MERCURIC OXIDE MODIFIED

Mercuric oxide, use in oxidation of hydrazones, 50, 28 with 3-chlorocyclobutanecar-boxylic acid and bromine to give l-bromo-3-chlorocyclo-butane, 51, 106 MERCURIC OXIDE-MODIFIED HUNS-DIECKER REACTION 1-BRQMO-... 

MERCURIC OXIDE-MODIFIED HUNSDIECKER REACTION 1-BROMO-3-CHLOROCYCLOBUTANE... 

Lampman, G. M., Aumiller, J. C. Mercuric oxide-modified Hunsdiecker reaction. 1-Bromo-3-chlorocyclobutane. Org. Synth. 1971, 51, 106-108. 

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." ... 

In a 1-1. three-necked round-bottomed flask, wrapped with aluminum foil to exclude light, and equipped with a mechanical stirrer, a reflux condenser, and an addition funnel, is suspended 37 g. (0.17 mole) of red mercuric oxide (Note 1) in 330 ml. of carbon tetrachloride (Note 2). To the flask is added 30.0 g. (0.22 mole) of 3-chlorocyclobutaneearboxylic acid (Note 3), and the mixture is heated to reflux while stirring. To the mixture is added dropwise a solution of 40 g. (0.25 mole) of bromine in 180 ml. of carbon tetrachloride as fast as possible (4-7 minutes) without loss of bromine from the condenser (Note 4). After a short induction period, carbon dioxide is evolved at a rate of 150-200 bubbles per minute (Note 5). The solution is allowed to reflux until the rate of carbon dioxide evolution slows to about 5 bubbles per minute. This will usually take 25-30 minutes (Note 6). The mixture is then cooled in an ice bath, and the precipitate is removed by filtration. The residue on the funnel is washed with carbon tetrachloride, and the filtrates are combined. The solvent is removed by distillation using a modified Claisen distillation apparatus with a 6-cm. Vigreux column, and vacuum distillation of the residual oil gives 13-17 g. (35-46%) of... 

Hmtsdiecker Cristol reaction. (I, 657). A detailed procedure for the preparation of l-bromo-3-chlorocyclobutanc by the modified Hunsdiecker reaction has been published. A l-l. three-necked, round-bottomed flask wrapped with aluminum foil to exclude light and equipped with a mechanical stirrer, a reflux condenser, and an addition funnel, is charged with 37 g. (0.17 mole) of red mercuric oxide and 330 ml. 

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... 

A classical procedure of Carpenter for the preparation of (difluoroiodo)arenes involves a one-step reaction of (dichloroiodo)arenes with yellow mercuric oxide and 48% aqueous hydrofluoric acid in dichloromethane [56]. The resulting solution of (difluoroiodo)arenes in dichloromethane can be used in subsequent reactions without additional purification. A drawback of this method is the use of a large quantity of harmful HgO to remove the chloride ion from the reaction mixture. A convenient modified procedure without the use of HgO consists of the treatment of iodosylarenes 5 with 40-46% aqueous hydrofluoric acid (Scheme 2.2) followed by crystallization of products 6 from hexane [30,31]. It is important that the freshly prepared iodosylarenes 5 are used in this procedure. 

Over the years, several different battery technologies have been tried. Including mercury-zinc, rechargeable silver-modified-mercuric-oxide-zinc, rechargeable nickel-cadmium, radioactive plutonium or promethium, and lithium with a variety of different cathodes. Lithium-cupric-sulfide and... 

Early workers relied completely on the use of heavy metal salts in the hydrolysis of dithioacetals. The initial use of mercuric chloride with cadmium carbonate in hydroxylic medium was modified and generally improved by the substitution of mercuric oxide for the cadmium carbonate . However, in some cases the results of this method of hydrolysis have been disappointing. This is especially true in the recovery of aldehydes and steroidal ketones from their dithioacetals. Recently, numerous new methods of hydrolysis have emerged significantly changing the stature of dithioacetals as blocking groups. 

Two groups have independently concluded that the modified Huns-diecker reaction, using mercuric oxide and halogen, proceeds by the intermediacy of the mercuric carboxylate salt (Scheme 9), and does not involve bromine oxide, as had been proposed earlier. 

The chapter on Mercuric Oxide Batteries was written by Denis Naylor, now deceased, for the 1" and 2 Editions. His work was updated and modified for the 3 Edition by David Linden. 

Metelka R, Vytfas K, Bobrowski A (2000) Effect of the modification of mercuric oxide on the properties of mercury films at HgO-modified carbon paste electrodes. J Solid State Electrochem 4 348-352... 

The oxidation of amines by mercuric acetate is an old reaction (54) which up until recent years was employed primarily to modify alkaloid structures (55). A systemic study of the oxidizing action of mercuric acetate by Leonard and co-workers led to the development of a general method for the synthesis of enamines from cyclic tertiary amines. An observation made after a large number of compounds were oxidized, but which is worth noting at the onset, is that a tertiary hydrogen alpha to the nitrogen atom is removed preferentially to a secondary a-hydrogen. 

Mercuric acetate has been used for the oxidation of amine groups to give modified alkaloid structures [105-120]. 

Instead of making a direct volumetric determination of the hydrosulphite it is possible to modify the process by estimating volumetrically the product of a primary reaction. For example the hydrosulphite solution may be submitted to atmospheric oxidation and the resulting acidity determined with standard alkali,2 or a mercuric salt may be reduced, the mercury produced being estimated subsequently by the addition of standard iodine solution and titration of the excess of iodine one molecule of hydrosulphite is equivalent to an atom of mercury and therefore to two atoms of iodine.4 Similarly, instead of the gravimetric estimation of silver as described above, the latter may be redissolved in nitric acid and determined volumetrically.5... 

Cinnabar and vermilion usually contain only small proportions of impurities from the prime materials vermilion may also contain impurities due to the method of preparation, namely, small quantities of metallic mercury, mercuric nitrate and free sulphur. These products are, however, often adulterated with ferric oxide, minium, chrome red, brickdust, gypsum, heavy spar, clay, ammonium chloride, dragon s blood, carmine and artificial organic dyes. Sometimes also arsenic and antimony sulphides are added to modify the colour. 

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