Adapter, Claisen

Prepare a paste out of 65g Sodium Azide (lm NaN ) and 65mL of water in a beaker. Add 400mL of either Chloroform or Benzene to this paste (depending on what you have available, but be consistent later on) and stir well. Dump this mixture into a round bottom flask situated in an ice/salt bath, drop in a stirrer magnet, attach a Claisen adapter, addition funnel, and thermometer. Let this mixture cool to OC. 

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 Claisen adapter in the distilling flask allows temperature readings to be taken and can help stop your compound from splashing over into the distillation receiver (Fig. 78). Also, you could use a three-neck flask (Fig. 79). Think And, of course, use some glassware too. 

There are at least two ways to set up an addition and reflux, using either a three-neck flask or a Claisen adapter. I thought I d show both these setups with drying tubes. They keep the moisture in the air from getting into your reaction. If you don t need them, do without them. 

A. Sodium p-trimethylsilylethanesulfonate (1). To a 500-mL, round-bottomed flask (Note 1) flushed with argon and equipped with a magnetic stirring bar is added vinyltrimethylsilane (28.0 mL, 18.2 g, 181 mmol), methanol (70 mL), and tert-butyl perbenzoate (0.70 mL, 0.70 g, 3.6 mmol) (Notes 2 - 4). To this solution is added a solution of sodium bisulfite, NaHSC>3, (36.1 g, 347 mmol) in 70 mL of water (Notes 5 -7). The flask is equipped with a Claisen adapter bearing an immersion thermometer and reflux condenser, and the resulting suspension is heated in an oil bath at 50°C... 

B. (3-Bromo-3,3-difluoropropyl)trimethylsilane. A 1-L, four-necked flask is equipped with a mechanical stirrer, thermometer, Claisen adapter, septum inlet, reflux condenser (the top of which is connected to a calcium chloride drying tube), and a solid addition funnel. The flask is charged with (1,3-dibromo-3,3-difluoropropyl)trimethylsilane (78.3 g, 0.25 mol), and anhydrous dimethyl sulfoxide (200 mL), and the solid addition funnel is charged with sodium borohydride (11.5 g, 0.30 mol) (Notes 7 and 8). The stirred solution is warmed to 80°C, and sodium borohydride is added at a rate sufficient to maintain a reaction temperature of 80-90°C (Note 9). Toward the end of the addition, an additional portion of dimethyl sulfoxide (200 mL) is added via syringe to lower the viscosity of the reaction mixture. After the addition is complete, the mixture is cooled in an ice-water bath, diluted with 100 mL of pentane, and cautiously quenched with 12 M hydrochloric acid until no further gas evolution occurs. The mixture is transferred to a separatory funnel and washed with three, 100-mL portions of 5% brine. The pentane extract is dried over calcium chloride and the solvent removed through a 15-cm Vigreux column. Further fractionation yields 41.5 g (72%) of 3-bromo-3,3-difluoropropyltrimethylsilane, bp 139-141 °C (Note 10). 

A Claisen adapter can be added to allow use of both inlet tube and thermometer. If you must decide between the two then pick the inlet tube. 

A 500-mL, three-necked, round-bottomed flask is equipped with a 25-mL pressure-equalizing dropping funnel, a mechanical stirrer, and a Claisen adapter fitted with a nitrogen inlet adapter and a low temperature thermometer (Note 1). The flask is charged with 11.5 g (0.077 mol) of (R)-(-)-carvone (Note 2), 10.8 g (0.079 mol) of 1-methyl-l-(trimethylsilyl )allene (Note 3), and 180 mL of dry dichloromethane (Note 4), and then cooled below -75°C with a dry ice-acetone bath while a solution of 17.4 g (0.092 mol) of titanium tetrachloride (Note 5) in 10 ml of dichloromethane is added dropwise over 1 hr. After 30 min, the cold bath is removed, and the reaction mixture, which appears as a red suspension, is allowed to warm to 0°C over approximately 30 min. The resulting dark red solution is poured slowly into a 2-L Erlenmeyer flask containing a magnetically-stirred mixture of 400 mL of diethyl ether and 400 mL of water (Note 6). The aqueous phase is separated and extracted with... 

The dropping funnel and the reflux condenser were connected to the same neck using a Claisen adapter. 

