Separation into two layers

Dibromobutane from 1 4 butanediol). In a 500 ml. threenecked flask fltted with a stirrer, reflux condenser and dropping funnel, place 154 g. (105 ml.) of 48 per cent, hydrobromic acid. Cool the flask in an ice bath. Add slowly, with stirring, 130 g. (71 ml.) of concentrated sulphuric acid. To the resulting ice-cold solution add 30 g. of redistilled 1 4-butanediol dropwise. Leave the reaction mixture to stand for 24 hours heat for 3 hours on a steam bath. The reaction mixture separates into two layers. Separate the lower layer, wash it successively with water, 10 per cent, sodium carbonate solution and water, and then dry with anhydrous magnesium sulphate. Distil and collect the 1 4-dibromo-butane at 83-84°/12 mm. The yield is 55 g. 

Into a 500 ml. three-necked flask, provided with a mechanical stirrer, a gas inlet tube and a reflux condenser, place 57 g. of anhydrous stannous chloride (Section 11,50,11) and 200 ml. of anhydrous ether. Pass in dry hydrogen chloride gas (Section 11,48,1) until the mixture is saturated and separates into two layers the lower viscous layer consists of stannous chloride dissolved in ethereal hydrogen chloride. Set the stirrer in motion and add 19 5 g. of n-amyl cyanide (Sections III,112 and III,113) through the separatory funnel. Separation of the crystalline aldimine hydrochloride commences after a few minutes continue the stirring for 15 minutes. Filter oflF the crystalline solid, suspend it in about 50 ml. of water and heat under reflux until it is completely hydrolysed. Allow to cool and extract with ether dry the ethereal extract with anhydrous magnesium or calcium sulphate and remove the ether slowly (Fig. II, 13, 4, but with the distilling flask replaced by a Claisen flask with fractionating side arm). Finally, distil the residue and collect the n-hexaldehyde at 127-129°. The yield is 19 g. 

Place 50 g. of anhydrous calcium chloride and 260 g. (323 ml.) of rectified spirit (95 per cent, ethyl alcohol) in a 1-litre narrow neck bottle, and cool the mixture to 8° or below by immersion in ice water. Introduce slowly 125 g. (155 ml.) of freshly distilled acetaldehyde, b.p. 20-22° (Section 111,65) down the sides of the bottle so that it forms a layer on the alcoholic solution. Close the bottle with a tightly fitting cork and shake vigorously for 3-4 minutes a considerable rise in temperature occurs so that the stopper must be held well down to prevent the volatilisation of the acetaldehyde. Allow the stoppered bottle to stand for 24-30 hours with intermittent shaking. (After 1-2 hours the mixture separates into two layers.) Separate the upper layer ca. 320 g.) and wash it three times with 80 ml. portions of water. Dry for several hours over 6 g. of anhydrous potassium carbonate and fractionate with an efficient column (compare Section 11,17). Collect the fraction, b.p. 101-104°, as pure acetal. The yield is 200 g. 

Ethyl bromoacetate (1). Fit a large modified Dean and Stark apparatus provided with a stopcock at the lower end (a convenient size is shown in Fig. Ill, 126, 1) to the 1-htre flask containing the crude bromoacetic acid of the previous preparation and attach a double surface condenser to the upper end. Mix the acid with 155 ml. of absolute ethyl alcohol, 240 ml. of sodium-dried benzene and 1 ml. of concentrated sulphuric acid. Heat the flask on a water bath water, benzene and alcohol will collect in the special apparatus and separate into two layers, the lower layer consisting of approximately 50 per cent, alcohol. Run ofi the lower layer (ca. 75 ml.), which includes all the water formed in the... 

With phenylalanine and tyrosine, the sodium salt of the derivative is sparingly soluble in water and separates during the initial reaction. Acidify the suspension to Congo red the salts pass into solution and the mixture separates into two layers. The derivative is in the etheresil lay and crystallises from it within a few minutes. It is filtered off and recrystaUised. 

