorine, trifiuoroacetic acid and trifiuoromethanesulfonic acid reacted with difiuorodiazirine under the conditions of its photolysis to form compounds (237)-(239) (64JHC233). 

Me3SiCH2CH=CH2i TsOH, CH3CN, 70-80°, 1-2 h, 90-95% yield. This silylating reagent is stable to moisture. Allylsilanes can be used to protect alcohols, phenols, and carboxylic acids there is no reaction with thiophenol except when CF3S03H is used as a catalyst. The method is also applicable to the formation of r-butyldimethylsilyl derivatives the silyl ether of cyclohexanol was prepared in 95% yield from allyl-/-butyldi-methylsilane. Iodine, bromine, trimethylsilyl bromide, and trimethylsilyl iodide have also been used as catalysts. Nafion-H has been shown to be an effective catalyst. 

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