A. Geranial. A 2-L, three-necked, round-bottomed flask is dried in an oven and equipped with a mechanical stirrer, thermometer, Claisen adapter, and two pressure-equalizing dropping funnels. The flask is charged with 500 mL of dichloromethane (Note 1) and 20 mL (29.2 g, 0.23 mol) of oxalyl chloride (Note 2). The solution is stirred and cooled at -50 to -60°C as 34 mL (37.5 g, 0,48 mol) of dimethyl sulfoxide (Note 3) in 100 mL of dichloromethane is added dropwise at a rapid rate. After 5 min 30.8 g (0.2 mol) of geraniol (Note 4) Is added dropwise over 10 min maintaining the temperature at -50 to -60 0. 

A. tert-Butylmalononitrile. In a dry 2-1. three-necked flask equipped with a thermometer, mechanical stirrer, and a Claisen adapter fitted with a dropping funnel and condenser protected with a drying tube is placed 200 ml. of nitromethane (Note 1). The flask is cooled to 0° in an ice-salt bath (Note 2), and anhydrous powdered aluminum chloride (90.0 g., 0.68 mole) is added with slow stirring through a powder funnel that temporarily replaces the thermometer. The temperature may rise to ca. 50° but quickly drops to 0°. Malononitrile (45.0 g., 0.68 mole) (Note 3) in 50 ml. of nitromethane is added through the dropping funnel at a rate such that the temperature is kept below 10° (approximately one hour), followed by slow dropwise addition of tert-butyl chloride (Note 4) (150 g., 1.62 moles) in 50 ml. of nitromethane at a rate such that the temperature is maintained... 

B. Ethyl 4-Methyl-E-4,8-ncmadienoate. A 500-ml. one-necked round-bottomed flask containing a magnetic stirring bar is fitted with a Claisen adapter, two thermometers, and a receiving flask as illustrated in Figure 1. To the flask is added 186 g. 

A 500-ml., three-necked, round-bottomed flask is equipped with a magnetic stirrer, a Claisen adapter in which are inserted two pressure-equalizing addition funnels, a nitrogen source, and an outlet to a series of traps (Fig. 1). Trap 1 is cooled to —78°C. (Dry Ice-acetone mixture) and is attached to a drying tube filled with potassium hydroxide. Traps 2 and 3, equipped with stopcocks, are cooled to —196°C. (liquid nitrogen ). All connections are made of... 

A 2-L, three-necked flask was equipped with an overhead mechanical stirrer, a Claisen adapter which contained a low-temperature thermometer, and a no-air stopper which held a gas dispersion tube for the introduction of carbon monoxide (Note 1). The flask was charged with 400 mL each of tetrahydrofuran (THF) and diethyl ether, 100 mL of pentane, and pinacolone (7.92 g, 79.1 mmol) (Note 2). The reaction solution was cooled to -110 C (Notes 3 and 4) under an argon atmosphere and carbon monoxide (Note 5) was bubbled in for 30 min. Then a solution of butyllithium (2.53 N solution in pentane, 31.0 mL, 78.43 mmol) (Note 6) was added at 0.6-1.0 mL/min by means of a syringe pump (Note 7). The reaction mixture was orange after the addition had been completed. The reaction mixture was stirred at -110°C for 2 hr while the carbon monoxide stream was continued. The liquid nitrogen Dewar was removed, and the reaction mixture was allowed to warm to room temperature over the course of 1.5 hr, during which time the color changed to yellow. 

A 500-mL flask is fitted with a Claisen adapter having a dropping funnel and calcium chloride drying tube the flask is charged with diethylamine... 

A. Methyl 3.6-dimethyl-3-hydroxy-6-heptenoate (Note 1). An oven-dried, threenecked, 500-mL, round-bottomed flask, is fitted with an efficient mechanical stirrer, a Claisen adapter bearing a reflux condenser with a nitrogen, inlet and rubber septum, and a thermometer. The flask is maintained under a static nitrogen pressure and charged with 5-methyl-5-hexen-2-one (24.20 g, 0.216 mol) (Note 2), trimethyl borate... 

To control foaming, the submitters recommend the use of a distillation flask larger than usual. In this instance, they used a 250-mL flask fitted with a Claisen adapter. 

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