Alumina method

Soufiaoui reported that arylnitrile oxides 10 can be generated under microwaves not only from aromatic oxime chlorides, such as 174, by the action of alumina (Method A) but also from aryloximes, such as 176, by the addition of a chlorination agent, N-chlorosuccinimide (NCS), supported on alumina (Method B) (Scheme 9.54) [29a]. Both methods afforded identical cydoadducts in similar yields - when indene was used as the dipolarophile the yield was 86%. In the absence of alumina, method B fails (reagents are less reactive and decompose) and method A does not yield any cydoadduct but a dimer of the dipole. 

Bases that have been assayed by aqueous alumina methods are listed in Table 5.11 [27-29,47]. 

F. Rubel Jr., The removal of excess fluoride from drinking water by the activated alumina method, in J.L. Shupe, H.B. Peterson, N.C. Leone (Eds.), Fluoride Effects on Vegetation, Animals and Humans, Paragon Press, Salt Lake city, 1983, pp. 345-349. 

Bougrin et al. [4d] reported two approaches for 1,3-dipolar cydoaddition of nitrile oxides in open vessels under the action of microwave irradiation. The arylnitrile oxides 99 can be generated in situ under the action of microwaves by two different methods - from aryloximes for example 97, by addition of a chlorinating agent such as NCS (N-chlorosuccinimide) supported on alumina (Method A) and from hydroxamoic chloride, for example 98, under the action of alumina (Method B) (Scheme 11.26). 

Shin et al. have used a two-step route to obtain 2-unsubstituted pyrimidines from 2-thioxo DHPM derivatives. Oxidation of 22 using Oxone on wet alumina (method A) or hydrogen peroxide in the presence of a catalytic amount of vanadyl sulfate (method B) provided 1,4-dihydropyr-imidines 41, which were oxidized to 2-unsubstituted pyrimidines 44 by KMn04. However, 22 (X = S, O) with KMn04 furnished 2-hydroxypyri-midine 45 (Scheme 20) (09SL599). 

Without going into details of the chromatographic method, a SAR separation (asphaltenes having been eliminated) can be performed in a mixed column of silica followed by alumina. The saturated hydrocarbons are eluted by heptane, the aromatics by a 2 1 volume mixture of heptane and toluene, and the resins by a 1 1 1 mixture of dichloromethane, toluene and methanol. 

The above methods for obtaining D, as well as other ones, are reviewed in Refs. 3-12, and Refs. 7-9 give tables of D values for various adsorbents. For example, D is close to 3 for the highly porous silica gels and close to 2 for nonporous fumed silica and for graphitized carbon black coconut charcoal and alumina were found to have D values of 2.67 and 2.79, respectively [7]. 

The method of obtaining aluminum metal by the electrolysis of alumina dissolved in cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult in France. Cryolite, a natural ore found in Greenland, is no longer widely used in commercial production, but has been replaced by an artificial mixture of sodium, aluminum, and calcium fluorides. 

To separate the oil added an equal volume of fresh cool water (note waited until solution cooled before adding the water). The oil started to drop out perfectly, used DCM to extract all traces of the oil. This woik up is by far the cleanest, easiest and simplest to date... (This dreamer was tried all method of ketone synthesis)... Once the oil was extracted, the extracts were pooled washed with sodium bicarbonate lx, saturated solution of NaCI 1x, and two washes with fresh dHzO... Some time was required for the work up as there was a little emulsion from the use of the base wash and then with the first water wash. The JOC ref suggested using an alumina column to remove the catalyst (could be a better way to go). 

The first was from a CA article [81]. Various alkenes, styrene and cycloalkenes were tried. But a more followable method is the following [82]. The supported salt of NaNs-AljOs was made by mixing the NaNs with the alumina in water then evaporating the mixture under vacuum in a water bath until dry ... 

Fig. 3.28 The Kiselev method for calculation of specific surface from the Type IV isotherm of a compact of alumina powder prepared at 64 ton in". (a) Plot of log, (p7p) against n (showing the upper (n,) and lower (n,) limits of the hysteresis loop) for (i) the desorption branch, and (ii) the adsorption branch of the loop. Values of. 4(des) and /4(ads) are obtained from the area under curves (i) or (ii) respectively, between the limits II, and n,. (6) The relevant part of the isotherm.

