Mercury exchange with

R = Me or CH3CO) (279). Retention of configuration when mercurials exchange with Pd(II) salts was also demonstrated by carbonylation of the Pd(II) products as discussed above 251). 

Vinylic bromides. Reaction of vinylcopper reagents (2) with bromine leads to products of oxidation (dienes). However, vinylic bromides can be prepared from (2) by a two-step procedure. For example, (3) undergoes copper-mercury exchange with retention of configuration on treatment with mercuric bromide (0.5 eq.) to give (4) in 74% yield. This compound is converted by bromine in... 

Potentiometric Titrations. If one wishes to analyze electroactive analytes that are not ions or for which ion-selective electrodes are not available, two problems arise. First, the working electrodes, such as silver, platinum, mercury, etc, are not selective. Second, metallic electrodes may exhibit mixed potentials, which may arise from a variety of causes. For example, silver may exchange electrons with redox couples in solution, sense Ag" via electron exchange with the external circuit, or tarnish to produce pH-sensitive oxide sites or Ag2S sites that are sensitive to sulfide and haUde. On the other... 

R2NC1, 91, 92 phenyl acetate, Fries rearrangement of, 475 phenyacetyl halides, acylation by, 173 2-phenylbenzoic acid, cycliacylation, 185 phenyl ethers, alkylation of, 149 —, bromination of, 130 —, hydrogen exchange with, 260 —, rearrangement of, 476 phenyl ethyl mercury, mercuridemercuration of, 359, 360... 

The mercuration of phosphonium derivatives has also been observed. The methylene group of the dimeric palladium complex 63 substituted by a carbonyl and a phosphonium functionality is readily mercurated upon reaction with Hg(OAc)2 to afford complex 64 (Equation (22)).7 Further studies demonstrated that the presence of a triphenylphosphonium group alone is sufficient to promote proton-mercury exchange. For example, the reaction of... 

Sulfonation of anthraquinone to form the 1-sulfonic acid is achieved at approximately 120°C with 20% oleum in the presence of mercury or a mercury salt as a catalyst [2], Without this catalyst, the reaction produces the 2-sulfonic acid. Exchange with aqueous ammonia (30%) at about 175°C under pressure converts the potassium salt of 1-sulfonic acid to 1-aminoanthraquinone in 70 to 80% yield. To avoid sulfite formation, the reaction is performed in the presence of an oxidant, such as m-nitrobenzosulfonic acid, which destroys sulfite. 

The procedure described illustrates a new general synthetic method for the preparation of (E)-3-allyloxyacryl ic acids and their conversion to a-unsubstituted y,5-unsaturated aldehydes by subsequent Claisen rearrangement-decarboxyl at ion. Such aldehydes are traditionally prepared by Claisen rearrangements of allyl vinyl ethers. Allyl vinyl ethers are typically prepared by either mercury-catalyzed vinyl ether exchange with allylic alcohols or acid-catalyzed vinylation of allylic alcohols with acetals. The basic conditions required for alkoxide addition to the betaine to produce carboxyvinyl allyl ethers, as described in this report, nicely complements these two methods. In addition, this Claisen rearrangement is an... 

Lithiation of dibenzofuran with butyllithium and mercuration both occur at the 4-position. Thallation occurs at the 2-position, however (57IZV1391). The mercury and thallium derivatives serve as a source of the iodo compounds by reaction with iodine. Bromodibenzofurans undergo bromine/lithium exchange with butyllithium and the derived lithio compounds may be converted into phenols by reaction with molecular oxygen in the presence of a Grignard reagent, into amines by reaction with O-methylhydroxylamine, into sulfinic acids by reaction with sulfur dioxide, into carboxylic acids by reaction with carbon dioxide and into methyl derivatives by reaction with methyl sulfate (Scheme 100). This last reaction... 

The hydration reaction of alkynes leading to carbonyl compounds is generally carried out in dilute acidic conditions with mercuric 1on salts (often the sulfate) as catalysts (ref. 5). Only very reactive alkynes (phenylacety-lene and derivatives) can be hydrated in strong acidic conditions (HgSO ) without mercury salts (ref. 6). Mercury exchanged or impregnated sulfonic resins have also been used in such reactions (ref. 7). Nevertheless, the loss of the catalyst during the reaction and environmental problems due to the use of mercury make this reaction method not as convenient as it should be for the preparation of carbonyl compounds. 

Mercury compounds are often used as electrophiles in displacements on organomercurials. There are five possible combinations of reactants in such mercury exchange reactions. A dialkylmercurial substrate may be attacked either by a mercury salt (Reaction 4.43) or by a monoalkylmercurial (Reaction 4.44) and likewise a monoalkylmercurial may react either with a mercury salt or with another monoalkylmercurial (Reactions 4.45 and 4.46). Finally, a dialkylmercurial may react with another dialkylmercurial (Reaction 4.47). (In Reactions 4.43-4.47 and in other reactions in this section, one of the reactants, and the fragments derived from that reactant in the products, are written in italics. This is done to make it easier to follow the course of the reaction.)... 

The first detailed study of the stereochemistry of a mercury exchange reaction that was known to be bimolecular was carried out as follows.83 Di-j-butyl-mercury was prepared by reacting optically active j-butylmercuric bromide with racemic i-butylmagnesium bromide as shown in Equation 4.48. 

The specific rotation of the initial. y-butyl bromide used by Charman, Hughes, and Ingold was —15.2°. The specific rotation of the product of the mercury exchange reaction was exactly half that, — 7.6°. When mercuric acetate or mercuric nitrate was used as the cleaving salt, the products showed a specific rotation of —7.5° and —7.8°, respectively. Thus this electrophilic substitution clearly proceeds with retention of configuration. 

Reddy, M. L. P. and Francis, T. (2001) Recent advances in the solvent extraction of mercury(II) with calixarenes and crown ethers, Solvent Extraction and Ion Exchange, 19(5), 839-863. 

Over the last two decades Russian workers have uncovered a host of interesting SE reactions with retention at an alkene center (Reutov, 1967b). These have involved exchanges with mercury, lead, tin, thallium, etc. attached to an alkene carbon ... 

Description Three RAM processes are available to remove arsenic (RAM I) arsenic, mercury and lead (RAM II) and arsenic, mercury and sulfur from liquid hydrocarbons (RAM III). Described above is the RAM II process. Feed is heated by exchange with reactor effluent and steam (1). It is then hydrolyzed in the first catalytic reactor (2) in which organometallic mercury compounds are converted to elemental mercury, and organic arsenic compounds are converted to arsenic-metal complexes and trapped in the bed. Lead, if any, is also trapped on the bed. The second reactor (3) contains a specific mercury-trapping mass. There is no release of the contaminants to the environment, and spent catalyst and trapping material can be disposed of in an environmentally acceptable manner. 

Thus, not only should alkylmercuric iodides and dialkylmercurials have a more nucleophilic carbon compared with the others, but their respective -Hg-X functions should also be better leaving groups in electrophilic substitution reactions. This latter prophesy is supported in part by the results of Hughes et al. from their kinetic studies of mercury exchange reactions (20). 

The synthesis of benzyl fluorides from benzyl halides is problematic due to the tendency to undergo Friedel Crafts reactions.The fluorination of benzyl bromide with thallium(l) fluoride gives impure benzyl fluoride and attempts to fluorinate benzyl halides with anti-mony(III) fluoride, silver fluoride, and potassium fluoride were all unsuccessful. Benzyl fluorides with substituents which deactivate the aromatic system towards Friedel-Crafts reactions are successfully obtained through halogen exchange with mercury(II) fluoride (Table... 

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