Pistols

The latter is connected above to a water-condenser and below to a flask which contains a liquid of appropriate boiling-point. The inner tube is connected to a water-pump. A more satisfactory pistol (Fig. 48(B)) consists of a wide glass tube A closed at each end by ground-glass caps. 

Where substances are sufficiently stable, removal of solvent from recrystallised materials presents no problems. The crystals, after filtering at the pump (and perhaps air-drying by suction), are heated in an oven above the boiling point of the solvent (but below this melting point of the crystals), followed by cooling in a desiccator. Where this treatment is inadvisable, it is still often possible to heat to a lower temperature under reduced pressure, for example in an Abderhalden pistol. This device consists of a small chamber which is heated externally by the vapour of a boiling solvent. Inside this chamber, which can be evacuated by a water pump or some other vacuum pump, is... 

Methods for removing water from solids depends on the thermal stability of the solids or the time available. The safest way is to dry in a vacuum desiccator over concentrated sulfuric acid, phosphorus pentoxide, silica gel, calcium chloride, or some other desiccant. Where substances are stable in air and melt above 100°, drying in an air oven may be adequate. In other cases, use of an Abderhalden pistol may be satisfactory. 

Bis-(chloromethyl)durene [3022-16-0] M 231.2, m 197-198 . Crystd three times from benzene, then dried under vacuum in an Abderhalden pistol. 

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]. 

Methoxynaphthalene [93-04-9] M 158.2, m 73.0-73.6°, b 273°/760mm. Fractionally distd under vacuum. Crystd from absolute EtOH, aqueous EtOH, benzene or n-heptane, and dried under vacuum in an Abderhalden pistol or distd in vacuo. [Kikuchi et al. J Phys Chem 91 574 1987.]... 

Methylnaphthalene [91-57-6] M 142.2, m 34.7-34.9 , b 129-130 /25mm. Fractionally crystd repeatedly from its melt, then fractionally distd under reduced pressure. Crystd from benzene and dried under vacuum in an Abderhalden pistol. Purified via its picrate (m 114-115°) as described for 1-methylnaphthalene. 

Naphthylamine [134-32-7] M 143.2, m 50.8-51.2 , b 160 , pK 3.94. Sublimed at 120° in a stream of nitrogen, then crystd from pet ether (b 60-80°), or abs EtOH then diethyl ether. Dried under vacuum in an Abderhalden pistol. Has also been purified by crystn of its hydrochloride from water, followed by liberation of the free base and distn finally purified by zone melting. CARCINOGEN. 

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. 

Phenylanisole (4-methoxybiphenyl) [361-37-6] M 184.2, m 89.9-90.1". Crystd from benzene/pet ether. Dried under vacuum in an Abderhalden pistol. 

A -Phenyl-l-naphthylamine [90-30-2] M 219.3, m 63.7-64.0°, pK j, -0.1. Crystd from EtOH, pet ether or benzene/EtOH. Dried under vacuum in an Abderhalden 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],... 

Tetramethylcyclobutan-l,3-dione [933-52-8] M 140.2, m 114.5-114.9°. Crystd from benzene and dried under vacuum over P2O5 in an Abderhalden pistol. 

Abderhalden pistol. [Das et al. J Chem Soc, Faraday Trans I 78 3485 1982.] HIGHLY POISONOUS and potentially explosive. 

The same applies to the use of spray pistols (spray guns and aerosol cans), the frequency of whose use ought probably to be reduced on account of the propellant gas (chlorofluorohydrocarbons) employed Manual depression of the button valve of the vertically held spray can shoots the propellant gas through a fine jet and drags the sucked-up reagent solution with it onto the vertically held chromatogram (water pump pnnciple)... 

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. 

The sample is placed in the barrel of the pistol and a drying agent (usually P2O5) placed in the handle. The evacuated system is heated by refluxing a liquid of the desired boiling point over the sample. 

Pistole,/. pistol gun torpedo fuse. Pistolengeblaae, n, hand-operated blast, Pitehanf, Pitahanf, m. pita hemp, pita, Pitot-rohr,n, -rfihre,/., Pitotsches Rohr. Pitot tube. 

Fig. 12.26 Diagrammatic arrangement of compressed air and hoses for wire pistols...

Improvements of the manual pistols have made it possible to use a much thicker wire which can be up to 8 mm dia for the softer metals. Recently, the range of the wire pistol has been extended by the spraying of plastic cords containing the material to be sprayed as a fine powder. This development, as yet, is not much used in the anticorrosives field. 

The vision of the late W E Ballard ensured that this chapter is still very relevant but there have been some changes in emphasis. Of the spraying techniques, the electric arc process is now generally more economical in operation than oxy-fuel gas processes. The rate of spraying is proportional to the current used and several types of equipment are available ranging from 200 to 1 000 A capacity. For manual operation, pistols using currents up to... 

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