Effervescence

The liquid becomes progressively darker in colour, and then effervesces gently as ethylene is evolved. Allow the gas to escape from the delivery-tube in T for several minutes in order to sweep out the air in F and B. Now fill a test-tube with water, close it with the finger, and invert the tube in the water in T over the delivery-tube so that a sample of the gas collects in the tube. Close the tube again with the finger, and then light the gas at a Bunsen burner at a safe distance from the apparatus. If the tube contains pure ethylene, the latter burns with a clear pale blue (almost invisible) flame if the ethylene still contains air, the mixture in the test-tube ignites with a sharp report. Allow the... 

To obtain lead formate, add about 100 ml. of water to the distillate and then stir powdered lead carbonate into the gently heated solution until no further effervescence of carbon dioxide occurs. Then boil the mixture vigorously and filter at the pump. 

Add in turn benzyl chloride (8 3 g., 8 o ml.) and powdered thiourea (5 gm.) to 10 ml. of 95% ethanol in a 100 ml. flask fitted with a reflux condenser. Warm the mixture on the water-bath with gentle shaking until the reaction occurs and the effervescence subsides then boil the mixture under reflux for 30 minutes. Cool the clear solution in ice-water, filter off the crystalline deposit of the benzylthiouronium chloride at the pump, wash it with ice-cold ethyl acetate, and dry in a desiccator. Yield, 11-12 g., m.p. 170-174°. The white product is sufficiently pure for use as a reagent. It is very soluble in cold water and ethanol, but can be recrystallised by adding ethanol dropwise to a boiling suspension in ethyl acetate or acetone until a clear solution is just obtained, and then rapidly cooling. 

To the cold solution, add about 2 ml. of 10% potassium iodide solution. A brisk effervescence of nitrogen occurs, and iodobenzene separates, usually as drops so small that in spite of their density they float on the surface. 

Beckmann Rearrangement. Prepare the 85% sulphuric acid by adding 50 ml. of the concentrated acid cautiously to 10 ml. of water, stirring the mixture meanwhile, and then cool the diluted acid in ice-water. Place 16 ml. of the cold acid in a 500 ml. beaker, add 8 g, of the pure oxime, and warm the mixture cautiously until effervescence begins, and then at once remove the heat. A vigorous reaction occurs, and is soon complete. Repeat this operation with another 8 g. of the oxime in a second beaker the reaction is too vigorous to be carried out with larger quantities. 

Preparation of REAOENTS.t It is essential for this preparation that the zinc powder should be in an active condition. For this purpose, it is usually sufficient if a sample of ordinary technical zinc powder is vigorously shaken in a flask with pure ether, and then filtered off at the pump, washed once with ether, quickly drained and without delay transferred to a vacuum desiccator. If, however, an impure sample of zinc dust fails to respond to this treatment, it should be vigorously stirred in a beaker with 5% aqueous sodium hydroxide solution until an effervescence of hydrogen occurs, and then filtered at the pump, washed thoroughly with distilled water, and then rapidly with ethanol and ether, and dried as before in a vacuum desiccator. The ethyl bromoacetate (b.p. 159 ) and the benzaldehyde (b.p. 179 ) should be dried and distilled before use. 

After 3 hours, replace the separating-funnel by a reflux condenser, and the thermometer by a stopper. Add 11 g. of zinc dust in small portions by rapid removal of the stopper at such a rate that the liquid is first brought to the boil (usually about 2 portions of 2 g. each) and is then maintained gently boiling. A ooid too rapid addition of the zinc, otherwise the reaction will become too vigorous, and rapid immersion of the flask in ice-water will be necessary to control the effervescence. 

Place a small quantity (t.e., about o-i g.) of the following substances (finely powdered) in a clean dry test-tube and add about I ml. of cone. H2SO4. Note any reaction in the cold, and then warm gently. Note any effervescence and any pronounced blackening (as distinct from mere darkening in colour). 

The evolution of nitrogen is not always entirely satisfactory as a test owing to the possible evolution of gaseous decomposition products of nitrous acid itself. The test may be performed as follows. To i ml. of chilled concentrated sodium nitrite solution add i ml. of dilute acetic acid. Allow any preliminary evolution of gas to subside, and then add the mixed solution to a cold aqueous solution (or suspension) of the amide note the brisk effervescence. 

