Funnel pressure equalizing

Pressure-equalizing dropping funnels these have a side arm linking the reservoir of the funnel to the inlet stem below the tap. The pressures in the reservoir and the reaction flask are equal, and liquid will flow into the reaction flask even when the stopper is in place in the funnel. Pressure-equalizing dropping funnels are very expensive and are normally only used for inert atmosphere reactions (p. 119). 

In figure 4 is shown how a separatory funnel and a pressure equalized addition funnel are made. The funnel part is just a PP funnel from the grocery store and what it is attached to is a stainless steel ball valve. See how the addition funnel is made by using a rubber stopper and an extra extension of tubing to the top of the funnel Well, that s how one can make a sealed addition funnel out of the ordinary glass separatory funnel that one gets with a distillation kit or from wherever. 

Setup your glassware for simple distillation with a claisen adapter, three way adapter, pressure-equalized addition funnel, water cooled condenser, vacuum adapter and receiver flask to catch any condensed solvent vapors. 

A. Methyl 2-oxaayalohexaneaar boxylate. A 500-mL, three-necked, round-bottomed flask is equipped with a mechanical stirrer, reflux condenser, and a pressure-equalizing dropping funnel bearing a nitrogen inlet (Note 1). The flask is flushed with nitrogen and charged with 18.02 g (0.20 mol) of dimethyl... 

A. 2-(Trimethtjlsiloxymethyl)allyltvimethylBilane. An oven-dried (Note 1) 2-L, three-necked, round-bottomed flask is equipped with an air-tight mechanical stirrer (Note 2), a 500-mL pressure-equalizing dropping funnel (Note 3), and a reflux condenser. The top of the condenser is connected to a three-way stopcock with one branch connected to a nitrogen source and the other to a variable pressure oil pump with a dry-ice trap (Note 4). The apparatus is flamed dry under a steady stream of nitrogen. The flask is... 

Methyl-2-propen-l-ol, purchased from Aldrich Chemical Company, was distilled from anhydrous potassium carbonate. It was added directly to the n-butyllithium solution using a long needle. The checkers quickly replaced the pressure-equalizing dropping funnel with a serum cap to carry out this addition. The funnel was fitted to a small dry flask to prevent the introduction of moisture during the addition period and replaced on the reaction flask immediately afterwards. 

A 500-mL dropping funnel, with pressure-equalizing arm, is used. 

Tetrahydrofuran, anhydrous, 99.9t (water content <0.006t) was purchased from Aldrich Chemical Company, Inc., and used as received. The vinyl bromide solution was prepared In a 500-mL, round-bottomed flask fitted with a glass stopper. The stoppered flask containing the tetrahydrofuran was chilled to about 5 C and weighed. The vinyl bromide, also chilled to about 5°C, was rapidly poured Into the tetrahydrofuran until the desired amount had been added. The flask was stoppered, the contents mixed by shaking, allowed to warm to about 16°C, and then added to the pressure-equalizing addition funnel. 

B. -Butyl- a-methyl- >-2-octalone. A 250-ml., three-necked flask equipped with a magnetic stirring bar, a reflux condenser, a 50-ml., pressure-equalizing funnel, and a rubber septum is charged with 1.4 g. (0.032-0.036 mole) of 55-60% sodium hydride dispersion in mineral oil... 

The apparatus consists of a 3-1. three-necked round-bottomed creased flask, with standard ball joints and an indented cone-shaped bottom (Note 1), which is heated by means of an electric mantle and is equipped with a high-speecT stirrer of stainless steel driven by a 10,000 r.p.m. motor (Note 2). One side neck is fitted with a bulb-type air-cooled condenser (Note 3), on top of which fits a 1-1. pressure-equalizing Hershberg dropping funnel (Note 4). The top of the dropping funnel is to be connected in turn to a U-tube containing a 1-cm. head of mercury. The entire apparatus is securely fastened to a sturdy support. 

A dry 500-ml round-bottomed three-necked flask fitted with a stirrer, internal thermometer, and a pressure-equalized dropping funnel is placed under nitrogen and the flask is charged with 0.148 mole of freshly distilled cyclohexanone and 0.148 mole of freshly distilled ethyl chloroacetate. A solution of 6.0 g of potassium and 125 mL of dry terr-butyl alcohol is introduced into the dropping funnel, and the system is exhausted and... 

N,N Dimethylcyclohexanecarboxamide A 500-ml three-necked flask is equipped with a reflux condenser (drying tube), a pressure-equalizing dropping funnel, and a magnetic stirrer. The flask is charged with 32 g (0.25 mole) of cyclohexanecarboxylic acid and thionyl chloride (45 g, 0.375 mole) is added over 5 minutes to the stirred acid. The flask is heated (oil bath) at a temperature of 150° for 1 hour. The reflux condenser is... 