Disposal. Fluorine can be disposed of by conversion to gaseous perfluorocarbons or fluoride salts. Because of the long atmospheric lifetimes of gaseous perfluorocarbons (see Atmospheric models), disposal by conversion to fluoride salts is preferred. The following methods are recommended scmbbing with caustic solutions (115,116) reaction with soHd disposal agents such as alumina, limestone, lime, and soda lime (117,118) and reaction with superheated steam (119). Scmbbing with caustic solution and, for dilute streams, reaction with limestone, are practiced on an industrial scale. 

Recovery from Bayer Liquor. The significant amount of primary gallium is recovered from the alumina industry. The main source is the sodium aluminate Hquor from Bayer-process plants that produce large quantities of alumina. Several methods have been developed to recover gallium from Bayer Hquor. 

A fourth ahoy separation technique is fractional crystallization. If shica is co-reduced with alumina, nearly pure shicon and an aluminum shicon eutectic can be obtained by fractional crystallization. Tin can be removed to low levels in aluminum by fractional crystallization and a carbothermic reduction process using tin to ahoy the aluminum produced, fohowed by fractional crystallization and sodium treatment to obtain pure aluminum, has been developed (25). This method looked very promising in the laboratory, but has not been tested on an industrial scale. 

Handling of alumina and coke presents dusting problems. Hoods and exhaust systems collect the dust, which is then separated from the exhaust air either by cyclones, electrostatic precipitators, filter bags, or a combination of these methods, and recycled to the process (see Air pollution control PffiTHODS). 

Small amounts of sodium aluminate are prepared in the lab by fusion of equimolar quantities of sodium carbonate [497-19-8] and aluminum acetate [139-12-8], A1(C2H202)3, at 800°C (4). Other methods involve reaction of sodium hycboxide with amorphous alumina or aluminum [7429-90-5] metal. Commercial quantities of sodium aluminate are made from hydrated alumina, in the form of aluminum hydroxy oxide [24623-77-6], AIO(OH), or aluminum hycboxide [21645-51 -2], Al(OH)3, a product of the Bayer process (5,6) which is used to refine bauxite [1318-16-7], the principal aluminum ore. 

The large majority of activated alumina products are derived from activation of aluminum hydroxide, rehydrated alumina, or pseudoboehmite gel. Other commerical methods to produce specialty activated aluminas are roasting of aluminum chloride [7446-70-0], AIQ calcination of precursors such as ammonium alum [7784-25-0], AlH2NOgS2. Processing is tailored to optimize one or more of the product properties such as surface area, purity, pore size distribution, particle size, shape, or strength. 

Bayerite (P-Aluminum Trihydroxide). Bayerite is rarely found in nature. It has been synthesized by several methods A pure product is prepared by the Schm b method (3) in wliich amalgamated aluminum reacts with water at room temperature. Other methods include rapid precipitation from sodium alurninate solution by CO2 gassing, aging of gels produced by neutrali2ation of aluminum salts with NH OH, and rehydration of transition rlio alumina. 

Method 1 siHca—alumina, siHca, alumina, titania, tungstic oxides, phosphates, 2eoHtes, and clays. 

Pulpstones. Improvements have been made in the composition and speed of the grinding wheel, in methods of feeding the wood and pressing it against the stone, in control of power to the stones, and in the size and capacity of the units. The first pulpstones were manufactured from quarried sandstone, but have been replaced by carbide and alumina embedded in a softer ceramic matrix, in which the harder grit particles project from the surface of the wheel (see Abrasives). The abrasive segments ate made up of three basic manufactured abrasive siUcon carbide, aluminum oxide, or a modified aluminum oxide. Synthetic stones have the mechanical strength to operate at peripheral surface speeds of about 1200—1400 m /min (3900 to 4600 ft/min) under conditions that consume 0.37—3.7 MJ/s (500—5000 hp) pet stone. 

Chemical recovery ia sodium-based sulfite pulpiag is more complicated, and a large number of processes have been proposed. The most common process iavolves liquor iaciaeration under reduciag conditions to give a smelt, which is dissolved to produce a kraft-type green liquor. Sulfide is stripped from the liquor as H2S after the pH is lowered by CO2. The H2S is oxidized to sulfur ia a separate stream by reaction with SO2, and the sulfur is subsequendy burned to reform SO2. Alternatively, ia a pyrolysis process such as SCA-Bidemd, the H2S gas is burned direcdy to SO2. A rather novel approach is the Sonoco process, ia which alumina is added to the spent liquors which are then burned ia a kiln to form sodium aluminate. In anther method, used particulady ia neutral sulfite semichemical processes, fluidized-bed combustion is employed to give a mixture of sodium carbonate and sodium sulfate, which can be sold to kraft mills as makeup chemical. 

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