Distilling Heads refluxing

Round-bottomed flasks (Fig. 22(A)) of various sizes and having necksof various lengths and widths. They can be closed with stoppers (Fig. 22(B)), or fitted with any of the following units reflux air-condensers (Fig. 22(C)) or water condensers (Fig. 22(D)) distillation heads, of the simple knee-tube type (Fig. 22(E)), or with a vertical joint (Fig. 22(F)) for thermometers, etc., or with... 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

When the reaction has subsided, boil the reaction-mixture under reflux for 2 hours then make it alkaline with sodium hydroxide solution, and distil it in steam until oily drops no longer come over in the aqueous distillate (1 2 litres). Extract the distillate thoroughly with ether ca. 150 ml.), and dry the ethereal extract over powdered sodium hydroxide. Filter the dry extract through a fluted filter-paper moistened with ether into a 200 ml. flask. Fit the flask with a distillation-head, or a knee-tube , and distil off the ether. Now replace the distillation-head by a reflux water-condenser, add 10 ml. of acetic anhydride, and boil the mixture under reflux for 10 15 minutes. 

To a 3QQ-mL, round-bottomed flask fitted with a water separator, (Note 1) which contains 15 g of Linde 4A molecular sieve l/16-1nch pellets and Is filled with toluene, are added 7.3 g (0.04 mol) of cyclododecanone, 11.4 g (0.16 mol) of pyrrolidine, 100 mL of toluene, and 0.57 g (0.004 mol) of boron trifluoride etherate. The solution is heated under reflux for 20 hr. The water separator is replaced by a distillation head, and about 90 mL of the toluene is removed by distillation at atmospheric pressure. The residue containing l-(N-pyrrolidino)-l-cyclododecene (1) is used in the next step without further purification (Note 2). 

In a 2-1. flask fitted with a total-reflux, variable-take-off distillation head is placed a solution of 53 g. (0.472 mole) of dihydroresorcinol (Note 1), 2.3 g. of -toluenesulfonic acid monohydrate and 250 ml. of absolute ethanol in 900 ml. of benzene. The mixture is heated to boiling and the azeotrope composed of benzene, alcohol, and water is removed at the rate of 100 ml. per hour. When the temperature of the distilling vapor reaches 78° (Note 2), the distillation is stopped and the residual solution is washed with four 100-ml. portions of 10% aqueous sodium hydroxide which have been saturated with sodium chloride. The resulting organic solution is washed with successive 50-ml. portions of water until the aqueous washings are neutral and then concentrated under reduced pressure. The residual liquid is distilled under reduced pressure. The yield of 3-ethoxy-2-cyclohexenone (Note 3), b.p. 66-68.5°/0.4 mm. or 115-121°/11 mm., Mq 1.5015, is 46.6-49.9 g. (70-75%). 

The reaction vessel is cooled to 30° and the reflux condenser replaced with a distillation head and condenser. The methylene chloride is removed by distillation, b.p. 35-55°. The residue is then transferred to a 500-ml. round-bottomed flask and distilled through a 30-cm. Vigreux column. The yield of a-chloroanisole is 266-271 g. (93-95%), b.p. 74-77° (13 mm.), w23d 1.5342 (Notes 5, 6, 7). 

In a 2-1 three-necked flask equipped with a stirrer, a reflux condenser, and a dropping funnel (Note 1) 832 g (4 0 moles) of phosphorus pentachloride is stirred with 250 ml. of phosphorus oxychloride (Note 2) To this is added with stirring 264 g (272 ml, 4 4 moles) of methyl formate (Note 3). During the addition the reaction vessel is cooled in an ice bath to maintain a reaction temperature of 10-20° The addition requires about 1.75 hours When the addition is complete, the solution is stirred at a temperature under 30° until all the phosphorus pentachloride has dissolved (about 1 hour) Then the stirrer is removed, the reflux condenser is replaced by a distilling head, and the reaction... 

In a 1-1. round-bottomed flask equipped with a condenser are placed 78.0 g. (0.56 mole) of commercial anhydrous potassium arbonate, 45.0 g. (0.50 mole) of methallyl chloride (Note 1), 55.0 g. (0.55 mole) of 2,4-pentanedione (Note 1), and 300 ml. of anhydrous ethanol (Note 2). The mixture is refluxed on a steam bath for 16 hours. The condenser is replaced by a distilling head and condenser, and about 200 ml. of ethanol is distilled from the mixture (Note 3). Ice water (600 ml.) is added to dissolve the salts, and the mixture is extracted three times with ether. The... 

