Desiccants magnesium sulfate

A stirred mixture of 11 g of 6-chloro-a-methylcarbazole-2-acetic acid ethyl ester, 100 ml ethanol and 100 ml of 3N sodium hydroxide was heated (N2 atmosphere). After 2 hours at reflux, the reaction mixture was concentrated to dryness under reduced pressure. Water (300 ml) and ice (200 g) were added to the residue and concentrated hydrochloric acid was added until the mixture was strongly acid. The acidic mixture was extracted with ether (3 X 200 ml). The ether extracts were combined, washed by extraction with water (3 x 100 ml) and dried over anhydrous magnesium sulfate. Following filtration of the desiccant and evaporation of the solvent, a yield of 9.8 g (98.2%) was obtained. Crystallization from CHCI3 yielded 6.2 g (62.0%) of 6-chloro-0 -methylcarbazole-2-acetic acid, MP 197°-198°C. A second crop of 1.6g,MP 195°-199°C was obtained from the mother liquors. 

Molecular sieves or magnesium sulfate were activated by heating at 500 °C for 2-14 hours and cooled in a desiccator under vacuum. 

Amines such as diethylamine, morpholine, pyridine, and /V, /V, /V, /V -tetramethylethylene-diamine are used to solubilize the metal salt and increase the pH of the reaction system so as to lower the oxidation potential of the phenol reactant. The polymerization does not proceed if one uses an amine that forms an insoluble metal complex. Some copper-amine catalysts are inactivated by hydrolysis via the water formed as a by-product of polymerization. The presence of a desiccant such as anhydrous magnesium sulfate or 4-A molecular sieve in the reaction mixture prevents this inactivation. Polymerization is terminated by sweeping the reaction system with nitrogen and the catalyst is inactivated and removed by using an aqueous chelating agent. 

B) Preparation of 5-Trifluoromethyl-2,4-Disulfamylaniline - The 5-trifluoromethylaniline-2,4-disulfonyl chloride obtained in step (A) is taken up in ether and the ether solution dried with magnesium sulfate. The ether is removed from the solution by distillation, the residue is cooled to 0°, and 60 ml of ice-cooled, concentrated ammonia water is added while stirring. The solution is then heated for one hour on a steam bath and evaporated in vacuo to crystallization. The crystallized product is 5-trifluoromethyl-2,4-disulfamylaniline, which is filtered off, washed with water and dried in a vacuum-desiccator over phosphorus pentoxide. After recrystallization from a mixture of 30% ethanol and 70% water, the compound has a MP of 247°-248°C. 

After the addition of the reactants is complete, the reaction is allowed to stir for an additional 30 min while the solution warms to room temperature. The reaction mixture is then transferred to a separatory funnel. The viscous organic bottom layer is separated from the aqueous layer and is dissolved in 200 mL of ether. The reaction vessel is washed with 100 mL of ether, and this ether portion is used to extract further the aqueous layer. The ether layers are combined, dried over magnesium sulfate, and filtered, and the solvent is removed under reduced pressure. The viscous oil is allowed to crystallize in an ice bath (0°C). The crystals are collected on a Buchner funnel, washed with 500 mL of water, and dried in a vacuum desiccator at 0.5 mm for 48 hr. 80.8 g (93%) of white crystalline bis(2,2,2-trichloroethyl) hydrazodicarboxylate (mp 85-89°C) is obtained. This material is sufficiently pure for the next preparation. However, further purification can be achieved using an Abderhalden drying apparatus (refluxing 95% EtOH for 12 hr at 0.05 mm MgS04 desiccant). Material purified in this way melted at 96.5-97.5°C (Notes 4 and 5). 

Dissolve the precipitate in chloroform and dry the solution with anhydrous magnesium sulfate. Filter off the desiccant, then remove the solvent at reduced pressure using a rotary evaporator to give an oily residue. 

Procedure Prepare two solutions, a sodium azide solution, and a silver nitrate solution by dissolving 10 grams of sodium azide into 90 milliliters of water, and dissolve 26 grams of silver nitrate into 224 milliliters of water. Then place each solution into a freezer and chill to about 5 Celsius. Thereafter, place the sodium azide into an ice bath, and then rapidly add the silver nitrate solution. Upon mixing, the SZ will instantaneously precipitate. After mixing both solutions, carefully filter-off the precipitated product, carefully wash with 100 milliliters of ice-cold water, and then dry in a desiccator filled with anhydrous magnesium sulfate. Do not vacuum dry or air-diy. The dry product should never be kept dry. For storage, keep the dry SZ suspended in a water free solvent such as kerosene. 

Procedure Place 200 milliliters of 70% nitric acid into a beaker, and then add 20 grams of mercury. Then rapidly stir this mixture at room temperature for 24 hours. Thereafter, slowly heat the mixture to about 78 Celsius with rapid stirring, and then carefully add 240 grams of 95% ethanol while stirring the reaction mixture. After the addition of the alcohol, remove the heat source, and allow the reaction mixture to cool to room temperature. Afterwards, continue to stir the reaction mixture for about 30 minutes at room temperature. Then, filter-off the precipitated mercury fulminate, wash with several hundred milliliters of cold water, and then dry in a desiccator filled with anhydrous magnesium sulfate. 

Procedure Place 20 milliliters of 25% ammonia solution into a flask, and then rapidly add 10 grams of silver-I-oxide. Thereafter, allow the mixture to stand in the dark for 20 hours at room temperature. After 20 hours, filter-off the precipitated crystals of silver nitride, wash with 100 milliliters of cold water, and then dry in a desiccator over anhydrous magnesium sulfate. Once the nitride is dry, immediately use for making priming mixtures. 

The enone 2.1b (0.9 g, 2.8 mmol), hydroxylamine hydrochloride (0.3 g, 4.2 mmol) and pyridine (0.3 g, 4.2 mmol) were heated at reflux in 100 mL of ethanol for 52 h. After cooling the mixture to room temperature, the solvent was removed under vacuum and the crude dissolved in ether, washed with 3 x 100 mL portions of 10% aqueous HCl and then with water. The organic layer was dried over magnesium sulfate. The desiccant was filtered off and the solvent was removed under reduced pressure. The crude product obtained was purified by flash chromatography (silica gel 60 230-400 mesh) using hexane/ethyl acetate (1 1) as eluant. The chromatography yielded 0.9 g (95%) of the oxime 2.1c as colorless crystals, mp 185 - 187 °C from ethanol. 

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