Inert atmospheres wetting

Alkali metal salts of diazomethane are very explosive when exposed to air in the dry state, and should be handled, preferably wet with solvent, under an inert atmosphere. See other diazo compounds... 

Explosive materials must be ground wet or in the presence of an inert atmosphere. 

A solution of 19 g indol-3-yl N,N-dibutylglyoxylamide in 350 mL anhydrous dioxane was added, slowly, to 19 g LAH in 350 mL dioxane which was well stirred and held at reflux temperature under an inert atmosphere. After the addition was complete, refluxing was maintained for an additional 16 h, the reaction mixture cooled, and the excess hydride destroyed by the cautious addition of wet dioxane. The formed solids were removed by filtration, washed with hot dioxane, the filtrate and washings combined, dried over anhydrous MgS04, and the solvent removed under vacuum. The residue was dissolved in anhydrous Et20 and saturated with anhydrous hydrogen chloride. The solids that formed were recrystallized from benzene/methanol to give 12.6 g (64%) of N,N-dibutyltryptamine hydrochloride (DBT) with a mp of 186-188 °C. 

Fig. 4.1. Photolysis under an inert atmosphere. The sample is contained in a quartz or glass vessel and stirred with a magnetic stir-bar. The vessel is jacketed and kept at constant temperature with a circulating fluid that can also act as a filter. An inert atmosphere is maintained by passing wet argon or nitrogen (the gas from a tank is bubbled through water) over the solution at - I ml s-1.

A suspension of 31.7 g LAH in 300 mL anhydrous THF, stirring under an inert atmosphere, was treated by the addition of a solution of 36 g l-(3-indolyl)-2-nitrobut-1 -ene in 285 mL anhydrous THF. This was added dropwise over the course of 3 h, while the mixture was being brought up to reflux temperature. The reaction mixture was held at reflux for an additional 2 h, then allowed to return to room temperature. After standing overnight, the excess hydride was destroyed by the cautious addi lion of 500 mL wet Et20, followed with 70 mL H20,100 mL THF, and finally 20 mL 50% NaOH. After 1 h additional stirring, the solids were removed... 

This sort of system can prepare a batch of granules in 60-90 minutes. However, whereas fluidised bed granulation is rapid and flexible it is not without its problems. The presence of finely divided powders means that the apparatus itself is a potential explosion hazard, although, obviously, these systems are constructed and used in such a way as to be safe. One possibility is to use nitrogen instead of air thus providing an inert atmosphere. A further problem is that a fluidised bed granulator is not the easiest piece of equipment to set up, particularly compared with a wet granulation system. 

All operations with phosphorus and reactive phosphides should be done in a hood or dry box and equipment should be on hand to deal with the possibility of a phosphorus fire. Phosphides may ignite if milled mechanically under ambient conditions and even highly purified red phosphorus may contain small inclusions of white phosphorus. Therefore, all grinding should be done under an inert atmosphere. On contact with wet air or wet inert gas, phosphides may produce phosphines (odor, selfignitability). Phosphines have also been shown to be physiologically active. ... 

The ammines of cobalt(II) are much less stable than those of cobalt(III) thermal decomposition of [Co(NH3)6]Cl2 is characterized by reversible loss of ammonia, whereas that of [Co(NH3)6]Cl3 is not. In his classic dichotomy of complexes, Biltz regarded [Co (NH 3)3] Cl 2 as the prototype of the normal complex and [Co(NH3)6]Cl3 as that of the Werner or penetration complex. Hexaamminecobalt-(II) chloride has been prepared by the action of gaseous ammonia on anhydrous cobalt (II) chloride or by displacing water from cobalt(II) chloride 6-hydrate with gaseous ammonia. It may also be synthesized in nonaqueous solvents by passing dry ammonia through solutions of cobalt(II) chloride in ethanol, acetone, or methyl acetate. Syntheses in the presence of water include heating cobalt(II) chloride 6-hydrate in a sealed tube with aqueous ammonia and alcohol and the treatment of aqueous cobalt(II) chloride with aqueous ammonia followed by precipitation of the product with ethanol. The latter method is used in this synthesis. Inasmuch as the compound is readily oxidized by air, especially when wet, the synthesis should be performed in an inert atmosphere. 

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