The catalyst is filtered, 200 g. (155 ml.) of 25% aqueous sodium hydroxide is added to the filtrate, and the mixture is heated under reflux for 1 hour. The condenser is replaced by a short Vigreux column and distillation head, and the heating is continued until most of the methanol has distilled. The two-phase residue is cooled and extracted with two 100-ml. portions of ether. The ether is removed on a steam bath, and the residue is distilled... 

The crude episulfone (3.0 g.) is placed in a 10-ml. round-bottomed flask fitted with a reflux condenser and is heated at 95° for 30 minutes, when it decomposes with loss of sulfur dioxide. The reflux condenser is replaced with a distillation head (Note 6), and the yellow residue is distilled under reduced pressure (water aspirator). d -2- Oxo-7,7-dimethyl -1 -vinylbicyclo [2.2.1] heptane... 

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. 

In a 1-1., three-necked, round-bottomed flask equipped with a constant-pressure dropping funnel, a mechanical stirrer, and a reflux condenser is placed 174 g. (1.0 mole) of ethyl azodicarbox-ylate in 150 ml. of ether. Freshly prepared cyclopentadiene (70 g., 1.06 moles) is added dropwise over a 1-hour period to the stirred ethereal solution of diethyl azodicarboxylate. During the addition a gentle reflux is maintained by external cooling with an ice-water bath as needed. When the addition is complete, the reaction mixture is allowed to stand for 4 hours, or less if the yellow color of the azodicarboxylic acid ester disappears. I he dropping funnel and condenser are replaced by a glass stoj)pcr and a short distillation head, respectively. The ether and unreactcd diene are distilled off on a steam bath and the... 

A mixture of 20 g (0.1 mol) of aluminum isopropoxide, 0.1 mol of an aldehyde or a ketone and 100 ml of dry isopropyl alcohol is placed in a 250 ml flask surmounted by an efficient column fitted with a column head providing for variable reflux. The mixture is heated in an oil bath or by a heating mantle until the by-product of the reaction - acetone - starts distilling. The reflux ratio is adjusted so that the temperature in the column head is kept at about 55° (b.p. of acetone) and acetone only is collected while the rest of the condensate, mainly isopropyl cohol (b.p. 82°), flows down to the reaction flask. When no more acetone is noticeable in the condensate based on the test for acetone by 2,4-dinitrophenylhydrazine the reflux regulating stopcock is opened and most of the isopropyl alcohol is distilled off through the column. The residue in the distilling flask is cooled, treated with 200 ml of 7% hydrochloric acid and extracted with benzene the benzene extract is washed with water, dried and either distilled if the product of the reduction is volatile or evaporated in vacuo in the case of non-volatile or solid products. Yields of the alcohols are 80-90%. 

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). 

A. Diethyl propionylsuccinate (1). A solution of 412 g. (2.4 mole) of diethyl maleate (Note 1), 278 g. (4.8 mole) of freshly distilled propionaldehyde (Note 2), and 1.2 g. (0.0048 mole) of benzoyl peroxide in a normal 2-1. Pyrex flask is heated under reflux while undergoing irradiation with an ultraviolet lamp (Note 3). The initial reflux temperature is 60°. After 2 hours another 1.2 g. (0.0048 mole) of benzoyl peroxide is added. Strong reflux and irradiation are maintained throughout the entire reaction period. After 18 hours total time, the internal pot temperature reaches 68°. At this point the last 1.2 g. (0.0048 mole) of benzoyl peroxide is added, and the reaction is continued for a total of 30 hours, at which time the pot temperature reaches 74.5°. The reflux condenser is then replaced by a distillation head. The excess propionaldehyde (119 g.) is distilled under atmospheric pressure, b.p. 48-49°. Succinate 1 is distilled under reduced pressure. The main fraction, b.p. 145-151.5° (15-16 mm), provides 417-449 g. (75-81%) of product having sufficient purity for use in the next step (Note 4). 

---