Flask, modified Claisen

Fermentation, 22, 53 Ferric nitrate, 23, 20 Fieser s solution, 21, 110 Filter fabric, Pyrex glass, 22, 33, 65 Vinyon, 22, 33, 67 Filter paper, hardened, 22, 45 Fischer indole synthesis, 22, 98 Flash distillation, 21, 85 Flask, modified Claisen, 22, 11 Fluorescence of 9-aminoacridine hydrochloride, 22, 7 Formaldehyde, 20, 60 Formalin, 22, 66 Formic acid, 20, 66, 102 23, 43 Formic acid, chloro-, benzyl ester, 23, 13... 

Filter paper, hardened, 22, 45 Shark skin, 25, 97 Fischer indole synthesis, 22, 98 Flash distillation, 21, 85 Flask, modified Claisen, 22,11 Fluorescence of 9-aminoacridine hydrochloride, 22, 7... 

A modified Claisen flask (Org. Syn. 1, 40) was used to fractionate the compound. Distillation under atmospheric pressure causes some decomposition (Read and Williams, J. Chem. Soc. 117, 1216 (1920)). 

After all of the cyclohexylbromopropene has been run in, heating is continued for about two hours, the mixture is cooled and 500 cc. of ether is added. This mixture is poured on 1.5 kg. of cracked ice in a 5-I. flask and then acidified with 280 cc. of concentrated hydrochloric acid. The ether layer is separated, dried over calcium chloride and transferred to a i-l. modified Claisen flask (Org. Syn. 1, 40) for distillation. The ether is distilled at ordinary pressure and then the cyclohexylpropine under diminished pressure. The product boiling up to ii5°/2o... 

The solution of sodium methyl sulfide in absolute alcohol is transferred to a 3-I. three-necked flask, which is placed on a steam bath and fitted with a dropping funnel, a reflux condenser, and a mechanical stirrer. The solution is heated until the alcohol begins to boil. Heating is then discontinued and 302 g. (3.7s moles) of ethylene chlorohydrin (Note 5) is added dropwise with efficient stirring over a period of about two hours (Note 6). The reaction mixture is concentrated by distilling as much of the alcohol as possible on the steam bath. The mixture is then allowed to cool and the sodium chloride removed by filtration. The flask is rinsed, and the sodium chloride washed with three loo-cc. portions of 95 per cent alcohol. The combined filtrate and washings are concentrated on the steam bath under reduced pressure until no further distillate passes over. The residue is then transferred to a modified Claisen flask (Org. Syn. Coll. Vol. i, 125) and fractionally distilled under reduced pressure. The yield is 238-265 g. (74-82 per cent of the theoretical amount based on the sodium used) of a product boiling at 68-7o°/20 mm. 

The reaction mixture is filtered through a Hirsch or Buchner funnel, and the bottle is rinsed with 50 ml. of benzene, which is also poured through the funnel. The filtrate is washed with two 50-ml. portions of 10% sodium chloride solution and three 2S-ml. portions of water (Note 4). The washings are extracted with three 10-ml. portions of benzene, and the combined benzene solutions are distilled under reduced pressure from a 250-ml. modified Claisen flask. The yield of ethyl -butylcyanoacetate, b.p. 108-109°/9 mm., is 79-81 g. (94-96%, based on the ethyl cyano-acetate used) (Note 5). 

In a 1-L rbf attached to a Dean-Stark trap, equipped with a reflux condenser is placed distilled aniline (1, 46.5 g, 45.5 mL, 0.5 mol), commercially available ethyl acetoacetate (5, 65 g, 63.5 mL, 0.5 mol), benzene (100 mL) and glacial AcOH (1 mL). The flask is heated at about 125 °C, and the water which distills out of the mixture with the refluxing benzene is removed at intervals. Refluxing is continued until no more water separates (9 mL collects in about 3 hrs) and then for an additional 30 min. The benzene is then distilled under reduced pressure, and the residue is transferred to a 125 mL modified Claisen flask with an insulated column. The flask is heated in an oil or metal bath maintained at a temperature not higher than 120 °C while the forerun of 1 and 5 is removed and at 140-160 °C the product distills giving 78-82 g, 76-80% yield of 6. 

To obtain the trimethylene chlorohydrin, the distillate from this operation is heated for about one hour on a steam bath in order to drive out most of the excess hydrogen chloride. The distillate is then fractionated under reduced pressure (Note 3) in a modified Claisen flask (Org. Syn. 1, 40). The fractionating side arm should be 25 cm. in length. The fractions collected under 10 mm. are to 55°, 55-57°, 57-65°, 65-85°, 85-105°, residue. 

