Mercuric oxide bonds

Triphenylbismuth oxide [7173-99-1/, C gH BiO, has been prepared from triphenylbismuth dicyanide [41083-16-3], C2QH25B1N2, and mercuric oxide (151), and from triphenylbismuth dichloride and moist silver oxide (152). The ir and Raman spectra of this compound suggest that it is polymeric and has Bi—O—Bi bonds (153). Triphenylbismuth dihydroxide, and triarylbismuth hydroxide haUdes, eg, triphenylbismuth hydroxide chloride... 

In a modified procedure the free carboxylic acid is treated with a mixture of mercuric oxide and bromine in carbon tetrachloride the otherwise necessary purification of the silver salt is thereby avoided. This procedure has been used in the first synthesis of [1.1.1 ]propellane 10. Bicyclo[l.l.l]pentane-l,3-dicarboxylic acid 8 has been converted to the dibromide 9 by the modified Hunsdiecker reaction. Treatment of 9 with t-butyllithium then resulted in a debromination and formation of the central carbon-carbon bond thus generating the propellane 10." ... 

The hydration of triple bonds is generally carried out with mercuric ion salts (often the sulfate or acetate) as catalysts. Mercuric oxide in the presence of an acid is also a common reagent. Since the addition follows Markovnikov s rule, only acetylene gives an aldehyde. All other triple-bond compounds give ketones (for a method of reversing the orientation for terminal alkynes, see 15-16). With allqmes of the form RC=CH methyl ketones are formed almost exclusively, but with RC=CR both possible products are usually obtained. The reaction can be conveniently carried out with a catalyst prepared by impregnating mercuric oxide onto Nafion-H (a superacidic perfluorinated resinsulfonic acid). ... 

Barton oxidation was the key to form the 1,2-diketone 341 in surprisingly high yield, in order to close the five-membered ring (Scheme 38). The conditions chosen for the deprotection of the aldehyde, mercuric oxide and boron trifluoride etherate, at room temperature, immediately led to aldol 342. After protection of the newly formed secondary alcohol as a benzoate, the diketone was fragmented quantitatively with excess sodium hypochlorite. Cyclization of the generated diacid 343 to the desired dilactone 344 proved very difficult. After a variety of methods failed, the use of lead tetraacetate (203), precedented by work performed within the stmcmre determination of picrotoxinin (1), was spectacularly successful (204). In 99% yield, the simultaneous formation of both lactones was achieved. EIcb reaction with an excess of tertiary amine removed the benzoate of 344 and the double bond formed was epoxidized with peracid affording p-oxirane 104 stereoselectively. Treatment of... 

Photochemical Cleavage (see p. 335). The energy of light of 600-300 nm is 48-96 kcalmoP (200-400 kJ moP ), which is of the order of magnitude of covalent-bond energies. Typical examples are photochemical cleavage of alkyl halides in the presence of triethylamine, alcohols in the presence of mercuric oxide and iodine,alkyl 4-nitrobenzenesulfenates, chlorine, and of ketones ... 

The latest data on mercurous halides (Table 26.1) do not confirm the earlier conclusion that the length of the Hg-Hg bond increases with decreasing electronegativity of the halogen. Organic mercurous compounds containing the system -C-Hg-Hg-C- are not known. Mercurous oxide is apparently a mixture of HgO and Hg. ... 

Catalyst for addition to acetylenes. The conversion of 1-ethynylcyclohexanol to 1-acetylcyclohexanol by hydration of the triple bond is accomplished by dissolving 5 g. of Mallinckrodt red mercuric oxide in a solution of 8 ml. of coned, sulfuric... 

The recently determined structure of mercuric oxide has two short collinear Hg-0 bonds and two much weaker bonds at right angles (6). The sulfide is dimorphic. One form has the tetrahedrally coordinated sphalerite structure (Table Y) the other, cinnabar (5), contains infinite chains like those of the oxide. Here, however, the packing of the chains is different and is such as to complete a very distorted octahedral environment... 

The second piece of evidence against Robinson s strychnine formula arises from the bromine oxidation of Wieland s Ci7-acid. If the double bond of Wieland s acid (XXVIII) is oxidized with bromine-hydrobromic acid reagent (106, 111), the keto aldehyde, XLV, is formd. It may be further oxidized by mercuric oxide to the corresponding acid (XLVI). Reduction of one of the ketonic groups of XLVI to an alcohol and dehydra-... 

The brucine double bond of the acid Ci7H2206N has been oxidized (3 Br2 -1- HBr) to the aldehydic acid, C17H22O7N2, and this in turn converted to the dicarboxylic acid C17H22O8N2 by mercuric oxide (107). 

Oxidation numbers for Hg (I) and (II), as in Hg20, mercurous oxide, HgO, mercuric oxide, and Hg 0 2 [mercuiy(ll) peroxide]. The mercurous ion is dimercury(2+) or dimercury(I), Hg2. Relativity greatly strengthens the Hg-Hg bond but may also explain the metal s liquidity. Relativity shrinks and stabilizes mercury s 6s orbital, making Hg rather like a noble gas but favoring linear sp hybrids with more (1/2 s) low-energy s nature than the tetrahedral sp (1/4 s). The many (linear) oigano-mercury compounds are excluded here. 

Methylation of avermectins B and B2 leads to the corresponding derivatives of the A series (49). A procedure involving the oxidation of the 5-methoxy group with mercuric acetate and NaBH reduction of the 5-keto-intermediate allows the conversion of the A to the B components (50). The 23-hydroxy group of the "2" components, after selective protection of the other secondary hydroxy groups, is converted to a thionocarbonate, which can be elirninated to give the 22,23-double bond of the "1" components alternatively it can be reduced with tributyltin hydride to the 22,23-dihydro derivatives (= ivermectins) (51). 

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