Funnel manipulation

Some of the more obvious sources of contamination of solvents arise from storage in metal drums and plastic containers, and from contact with grease and screw caps. Many solvents contain water. Others have traces of acidic materials such as hydrochloric acid in chloroform. In both cases this leads to corrosion of the drum and contamination of the solvent by traces of metal ions, especially Fe. Grease, for example on stopcocks of separating funnels and other apparatus, e.g. greased ground joints, is also likely to contaminate solvents during extractions and chemical manipulation. 

In a 1-1. three-necked flask equipped with a dry ice-acctone condenser and a sealed mechanical stirrer is placed 700 ml. of commercial, anhydrous, liquid ammonia. To the stirred ammonia is added a small piece of potassium metal. (Caution1 Care should he exercised in handling potassium metal, since it is extremely reactive and it ignites on contact with water, atmospheric moisture, or alcohol. It should he manipulated under toluene or xylene, and blotted with filter paper before addition.) After the appearance of a blue color a few crystals of ferric nitrate hydrate (ca. 0.1 g.) are added, followed by small pieces of freshly cut potassium metal until 7.0 g. (0.18 g. atom) has been added. After all the potassium has been converted to the amide (Note 7), 24.9 g. (0.154 mole) of sodio-2-formyl-6-methylcyclohexanone is added carefully through a powder funnel (Note 8). After 1 hour a solution of 28.2 g. (0.21 mole) of w-butyl bromide (Note 9) in 50 ml. of anhydrous ether is added dropwise from an addition funnel. The mixture is stirred for 3 hours, and then the dry ice-acetone condenser is replaced by a water condenser. A steam bath is placed under the flask, and the ammonia is evaporated (Caution ) as 400 ml. of anhydrous ether is added. When the... 

The preparation of single isomers for methanol dimer, trimer, and presumably tetramer [16] in a supersonic jet expansion contrasts the structural diversity that can be prepared and manipulated in cryogenic matrices [34]. It underscores the ability of supersonic jet expansions to funnel all intermolecular isomers down to the global minimum, if there are no major barriers to overcome on the way. 

The use of a large funnel attached to a stream of inert gas situated above the bench is particularly useful when opening bottles of hygroscopic or hydrolytically unstable materials. This technique relies for its success on a fast stream of clean and dry inert gas. It is of course wasteful when used over long periods, but it does allow almost the same flexibility of manipulation as on the open bench. 

Use of a ceramic Buchner funnel with coarse filter paper is recommended to avoid scraping a glass frit during removal of 1. A rubber spatula is recommended for stirring and manipulation of the filter cake. The filter cake can be conveniently removed from the funnel by applying a small amount of air pressure to the stem. 

The temperature of the reaction mixture in this highly exothermic manipulation should be kept below 20°C to avoid loss of the low-boiling product. An addition funnel can be used for the dropwise delivery of the aqueous saturated ammonium chloride solution, while leaving the reflux condenser in place. 

Caution. Because of the poisonous nature of arsenic compounds and sulfur dioxide, all manipulations must be carried out in an efficient fume hood. 100 g (0.505 mol) of As203 are placed in a 500-mL, two-necked, round-bottomed flask, or a one-necked flask fitted with a Claisen head with a dropping funnel, a water-cooled reflux condenser, and a magnetic stirrer... 

In a 1-1. three-necked round-bottomed flask (Note 1) are placed 90.0 g. (0.456 mole) of benzanilide2 (Note 2) previously-dried in an oven at 120° (Note 3) and 95 g. (0.456 mole) (Note 4) of phosphorus pentachloride. The solids are mixed by shaking, and lumps are reduced by manipulation with a rod. A short reflux condenser and a small dropping funnel are attached. 

By rapid manipulation it is possible to obtain a product of fair quality. The moist product is susceptible to air oxidation, as is shown by a development of pink coloration on the crystals. The filtration is best carried out under a blanket of carbon dioxide or nitrogen obtained by inverting a funnel attached to a source of carbon dioxide or nitrogen over the Buchner funnel. 

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