After standing about three hours, the diphenylamine hydrochloride is filtered and washed with benzene (Note 10). The benzene is distilled from the filtrate (Note n) and the residual triphenylamine is transferred to a 500-cc. modified Claisen flask (Org. Syn. 1, 40) and distilled under reduced pressure. The first fraction consists of some benzene, then the temperature rises rapidly and a few cubic centimeters of deeply colored distillate comes over just before the amine fraction, which is collected at i95-205°/io-i2 mm. The distillate is a yellow liquid which soon solidifies to a light yellow solid. The side arm of the distilling flask should be of rather large bore (about 10 mm.) to prevent clogging by the amine which solidifies. The crude product weighs 220-235 g. and melts at 120-124°. 

Prepare 26 g. of molecular sodium in a 1500 ml. round-bottomed flask (Section II,50,d, Method 1). Cover the sodium with 625 ml. of sodium-dried A.R. benzene fit the flask with an efficient reflux condenser protected from the air by means of a calcium chloride (or cotton wool) guard tube. Add 151 5 g. of diethyl adipate (Sections 111,99 and 111,100) in one lot, followed by 1 6 ml. of absolute ethyl alcohol. Warm the flask on a water bath until, after a few minutes, a vigorous reaction sets in and a cake of the sodio compound commences to separate. Keep the flask well shaken by hand during the whole of the initial reaction. After the spontaneous reaction has subsided, reflux the mixture on a water bath overnight, and then cool in ice. Decompose the product with ice and dilute hydrochloric acid (1 1) add the acid until Congo red paper is turned blue. Separate the benzene layer, and extract the aqueous layer with 100 ml. of benzene. Wash the combined extracts with 100 ml. of 5 per cent, sodium carbonate solution and 160 ml. of water dry over a KWe anhydrous magnesium sulphate. Remove the benzene under atmospheric pressure (Fig. II, 13, 4, but with modified Claisen flask), and fractionate the residue under reduced pressure. Collect the 2-carbethoxy-epelopentanone at 108-111°/15 mm. (96 g.). Upon redistillation, the product boils at 102°/H mm. 

The contents of the flask are then poured upon 600 g. of cracked ice, and, with hand stirring, 75 ml. of hydrochloric acid (sp. gr. 1.18) is added. The cold mixture is now filtered through glass wool in an ordinary funnel into a 2-1. separatory funnel. The aqueous layer is separated and extracted once with 250 ml. of ether (Note 7). The combined extract and main product are dried over 30 g. of calcium chloride, the ether is removed on a steam bath, and the residue is distilled using a 500-ml. modified Claisen flask.6 The selenophenol is collected at 57-59°/8 mm. or 84-86°/25 mm. the yield is 43-54 g. (57-71%) (Notes 6 and 9 through 14). The product should be sealed at once in a glass vial (Note 8). 

The 2-chlorolepidine is extracted, using two 750-ml. portions of ether (Note 1). The extract is shaken with two 200-ml. portions of water and then dried over 50 g. of potassium carbonate. After removal of the ether, the residual oil is distilled from a 200-ml. modified Claisen flask.2 The colorless distillate boils at 132-135°/3 mm. and weighs 118-122 g. (89-92%). The distillate is melted if necessary and poured into 250 ml. of petroleum ether (b.p. 40-50°) the solution is then chilled in a freezing mixture the crystals are filtered by suction and dried in a vacuum desiccator over paraffin. The snow-white 2-chlorolepidine melts at 58-59° and weighs 114-118 g. (86-89%). 

The residue is then placed in a modified Claisen flask (Org. Syn. 22, 11) and distilled under reduced pressure. Dimethyl-acrylic acid distils at 100-106°/20 mm. The yield of white solid is 49-53 g. (49-53 per cent of the theoretical amount). This product melts at 60-65°. It may be further purified by recrystallization from petroleum ether (b.p., 60-70°) or water (Note 5). 

While still warm, the reaction mixture is transferred to a 250-cc. modified Claisen flask (Org. Syn. Coll. Vol. 1, 1941, 130) fitted fox distillation under reduced pressure. Any hydrogen bromide remaining in the reaction mixture is removed by heating at 120° under the vacuum of a water pump. The product is then distilled "under reduced pressure. The fore-run of less than 15 g. 

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