Fenske column

Sodium ethoxide from sodium (3.67 g) in absolute alcohol (64 ml) was added over 20 minutes with stirring to a mixture of ethyl 4-i-butylphenylacetate (28.14 g) and ethyl carbonate (102 ml) at lOO C. The reaction flask was fitted with a Fenske column through which alcohol and then ethyl carbonate distilled. After 1 hour when the still head reached 124°C heating was discontinued. Glacial acetic acid (12 ml) and water (50 ml) was added to the stirred ice-cooled mixture and the ester isolated in ether, washed with sodium carbonate solution, water and distilled to give ethyl 4-i-butylphenylmalonate. 

For the liberation of N-methylethylamine, a 1-1. Claisen flask is equipped with a 250-ml. separatory funnel and an efficient condenser for distillation. The receiver is cooled with a mixture of acetone and dry ice (Note 7). A solution of 100 g. (2.5 moles) of sodium hydroxide in 100 ml. of water is added to the flask and kept at about 100° by heating on a steam bath. The aqueous solution of N-methylethylamine hydriodide is added to this solution through the separatory funnel in the course of 1.5 hours. After the addition is complete, the final solution is heated for an additional 30 minutes. Crude N-methylethylamine, b.p. 30-70°, collects in the cooled receiver. It is purified by distillation from 25 g. of solid potassium hydroxide in a 250-ml. modified Claisen flask fitted with a 25-cm. Fenske column and a receiver cooled by dry ice and acetone. N-Methylethylamine is collected at 34-35° weight 49-55 g. (83-93%) 2 3 4 5d 1.3830. 

The condenser is arranged for downward distillation, and the water is removed from the product by codistillation with 200 ml. of benzene. The residue, N-benzylideneethylamine, is purified by distillation through a 25-cm. Fenske column b.p. 52-53° (4.5 mm.) n23d 1.5400 weight 470-523 g. (80-89%) (Note 2). 

Materials 1,3-Dioxolane (1) and 1,3-dioxepane (5) were prepared and purified conventionally. Compound 1 contained no impurities detectable by GLC, but 5 contained a trace of tetrahydrofuran (THF) which could not be removed even by distillation on a Fenske column with a reflux ratio of 50 1 4-methyl-l,3-dioxolane (4) was prepared by Astle s method [10]. All monomers were dried preliminarily by storage over LiAlH4 in reservoirs attached to a conventional high-vacuum line fitted only with all-metal valves, and then stored with liquid Na-K alloy until used. Methylene dichloride was purified conventionally, distilled on a Normatron 1.5 m column, dried i.vac. over LiAlH4 on a conventional high-vacuum line, and then stored for 24 h over a fresh sodium film immediately before use, in a reservoir attached to the vacuum line. 

A Fenske column packed with glass helices previously de-... 

Pent-2-ene (mixed isomers) [109-68-2] M 70.1, b 36.4 , d 0.650, n 1.38003, n 1.3839. Refluxed with sodium wire, then fractionally distd twice through a Fenske column. 

Benzyl bromoacetate [5437-45-6] M 229.1, b 96-98°/0.1mm, 146°/12mm, 166-170°/22mm, 1.444, n2D5 1.5412. Dilute with Et20, wash with 10% aqueous NaHCO, H2O, dry (MgS04) and fractionate using a Fenske column. [JCS 1521 1956]. LACHRYMATORY... 

Refluxed with sodium wire, then fractionally distd twice through a Fenske column. 

The contents of the flask are transferred to a 1.5-1. round-bottomed flask, 0.5-1 g. of copper carbonate is added, and the liquid is fractionally distilled in vacuo with the aid of a Fenske column (Fig. 1) (Notes 2 and 3). The following fractions are collected. 

A column such as the Whitmore-Lux or Fenske column (p. 2, Fig. 1) provided with an electrically heated jacket is essential. 

In a 3-1. three-necked round-bottomed flask fitted with a reflux condenser and a mercury-sealed stirrer, 250 g. (2 moles) of 1,3-dichloro-2-butene (Note 1) and 1.25 1. of 10% sodium carbonate are heated at reflux temperature for 3 hours. The 3-chloro-2-buten-l-ol is extracted with three 300-ml. portions of ether, which are then dried over anhydrous magnesium sulfate. The ether is removed by distillation through a 20-cm. Fenske column, and the residue is distilled from a 250-ml. Claisen flask, yielding 134 g. (63%) of 3-chloro-2-buten-l-ol, b.p. 58-60°/8 mm., 1-4670. 

The filtrates from two such runs are combined and distilled through a Whitmore-Fenske column of 10-15 theoretical plates at a 5 1 reflux ratio. The yield of fer/.-butylamine is 55-60 g. (75-82%) the product boils at 44-44.5°, and its refractive index is n 1.3770 (Note 8). 

A mixture of 1 kg. (6.26 moles) of ethyl malonate, 540 g. (9.3 moles) of acetone, 800 g. (7.8 moles) of acetic anhydride, and 120 g. of fused zinc chloride is heated to reflux for 24 hours. To the cooled mixture is added 800 ml. of benzene, and the resulting solution is washed with four 600-ml. portions of water. The combined water washes are extracted with two 100-ml. portions of benzene, and the benzene extracts are washed with water and added to the main benzene solution. The benzene solution is distilled through a Vigreux column, and 1.2 kg. of crude ethyl isopropylidinemalonate is collected in the range 60-125°/18 mm. This material is redistilled through a 70 by 1.2 cm. Fenske column to give 411 g. of diethyl malonate, b.p. 81-83°/9 mm., and 654 g. (62%) of ethyl isopropylidinemalonate, b.p. 111-11379 mm., n25 1.4478.. ... 

A mixture of 100 g. of concentrated sulfuric acid and 50 g. of concentrated nitric acid is added dropwise with vigorous stirring to 50 g, (0.47 mole) of o-xylene cooled to —10° to 0°. The reaction mixture is poured into water, and the precipitated organic matter is separated and washed with dilute aqueous sodium hydroxide solution. The product is distilled from a Claisen flask, and the fraction boiling at 115-130°/15 mm. is collected and redistilled through a 100-cm. Fenske column to give 61 g. (86%) of 3-nitro-l,2-dimethylbenzene boiling at 127-130°/18 mm. The residue from either of the above distillations should not be heated more than necessary, since it may decompose explosively. 

NN dimethylformamide, if necessary, purify as follows, dry 1 litre N.N dimethyl-formamide by standing over 50 g of anhydrous potassium carbonate for 3 d. Distill the product through an 80 cm Fenske column. Discard the first 200 cm of distillate and collect in a dry flask the fraction boiling between 151.5 and 153°C. 

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