Spinning-band column distillation

A mixliirc ofKllF, (2.7 kg. 34.6 mol) and lelraethylciie glycol (3 L) was heated to 150 C in an autoclave. 1 he epoxide (28 mol) was added continuously over 4 h and the mixture was heated for a further 4h at this temperature. Then the low-boiling products were distilled from the mixture under reduced pressure. Mixtures of isomeric products were separated by spinning-band column distillation. 

Pyrrolidon la (8.51 g, 100 mmol) or caprolactam Ic (11.30g, 100 mmol) and LiOH H20 (4.25 g, 100 mmol) were dissolved in water (30 mL) and evaporated to dryness in order to get a homogeneous mixture that was heated under N2 to 270 °C for 4 h under reflux, then distilled over and pure 3a (88%, bpi4 83 °C) or 3c (55%, bpi 94 °C) was obtained by spinning band column distillation. 

Hydroformylation of 2,6-dimethyl-l,5-cyclooctadiene in 300g scale under similar conditions gave rise to a mixture of unsaturated and saturated monoaldehydes as well as to the corresponding dialdehyde (Scheme 6.27) [104]. All three compounds, which have been separated by means of a spinning band column distillation, are characterized by different odors. It was suggested to employ them as scent boosters to force the aroma of citrus scents. 

In a similar manner, 3,7-dimethylocten-l-en-7-ol was treated on a small scale (18 g) to give an aldehyde with a pleasant scent (Scheme 6.42) [136]. The product was isolated by spinning-band column distillation. It was used as a main component (35%) for the production of a perfume. 

A final distillation at 760 mm. through a 50-cm. stainless-steel spinning band column yields 41 g. (64% from methylenecyclopropane) of pure cyclobutanone (b.p. 100-101°) (Notes 19, 20). 

N-Cyclohex-l-enylpyrrolidine (9 g 0 06 mol) was dissolved in pentane with A -ethyldiisopropylamine (7.8 g 0.06 mol). Perfluorohexyl iodide (13.4 g, 0.03 mol) IS added to the solution. Aprecipitate of A-ethyldiisopropylamine hydroiodide IS formed instantly After 3 h, the precipitate is filtered off, and the solution is evaporated The crude liquid is hydrolyzed with 6 mL of 40% sulfuric acid The mixture is stirred for 3 h and extracted with ether. The ether layer is neutralized with aqueous sodium hydrogen carbonate, washed with water, and dried over magnesium sulfate. The solvent is evaporated, and the residue is distilled. A second distillation with a spinning-band column yields 7 9 g (63%) of pure 2-(perfluoro-hexyl)cyclohexanone (bp, 71 -73 °C at 0 4 mm of Hg). 

Farnesol was obtained from Fluka AG (Buchs, CH9470, Switzerland) as a mixture of 65% (E), (E)- and 35% (Z), (E)- isomers. It is also available from the Aldrich Chemical Company, Inc. This procedure works equally well with pure (E), (F)-famesol, which may be obtained from the above mixture by careful distillation, at reduced pressure, through a Nester-Faust Teflon spinning-band column. 

The drying agent is removed by filtration, and the filtrate is distilled under nitrogen through a spinning band column (Notes 6 and 7). The fraction, boiling at 92-93° (725 mm.), is collected to yield 54.2-60.0 g. (66-73%, based on chloroform) of lerf-butyl isocyanide (Notes 8 and 9). 

Pure (A)-1 -chloropropene was obtained by careful distillation of a mixture of (E)- and ( )-l -chloropropene (available from Columbia Organic Chemicals Company Inc.) using a Nester-Faust Teflon annular spinning band column [(Z)-l-chloropropene has b.p. 33° (A)-l-chloropropene has b.p. 37°]. Small quantities of powdered sodium bicarbonate and hydroquinone (1,4-benzenediol) placed in the distillation flask inhibit acid-catalyzed isomerization and polymerization. Gas chromatographic analysis of the material used in these experiments on a 4-m., 15% l,2,3-tris(2-cyanoethoxy)propane (TCEP) on Chromosorb P column, operated at room temperature, typically indicated that it had isomeric purity >99.9%. (A)- 1-Chloropropene is stable for several months at room temperature, but it should be stored in a cool place. 

The reaction mixture is then cooled to 35-40° and poured into a stirred solution of 230 g. of sodium chloride and 6.0 g. of sodium acetate in 600 ml. of water at 40°. The mixture is stirred for 15 minutes and then is transferred to a separatory funnel the layers are separated, and the lower, aqueous layer is discarded. The crude product is distilled at reduced pressure through a stainless steel spinning-band column (Note 5). The yield of the /3-lactone dimer of dimethylketene is 122-132 g. (61-67%) b.p. 69-71.5° (14 mm.) (Note 6). The product may be redistilled and the fraction boiling at 119.5-120° (150 mm.), 20d 1.4380, collected. 

A 45-cm. spinning band column was employed by the submitter, but any distillation column with a low holdup may be used. Since the products have widely different boiling points, careful fractionation during distillation is not needed. Because the phenylsulfur trifluoride and benzenesulfinyl fluoride slowly attack glass, all equipment should be rinsed with water and acetone immediately after use to minimize etching. 

A 25-cm spinning band column of 12 theoretical plates, manufactured by NORMAG GmbH, D-6238 Hofheim, FRG, has been used by the submitters. The checkers found a 30-cm Vigreux distillation column just as suitable for the separation. 

The submitters used a 40-cm. spinning band column. Owing to polymerization of the product, the checkers obtained consistently low yields when this column was used. Distillation through a 40-cm. Vigreux column gave the indicated yield without a significant decrease in product purity. 

It appears necessary to effectively remove the residual o-xylenc during this distillation in order that it not interfere (by liberation of hydrogen bromide) with the subsequent bromination of the epoxide. The checkers used a spinning-band column for this distillation. 

The only volatile impurity at this point is bicyclo[2.2.1]-hepta-2,5-diene. If the irradiation has been carried out for a sufficient period of time, the amount of diene present is less than 2%. Distillation through an efficient column will remove most of the diene [bicyclo[2.2.l]hepta-2,5-diene, b.p. 91° (760 mm.), 51° (200 mm.)]. Traces of acid3 and noble metal ions and complexes4 may cause quadricyclane to isomerize to the diene. The checkers used a 60-cm. Teflon-coated spinning-band column... 

In a Hanovia 550-watt immersion photochemical reactor (Note 1) equipped with a magnetic stirrer and water condenser (Note 2) are placed 1 1. of diethyl ether, 180 g. (1.96 moles) of bicyclo[2.2. l]hepta-2,5-diene (Note 3), and 8 g. of acetophenone. The system is flushed briefly with a stream of nitrogen and then irradiated for a,bout 36-48 hours (Note 4). After irradiation, the ether is removed by distillation through a 20-cm. Vigreux column (Note 5). The residue, a clear liquid weighing about 185 g., is distilled through a spinning-band column under reduced pressure (Note 6). Quadricyclane is obtained as a colorless liquid, b.p. 70° (200 mm.). The yield is 126-145 g. (70-80%) (Note 7). 

The purest available commercial samples of acetaldehyde, ethyl ether, and amines were purified by fractional distillation, either by conventional means or by using a spinning band column (Biichi). N-Methyl-diethylamine was prepared from diethylamine (4) and N,N-dimethyl-ethylamine from ethylamine (5). 

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