Recry stallization

RABRM Research Association of recryt(d) recry stallize(d)... 

Procedure Add 90 grams of 90% nitric acid to a 500-milliliter Erlenmeyer flask and then begin stirring. Then add 100 grams of powdered pentaerythritol in small increments over a period of 2 hours while keeping the 90% nitric acid at a temperature around 40 Celsius at all times (do not let the reaction temperature rise above 45 Celsius). After addition of the pentaerythritol, cool the reaction mixture to room temperature. When the reaction mixture reaches room temperature, add the entire reaction mixture to 500 milliliters of ice-cold water. Then, filter-off the precipitated PETN solid, wash with 800 milliliters of cold water, and then vacuum dry or air-dry the product (do not use heat to dry the PETN). Purify the PETN by recry stallizing from 1000 milliliters of a 50%acetone/50%alcohol mixture (prepare by dissolving 500 milliliters of acetone to 500 milliliters of 95% ethanol), then wash the product with 1000 milliliters of cold water, and then vacuum dry or air-dry. 

A stirred solution of l,2-di(acetylamino)benzene (38) (19.2 g, 0.1 mol), triethyl-amine (30.1 g, 0.298 mol), and toluene (300 ml) is heated under reflux while trimethylchlorosilane (37.9 ml, 0.298 mol) in toluene (50 ml) is added. After heating (4h), the triethylamine hydrochloride is filtered off, and the solvent is removed under reduced pressure. Distillation in vacuo gives the silyl derivative (40) as a fraction, bi 107°C (92%). Addition of triflic acid (0.033 g) to (40) (2.026 g, 0.006 mol) induces instant cyclization at room temperature. The l-acetyl-2-methylbenzimidazole separates as a solid, and is recry stallized from diethyl ether in 100% yield, m.p. 80 C. 

Benzoylphenyl Tellurium Chloride In a dry, 100 ml flask fitted with a reflux condenser topped with a drying tube are placed 6.5 g (20 mmol) of 2-carboxyphenyl phenyl tellurium, 5 ml (30 mmol) of butyl dichloromethyl ether, and 0.2 g (1.5 mmol) of anhydrous zinc chloride. The mixture is heated on a boiling water bath for 2 h, then diluted with carbon tetrachloride, charcoal is added, and the mixutre is filtered. The filtrate is evaporated to dryness and the residue is recry stallized from benzene/hexane yield 6.3 g (80%) m.p. 113-114". 

If the product is colored or low melting it may be purified further by recry.stallization from 6(K) ml. of petroleum ether... 

A (Alternative) JCS 2834(1962). 4.8 g Mg turnings, 32 g ethyl iodide in 20 ml dry anisole. Cool to 0° and add dropwise 15.6 g indole in 20 ml anisole. Stir one-half hour at 20° eool to 0° and treat with 20 ml prop-2-yny 1-bromide in 10 ml anisole over 20 minutes. Continue stirring one hour at 0° and let stand at room temperature twelve hours. Cool to 0°, add 100 ml ether, 200 ml water, 12 ml glacial acetic acid, 100 ml water, and extract with 5X25 ml ether. Wash with NaHCOs and dry, evaporate in vacuum the extract to get 8 g oily material which precipitates on standing in refrigerator. Add V2g HgS04 to 100 ml 2N sulfuric acid stir and heat on steam bath and add 15 g of the precipitate in 100 ml ethanol. Stir and heat two hours and pour into water. Basify with NaHCOs to get 3 g (I) (recry stallize-benzene). 

Fig. 3.1-188 Strain rate versus stress for AKS-W wires tested at 2527 °C. Wright 1978 [1.162] AKS-W wire with a diameter of 0.183 mm atmosphere = vacuum better than 7 X10 Pa heating rate = approximately 2000 °C/s GAR = 35 10 pre-recry stallized at 25 27 ° C/10 min. Zilberstein 1998 [1.215] AKS-W wire with a diameter of 0.178mm atmosphere = vacuum GAR = 31 1 pre-recrystallized at 2527 °C/15 min...

This is then reacted with 0.5 moles of chloroacetic acid per mole of sodium to form sodium hydroxyethoxyacetate. (See Figure 3) Excess ethylene glycol and by-products of the reaction are removed by distillation and by washing with acetone. The sodium hydroxt etlioxyacetate is converted to the free hydroxy acid by the addition of hydrochloric acid. The resulting sodium chloride is removed by precipitation with ethanol, followed by filtration. In the presence of MgCOj, the hydroxyacid is then heated in a distillation apparatus to about 200 C. Upon further heating, crude p-dioxanone is formed and distilled over at 200-220°C. The crude p-dioxanone is purified to over 99% by multiple recry stallizations and/or distillations. 

Mechanical properties Symbol Units Silicmi carbide, sintered Silicon carbide, silicon- infiltrated Silicon carbide, recry stallized Silicim carbide, nitride-bonded Boron carbide... 

Concentration - O OlM at half-neutralization. Glycine (0 0375 g.i, recry.stallized fioin water and dried in air at llO for an hour, uas dissolved in 47 5 ml. of ion-free water and titrated under nitrogen (to exclude carbon dioxide). 

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