Claisen distilling head

Fig. 11, 56, 7 is a Claisen distillation head. The lower cone is usually B19 or 24 and the side cone is generally 19 (sometimes 24) thesockets... 

The potassium salt of dimethyl sulfoxide can also be prepared in the following manner. In a 1-1. three-necked flask equipped with an all-glass mechanical stirrer, a 125-ml. dropping funnel containing 90 ml. of dry dimethyl sulfoxide (Note 1), and a Claisen distillation head and condenser is placed 425 ml. of dry 2-butyl alcohol (Note 1). The system is flushed with dry... 

A 1-1., two-necked, round-bottomed flask is equipped with a 1-1. addition funnel and a Claisen distillation head and water-cooled condenser. The cooled reaction mixture is transferred to the funnel, and enough of it is admitted to the flask to half-fill the latter. The 1,2-dichloroethane, b.p. 83-84°, is distilled with the use of magnetic stirring to maintain even ebullition the... 

A 1-1. round-bottomed flask fitted with a reflux condenser bearing a soda-lime drying tube is successively charged with 100 ml. of anhydrous benzene, 36.6 g. (0.50 mole) of w-butylamine, and 63.7 g. (61 ml., 0.60 mole) of benzaldehyde (Note 1). The mixture is heated under reflux for 30 minutes (Note 2). The condenser is replaced by a Claisen distillation head, and the mixture is distilled until the temperature reaches 100° (Note 3). The residue, which is mostly N-benzylidenebutylamine, is cooled, and the distillation head is replaced by the reflux condenser bearing a soda-lime drying tube. 

The Claisen distillation head was filled with glass wool to avoid formation of foam. The checkers found that constant heating of the distillation apparatus with a heat gun greatly facilitates the rate of distillation and minimizes the column holdup. 

The reflux condenser is replaced by a Claisen distillation head, and the reaction mixture is distilled until the temperature of the vapor reaches 140°. The residue is transferred to a smaller flask and fractionated through a 30-cm. column packed with glass helices. A low-boiling fraction containing ethylidene diacetate and diethyl malonate is collected first, followed by 79-89.5 g. (68-77%) of diethyl ethylidenemalonate b.p. 102-106°/10 mm. %>5 1.4394 (Note 1). 

Place 45 g (0.37 mol) of benzamide (prepared from benzoyl chloride, cf. Expt 5.154) and 80 g (0.56 mol) of phosphorus pentoxide in a 250-ml round-bottomed flask (for exact experimental details on the handling and weighing out of phosphoric oxide, see isobutyronitrile, Expt 5.160). Mix well. Fit the flask with a Claisen distillation head (Fig. 2.13(c)) and distil under reduced pressure using a water pump with an air leak in the system so that a pressure of about 100 mmHg is attained. Heat the flask with a free flame until no more liquid distils the nitrile will pass over at 126-130 °C/100 mmHg. Wash the distillate with a little sodium carbonate solution, then with water, and dry over anhydrous calcium chloride or magnesium sulphate. Distil under normal pressure from a 50-ml flask the benzonitrile passes over as a colourless liquid at 188-189 °C. The yield is 28 g (74%). The i.r. spectrum of benzonitrile is shown in Fig. 3.39. 

A typical vacuum distillation apparatus is illustrated in Fig. 1. It is constructed of a round-bottomed flask (often called the pot ) containing the material to be distilled, a Claisen distilling head fitted with a hair-fine capillary mounted through a rubber tubing sleeve, and a thermometer with the bulb extending below the side arm opening. The condenser fits into a vacuum adapter that is connected to the receiver and, via heavy-walled rubber tubing, to a mercury manometer and thence to the trap and water aspirator. 

S. 3-(1,1-Dimethylethyl) 4-methyl (S)-2,2-dimethyl-3,4-oxazolidinedi-carboxylate. To a 2-L, three-necked, round-bottomed flask, equipped with a magnetic Stirring bar, Claisen distilling head, thermometer, and reflux condenser protected from moisture by a calcium sulfate-filled drying tube are added a solution of N-Boc-L-serine methyl ester (48.5 g, 0.22 mol) in benzene (770 mL), 2,2-dimethoxypropane (55 mL, 47 g, 0.45 mol), and p-toluenesulfonic acid monohydrate (0.593 g, 3.1 mmol, Note 9). The colorless solution is heated under reflux (oil bath temperature, 110°C) for 30 min, then slowly distilled until a volume of 660 mL is collected over 4 hr when the reaction Is judged to be complete by TLC (Notes 10 and 11). The cooled, amber solution is partitioned between saturated sodium bicarbonate solution (200 mL) and ethyl ether... 

Fig. I-I (com.) (z) Claisen distilling head with Vigreux column (aa) Graham condenser (bb) West condenser (cc) Allihn condenser (dd) Friedrichs condenser (ee) collecting adapter (ff) vacuum adapter (gg) straight vacuum adapter.

A mixture of 118 g 5-phenyl-3-pyrazoline 46, prepared by procedure 30 g pulverized potassium hydroxide and 2.5 g asbestos was heated in a 1 L, three-necked flask equipped with a stirrer and a Claisen distillation head. The temperature was raised slowly and the heat was shut off at the first sign of reaction. When the exothermic reaction ceased the temperature was again raised and the product was distilled. Both the distillate and the residue were steam distilled and the steam distillate was taken up in ether and dried first with sodium sulfate and then with sodium and redistilled. The product 47 was collected at 60-63 C (11 mm Hg) and was finally... 

Claisen distilling head, round-bottom flask, low-temperature reactor, safety glasses, laboratory coat, and protective gloves. 

---