Vinylacetic acid. Place 134 g. (161 ml.) of allyl cyanide (3) and 200 ml. of concentrated hydrochloric acid in a 1-htre round-bottomed flask attached to a reflux condenser. Warm the mixture cautiously with a small flame and shake from time to time. After 7-10 minutes, a vigorous reaction sets in and the mixture refluxes remove the flame and cool the flask, if necessary, in cold water. Ammonium chloride crystallises out. When the reaction subsides, reflux the mixture for 15 minutes. Then add 200 ml. of water, cool and separate the upper layer of acid. Extract the aqueous layer with three 100 ml. portions of ether. Combine the acid and the ether extracts, and remove the ether under atmospheric pressure in a 250 ml. Claisen flask with fractionating side arm (compare Fig. II, 13, 4) continue the heating on a water bath until the temperature of the vapour reaches 70°. Allow the apparatus to cool and distil under diminished pressure (compare Fig. II, 20, 1) , collect the fraction (a) distilling up to 71°/14 mm. and (6) at 72-74°/14 mm. (chiefly at 72 5°/ 14 mm.). A dark residue (about 10 ml.) and some white sohd ( crotonio acid) remains in the flask. Fraction (6) weighs 100 g. and is analytically pure vinylacetic acid. Fraction (a) weighs about 50 g. and separates into two layers remove the water layer, dry with anhydrous sodium sulphate and distil from a 50 ml. Claisen flask with fractionating side arm a further 15 g. of reasonably pure acid, b.p. 69-70°/12 mm., is obtained. 

Diethylaniline. Use 28 g. of pure aniline and 36 g. (34 ml.) of purified ethyl phosphate, and proceed exactly as described for dimethylaniline. The reaction is not so vigorous initially. Separation into two layers occurs after 30 to 90 minutes. The yield of diethylaniline, b.p. 215-216°, is 41-5 g. 

Neutralise the cold contents of the flask with 500-600 ml. of 40 per cent, aqueous sodium hydroxide solution, equip the flask for steam distillation and steam distil until about 1 litre of distillate is collected. The steam distillate separates into two layers. Add solid sodium hydroxide (< 100 g.) to complete the separation of the two layers as far as possible. Remove the upper (organic) layer and extract the aqueous layer with three 50 ml. portions of chloroform. Dry the combined organic layer and chloroform extracts with anhydrous potassium carbonate and distil the mixture through a short fractionating column (e.g., an 8 Dufton column) after a fore run of chloroform, followed by pyridine, collect the crude 4-ethylpyridine at 150-166° (49 g.). Redistil through a Fenske-... 

Samples that contain suspended matter are among the most difficult types from which to obtain accurate pH readings because of the so-called suspension effect, ie, the suspended particles produce abnormal Hquid-junction potentials at the reference electrode (16). This effect is especially noticeable with soil slurries, pastes, and other types of colloidal suspensions. In the case of a slurry that separates into two layers, pH differences of several units may result, depending on the placement of the electrodes in the layers. Internal consistency is achieved by pH measurement using carefully prescribed measurement protocols, as has been used in the determination of soil pH (17). 

A. ot-Chloroelhyl ethyl ether. A mixture of 200 g. (201 ml.) of redistilled paraldehyde, b.p. 121-122.5° (equivalent to 4.54 moles of acetaldehyde), and 200 g. (254 ml., 4.34 moles) of absolute ethanol is placed in a 1-1. three-necked flask fitted with a mechanical stirrer and a gas inlet tube reaching to the bottom of the flask. The mixture is cooled to —5° in a mixture of Dry Ice and acetone, and dry hydrogen chloride (Note 1) is passed into the stirred reaction mixture maintained at about —5° until 200 g. (5.48 moles) has been absorbed. During this operation, which requires about 2 hours, the reaction mixture separates into two layers. The upper layer of crude a-chloroethyl ethyl ether is re-... 

The amine, under the name N,N,N, N -tetramethyl-methylenediamine, may be purchased from Ames Laboratories, South Norwalk, Connecticut. The checkers prepared it by the following procedure. A solution of 60.7 g. (0.75 mole) of 37% aqueous formaldehyde solution is placed in an 800-ml. beaker equipped with a mechanical stirrer and thermometer, and cooled in an ice bath. Two hundred seventy-one grams (1.50 moles) of a 25% aqueous solution of dimethylamine is added to this solution at a rate such that the reaction temperature is kept below 15°. The solution is stirred for 30 minutes after the addition is complete, and potassium hydroxide pellets (approximately 150 g.) are added in portions until the reaction mixture separates into two layers. The upper layer is separated, dried over potassium hydroxide pellets overnight, and distilled to give 59 -64 g. (77-83%) of bis(dimcthylamin())mclliane, b.p. 83 84°. ... 

Because alkyl halides are insoluble in water, a mixture of an alkyl halide and water separates into two layers. When the alkyl halide is a fluoride or chloride, it is the upper layer and water is the lower. The situation is reversed when the alkyl halide is a bromide or an iodide. In these cases the alkyl halide is the lower layer. Polyhalogenation increases the density. The compounds CH2CI2, CHCI3, and CCLi, for example, are all more dense than water. 

