Alkalis carbon

A halogen atom directly attached to a benzene ring is usually unreactive, unless it is activated by the nature and position of certain other substituent groups. It has been show n by Ullmann, however, that halogen atoms normally of low reactivity will condense with aromatic amines in the presence of an alkali carbonate (to absorb the hydrogen halide formed) and a trace of copper powder or oxide to act as a catalyst. This reaction, known as the Ullmant Condensation, is frequently used to prepare substituted diphenylamines it is exemplified... 

Silicon Alkali carbonates, calcium, chlorine, cobalt(II) fluoride, manganese trifluoride, oxidants, silver fluoride, sodium-potassium alloy... 

The oxidant preheater, positioned in the convective section and designed to preheat the oxygen-enriched air for the MHD combustor to 922 K, is located after the finishing superheat and reheat sections. Seed is removed from the stack gas by electrostatic precipitation before the gas is emitted to the atmosphere. The recovered seed is recycled by use of the formate process. Alkali carbonates ate separated from potassium sulfate before conversion of potassium sulfate to potassium formate. Sodium carbonate and potassium carbonate are further separated to avoid buildup of sodium in the system by recycling of seed. The slag and fly-ash removed from the HRSR system is assumed to contain 15—17% of potassium as K2O, dissolved in ash and not recoverable. 

Tantalum Oxides. Tantalum pentoxide [1314-61 -0] Ta20, (mp = 1880°C, density = 8.73 g/cm ) is a white powder existing in two thermodynamically stable modifications. The orthorombic P-phase changes at 1360°C into the tetragonal a-modiftcation. The existence of an S-modiftcation has also been reported (70). Tantalum pentoxide reacts slowly with hot hydrofluoric acid but is insoluble in water and in most solutions of acids and alkalies. For analytical purposes, it can be dissolved by fusion with alkali hydroxides, alkali carbonates, and potassium pyrosulfate. 

GirhotolAmine Process. This process developed by the Girdler Corporation is similar in operation to the alkali carbonate processes. However, it uses aqueous solutions of an ethanolamine, ie, either mono-, di-, or triethanolamine. The operation of the Girbotol process depends on the reversible nature of the reaction of CO2 with monoetbanolamine [141-43-5] to form monoethanolamine carbonate [21829-52-7]. 

Berberilic acid, CgoHjgOgN, m.p. 177-82°, is dibasic, and furnishes a dimethyl ester, m.p. 173°. When heated to about 180°, the acid passes into ANHYDROBERBERiLic ACID, CjgHjjOgN, colourless needles, m.p. 236°, soluble in alkali carbonate solutions with the formation of berberilates. When ammonium berberilate is dried under reduced pressure, a molecular proportion of ammonia is lost with the formation of the ammonium salt of the anhydro-acid, from which other salts, and the methyl ester, m.p. 178°, have been obtained. Berberilic acid is hydrolysed by hot dilute sulphuric acid to hemipinic acid (I) and oi-aminoethylpiperonylic acid (II), large tabular crystals, m.p. 180-2°. Berberilic acid is therefore represented by (III). 

Flgure 4.7 Solubilities of alkali carbonates and bicarbonales (hydrogencarbonates). (H. Stephen and T. Stephen, Solubilities of Inorganic and Organic Compounds, Vol. 1, Part 1, Macmillan, New York.). 

To a solution of 20 parts of thiamine hydrochloride in 30 parts of water is added an aqueous solution of sodium hydroxide (7.2 parts of NaOH in 30 parts of water), and the mixture is cooled with water. The mixture is allowed to stand for 30 minutes, 60 parts of chloroform is added, followed by a solution of 30 parts of crude sodium tetrahydrofurfurylthiosulfate in 30 parts of water, and the whole is stirred for 30 minutes. The chloroform layer is separated and the aqueous layer is extracted twice with 20 parts of chloroform. All the chloroform solutions are combined and shaken with 50 parts of 5% hydrochloric acid. The acid solution is decolorized and neutralized with alkali carbonate, whereupon thiamine tetrahydrofurfuryl disulfide separates out in the resinous state but soon solidifies [MP 129 (decomp.)]. The yield is 16 parts. Recrystallization from ethyl acetate gives colorless prisms melting at 132°C (decomp.). 

Preparation of the Final Isethionate Product The diisethionate may be produced by treating a solution of the dihydrochloride with alkali carbonate, separating and dissolving the resultant base in aqueous isethionic acid and precipitating the diisethionate with acetone. The product may be purified by dissolving in hot methyl alcohol containing a trace of water followed by precipitation by the cautious addition of acetone. The diisethionate has a MP of 286°C. 

