Water-dried powder

Fire Hazards - Flash Point Not flammable but may cause fires upon contact with combustible materials Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents Flood with water, dry powder (e.g., graphite or powdered limestone) Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Not pertinent Behavior in Fire Can increase the intensity of fires Ignition Temperature Not pertinent Electrical Hazard Not pertinent Burning Rate Not pertinent. 

A sample of water-dried powder was exposed to an atmosphere practically saturated with water vapor. Portions were removed each day one part was fired in the gun, and another part was analyzed for total volatile matter (TV) and for volatile matter driven off by an hour s heating at 100° (external moisture, EM). 

Flash point, 62°C auto-ignition temperature, 192°C. Extinguish fires with water, dry powder, or foam.3... 

Materials that become more hazardous when contacted with water comprise another important class of incompatible materials. For example, carbonyl sulphide (COS) and calcium sulphide (CaS) both release toxic H2S on contact with water. Dry powders of sodium or potassium cyanide release toxic HCN in the presence of moisture. Care must be taken to prevent such materials from coming into contact with water during processing and storage. The 1985 Bhopal accident was started by a runaway reaction involving a water-sensitive chemical. 

Portable fire extinguishers may be filled with water, dry powder, foam, or carbon dioxide. They are usable from 8-120 seconds, depending on the size of the extinguisher and the chemical inside. The proper fire extinguisher should be placed in the proper place at a... 

Surfactants form inverted micelles in oil medium without the use of water. Dry powders of salts can, therefore, be dispersed in the surfactant solution and reduced with reducing agents such as LiBH4 and Na in oil. Extremely reactive and even pyrophoric reducing agents can be used since water is absent in the system. Wilcoxon and coworkers [420-422] have made use of this method to synthesize Au, Si, and Ge nanocrystals. Si and Ge nanocrystals were obtained by dispersion of the halides in an inverted micelle followed by reduction with LiAlH4 in THF. 

Agar occurs as a cell-wall constituent of the red marine algae Rho ophyceae, from which it is extracted by hot water, and marketed as a dry powder, flakes, or strips. It dissolves in hot water and sets on cooling to a jelly at a concentration as low as 0-5%. Its chief uses are as a solid medium for cultivating micro-organisms, as a thickener, emulsion stabilizer in the food industry and as a laxative. 

Place 20 g. of dry powdered benzoic acid in C, add 15 ml. (25 g., i.e., a 30% excess) of thionyl chloride and some fragments of porcelain, and then clamp the apparatus on a boiling water-bath as shown so that no liquid can collect in the side-arm of C. Heat for one hour (with occasional gentle shaking), by which time the evolution of gas will be complete. Cool the flask C, detach the condenser and fit it to the side-arm for distillation, using a 360° thermometer for the neck of C. To the lower end of the condenser fit a small conical flask G (Fig. 67(B)) by a cork carrying also a calcium chloride tube. 

Heat together under very efficient water reflux 1 g. of freshly fused dry powdered ZnClg, 2 ml. of diethyl ether and 0 5 g. of 3,5 -dinitrobenzoyl chloride for 2 hours. Shake the product with 5 ml. of water and ther add 10% NaOH solution until all the ZnCl, and excess of 3,5-dinitro> benzoyl chloride and 3,5-dinitrobenzoic acid have gone into solution. Filter at the pump and recrystallise from petroleum (b.p. 40-60°) to obtain ethyl 3,5-dinitrobenzoate, m.p. 93°. (M ps. of other 3,5 dinitro-benzoates, p. 536.)... 

Phthalide. In a 1 litre bolt-head flask stir 90 g. of a high quality zinc powder to a thick paste with a solution of 0 5 g. of crystallised copper sulphate in 20 ml. of water (this serves to activate the zinc), and then add 165 ml. of 20 per cent, sodium hydroxide solution. Cool the flask in an ice bath to 5°, stir the contents mechanically, and add 73-5 g. of phthalimide in small portions at such a rate that the temperature does not rise above 8° (about 30 minutes are required for the addition). Continue the stirring for half an hour, dilute with 200 ml. of water, warm on a water bath imtil the evolution of ammonia ceases (about 3 hours), and concentrate to a volume of about 200 ml. by distillation vmder reduced pressure (tig. 11,37, 1). Filter, and render the flltrate acid to Congo red paper with concentrated hydrochloric acid (about 75 ml. are required). Much of the phthalide separates as an oil, but, in order to complete the lactonisation of the hydroxymethylbenzoic acid, boil for an hour transfer while hot to a beaker. The oil solidifles on cooling to a hard red-brown cake. Leave overnight in an ice chest or refrigerator, and than filter at the pump. The crude phthalide contains much sodium chloride. RecrystaUise it in 10 g. portions from 750 ml. of water use the mother liquor from the first crop for the recrystaUisation of the subsequent portion. Filter each portion while hot, cool in ice below 5°, filter and wash with small quantities of ice-cold water. Dry in the air upon filter paper. The yield of phthalide (transparent plates), m.p. 72-73°, is 47 g. 

Methyl p-toluenesulphonate. This, and other alkyl esters, may be prepared in a somewhat similar manner to the n-butyl ester with good results. Use 500 g. (632 ml.) of methyl alcohol contained in a 1 litre three-necked or bolt-head flask. Add 500 g. of powdered pure p-toluene-sulphonyl chloride with mechanical stirring. Add from a separatory funnel 420 g. of 25 per cent, sodium hydroxide solution drop by drop maintain the temperature of the mixture at 23-27°. When all the alkali has been introduced, test the mixture with litmus if it is not alkaline, add more alkali until the mixture is neutral. Allow to stand for several hours the lower layer is the eater and the upper one consists of alcohol. Separate the ester, wash it with water, then with 4 per cent, sodium carbonate solution and finally with water. Dry over a little anhydrous magnesium sulphate, and distil under reduced pressure. Collect the methyl p-toluenesulphonate at 161°/10 mm. this solidifies on cooling and melts at 28°. The yield is 440 g. 

To a solution of 22 g of K0-tert.-Ci,H9 (see Exp. 4, note 2) in 400 ml of anhydrous liquid ammonia were added 22 g of the bis-ether (note 1). After stirring for 4 h, 20 g of powdered ammonium chloride were introduced in small portions. The ammonia was removed by placing the flask in a water-bath at 40°C, then 200 ml of water were added and five extractions with small portions of redistilled pentane were carried out. The combined extracts were washed with water, dried over magnesium sulfate and then concentrated in a water-pump vacuum. The residue was carefully distilled through a 40-cm Vigreux column, giving the allenic bis-ether,... 

Solid Polymer. Completely dry polyacrylamide is a brittle white soHd. Commercially available dry polyacrylamide powders are typically dried under mild conditions and usually contain 5—15% water. The powders are hygroscopic, and generally become increasingly hygroscopic as the ionic character of the polymer increases. Cationic polymers are particularly hygroscopic. 

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