Applications Barium carbonate

Uses. Hiere are several different grades of barium carbonate manufactured to fit the specific needs of a wide variety of applications very fine, highly reactive grades are made for the chemical industry coarser and more readily haridleable grades are mainly supplied to the glass industry ... 

Formolysis and acetolysis are not common methods for cleavage of glycosidic linkages. They do have some unique applications, however. For instance, methylated polysaccharides are not generally soluble in hot water, and consequently, hydrolysis is best preceded by formolysis under these circumstances. For example, 5 mg of methylated polysaccharide is dissolved in 3 mL of 90% formic acid, and the solution is kept for 2 h at 100°. The formic acid is removed by evaporation at 40°. The residue is dissolved in 1 mL of 250 mM sulfuric acid and the solution is heated for 12 h at 100°, cooled, the acid neutralized with barium carbonate, the... 

The investigations of materials obtained from nano-sized particles showed that they have unknown properties or enhanced characteristics compared to common materials. Many alkaline carbonates have take in especially application in practice. Calcium carbonate is widely used for production of toothpaste, binding agents, etc. [12,13]. Barium carbonate is used mainly in glass production industries, as well as water softening agent, etc. Both substances are crystalline, with rhombic lattice and practically insoluble in water [12]. 

The applications of barium compounds are varied and include use as oil-drilling mud. Barium carbonate is sometimes employed as a neutralizing agent for sulfuric acid and, because both barium carbonate and barium sulfate are insoluble, no contaminating barium ions are introduced. The foregoing application is found in the synthetic dyestuff industry. 

An efficient procedure for the formation of primary bromides is the reaction of 4,6-O-benzylidene hexopyranosides with A-bromosuccinimide (NBS) in the presence of barium carbonate. This reaction leads to the corresponding 4-0-benzoyl-6-bromide-6-deoxy-glycoside (Scheme 3.4a).17 Probably, the reaction proceeds by the radical bromination of the benzylic carbon atom followed by rearrangement to the 6-deoxy-6-bromo derivative. The application of this method is very efficient since the benzylidene functionality can act as a protecting group but can be oxidatively cleaved to give a 6-deoxy-6-bromo derivative. 

The main electroceramic applications of titanium dioxide derive from its high dielectric constant (see Table 6). Rutile itself can be used as a dielectric in multilayer capacitors, but it is much more common to use Ti02 for the manufacture of alkaline-earth titanates, eg, by the cocalcination of barium carbonate and anatase. The electrical properties of these dielectrics are extremely sensitive to the presence of small (<20 ppm) quantities of impurities, and high performance titanates require consistendy pure (eg, >99.9%) Ti02. Typical products are made by the hydrolysis of high purity titanium tetrachloride. 

Alkaline-Earth Titanates. Some physical properties of representative alkaline-earth titanates are listed in Table 15. The most important applications of these titanates are in the manufacture of electronic components (109). The most important member of the class is barium titanate, BaTi03, which owes its significance to its exceptionally high dielectric constant and its piezoelectric and ferroelectric properties. Further, because barium titanate easily forms solid solutions with strontium titanate, lead titanate, zirconium oxide, and tin oxide, the electrical properties can be modified within wide limits. Barium titanate may be made by, eg, cocalcination of barium carbonate and titanium dioxide at ca 1200°C. With the exception of Ba iO barium orthotitanate, titanates do not contain discrete TiO4 ions but are mixed oxides. Ba2Ti04 has the p-I SC structure in which distorted tetrahedral TiO4 ions occur. 

Applications The most important utilization sector for barium carbonate is the manufacture of clay tiles and ceramic products, the addition of barium carbonate hindering the bleeding of salts (sodium and calcium sulfate). In the USA 30% of the consumption is devoted to this use. A further 30% is consumed in the glass industry (e.g. for the manufacture of optically special glasses and television screens). About 20%i is used in the manufacture of other barium compounds. Other uses are in special... 

The process giving the most accurate results is that of Bunsen, in which the urea is decoinxmsed into COj and NHs, the former of which is weighed as barium carbonate. Unfortunately, this process requires an expenditure of time and a degree of skill in manipulation which render its application possible only in a well-appointed laboratory. 

