O-Iodobenzoic acid

Ullman condensation of m-trifluoromethylaniline (13) with o-iodobenzoic acid in the presence of copper-bronze affords flu-fenamic acid (14). An analogous reaction of o-chlorobenzolc acid with 2,3-dimethylaniline (15) gives mefenamic acid (16) meclofenamic acid (18) is obtained by Ullman condensation employing 2,6-dlchloro-3-methylaniline (17). 

Potassium persulfate, reagent for oxidation of o-iodobenzoic acid, 46, 107... 

It has been proved that the benzyne intermediate can be easily prepared from o-iodobenzoic acid and potassium peroxydisulfate in sulfuric acid. Water-soluble vicinal diols are converted into their corresponding aldehydes in the presence of Ag(I) catalyst. ... 

Efficient new methods for oxidation are always welcome. The Dess-Martin periodinane has become the workhorse for alcohol to aldehyde or ketone conversion in organic research labs around the world. Viktor V. Zhdankin of the University of Minnesota, Duluth has described (Chem. Commun. 2004, 106) a complementary family of reagents. Oxidation of an ester I of o-iodobenzoic acid with NaOCl delivers 2. Depending on the ester, the reagent 2 is soluble and an effective oxidant, with KBr catalysis, in a wide range of organic solvents. Presumably, the spent oxidant can be recovered and recycled. 

The pathway by which the reactions are considered to occur involves attack of the enolate anion at the 1 0 bond of o-iodosyl benzoic acid followed by reductive elimination of o-iodobenzoic acid upon addition of methoxide to the carbonyl group. Ring opening of the epoxide thus formed yields the hydroxy dimethyl acetal ... 

Iodine, detection of, 1041, 1042, 1043, 1045 recovery of, 647 Iodine monochloride, 974 5-Iodo-2-ammotoluene, 647 p-Iodoaniline, 647 Iodobenzene, 533, 538, 591, 598 Iodobenzene diacetate, 541 Iodobenzene dichloride, 534, 541 o-Iodobenzoic acid, 760... 

A. Diphenyliodonium-2-carboxylate. An Erlenmeyer flask containing 80 ml. of concentrated sulfuric acid (Note 1) is placed in an ice bath to cool. To a 2-1. three-necked flask are added (Note 2) 20 g. (0.081 mole) of lump-free o-iodobenzoic acid (Note 3) and 26 g. (0.096 mole) of potassium persulfate (Note 4.) The flask is cooled in an ice bath, the chilled sulfuric acid is added, and the flask is swirled in an ice bath for 4-5 minutes to produce an even suspension and to control the initial exothermal reaction. The flask is then removed from the ice bath and the time is noted. 

The o-iodosobenzoic or o-iodobenzoic acids, recovered from the work-up of oxidations with Dess-Martin periodinane, can be recycled back to this oxidant by oxidation to IBX, followed by transformation of IBX into Dess-Martin periodinane.2... 

In this work-up, the periodinane species 38s, resulting from the reduction of Dess-Martin periodinane, is further reduced with sodium thiosulfate to o-iodobenzoic acidh that is removed with a sodium bicarbonate aqueous solution. The treatment with sodium thiosulfate is normally made in the presence of sodium bicarbonate as buffer. This is the most common work-up because it is done under almost neutral conditions and the organic periodinane 38 is destroyed thus, avoiding a possible difficult chromatographic separation from the product. The o-iodobenzoic acid can be recycled back to Dess-Martin periodinane by oxidation. 

The o-iodoxybenzoic acid (37) (p. 181) commonly known as IBX was prepared for the first time more than a century ago by Hartman and Meyer by oxidation of o-iodobenzoic acid with KBrC>3.4 This compound was not explored in organic synthesis for a long time because it was wrongly supposed that its virtual lack of solubility in common organic solvents would preclude any synthetic usefulness. IBX came to the attention of the organic... 

