Abderhalden pistol

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. 

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. 

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. 

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. 

Benzidine [92-87-5] M 184.2, m 128-129 . Its soln in benzene was decolorized by percolation through two 2-cm columns of activated alumina, then concentrated until benzidine crystd on cooling. Recrystd alternatively from EtOH and benzene to constant absorption spectrum [Carlin, Nelb and Odioso JACS 73 1002 7957]. Has also been crystd from hot water (charcoal) and from ethyl ether. Dried under vac in an Abderhalden pistol. Stored in the dark in a stoppered container. CARCINOGENIC. 

Abderhalden pistol. Has also been purified by crystn of its hydrochloride from water, followed by liberation of... 

P-Naphthylamine [91-59-8] M 143.2, m 113". Sublimed at 180° in a stream of nitrogen. Crystd from hot water or benzene. Dried under vacuum in an Abderhalden pistol. CARCINOGEN. 

V,A, V, V -Tetramethylbenzidine [366-29-0] M 240.4, m 195.4-195.6 . Crystd from EtOH or pet ether, then from pet ether/benzene, and sublimed in a vacuum. [Guarr et al. JACS 107 5104 7955], Dried under vac in an Abderhalden pistol, or carefully on a vacuum line. 

Sodium azide [26628-22-8] M 65,0. Crystd from hot water or from water by the addition of absolute EtOH or acetone. Also purified by repeated crystn from an aqueous solution saturated at 90° by cooling it to 10°, and adding an equal volume of EtOH. The crystals were washed with acetone and the azide dried at room temperature under vacuum for several hours in an Abderhalden pistol. [Das et al. JCSFT 178 3485 1982],... 

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