Lecithin is added to foods such as mayonnaise as an emulsifying agent to prevent the fat and water from separating into two layers. 

To 10 g of cyclohexane-1,4-oxide is added 48% aqueous hydrobromic acid (60 g). The phases are mixed thoroughly and allowed to stand at room temperature until the solution separates into two layers (usually 5 days). The mixture is saturated with sodium chloride and extracted twice with 25-ml portions of ether. The ether layer is washed with an equal volume of saturated sodium bicarbonate solution, then with the same amount of water. Finally, the ether solution is dried over anhydrous sodium sulfate, the ether is evaporated, and the residue is allowed to cool, whereupon crystallization should follow. The crude product may be recrystallized from petroleum ether giving material of mp 81-82° (yield, 11 g). 

The identification of camphene is best carried out by its conversion into isobomeol under the influence of acetic acid in the presence of sulphuric acid. In order to effect this conversion, 100 grams of the fraction containing the terpene in substantial quantity are mixed with 250 grains of glacial acetic acid and 10 grams of 50 per cent, sulphuric acid. Tne mixture is heated for two to three hours on a water-bath to a temperature of 50° to 60°. At first the liquid separates into two layers, bat soon becomes homogeneous and takes on a pale red colour. Excess of water is added, and the oil which is precipitated, and which contains the isobomeol in the form of its acetate, is well washed with water repeatedly. It is then saponified by heating with alcoholic potash solution on a water-bath. The liquid is then evaporated and extracted with water, and the residue recrystallised from petroleum ether. 

N2 and 0 liquids. The limited miscibility of ozone in oxygen is of practical importance because the dense, ozone-rich layer which settles to the bottom, is easily expld. The mutual solubility of the two liqs decreases when the temp is reduced. Thus, liq ozone and oxygen are completely miscible above 93.2°K (at which temp the total pressure is 1.25 atm), but at 90.2°K (the atm-bp of liq oxygen), there is separation into two layers, containing 17.6 and 67.2 mole % ozone, respectively. 

As an example consider the exchange reaction between benzyl iodide and free iodide ions, Eq. (3-43).6 Mixing ethanolic solutions of benzyl iodide and radio-labeled potassium iodide started the isotopic exchange. At different times, samples were withdrawn and added to a benzene-water mixture, causing separation into two layers. The aqueous layer contained the iodide ions, and the organic layer contained the benzyl iodide. The activity of 1311 was determined in each layer. 

Vigorous stirring action is necessary to disperse the heavy, viscous mixture. The use of a magnetic stirrer is not advisable since the mixture may separate into two layers. A mechanical stirrer with ground-glass shaft and bearing lubricated with 1,2-dichloroethane is recommended. 

It is observed that the CA dynamics, with these rules, results in a pattern in which clusters of X are scattered among clusters of Y. This is not what is seen in the laboratory. In reality, two immiscible liquids will separate into two layers, each responding to a different influence from gravity. What the CA model shows is the separation experienced in the weightlessness of space. A gravity rule must be added. 

The liquid-phase hydration of cyclohexene is carried out by a Japanese company with a slurry of zeolite ZSM-5 as the catalyst. Here, the product separates into two layers and cyclohexano leaves in the organic cyclohexene phase and the catalyst stays in the aqueous phase, which is recycled. The two-phase strategy, therefore, has special significance in this case. A recent publication by Ogawa et al. (1998a) gives some details of this system. 

Place 75 g. (74 ml.) of benzyl cyanide (Section IV,160), 125 g. (153 ml.) of rectified spirit and 150 g. (68 ml.) of concentrated sulphuric acid in a 760 ml. round-bottomed flask, fitted with an efficient reflux condenser. Reflux the mixture, which soon separates into two layers, gently for 8 hours, cool and pour into 350 ml. of rvater. Separate the upper layer. Dissolve it in about 75 ml. of ether (1) in order to facilitate the separation of the layers in the subsequent washing process. Wash the ethereal solution carefully with concentrated sodium bicarbonate solution until effervescence ceases and then with water. Dry over 10 g. of anhj drous magnesium sulphate for at least 30 minutes. Remove the solvent with the aid of the apparatus. shown in Fig. II, 13, 4 and distil from an air bath (Fig. II, 5, 3). The ethyl phenylacetate passes over at 225-229° (mainly 228°) as a colourless liquid the yield is 90 g. Alternatively, the residue after removal of the ether may be distilled in a CJlaisen flask under diminished pressiue (Fig. II, W, ) , collect the ester at 116-118°/20 mm. 

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