Absorption anhydrous oxides

L. Holmia, for Stockholm). The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after cleve s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. 

Industrial production of sodium nitrite is by absorption of nitrogen oxides (NO ) into aqueous sodium carbonate or sodium hydroxide. NO gases originate from catalytic air oxidation of anhydrous ammonia, a practice common to nitric acid plants ... 

Dicyclopentadiene (50 g, 0.38 mole) is dissolved in 100 ml of anhydrous ether. Platinum oxide (0.25 g) is added, and the mixture is hydrogenated in a Parr apparatus at an initial pressure of 50 psi. Initially the reaction mixture becomes warm. The absorption of 2 mole equivalents of hydrogen takes 4-6 hours. The mixture is filtered by suction to remove the catalyst, and the filtrate is distilled at atmospheric pressure through a short fractionating column. 

Thorium oxide on activated carbon was prepared by absorption of thorium nitrate from its solution in anhydrous acetone on the activated carbon Supersorbon. The excess solution was decanted, the catalyst was dried at 80 °C, and the adsorbed thorium oxide was decomposed by excess 5% ammonium hydroxide solution. After repeated washing and decanta-nation with distilled water and acetone, the catalyst was dried at 180°C. It was then stabilized by heating to 360°C for 5 hr in a stream of nitrogen. The content of thorium oxide was 2.9% (wt.). The BET surface area was 870 m2/g. Prior to kinetic measurements, the catalyst was modified by passing over acetic acid vapors (100 g acid/1 g catalyst). 

Before finally assembling the apparatus, the various units are charged as follows A is one-third filled with water to serve as a bubble counter. Generator B is about one-quarter filled with dry arsenious oxide, pea size or powdered. Drying towers G and H are filled with anhydrous calcium chloride. (It is well to place a wad of glass wool in front of the entrance and exit tubes.) In each of the two absorption bottles J and K is placed 200 g. of ethyl malonate. Dish L is filled with an ice-salt freezing mixture. 

Phosphorus(V) oxide is very hygroscopic and the bottle must be closed except when an addition is made. The reactor is cooled with ice water so that the reaction temperature is maintained at 5-10°. Methanol (125 mL)is added drop-wise to the stirred solution to precipitate the crude ammonium tetrametaphos-phate, which is collected by suction filtration, washed with methanol, and dried in vacuum over anhydrous CaS04. The product weighs 33 g and contains about 65% of its phosphorus as tetrametaphosphate. The remainder is a mixture of ortho-, trimeta- and short-chain phosphates. Any lumps are crushed and the crude ammonium tetrametaphosphate is spread in a no. 1 porcelain evaporating dish and heated for 2 hours at 240° in a slow stream,of anhydrous ammonia (about 100 mL/min or 3-5 g/hr). Care is taken to avoid absorption of moisture before or during heating, as this adversely affects the formation of the product. 

They afford greater protection and are more absorptive. The base may be anhydrous or water soluble e.g. zinc oxide paste. 

Diammino-stannous Chloride, [Sn(NH3)2]Cl2.—If dry ammonia gas is passed over anhydrous stannous chloride, immersed in a freezing mixture, a yellow powder is formed of composition SnCl2.2NH3. It blackens on exposure to light, and moist air attacks the substance, with formation of stannous oxide and ammonium chloride. If absorption is allowed to take place at ordinary temperature a mixture of mon-ammino-stannous chloride, [Sn(NH3)]Cl2, and diammino-stannous chloride, [Sn(NH3)2]Cl2, is obtained whilst at 100° C. stannous chloride is claimed to absorb ammonia gas, with formation of a white powder of composition corresponding to monammino-stannous chloride, [Sn(NH3)]Cl 2. 

Oxidation of n-butane and butenes requires higher reaction temperatures (400-480°C). Since more water is produced in this reaction, most of the product is recovered in the form of maleic acid. The currently best process is the Alma (Alusuisse) process.1015-1018 Its main features are a fluidized-bed reactor and an anhydrous product recovery. Because of the better temperature control, a lower air hydrocarbon ratio can be employed (4 mol% of n-butane). Instead of absorption in water, maleic anhydride is recovered from the reactor effluent gas by a high-boiling organic... 

Anhydrous VO(aca)2 was prepared as described in the literature.44 Analyzed VOSfVSHjO was obtained from Struers Co., Copenhagen. Solntion spectral measurements were made using a Zeiss instrument. Reflectance spectra were obtained with a Beckman DU equipped with a standard reflectance attachment. Magnesium oxide was used as a standard. The resolution of the bands in the reflectance spectrum of VOS0< 5H 0 did not differ from the resolution achieved for the crystal absorption spectrum A shown in Fig. 5. 

Supports used for obtaining Ziegler-Natta catalysts can differ essentially from one another. Some of the supports may contain reactive surface groups (such as hydroxyl groups present in specially prepared metal oxides) while others do not contain such reactive functional groups (such as pure anhydrous metal chlorides). Therefore, the term supported catalyst is used in a very wide sense. Supported catalysts comprise not only systems in which the transition metal compound is linked to the support by means of a chemical covalent bond but also systems in which the transition metal atom may occupy a position in a lattice structure, or where complexation, absorption or even occlusion may take place [28]. The transition metal may also be anchored to the support via a Lewis base in such a case the metal complexes the base, which is coordinatively fixed on the support surface [53,54]. 

Ciprofloxacin was determined in tablets and intravenous infusion solutions by an oxidative spectrophotometric method [15]. A yellow-orange complex was obtained upon reaction of ciprofloxacin with 5% ammonium sulfamate, 5 N H2S04, and 0.1 M cerium(IV) ammonium sulfate. The complex was extracted into CHC13, dried with anhydrous Na2S04, and measured at 345 nm within up to 4 h. Beer s law was obeyed over the range of 12-120 pg/mL, and the molar absorptivity was found to be 5090. 

Hazards Handle 99% anhydrous hydrazine with care. Never distill it in the presence of air, and keep it out of contact with strong oxidizers. Wear gloves, and use proper ventilation when handling cyanogen bromide. Cyanogen bromide is highly poisonous, and inhalation of vapors, or skin absorption can be fatal toxic effects are similar to hydrogen cyanide. 

Handling, Storage, and Precautions although air stable at rt, storage under anhydrous conditions under an inert atmosphere is recommended both to prevent the slow air oxidation of the phosphorus(III) ligating groups and absorption of atmospheric moisture. 

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