Mercury oxide-iodine, alkyl

Within the context of toxicological and clinical importance, speciation studies have been focused on relatively few elements, mainly aluminum, antimony, arsenic, chromium, iodine, lead, mercury, platinum, selenium and tin. However, coupled HPLC-ICP-MS has most often been used for speciation of arsenic, selenium, iodine and, to a lesser extent, mercury. The primary species of these elements include different oxidation states, alkylated metal and/or metalloid compounds, selenoamino acids and selenopeptides.In addition, applications in smdies on the pharmacokinetics of metal-based drugs (mainly platinum complexes) and metalloproteins should be included. " In the following sections, the advances in speciation smdies of individual elements are reviewed. 

Although the net quantum yield of photodecomposition is found to be very small in the gas phase (typically 0.05), it has been found that in the presence of silver,16 mercury,16 oxygen,17 or nitric oxide,18 the quantum yield increases markedly. The two metals scavenge both atomic and molecular iodine, and the two gases scavenge alkyl radicals, thus suppressing both of the two possible inhibiting secondary steps. 

Saccharin 218 is obtained by KMn04 oxidation of o-methylbenzenesulfonamide 217 (Scheme 126). Various V-alkylsaccharins 219 (n = 2) and A-alkyl-l,2-benzisothiazolin-3-one A-oxides 219 (n= 1) are conveniently prepared in moderate to good yields by the reaction of A-alkyl(0-methylarene)sulfonamides with (diacetoxyiodo)benzene in the presence of iodine under irradiation with a tungsten or mercury lamp <1999T14885, CHEC-III(4.05.9.1.2)599>. 

The degradation of carboxylic acids to alkyl halides using mercuric oxide and halogens involves the initial formation of the mercuric salt of the acid, followed by a normal Hunsdiecker reaction of the salt with halogen. The relative insensitivity of the reaction to water is a consequence of the solubility of the mercury salts in the solvent (CC14). There are two limitations tertiary acids are not degraded, and use of iodine as the halogen frequently leads to the ester RCOOR as the major product. The yields in the modified reaction are usually lower than those obtained with the silver salt method.2... 

Alkyl hypochlorites and hypobromites are relatively stable molecules alkyl hypoiodites can only be prepared in situ, usually by the reaction of alcohols with metal acetates or oxides and iodine or by the reaction of alcohols with a hypervalent iodine compound and iodine.1319 Alkyl hypochlorites and hypoiodites can be utilized in reactions that parallel those of the organic nitrites (Barton reaction Section 6.4.2). For example, the photochemistry of the steroidal hypoiodite 497, prepared by the reaction of the corresponding alcohol with iodine oxide (I2O) generated from mercury(II) oxide and molecular iodine in situ, affords a new five-membered ring via an O I bond fission, 1,5-hydrogen abstraction and substitution (Scheme 6.244).1353... 

Monoiodination of 2-substitnted thiophenes, whether the substituent is activating or deactivating, proceeds efficiently at the remaining a-position using iodine with iodobenzene diacetate. 3-Alkyl-thiophenes can be monobrominated or monoiodinated at C-2 using Af-bromosuccinimide, or iodine with mercury(II) oxide, respectively. 

The intramolecular additions of alkoxyl groups to carbon-carbon double bonds to give P-iodo-alkyl ethers from alkyl hypoiodites under photolytic conditions have been reported. Suginome and collaborators found that the formation of a-iodoepoxides arising from an intramolecular a, P-addition of an allylic alkoxyl radical is a major general process in the photolysis of tertiary and some secondary allylic alcohol hypoiodites in the presence of mercury (11) oxide and iodine in benzene. Thus, 5-hydroxy-SP-cholest-3-ene gave epimeric a-iodoepoxides in a ratio of 10 1 in 86% yield as outlined in Scheme 86. Similar reaction of l-alkylcyclohex-2-en-l-ols gave a mixture of cis- and tr s-a-iodoepoxides (Scheme 87). The addition of pyridine dramatically enhanced the yield of the addition product. The yields of the a-iodoepoxides obtained from the photolysis of l-alkylcyclohex-2-en-l-ols and the ratios of cis- to trans-isomers are summarized in Table 109.1. 

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