Iodo acid

Higher-molecular-weight normal 2-alkenoic acids have been prepared in poor yields by the Doebner condensation of aldehydes with malonic acid,5-7 and by the Reformatsky reaction of aldehydes with ethyl bromoacetate followed by dehydration.8 The a-iodo acid, prepared from the bromo acid, has been dehydrohalogenated with potassium hydroxide in ethanol,9 but large quantities of the a-hydroxy acid are formed as a by-product which is difficult to separate in some instances. The present procedure is an adaptation of a published method.6... 

The splitting of (XII) took place smoothly with constantboiling hydriodic acid to give the pure iodo acid. The fluorina-tion of (XIII) was more facile than that of (XIV). In fact, with the latter acid, hydrogen iodide was eliminated to some extent with the production of ethyl hept-6-enecarboxylate, which was effectively removed by conversion into the dibromide with bromine, followed by distillation. 

Method B The -iodo acid chloride (2 mmol) is added to the solid TEBA-MoS4 (l. 34 g, 2.2 mmol) and the mixture is ground together for 15 min. The thiolactone is extracted from the solid mass with CH2Cl2 and purified by chromatography from silica (n = 3,52% n = 4, 70%). 

Recently, Duirk et al. [34] showed evidence that iodinated X-ray contrast media (ICM), such as iopamidol, constitute an iodine source to form iodo-THM DBFs, e.g., dichloroiodomethane, and iodo-acid DBFs, e.g., iodoacetic acid, in chlorinated and chloraminated drinking waters. However, the complete reaction pathway is not fully understood yet, and it is under further investigation. Chloraminated and chlorinated source waters with iopamidol were genotoxic and cytotoxic in mammalian cells. This is in agreement with the previously reported high genotoxicity and cytotoxicity of the iodo-acids and iodo-THMs [20, 21]. 

MS, chemical ionization-MS, and sometimes GC/infrared spectroscopy (IR) have been used with GC/MS to obtain structural information. Examples of the use of GC/ MS for identifying new DBFs include the recent identification of iodo-acids. The iodo-acids were discovered in drinking water treated with chloramination through the use of full-scan GC/MS on the methylated extracts. Empirical formula information for both the molecular ions and the fragment ions was obtained by high-resolution electron ionization (EI)-MS, and the spectra were interpreted to yield tentative identifications of five new iodo-acids (iodoacetic acid, bromoiodoacetic acid, ( )-3-bromo-3-iodopropenoic acid, (Z)-3-bromo-3-iodopropenoic acid, and )-2-iodo-3-methylbutenedioic acid). Structural assignments were then confirmed by the match of mass spectra and GC retention times to authentic chemical standards, several of which had to be synthesized. 

For methods for the conversion of lactones into co-iodo acids see p. 733. Experiment 5.164 2-BROMOHEXANOIC ACID... 

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 molten mixture of iodo-acid and silver is maintained at 100°—120° until it thickens and the temperature is then raised to 150°—160°. After remaining at this temperature for two or three hours the mixture is cooled and then extracted with boiling water, The aqueous extract, on evaporation, deposits a considerable crust of adipic acid which is separated. A further quantity of adipic acid is obtained by evaporating the mother-liquor, and the whole may be recrystallised from hot water. Colourless crystals m.p, 148°-149°,... 

The corresponding bromine derivative, H2Pt(CN)4Br2, has been obtained, and several salts of these adds and of the iodo acid have also been prepared.3... 

A carboxyl group is removed from a heterocyclic nucleus in much the same way as from an aromatic nucleus (method 13), i.e., by thermal decomposition. The pyrolysis is catalyzed by copper or copper salts and is frequently carried out in quinoline solution. The reaction is important in the synthesis of various alkyl and halo furans. Furoic acid loses carbon dioxide at its boiling point (205°) to give furan (85%). A series of halo furans have been made in 20-97% yields by pyrolysis of the corresponding halofuroic acids. The 5-iodo acid decarboxylates at a temperature of 140°, whereas the 3- and 5-chloro acids requite copper-bronze catalyst at 250°. ... 

Cyclamenol A is one of the very few noncarbohydrate and nonpeptide natural products that inhibits leukocyte adhesion to endothelial cells. Bis-vinyl iodide (70), a precursor for cyclamenol A, is prepared from iodo acid 68 and amine 69.27... 

A tandem cross-coupling-lactonization between terminal alkyne 19 and Z-iodo acid 20 was anticipated to afford freelingyne, a sesquiterpene from Eremophilia freelingiiP Curiously, presumed free-radical involvement prevented the desired course of reaction. 

A Finkelstein substitution with practical utility was reported some years ago (Fig. 34).130 An co-bromo fatty acid undergoes halogen exchange with radioactive Na 23i to provide the labelled iodo acid, used as a tracer for the medical exploration of cardiac metabolism. The sonochemical reaction conducted in butanone provides quantitative yields of the expensive and thermally labile product, and the presence of water in the solvent, up to 7%, is tolerated. In comparison, the usual method requires heating at ca. 180 C and anhydrous conditions, and the purity of the product is much less satisfactory. It can be noticed that the unusually high temperature of the sonochemical reaction, close to the solvent boiling point, makes an interpretation hazardous. A second case of a Finkelstein substitution, a mesylate-iodine exchange, was published recently without experimental detail. i... 

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