Sand-sodium base

Sand-sodium base. See Sodium-sand base a-Santalene, 42 Sobering process, 118-119 Schiff bases. See Imines 9,10-Secosteroids (calciferols and tachysterols), 31-32, 34, 281-283, 289 Seebach-Frater alkylation, 27. AT-Selectride = potassium hydrotris(l-mcthylpropyl)borate(l —) (KBHBVl), 107 XS-Selectride 1 — potassium tris(l,2-dimethyl-propyl)hydroborate(l —) (KBHSiay), 107 Z-Selectride = lithium hydrotri (l-... 

In a sophisticated variation of the Knoevenagel condensation ("Panizzi ) methyl 3,3-dimethoxypropanoate (from ketene and dimethoxymethenium tetrafluoroborate D.J. Crosby, 1962) is used as a d -reagent. Because only one carbonyl group activates the methylene group, a strong base with no nucleophilic properties (p. 10) has to be used. A sodium-sand mixture, which presumably reacts to form silicate anions in the heat, was chosen... 

The addition of celite or HyfloSupercel to increase the contact surface with the extraction solvent and help filtration is often utilized during extraction. In case of interaction of such filter aids with the food, treated sand can be employed instead. Weak bases such as NaHCOj, MgC03, or CaC03 (1 g/10 g sample) to neutralize acids liberated from tissues and antioxidants (0.1% BHT, 5% pyro-gallol, ascorbic acid, and sodium ascorbate) to avoid oxidation can be added during extraction. ... 

The monazite sand is heated with sulfuric acid at about 120 to 170°C. An exothermic reaction ensues raising the temperature to above 200°C. Samarium and other rare earths are converted to their water-soluble sulfates. The residue is extracted with water and the solution is treated with sodium pyrophosphate to precipitate thorium. After removing thorium, the solution is treated with sodium sulfate to precipitate rare earths as their double sulfates, that is, rare earth sulfates-sodium sulfate. The double sulfates are heated with sodium hydroxide to convert them into rare earth hydroxides. The hydroxides are treated with hydrochloric or nitric acid to solubihze all rare earths except cerium. The insoluble cerium(IV) hydroxide is filtered. Lanthanum and other rare earths are then separated by fractional crystallization after converting them to double salts with ammonium or magnesium nitrate. The samarium—europium fraction is converted to acetates and reduced with sodium amalgam to low valence states. The reduced metals are extracted with dilute acid. As mentioned above, this fractional crystallization process is very tedious, time-consuming, and currently rare earths are separated by relatively easier methods based on ion exchange and solvent extraction. 

Sodium hydroxide, NaOH, is a very strong base, commonly used as a drain deaner. Why is this chemical only helpful in unclogging natural materials, such as hair or grease, and not synthetic materials, such as plastic, or inorganic materials, such as sand ... 

Calcium hydroxide is an extremely important base (34 billion pounds of the oxide and hydroxide are produced annually) that is used on a large scale because it is less expensive than sodium or potassium hydroxide. One of the major uses of Ca(OH)2 is in the production of mortar. In this use, the Ca(OH)2 reacts with carbon dioxide from the atmosphere to produce CaC03 (limestone), which binds the particles of sand and gravel together in concrete. 

The reduction of esters by sodium and alcohol (Bouveault-Blanc) is widely used. An alcoholic solution of the ester is added to a large excess of sodium under benzene or toluene. The use of absolute alcohol is essential otherwise an appreciable quantity of acid is produced by saponification. Straight-chain primary alcohols containing up to thirty-five carbon atoms have been made by the reduction of the corresponding esters with sodium sand and n-butyl alcohol. An improved technique based on the mechanism of the reaction is described. By this procedure a xylene solution of the ester and the reducing alcohol is added to molten... 

When a membrane-based desalination process is used, seawater is first collected and pumped to the water-treatment plant. Sodium hypochlorite is injected periodically after the intake pumps to prevent biological growth within the water-treatment system. Suspended solids are retained by sand filters or MF. The filtered water is then acidified. 

The various alkylaminations appear in Table IV. All were carried out by refluxing sodium sand in toluene containing the primary amine and catalyst until all or most of the sodium was consumed. The pyridine base was added in the second step with evolution of hydrogen (80UP1). 

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