Mercury method

The toxic nature of mercury and its compounds has caused concern over environmental pollution, and governmental agencies have imposed severe restrictions on release of mercury compounds to waterways and the air (see Mercury). Methods of precipitation and agglomeration of mercurial wastes from process water have been developed. These methods generally depend on the formation of relatively insoluble compounds such as mercury sulfides, oxides, and thiocarbamates. MetaUic mercury is invariably formed as a by-product. The use of coprecipitants, which adsorb mercury on their surfaces facihtating removal, is frequent. 

It is useful to measure the melting point of the solid resins. This can be done either by the ring and ball technique or by Durrans mercury method. In the latter method a known weight of resin is melted in a test tube of fixed dimensions. The resin is then cooled and it solidifies. A known weight of clean mercury is then poured on to the top of the resin and the whole assembly heated, at a fixed rate, until the resin melts and the mercury runs through the resin. The temperature at which this occurs is taken as the melting point. 

Scheme 9. Danishefsky s synthesis of bicyclo[3.3.0]octane 52 using Giese s reductive mercury method.

A much more accurate method of determining the pore volume of a catalyst sample is the helium-mercury method. One places a known weight of catalyst (IT) in a chamber of known volume. After the chamber has been evacuated, a known quantity of helium is admitted. From the gas laws and measurements of the temperature and pressure, one may then proceed to... 

Mercury Methods of Sampling, Preservation, and Analysis Economic and Technical Review Report EPS 3-EC-81-4, Environment Canada, 1981. 

European Standard. 2007. Water quality. Determination of mercury. Method using atomic absorption spectrometry. EN 1483. European Committee for Standardization, Brussels, Belgium. 

Because no known material can remain indefinitely undamaged by severe cavitation, the only sure solution is to eliminate it. The greatest damage is caused by a dense pure liquid with high surface tension (e.g., water or mercury). Methods to eliminate cavitation include the reduction... 

There are several methods commonly employed to measure the softening point, such as the ring-and-ball method and Durran s mercury methods. These measure the temperature at which the resin reaches an arbitrary softness. 

An alternative way of making alkyl radicals the mercury method... 

Scheme 4. Formation of 1,3-dimethyl-hexahydropyrimid-2-ylidene by the mercury method .

After the successful synthesis of several diamino carbenes, we tried to broaden the scope of application of the mercury method to monoamino carbenes. Note that our group using the deprotonation method reported the first examples of stable aryl amino carbene [15]. 

With the synthesis of amino oxy carbenes, we could also verify the applicability of the new method, and show that the mercury method might be an alternative to traditional ways for preparing stable amino carbenes. Aryl-, chloro- and hydrogeno-amino carbenes were formed as transient intermediates in our experiments and underwent dimerization. The dimers were generally obtained in good yields. 

Beckert WF, Messman JD, Churchwell ME, et al. 1990. Evaluation of SW-846 cold-vapour mercury methods 7470 and 7471. In Friedman D, ed. Waste testing and quality assurance. Second volume. Philadelphia, PA American Society for Testing and Material, STP 1062 247-257. 

Dichlorocarbene, generated from chloroform/potassium fert-butoxide, undergoes addition to a series of tertiary allylamines (and amides).If the dichlorocarbene was produced by the trichloromethyl(phenyl)mercury method, apart from the 1,1-dichlorocyclopropane derivatives, other products were isolated (see Houben-Weyl, Vol. 4/3, p 180). 

The chloroform and base/phase-transfer catalyst or potassium tert-butoxide and bromodichlo-romethyl(phenyl)mercury methods are useful for the cyclopropanation of allyl- and vinylsilanes (see also Houben-Weyl, Vol, E19b, p 1451). Typical examples are given in Table 22. 

Vinyl, allyl and homoallyl derivatives of germanium and tin also form the corresponding cyclopropanes with dichlorocarbene generated by the chloroform/potassium /er/-butoxide or bromodichloromethyl(phenyl)mercury methods (Table 23). ... 

There are only a few examples of cyclopropanes prepared via the addition of dichlorocarbene to alkenenitriles. Depending on the structure of the unsaturated nitrile, the chloroform/base/phase-transfer catalyst or dichlorohalomethyl(phenyl)mercury methods are used in the former case, the formation of the adducts of trichloromethyl anion competes considerably. Thus, acrylonitrile, but-2-enenitrile and 3-phenylpropenenitrile gave, by the phase-transfer catalytic method, Michael adducts exclusively. The same occurs if acrylonitrile reacts with trihalomethyl(phenyl)mercury and sodium iodide mixture. An example is the formation of 1 and... 

A more accurate procedure is the helium-mercury method. The volume of helium displaced by a sample of catalyst is measured then the helium is removed, and the volume of mercury displaced is measured. Since mercury will not fill the pores of most catalysts at atmospheric pressure, the difference in volumes gives the pore volume of the catalyst sample. The volume of helium displaced is a measure of the volume occupied by the solid material. From this and the weight of the sample, the density of the solid phase, P5, can be obtained. Then the void fraction, or porosity, of the particle, p, may be calculated from the equation... 

EN Standard (1998) Water quality - determination of mercury - methods after enrichment by amalgamation. EN 12338 1998. 

Method A Mercury method NaBH4. CH2C12. B Barton method CH2C12, hv. 

Similar inductions are observed in the hydrogen abstraction of amide-substituted radicals, intermediates in the addition reactions to chiral 2,5-dimethylpyrrolidine amide acrylates 3 using the mercury method 14. 

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