A second method of isolating a salt of the acid, which is applicable in all cases, is based on the facts that the barium salts of sulphonic acids are soluble in water, whereas barium sulphate is insoluble. The mixture of sulphuric acid and sulphonic caid is diluted with water, and neutralized with barium carbon-tae. The solution is then heated and filtered. On evaporation the barium salt of the sulphonic acid is obtained. The free acid may be prepared by adding to a solution of the barium salt the amount of sulphuric acid required to precipitate the barium as sulphate. 

The application of thermal analysis in combination with XRD and FTIR showed that the thermal decomposition of a mixture of barium carbonate and tin tetrahydroxide results in the formation barium staimate that has a cubic perovskite structure and can be used as a sensor for the detection of liquefied petroleum gas [115]. Koferstein and coworkers demonstrated that, starting from... 

The micro-procedure of Ghimicescu (1935e) can also be used for larger amounts. It too is based on isolation of barium lactate in 80% alcohol and conversion to barium carbonate. Seiler (1941) pointed out that the Mdslinger technique was not applicable to sweet or fruit wines. He questioned if a calculation of the original malic acid content based on determination of the final lactic acid content was justified. 

Stability and Reactivity data from MSDSs. These data offer a wealth of information for predicting or interpreting chemical reactions that would be applicable to various courses, including general chemistry, organic chemistry, and inorganic chemistry. In particular, MSDSs from MDL Information Systems, Inc. list extensive reaction information under "Incompatibilities." For example, magnesium is incompatible with barium carbonate because of the formation of an explosive acetylide (21). Have your students write the reaction. 

Barium Carbonate 20 90 8 Neglible effect should be suitable for all applications ... 

Rodden and Warf2i have described the application of several carriers ferric, aluminum, and calcium hydroxide. The use of barium carbonate and thorium hexametaphosphate has been mentioned In the section on Inorganic precipitants. Msig-... 

For electrical insulation china clay is commonly employed whilst various calcium carbonates (whiting, ground limestone, precipitated calcium carbonate, and coated calcium carbonate) are used for general purpose work. Also occasionally employed are talc, light magnesium carbonate, barytes (barium sulphate) and the silicas and silicates. For flooring applications asbestos has been an important filler. The effect of fillers on some properties of plasticised PVC are shown in Figure 12.21 (a-d). 

This latter point was stressed by some of us in a recent report studying NO storage and reduction on commercial LSR (lean storage-reduction) catalysts, in order to catch valuable information about the behaviour of typical NO storage materials in real application conditions. Nature, thermal stability and relative amounts of the surface species formed on a commercial catalyst upon NO and 02 adsorption in the presence and in the absence of water were analysed using a novel system consisting of a quartz infrared reactor. Operando IR plus MS measurements showed that carbonates present in the fresh catalyst are removed by replacement with barium nitrate species after the first nitration of the material. Nitrate species coordinated to different barium sites are the predominant surface species under dry and wet conditions. The difference in the species stabilities suggested that barium sites possess different basicity and, therefore, that they are able to stabilize nitrates at different temperatures. At temperatures below 523 K, nitrite species were observed. The presence of water at mild temperatures in the reactant flow makes unavailable for NO adsorption the alumina sites [181]. 

Highly pure lanthanum oxide is used to make optical glass of high refractive index for camera lenses. It also is used to make glass fibers. The oxide also is used to improve thermal and electrical properties of barium and strontium titanates. Other applications are in glass polishes carbon arc electrodes fluorescent type phosphors and as a diluent for nuclear fuels. In such apph-cations, lanthinum oxide is usually combined with other rare earth oxides. 

Alkaline hydrolysis with barium, sodium, or lithium hydroxides (0.2-4 M) at 110°C for 18-70 h126-291 requires special reaction vessels and handling. Reaction mixtures are neutralized after hydrolysis and barium ions have to be removed by precipitation as their carbonate or sulfate salts prior to analysis which leads to loss of hydrolysate. Correspondingly, peptide contents are difficult to perform by this procedure. Preferred conditions for alkaline hydrolysis are 4M LiOH at 145 °C for 4-8 h where >95% of tryptophan is recovered 291 An additional inconvenience of the alkaline hydrolysis procedure is the dilution effect in the neutralization step and thus the difficult application to the analyzer if micro-scale analysis is to be performed. The main advantage is the good recovery of tryptophan and of acid-labile amino acid derivatives such as tyrosine-0-sulfate1261 (Section 6.6) as well as partial recovery of phosphoamino acids, particularly of threonine- and tyrosine-O-phosphate (Section 6.5). 

---