Drying compounds

Experiment 4. Choice of Solvent and Complete Recrystallisation. Students should be supplied with distilled water and with the more common organic solvents, and also with the compounds mentioned below. Taking each compound in turn they should decide, by the methods described in (i) above, which of these six solvents is the best for recrystallisation. They should then recrystallise about 5 g. of at least two of the compounds, dry the product, and whenever possible take its melting-point. 

Dry basis natural mbber compound recipe, in part by wt high ammonia natural latex mbber concentrate, 100.0 potassium hydroxide, 0.5 Nacconal 90F (alkylarenesulfonate (AHied Chemical Co.)), 1.0 zinc oxide, 3.0 sulfur, 1.0 ZMBT, 1.0 zinc diethyldithiocarbamate (ZEDC) (trade names Ethazate (Uniroyal, Inc.), Ethyl Zimate (R. T. Vanderbilt), 0.3 antioxidant, as indicated. Wet-basis natural mbber compound recipe, in parts by wt natural latex (NC 356), 167.9 potassium hydroxide, 2.5 Nacconal 90F, 5.0 zinc oxide, 5.45 sulfur, 1.65 ZMBT, 2.0 ZEDC, 2.0 antioxidant, as indicated. AH films poured from freshly mixed compounds, dried overnight in place, then lifted and dried 1 h in air at 50°C before curing. 

DRYING AGENTS FOR CLASSES OF COMPOUNDS Dried with... 

A solution of 438 mg of diac in methanol (20 ml) and ammonia solution (SG 0.88 20 ml) was iodinated at 0°C with 1.8 ml 1 N iodine solution. The product was isolated in almost theoretical yield in a manner similar to that described for tetrac. After crystallization from 50% (v/v) methanol, triac was obtained as colorless needles which melted over the range 65°C to 90°C according to the rate of heating. The molten form resolidified at about 110°C and finally melted at 180 C to 181°C without decomposition. The compound, dried at 25°C/3 mm over silica gel, contains methanol of crystallization. 

The Philips catalyst [290] is probably the most important. It is still used for producing over 60% of the world s polyethylene. The most frequently used kind is prepared by impregnating a support (silica, silicoalumina, etc. with a surface area > 200 m2 g-1) with Cr compounds, drying and activating with a stream of dry air (with addition of CO) at 700-1100 K. Chromates are assumed to be formed, but only a small part forms active centres... 

LITHIUM HYPOCHLORITE COMPOUND, dry, containing more than 39% available chlorine (DOT) see LHJOOO... 

It is easily soluble in hot alcohol but insoluble in ether. p-Tolylarsen-oxide melts at 156° C., and has similar properties to the foregoing compound. Dry chlorine converts it to p-tolylarsenic oxychloride, C,H7.AsOCl2. m-Tolylarsenoxide only occurs as a aoscous mass. ... 

A compound dry and with no water of crystallization yielded the following results Carbon and Hydrogen by Combustion... 

---