Iodonium hydroxide

A small portion of the iodosobenzene is probably oxidised to iodoxy-benzene, C6HSI02, which reacts with the hypothetical hydroxide, C6H5. I(OH)2, to give diphenyl iodonium hydroxide and iodic acid. This base is present in the alkaline filtrate from the iodosobenzene. The sulphur dioxide reduces the iodic acid to hydriodic acid, which, combining with the iodonium base, forms an iodide insoluble in cold water. 

Phenyl lodonium Hydroxide.—These iodoso compounds are derivatives of the hypothetical base, CeHs—I(0H)2, phenyl iodonium hydroxide. When a solution of iodoso benzene is heated it decomposes as follows ... 

Di-phenyl lodonium Hydroxide.—When iodoso benzene and iodoxy benzene, mixed in molecular proportions, are treated with silver hydroxide a strongly basic hydroxide compound is obtained of the formula (C6H5)2=I(OH), known as di-phenyl iodonium hydroxide. 

Iodonium Hydroxide.—These iodonium compounds are considered as derivatives of a hypothetical base, H2l(OH), iodonium hydroxide, as above. 

IODONIUM CHLORIDE 1-PHENYL-2, 4-PENTANEDIONE, 51, 128 4-Phenyl-l-carbethoxysemicar-bazide, from ethyl hydra-zinecarboxylate and phenyl isocyanate, 51, 122 with potassium hydroxide to give 4-phenylurazole, 51,... 

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. 

In a rare example of the use of iodonium salts for heteroatom-heteroatom bond formation, diaryliodonium halides were employed with sodium 0,0-diethyl phosphoroselenolate for a one-pot synthesis of diaryl diselenides (Scheme 9) [27]. These transformations probably occur via arylation of the phosphoroselenolate salt with the diaryliodonium ions, hydrolysis of the resulting aryl phosphoroselenolates with sodium hydroxide, and air oxidation of the arene-selenide ions thus produced. 

From iodine, too, iodonium compounds have been prepared, in which the iodine functions as a triad and a hydroxide with basic properties is known. 

The reaction is thought to proceed as shown in Figure B4.2. After hydroboration and addition of hydroxide anion to the boron atom, an iodonium species is formed which creates an electrophilic terminus for alkyl migration. (The migration occurs with retention of configuration of the alkyl group.) Finally an antiperiplanar elimination reaction gives the (Z)-alkene. 

To a stirred suspension of 2-amino-1,4-naphthoquinone (173 mg, 1 mmol) in dichloromethane (15 ml) was added [hydroxy(tosyloxy)iodo]benzene (411 mg, 1.05 mmol). After 20 min, the yellow iodonium salt which separated was collected, washed with dichloromethane and dried (520 mg, 95%). This salt (547 mg, 1 mmol) was added to a cold aqueous solution of 2% sodium hydroxide (2 mmol). The mixture was stirred until the yellow colour turned red, about 20 min the precipitate was collected, washed with water and ether and dried to give 2-phenyliodonio-l,4-naphthoquinone-3-imide (263 mg, 70%), m.p. 115-117°C. 

This synthesis of 1,2,3,4-tetraphenylnaphthalene (7) demonstrates the transient existence of benzyne (5), a hydrocarbon that has not been isolated as such. The precursor, diphenyliodonium-2-carboxylate (4), is heated in an inert solvent to a temperature at which it decomposes to benzyne, iodobenzene, and carbon dioxide in the presence of tetraphenylcyclo-pentadienone (6) as trapping agent. The preparation of the precursor (4) illustrates oxidation of a derivative of iodobenzene to an iodonium salt (2) and the Friedel-Crafts-like reaction of the substance with benzene to form the diphenyliodonium salt (3). Neutralization with ammoniuim hydroxide then liberates the precursor, inner salt (4), which, when obtained by crystallization from water, is the monohydrate. 

