Drying pistols

Bismethylaminoanthraquinone (Disperse Blue 14) [2475-44-7] M 266.3, A,max 640 (594)nm. Purified by thin-layer chromatography on silica gel plates, using toluene/acetone (3.1) as eluent. The main band was scraped off and extracted with MeOH. The solvent was evapd and the dye was dried in a drying pistol [Land, McAlpine, Sinclair and Truscott J Chem Soc, Faraday Trans I 72 2091 7976]. 

Nitrophenol [88-75-5] M 139.1, m 44.5-45.5 , pK 7.23. Crystd from EtOH/water, water, EtOH, benzene or MeOH/pet ether (b 70-90°). Can be steam distd. Petrucci and Weygandt [Anal Chem 33 275 1961] crystd from hot water (twice), then EtOH (twice), followed by fractional crystn from the melt (twice), drying over CaCl2 in a vacuum desiccator and then in an Abderhalden drying pistol. 

Tetra-n-butylammonium hexafluorophosphate [3109-63-5] M 387.5, m 239-241 . Recrystd from satd EtOH/water and dried for lOh in vac at 70°. It was also recrystd three times from abs EtOH and dried for 2 days in a drying pistol under vac at boiling toluene temperature [Bedard and Dahl J Am Chem Soc 108 5933 1986],... 

Cyclopropyltriphenylphosphonium Bromide (5). The lactone salt is pyrolyzed by placing it in a round-bottom flask fitted with an adaptor attached to a vacuum source (aspirator is sufficient). The flask is heated (oil bath) to 180-190° for 48 hours. The residue is a virtual quantitative yield of the tan product, which may be crystallized from ethyl acetate giving cream crystals, mp 189-190°. An alternate setup is convenient if a drying pistol (Abderhalden) is available. The compound is placed in the pistol, which is then evacuated. Decalin (bp approx. 187°) is refluxed over the pistol to provide the heating source. The work-up is the same. 

Reagent 111 was formed by dissolving 0.50 g (3.5 mmol) of II in 25 mL of water in a 50-mL round-bottom flask. To this solution was added 0.15 g (3.61 mmol) of sodium hydroxide, and the mixture was heated on a steam bath for 30 min. The water was removed and the residue suspended in hot toluene. The toluene suspension was filtered and the remaining solid dried in an Abderhalden drying pistol with phosphorus pentoxide. This procedure gave 0.55 g (99%) yield of Reagent 111. 

Phenyl-2(lH)Pyridone Sodiim Salt. A solution of sodium metal (0.25 g, 11.3 mmol) and anhydrous methanol (10 mL) was allowed to react to form sodium methoxide. Pyridone IV (1.88 g, 11 mmol) was added to the solution and allowed to stand at room temperature for 24 h. The methanol was removed under reduced pressure and the residue was extracted with hot benzene 3 times and dried in the Abderhalden drying pistol for 30 min. The yield was 1.7 g (82%). 

Commonly an amorphous solid may have solubility in both aqueous and DMSO that is over 100 hmes higher than any of the crystalline forms. An amorphous solid can be inadvertently created from a crystalline material, e.g. by heating a crystalline hydrate or solvate for a short time period below its melhng point in a drying pistol. 

Triphenylphosphine, m.p. 80-81°, was obtained from Eastman Organic Chemicals and was kept in a drying pistol held at approximately 65° (1 mm.) for approximately 18 hours prior to use. When only 10-20% excess triphenylphosphine was employed the yield of geranyl chloride was approximately 75%, but the small amount of unreacted geraniol which remained rendered product isolation more difficult. 

Sodium iodide was obtained from Acros Organics, a Fisher Scientific Company, and dried in a "drying pistol" under vacuum at 113°C in the presence of phosphorus pentoxide (P2O5). 

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