In a three-necked flask fitted with a thermometer, a stirrer, a condenser (drying tube), and a pressure-equalizing addition funnel, HMPT (25 ml, 0.14 mole) and anhydrous ether (30 ml) are introduced. Finely divided lithium (1.75 g, 0.25 g-atom) is then added... 

A 500-ml three-necked flask is fitted with a condenser, a pressure-equalizing dropping funnel, a magnetic stirrer, and a thermometer. The flask is charged with a mixture of 33.6 g (0.48 mole) of 2-methyl-2-butene and 180 ml of a 1 M solution of sodium boro-hydride in diglyme. The flask is cooled in an ice bath and stirring begun. Boron trifluoride etherate (0.24 mole) is added dropwise to the mixture and the solution is stirred at 0° for 2 hours. 

A 500-ml, three-necked, round-bottom flask is fitted with a mechanical stirrer, a pressure-equalizing addition funnel and a reflux condenser (drying tube). The flask is charged with 100 ml of dry dimethylformamide, 9.2 ml (0.1 mole) of dry -butyl alcohol, and 28 g (0.107 mole) of dry triphenylphosphine. The flask is cooled in a water bath, stirring is begun, and bromine (approx. 16 g, 0.1 mole) is added over about 15 minutes. 

In a 250-ml three-necked flask fitted with a magnetic stirrer, a pressure-equalizing dropping funnel, and a thermometer is placed a solution of l,4-cyclohexanediol(l 1.4g, 0.10 mole), 35 ml of chloroform, and 27 ml of dry pyridine. The solution is cooled in an ice bath to 0-5 and is maintained below 5 throughout the addition. A solution of benzoyl chloride (14 g, 0.10 mole) in 30 ml of dry chloroform is added with stirring at a rate so as to keep the temperature below 5° (approx. 40 minutes). After completion of the addition, the mixture is allowed to come to room temperature and stand overnight. The chloroform solution is washed four times with 50-mI portions of water, once with 50 ml of 5 % sulfuric acid solution, and finally with saturated sodium chloride solution. The chloroform solution is then dried (sodium sulfate), and the solvent is removed. Fractionation of the residue gives a cis and trans mixture of 4-benzoyloxycyclohexanol, bp 175-17870.2 mm, as a very viscous oil, yield about 55%. 

The reaction is carried out under argon in a 2-liter three-necked flask fitted with a mechanical stirrer, reflux condenser, 250-ml pressure-equalizing addition funnel, and gas inlet and outlet. After purging with argon, the flask is charged with a solution of 89 g (0.48 mole) of ferrocene in 1 liter of dry tetrahydrofuran. The solution is next heated to 45°, and there is added dropwise with stirring, 155 ml (0.29 mole) of an -butyllithium solution (15% in heptane-pentane, 2 1, Foote Mineral Co.) during a period of 75 minutes. The resultant solution is maintained at 45° for an additional 2 hours, then is cooled to —77° by means of an external Dry Ice-chloroform bath. 

A dry 5(X)-mI flask equipped with a thermometer, pressure-equalizing dropping funnel, and magnetic stirrer is flushed with nitrogen and then maintained under a static pressure of the gas. The flask is charged with 50 ml of tetrahydrofuran and 13.3 ml (0.15 mole) of cyclopentene, and then is cooled in an ice bath. Conversion to tricyclo-pentylborane is achieved by dropwise addition of 25 ml of a 1 M solution of diborane (0.15 mole of hydride see Chapter 4, Section 1 for preparation) in tetrahydrofuran. The solution is stirred for 1 hour at 25° and again cooled in an ice bath, and 25 ml of dry t-butyl alcohol is added, followed by 5.5 ml (0.05 mole) of ethyl bromoacetate. Potassium t-butoxide in /-butyl alcohol (50 ml of a 1 M solution) is added over a period of 10 minutes. There is an immediate precipitation of potassium bromide. The reaction mixture is filtered from the potassium bromide and distilled. Ethyl cyclopentylacetate, bp 101730 mm, 1.4398, is obtained in about 75% yield. Similarly, the reaction can be applied to a variety of olefins including 2-butene, cyclohexene, and norbornene. 

A dry, 500-ml, three-necked flask is fitted with a mechanical stirrer, a condenser, and a pressure-equalizing dropping funnel. The system is swept out with nitrogen and a slight positive pressure of nitrogen is maintained by venting the system to a mercury filled U-tube. In the flask is placed 21 g (0.187 mole) of dry potassium /-butoxide, and the flask is cooled in an ice-salt bath. 

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