Steels Nitrate ion Sti ong alkali Carbonate/bicarbonate Liquid ammonia Hydrogen sulfide (aqueous) Cyanide ion... 

A large number of electrolytic treatments of magnesium, anodic or a.c., have been developed, in which adherent white or grey films consisting of fluoride, oxide, hydroxide, aluminate or basic carbonate are deposited from alkaline solutions containing caustic alkali, alkali carbonates, phosphates, pyrophosphates, cyanides, aluminates, oxalates, silicates, borates, etc. Some films are thin, and some are relatively thick. All are more or less absorbent and act as good bases for paint, though none contributes appreciable inhibition. All can, however, absorb chromates with consequent improvement of protective efficiency. 

Discussion. The hydroxides of sodium, potassium, and barium are generally employed for the preparation of solutions of standard alkalis they are water-soluble strong bases. Solutions made from aqueous ammonia are undesirable, because they tend to lose ammonia, especially if the concentration exceeds 0.5M moreover, it is a weak base, and difficulties arise in titrations with weak acids (compare Section 10.15). Sodium hydroxide is most commonly used because of its cheapness. None of these solid hydroxides can be obtained pure, so that a standard solution cannot be prepared by dissolving a known weight in a definite volume of water. Both sodium hydroxide and potassium hydroxide are extremely hygroscopic a certain amount of alkali carbonate and water are always present. Exact results cannot be obtained in the presence of carbonate with some indicators, and it is therefore necessary to discuss methods for the preparation of carbonate-free alkali solutions. For many purposes sodium hydroxide (which contains 1-2 per cent of sodium carbonate) is sufficiently pure. 

Sato et al. " measured the viscosities of some binary and ternary alkali carbonates. Since melt creep must be prevented, a highly sintered alumina crucible was used instead of a gold-plated nickel crucible. Homogeneity of a mixture sample was achieved by gas bubbling. A laser beam is combined with a computer-assisted time counter to obtain the logarithmic decrement. Roscoe s equationi3i has been used for calculation of the viscosity, while it has been claimed by Abe et al. that the viscosities calculated from Roscoe s equation are 0.6-1.5% lower than those from more rigorous equations. 

Figure 28. Isotherms of the shear viscosities of (Li, Na)2C03. (Reprinted from Y. Sato, T. Yamamura, H. Zhu, M. Endo, T. Yamazaki, H. Kato, and T. Ejima, Viscosities of Alkali Carbonate Melts for MCFC, in Carbonate Fuel Cell Technology, D. Shores, H. Mam, I. Uchida, and J. R. Selman, eds., p. 427, Fig. 9, 1993. Reproduced by permission of the Electrochemical Society, Inc.)...

Length change of concrete due to alkali-carbonate rock reaction ASTM C1105... 

Petit A process for removing hydrogen sulfide and hydrogen cyanide from gas streams by scrubbing with an alkali carbonate solution and regenerating the liquor with carbon dioxide. Invented by T. P. L. Petit. 

Acid chlorides are also used in order to determine whether or no an unidentified substance contains alcoholic or phenolic hydroxyl groups. If a substance reacts with an acid chloride, such a hydroxyl group is present, since all groups in which oxygen is combined in other ways, e.g. in ether linkage, are indifferent to this treatment. The reaction can be considerably facilitated by the addition of alkali or of alkali carbonate. 

Molten Carbonate Fuel Cell (MCFC) The electrolyte in this fuel cell is usually a combination of alkali carbonates, which is retained in a ceramic matrix of LiA102. The fuel cell operates at 600 to 700°C where the alkali carbonates form a highly conductive molten salt, with carbonate ions providing ionic conduction. At the high operating temperatures in MCFCs, Ni (anode) and nickel oxide (cathode) are adequate to promote reaction. Noble metals are not required. 

If solid samples are insoluble in water, some decomposition procedure must be used. For inorganic materials, decomposition with mineral acids is most often employed (for a survey of decomposition techniques see [33]). When the sample cannot be dissolved in an acid, it can either be fused (most often with alkali carbonates, hydroxides or their mixtures [157, 47]) or sintered (usually with mixtures of alkali carbonates with divalent metal oxides, sometimes in the presence of oxidants [54]). Sintering is usually preferable, because then contamination of the sample and the resultant ionic strength are lower than is the... 

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