Two polyvalent iodine compounds arising from o-iodobenzoic acid have been found to be useful synthetic reagents. Thus oxidation of the iodo acid (7) with potassium persulphate, followed by the addition of benzene and treatment with potassium iodide gives the iodonium iodide (8) which is converted into diphenyliodonium-2-carboxylate [DPIC (9)] with aqueous alkali (Expt 6.35).16... 

The periodinane (10) may also be prepared from o-iodobenzoic acid by oxidation with potassium bromate and then treatment with acetic anhydride18 (see Expt 6.36 for detailed formulation). It should be noted that the organic derivatives of pentacoordinate iodine(v) are termed periodinanes.18b This compound (the systematic name is l,l,l-triacetoxy-2,l-benzoxiodol-3(3//)-one) has found use as an oxidant of primary alcohols to aldehydes and alicyclic ketones to secondary alcohols it is claimed to have advantages over the chromium-based oxidation reagents. 

Potassium persulphate (42.0 g, 0.156 mol) is added at 10 °C over 40 minutes to a solution of o-iodobenzoic acid (20.0 g, 0.0807 mol) in 80 ml of concentrated sulphuric acid, and the mixture is kept at this temperature for an additional 20 minutes. Benzene (75 ml) (CAUTION) is added, and the mixture is stirred for 3 hours at 25 °C and then poured on to ice. A small amount of 2-carboxydiphenyliodonium bisulphate is collected. The addition of 40 g of potassium iodide in a minimum of water precipitates the iodonium iodide. The salts are combined and stirred with 200 ml of 5 m sodium hydroxide, and the product (DPIC) is collected and washed with water. Recrystallisation from c. 350 ml of water gives 20.1 g (77%) of DPIC as coarse prisms (not hydrated), m.p. 223-225 °C. 

Iodoxybenzoic acid. Potassium bromate (76.0 g, 0.45 mol) is added over a half-an-hour period to a vigorously stirred mixture of o-iodobenzoic acid (85.2 g, 0.34 mol) and 730 ml of 0.73 m sulphuric acid. During the addition the reaction mixture is kept below 55 °C. The mixture is warmed to 65 °C and stirred for 3.6 hours. Cooling to 0°C, filtering, and washing with 1000 ml of water and two 50-ml portions of ethanol give the product (89.1 g, 93%). 

Filtering the slurry in an inert atmosphere and washing with 180 ml of ether gives the product (35.1 g), 93 per cent in overall yield from o-iodobenzoic acid. This compound has an indefinite shelf-life when stored in a sealed container. 

Many of these iodanes are formed by oxidation of ortho-iodobenzoic acids or certain orf/zo-iodophenylated alcohols with Cl2, AcOOH, f-BuOCl, CF3OF or magnesium monoperoxyphthalate. Among A3-iodanes more important are those derived from o-iodosobenzoic acid which is obtained from the mild oxidation of o-iodobenzoic acid. An improved yield for o-iodosobenzoic acid was obtained by hydrolysis of its acetyl derivative which in turn was prepared from o-iodobenzoic acid and acetyl nitrate in acetic anhydride, at room temperature (Scheme 14) [52]. 

The Dess-Martin reagent was prepared in two steps from o-iodobenzoic acid which was first converted into the isolable o-iodylbenzoic acid , of cyclic structure. The original procedure for the second step was substantially improved. 

Iodonium salts with a hydroxyl or a carboxyl group are readily converted into their inner salts, i.e. zwitterionic compounds of various types. 2-(Phenyliodonio) benzoate, whose structure may be cyclic, belongs to this category it is prepared from o-iodobenzoic acid upon oxidation and coupling with benzene (or arenes) [51], On strong heating, iodobenzene and carbon dioxide are eliminated, with formation of benzyne ... 

Chlorine was passed into a cold solution of o-iodobenzoic acid (15 g, 60 mmol) in chloroform (400 ml) until no more precipitate was formed. The yellow crystalline mass formed (16 g, 82%) was collected and dissolved in aqueous sodium hydroxide on careful acidification with dilute hydrochloric acid iodosylbenzoic acid precipitated (10 g, 62%) as colourless crystals, m.p. 230-231°C (from water). An... 

---