Carbonates dried precipitated

Plastics. The fastest-growing use of whiting (microcarbonate fillers) is in the plastics industry where dry, pulverized limestone is used intensively for most types of plastics. Other carbonate fillers, precipitated calcium carbonate, oyster sheU, marble, and wet-ground limestone, are also used. 

Naphthalenesulfonic Acid. The sulfonation of naphthalene with excess 96 wt % sulfuric acid at < 80°C gives > 85 wt % 1-naphthalenesulfonic acid (a-acid) the balance is mainly the 2-isomer (P-acid). An older German commercial process is based on the reaction of naphthalene with 96 wt % sulfuric acid at 20—50°C (13). The product can be used unpurifted to make dyestuff intermediates by nitration or can be sulfonated further. The sodium salt of 1-naphthalenesulfonic acid is required, for example, for the conversion of 1-naphthalenol (1-naphthol) by caustic fusion. In this case, the excess sulfuric acid first is separated by the addition of lime and is filtered to remove the insoluble calcium sulfate the filtrate is treated with sodium carbonate to precipitate calcium carbonate and leave the sodium l-naphthalenesulfonate/7J(9-/4-J7 in solution. The dry salt then is recovered, typically, by spray-drying the solution. 

Standard solution of silica. Fuse 0.107 g of pure, dry precipitated silica with 1.0 g of anhydrous sodium carbonate in a platinum crucible. Cool the melt, dissolve it in de-ionised water, dilute to 500 mL, and store in a polythene bottle. 1 mL = 0.1 mg Si. Dilute as appropriate, say, to 1 mL = 0.01 mg Si. 

In the OH series, two phases were detectable by XRD in the dried precipitate. One was a phase with the pyroaurite structure, carbonate having presumably arisen from atmospheric CO2, and the other brucite, Mg(OH)2, 0 which pyroaurite is closely related structurally. For both the CCP and IP series, the only structure identifiable in the dried precipitate was that of magnesium hydroxy carbonate. X-ray analysis of the calcined precursors showed MgO together with y-Fe203 in the case of the OH series and HT, but -Fe203 with the CCP and IP series. MgFe204 spinel was also detectable in some cases. 

Cool and filter. Dissolve in the minimum volume of hot water, treat with about 0-5 per cent, by weight of decolourising carbon, filter, precipitate the base with 50 per cent, acetic acid imtil just acid to litmus (avoid an excess of acid), filter off the sulphapyridine at the pump, wash thoroughly with hot water, and dry to constant weight at 90° (about 12 horirs). Alternatively, the cold solution of the sodium salt may be just acidified with dilute hydrochloric acid with very vigorous stirring the presence of a local excess of acid must be avoided since sulphapyridine is hydrolysed by mineral acids to sulphanilic acid and 2-aminopyridine. 

If the water then evaporates, the dry calcium bicarbonate decomposes, recreating calcium carbonate, which precipitates and forms hard deposits and incrustations while carbon dioxide and water are released into the atmosphere ... 

Basic carbonate is obtained from its naturally occurring minerals. It also may be prepared by mixing a solution of copper sulfate with sodium carbonate. The precipitate is then filtered and dried. 

In the analytical determination of the hyponitrites, W. Zorn treated soln. of the free acid, or of its salts in cold dil. nitric acid with an excess of silver nitrate, and just neutralized the free acid with ammonia or sodium carbonate. The washed and dried precipitate was weighed as silver hyponitrite, or weighed as metal or chloride. A. Thum treated the aq. soln. of the acid with an excess of a soln. of permanganate, and in 15 minutes added sulphuric acid after standing for another hour the soln. was warmed to 30°, and treated with a known quantity of 0-1A-oxalie acid sufficient to decolorize the permanganate. The excess oxalic acid was determined by permanganate titration. A. Hantzsch and A. Sauer, and... 

The combined ethyl acetate extracts were filtered to remove water droplets and stored at 0° until all urine extractions were completed, and then refiltered and concentrated to about one-tenth the volume under diminished pressure. The hot solution was treated with decolorizing carbon, dried with anhydrous sodium sulfate, filtered, and the crude product precipitated by means of a slight excess of a hot, saturated solution of cinchonidine in ethyl acetate (analytical grade) completeness of precipitation was tested at intervals by centrifuging a test portion and adding a cold, saturated solution of cinchonidine in ethyl acetate to the supernatant liquor. 

The sol-gel method has been conveniently employed for the synthesis of 123 compounds such as YBa2Cu307 and the bismuth cuprates. Materials prepared by such low-temperature methods have to be annealed or heated under suitable conditions to obtain the desired oxygen stoichiometry as well as the characteristic high Tc value. 124 cuprates, lead cuprates and even thallium cuprates have been made by the sol-gel method the first two are particularly difficult to make by the ceramic method. Coprecipitation of all the cations in the form of a sparingly soluble salt such as carbonate in a proper medium (e.g. using tetraethyl-ammonium oxalate), followed by thermal decomposition of the dried precipitate has been employed by many workers to prepare cuprates. 

Dicyanoaniline (31.4 g) was treated with nitrosylsulfuric acid (72 g) at 0°C to 5°C in 300 ml of 50% aqueous sulfuric acid, and the batch was stirred for 1 hour. This mixture was then slowly poured into a solution of aniline (20.4 g) and urea (4.5 g) dissolved in 300 ml of 50% aqueous sulfuric acid and then stirred for an additional hour at 0°C to 5°C. Thereafter the reaction mixture pH was raised to 5.5 with sodium carbonate. A precipitate formed that was filtered off under suction, washed with water, and dried 34 g of product were isolated. This material was used in the next step without further purification. 

Preparation. Zinc carbonate is precipitated from 0.1 M zinc sulfate solution by addition of 0.1 M sodium carbonate solution and dried under vacuum. 

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