Treatment with moist silver oxide gives a solution of the corresponding hydroxide dry silver oxide does not yield an oxide but decomj)oses the chloride with formation of mercury diphenyl, mercuric oxide, and silver chloride. When an acetone solution of phenylmercuric chloride is treated with a similar solution of sodium iodide, phenylmercuric iodide is formed." Arsenic trichloride heated at 100° C. for four to five hours with the chloride delds phenyl dichloroarsine. With phenyl iododichloride it yields mercuric chloride and diphenyl iodonium chloride. Ethyl mercaptan decomposes phenylmercuric chloride at 150° 0. jitlding ethyl thio-mercurie chloride, ClHg.SEt. ... 

We note later some cations containing exclusively halogen atoms. Iodine also forms ions (R-I-R)" in which the groups R are usually aromatic radicals (Ar). The halides (Ar-I-Ar)X are not very stable, but the hydroxides are strong bases, proving dissociation to (Ar-I—Ar) ions. These iodonium compounds are the analogues of ammonium and sulphonlum compounds ... 

Among the reactions of diaryliodonium salts with inorganic compounds, their hydrolysis has been studied in detail.40.41,43,51-53 jhe hydrolysis reaction proceeds quite slowly in boiling water. However, in the presence of aqueous alkali, the hydrolysis takes place in a few days for diphenyl-iodonium bromide to afford a mixture of iodobenzene, bromobenzene and phenol. With weakly nucleophilic anions, the reaction affords iodobenzene, phenol and a small amount of diphenylether. The reaction was considered to involve an unstable hydroxydiaryliodane, which is likely to be in equilibrium with diaryliodonium hydroxide. Decomposition of the hydroxyiodane leads to the... 

Arylphosphonic acid esters are produced in the reaction of diaryl iodonium salts with trialkyl phosphites in the presence of copper salts, but despite the simplicity of the procedure yields are low owing to side reactions. The cyclic bisarylphosphinic acid (66) is conveniently prepared by fusion of the phosphine oxide (67) with sodium hydroxide. A successful... 

Most iodonium ylides have low thermal stability and can be handled only at low temperature or generated and used in situ. The relatively stable and practically important iodonium ylides, the dicarbonyl derivatives PhIC(COR)2 [535,540-543] andbis(organosulfonyl)(phenyliodonium)methanides, PhIC(S02R)2 [544-547], are prepared by the reaction of (diacetoxyiodo)benzene with the appropriate dicarbonyl compound or disulfone under basic conditions. A general procedure for the synthesis of phenyliodonium ylides 397 from malonate esters 396 is based on the treatment of esters 396 with (diacetoxyiodo)benzene in dichloromethane in the presence of potassium hydroxide (Scheme 2.115) [542]. An optimized method for preparing bis(methoxycarbonyl)(phenyliodonium)methanide (399) by using reaction of dimethyl malonate... 

Mr,w M = 1.12), was spin-coated from a 1-butanol solution directly onto the lower layer. The PHOSt layer is loaded widi a 5 % mass fraction of the photoacid generator, di(tert-butylphenyl) iodonium perfluorooctanesulfonate. The bilayer is subjected to another PAB for 90 s at 130 C. The model bilayer stack was exposed with a broadband UV dose of 1000 mJ/cm to generate acid within the top PHOSt layer followed by PEB at 110 C for varying times of 15 s, 20 s, 30 s, and 90 s. The original PHOSt layer and the soluble deprotected d-PBOCSt reaction products were removed (developed) by immersion in a 0.26 N tetramethylammonium hydroxide (TMAH) solution for 30 s followed by a rinse with deionized water. The use of deuterated PBOCSt facilitates the measurement of the deprotection profile using neutron reflectometry, described below. The approximate deprotection reaction of d-PBOCSt into PHOSt is shown schematically in figure 1. Neutron Reflectivity... 

Preparation by hypervalent iodine oxidation of 5-bromo-resacetophenone with iodosobenzene diacetate in the presence of potassium hydroxide in methanol via the rearrangement of iodonium yUde previously formed (35%) [3511]. 

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