Mercury compounds reagents

RM can be a traditional Grignard reagent or an organolithium, 2inc, aluminum, or mercury compound. The Grignard route is employed commercially for production of tertiary phosphines, even though these reactions are subject to side reactions. Yields are often low, eg, 40—50% for (C4H )2P prepared via a Grignard reaction (18). A phosphoms—carbon bond can form from the metathetical reaction of a phosphoms haUde and a pseudohaUde salt. 

Methyl ketones are important intermediates for the synthesis of methyl alkyl carbinols, annulation reagents, and cyclic compounds. A common synthetic method for the preparation of methyl ketones is the alkylation of acetone derivatives, but the method suffers limitations such as low yields and lack of regioselectivity. Preparation of methyl ketones from olefins and acetylenes using mercury compounds is a better method. For example, hydration of terminal acetylenes using HgSO gives methyl ketones cleanly. Oxymercuration of 1-olefins and subsequent oxidation with chromic oxide is... 

Organomercury reagents do not react with ketones or aldehydes but Lewis acids cause reaction with acyl chlorides.187 With alkenyl mercury compounds, the reaction probably proceeds by electrophilic attack on the double bond with the regiochemistry being directed by the stabilization of the (3-carbocation by the mercury.188... 

In many syntheses activation is not effected by sonochemical preparation of the metal alone but rather by sonication of a mixture of the metal and an organic reagent(s). The first example was published many years ago by Renaud, who reported the beneficial role of sonication in the preparation of organo-lithium, magnesium, and mercury compounds [86]. For many years, these important findings were not followed up but nowadays this approach is very common in sonochemistry. In another early example an ultrasonic probe (25 kHz) was used to accelerate the preparation of radical anions [87]. Unusually for this synthesis of benzoquinoline sodium species (5) the metal was used in the form of a cube attached to the horn and preparation times in diethyl ether were reduced from 48 h (reflux using sodium wire) to 45 min using ultrasound. 

A rapid distribution of the added material is necessary to prevent a local excess of the reagent added. This is very important when hydrochloric acid is added, as this tends to decompose the mercury compound. A convenient arrangement consists of a 3-way tube of about 15-mm. bore. The stirrer operates through the center tube. The other arms are used for the condenser and for the addition of material. A three-necked flask provided with a long-stemmed separatory funnel reaching below the stirrer may be used. 

Benzyllithiums. These reagents are generally prepared indirectly from ben-zyltin or mercury compounds or from benzyl ethers. They can also be prepared by reaction of benzylphenyl or benzylmethyl selenides with n-, sec- or f-BuLi, since cleavage occurs exclusively at the benzyl—selenium bond.2... 

One of the very important traditional uses for alkyl mercury compounds has been their use as reagents in preparations of more reactive organometallic compounds. The trifluoromethyl mercurial is also beginning to demonstrate a similar utility as a precursor, for example, in the synthesis of the more reactive reagent (CF3)2Cd glyme. The latter material is clearly a superior agent for the formation of products of only limited thermal stability, since it is active at ambient temperatures and the reactions generally require only a few minutes, or at most a few hours. 

Both lead and mercury speciation has been performed by Shum and coworkers [43]. Direct injection nebulization and an ion-pair separation with a microbore LC column were used with ICP-MS detection. A mobile phase of 20 80% v/v ace-tonitrile/water with 5 mM ammonium pentanesulfonate ion pairing reagent at pH 3.4 was used to separate inorganic lead, inorganic mercury, and three organomer-cury species. Detection limits, based on peak area calculations, were 0.2 pg of Pb for all the lead compounds and 7-18 pg of Hg for the mercury compounds. Spiked urine samples were analyzed to evaluate the performance of the method. 

Lovenberg, Buchanan, and Rabinowitz (65) tested the response of ferredoxin to mercury compounds. Two mercurial reagents used, p-mer-curibenzoate (PCMB) and o-((3-hydroxymercuri-2-methoxypropyl)car-bamyl)phenoxyacetate (sodium mersalyl) reacted rapidly with ferredoxin and caused a bleaching of the visible spectrum and a concomitant loss of biological activity. C. pasteurianum ferredoxin was titrated with PCMB as described by Boyer (24) and the results showed that 20 moles of PCMB reacted with 1 mole of ferredoxin. In another determination, 2 moles of PCMB reacted with 1 mole of sodium sulfide. Since ferredoxin contained 7 moles of inorganic sulfide and 8 moles of half-cystine residues, 22 (7 x 2 = 14 14 + 8 = 22) moles of PCMB would be expected to react with 1 mole of ferredoxin. These data, summarized in Table 8, are consistent with the existence of two types of sulfur in ferredoxin. This conclusion was supported by the presence of half-cystine residues in ferredoxin after inorganic sulfide had been removed by acid hydrolysis, as well as results of sulfur analyses, which showed an amount of sulfur greater than could be attributed to half-cystine residues. 

Cathode in the electrolytic production of chlorine and caustic soda lamps arc rectifiers mercury cells switches thermometers barometers laboratory apparatus dental amalgams raw material for various mercury compounds fungicides antiseptics preservatives pharmaceuticals electrodes reagents... 

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