Crystallization precipitants

The reaction of the hydriodic acid with w-nitrobenzene-sulfonyl chloride is mildly exothermic, and iodine crystals precipitate as the reaction proceeds. 

In a study of crystal precipitation of calcium carbonate during the batch carbon-ation of lime water, individual crystals and agglomerated particles were observed as shown in Figure 8.18(a), (b) and (c), respectively (Wachi and Jones, 1991b). 

These concepts were implemented according to the following scheme the liquid element surrounding the bubble and the bulk are considered as two separate dynamic reactors that operate independent of each other and interact at discrete time intervals. In the beginning of the contact time, the interface is being detached from the bulk. When overcome by the bubble, it returns to the bulk and is mixed with it. Hostomsky and Jones (1995) first used such a framework for crystal precipitation in a flat interface stirred cell. To formulate it for a... 

For liquid-liquid crystal precipitation systems where the particle formation processes are fast, mixing becomes an important determiner of performance with a subtle interplay of micro- and mesomixing, which changes as scale of... 

Falope, G.O., Jones, A.G. and Zauner, R., 2001. On modelling continuous agglom-erative crystal precipitation via Monte Carlo simulation. Chemical Engineering Science, 56, 2567-2574. 

Jones, A.G., Hostomsky, J. and Waclii, S., 1996. Modelling and analysis of particle formation during agglomerative crystal precipitation processes. Chemical Engineering Communications, 146, 105-130. 

Preparation of S-Acetylsulfanilamido-S-Methy/isoxazole 0.9 gram of 3-amino-5-methyl-isoxazole in 5 cc of pyridine was allowed to react with 2.0 grams of acetylsulfanil chloride accompanied by the generation of heat. After about one hour, water was added to the reaction mixture and the crystal precipitated out was recrystallized from alcohol to give 2.5 grams of 3-acetylsulfanilamido-5-methylisoxazole, melting point (decomposition) 220° to 221°C. 

Humans have used dyes to create color since the dawn of history. Until the mid-nineteenth century, all dyes were of natural origin. Many came from plants, such as indigo, a dark blue dye that was extracted from the leaves of a native East Indian plant. In 1856, the young English chemist William Perkin stumbled upon the first synthetic dye. Perkin was trying to synthesize quinine, a valuable antimalaria dmg. None of his experiments met with success. As he was about to discard the residue from yet another failed reaction, Perkin noticed that it was colored with a purple tinge. He washed the residue with hot alcohol and obtained a purple solution from which strikingly beautiful purple crystals precipitated. Perkin had no idea what the substance was or what reactions had created it, but he immediately saw its potential as a new dye. 

Paquin in 1948 found that a strongly exothermic reaction occurred when 40% formaldehyde was added to a solution of sulfamide in 25% aqueous ammonia. At once beautiful crystals precipitated they were recrystallized from 96% alcohol to give a compound, C5H10N4SO2, mp 224-225 "C, in 88% yield.245 From the similar character to hexamethylenetetramine, he named this product pentamethylenetetramine sulfone it is 225. One year later, in 1949, Hecht and Henecka at Bayer research laboratory reported that a condensation product from one mole of sulfamide in strong mineral acid and two moles of formaldehyde showed very strong toxicity and was five times more toxic than strychnine. They called this product (226) tetra-methylenedisulfotetramine. 246... 

Dinitro-1,5-benzenediol was then reduced with stannous chloride in concentrated hydrochloric acid at 50-60°C. At the beginning, the solution was clear, then some white crystals precipitated form the reaction solution. After cooling, the resultant precipitate was collected by filtration and washed with cold water to give 2,4-diao ino-l,5-benzenediol dihydrochloride-no mp. before it decomposed above 2C0°C. 

C in a stream of inert gas. On cooling, white crystals precipitated from the mixture. The precipitate was recovered by filtration and washed with hexane (10 ml) to yield pure 3,5-di-f-butyl-4-hydroxy-benzylphosphonate (28.4 g, 80%) of mp 122°C, which exhibited NMR and analyses in accord with the proposed structure. 

Trimethyl phosphite (11.3 g, 0.091 mol) was added to a solution of 3-benzylidene-2,4-pentanedione (16.35 g, 0.091 mol) in dry methylene chloride. The solution was maintained under nitrogen for 24 h at 20°C and for an additional 5 h at 40°C. After this time, the solvent was evaporated, and the residue was dissolved in hexane. These actions were performed in the absence of moisture. The clear hexane solution was seeded with a crystal of the pure crystalline product (obtained by crystallization from hexane by standing for 2 weeks at 0°C), and after 8 h at 0°C the crystals precipitated yielding pure 2,2,2-tri-methoxy-3-phenyl-4-acetyl-5-methyl-A4-oxaphospholene (25.12 g, 88.4%) of mp 48-51°C. 

Drilling and cutting Solid lubricants Crystallization Precipitation Agglomeration... 

Structured products, such as cosmetics, detergents, surfactant foams, inks, paints, drugs, foods and agrochemicals, combine several functions and properties in a single product. Design of these structured products involve the creation and the control of the particle size distribution in operations such as crystallization, precipitation, generation of aerosols, and nanoparticles as well as... 

The overall kinetics of crystal precipitation has to consider that the process consists of a series of consecutive processes in simple cases, the slowest is the rate determining step. Assuming the volume diffusion is not the rate determining step, we still have at least the following reaction sequences ... 

Apparatus and Procedure for Supersolublllty Measurement. Same apparatus used In solubility measurement was also used In this experiment. Various amounts of qulzalofop-ethyl was dissolved Into 100 gr. of ethyl alcohol. In order to dissolve the compound completely, the solution was heated up to lOK higher than Its saturation temperature. After keeping the solution as such for about 20 minutes, the solution was cooled at the rate of 0.5K/mln. As well known. If the solution was supercooled beyond Its saturation temperature, crystallization did not occur Immediately. But as soon as a few crystals began to deposit, many crystals precipitated succeed-Ingly almost at the same time. The temperature at which crystals began to deposit was observed. Thus produced crystals were withdrawn and analyzed for Ofr-form content by using DSC and X-ray. 

Tripyridino-ferrous Sulphate, [Fe(C6H6N)3 ]S04.2H20, is formed when pyridine is added to an aqueous solution of ferrous sulphate. The brownish-yellow crystals precipitated have a strong odour of pyridine and decompose easily with formation of basic salts.3... 

To an ice-cooled (0°C to-—10°C) stirred flask containing 300 ml of water and 55.5 ml of concentrated hydrochloric acid is added dropwise over a 10 min period 33.5 gm (0.31 mole) of freshly distilled phenylhydrazine. Phenyl-hydrazine hydrochloride crystals precipitate as they are formed. Addition of... 

Sodium Sulphate Decahydrate. Drop a crystal of Glauber salt into the sodium sulphate solution in one of the flasks. Examine the shape of the crystals precipitating from the solution at room temperature (below 25 °C) under a microscope. 

Preparation of Potassium Nitrate. Pour 25 ml of water into a beaker and dissolve 12 g of sodium nitrate in it upon heating. Add an equivalent amount of potassium chloride to the solution. Cover the beaker with a watch glass and heat it on a gauze with a small burner flame until crystals precipitate. Can crystals form without evaporation of the solution Rapidly pour the hot liquid into a porcelain bowl and let it stand until crystals form. 

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