A brisk effervescence of COg without the formation of a precipitate indicates urea (if the NaOH used is free from carbonate). 

Blackening and effervescence when warmed with cone. HjSO. ... 

Action of nitrous acid. Dissolve 0 5 g. in a few ml. of dil. HCl. Add slowly 2 ml. of a 20% solution of sodium nitrite. A brisk effervescence takes place and almost colourless crystals of trimethylenetrinitrosamine, m.p. 105, separate out. 

Blackening with effervescence. Carbohydrates tartrates and lactates. 

Method B. Reflux a mixture of 101 g. of sebacic acid, 196 g. (248 ml.) of absolute ethjd alcohol and 20 ml. of concentrated sulphuric acid for 12 hours. Distil oft about half of the alcohol on a water bath dilute the residue with 500-750 ml. of water, remove the upper layer of crude ester, and extract the aqueous layer with ether. Wash the combined ethereal extract and crude ester with water, then with saturated sodium bicarbonate solution until effervescence ceases, and finally with water. Dry with anhydrous magnesium or sodium sulphate, remove the ether on a water bath, and distil the residue under reduced pressure. B.p. 155-157°/6 mm. Yield llOg. 

Place a mixture of 25 5 g. of n-valerio acid (Sections 111,83 and 111,84), 30 g. (37 -5 ml.) of dry n-propyl alcohol, 50 ml. of sodium-dried benzene and 10 g. (5-5 ml.) of concentrated sulphuric acid in a 250 ml. round-bottomed flask equipped with a vertical condenser, and reflux for 36 hours. Pour into 250 ml. of water and separate the upper layer. Extract the aqueous layer with ether, and add the extract to the benzene solution. Wash the combined extracts with saturated sodium bicarbonate solution until effervescence ceases, then with water, and dry with anhydrous magnesium sulphate. Remove the low boiling point solvents by distillation (use the apparatus of Fig. II, 13,4 but with a Claisen flask replacing the distilling flask) the temperature will rise abruptly and the fi-propyl n-valerate will pass over at 163-164°. The yield is 28 g. 

Carry out this preparation in the fume cupboard. Dissolve 100 g. of chloroacetic acid (Section 111,125), contained in a large porcelain basin or casserole, in 200 ml. of water. Warm the solution to about 50°, using a 200° thermometer as a stirring rod. Introduce 90 g. of pure, powdered sodium bicarbonate in small quantities at a time with stirring maintain the temperature at 50-60° until effervescence ceases. Now add 80 g. of pure, finely-powdered potassium cyanide (or an equivalent quantity of sodium cyanide), stir the mixture without further warming until the... 

Alternatively, the ester may be extracted with two SO ml. portions of ether. The ethereal solution is washed with concentrated sodium bicarbonate solution (handle the separatory funnel cautiously as carbon dioxide is evolved) until effervescence ceases, then with water, and dried over anhydrous magnesium sulphate. The ether is removed with the aid of the apparatus depicted in Fig. II, 13, 4, and the residual ester distilled. 

Mix 31 g. (29-5 ml.) of benzyl alcohol (Section IV, 123 and Section IV,200) and 45 g. (43 ml.) of glacial acetic acid in a 500 ml. round-bottomed flask introduce 1 ml. of concentrated sulphuric acid and a few fragments of porous pot. Attach a reflux condenser to the flask and boil the mixture gently for 9 hours. Pour the reaction mixture into about 200 ml. of water contained in a separatory funnel, add 10 ml. of carbon tetrachloride (to eliminate emulsion formation owing to the slight difference in density of the ester and water, compare Methyl Benzoate, Section IV,176) and shake. Separate the lower layer (solution of benzyl acetate in carbon tetrachloride) and discard the upper aqueous layer. Return the lower layer to the funnel, and wash it successively with water, concentrated sodium bicarbonate solution (until effervescence ceases) and water. Dry over 5 g. of anhydrous magnesium sulphate, and distil under normal pressure (Fig. II, 13, 2) with the aid of an air bath (Fig. II, 5, 3). Collect the benzyl acetate a (colourless liquid) at 213-215°. The yield is 16 g. 

Place 75 g. (74 ml.) of benzyl cyanide (Section IV,160), 125 g. (153 ml.) of rectifled spirit and 150 g. (68 ml.) of concentrated sulphuric acid in a 750 ml. round-bottomed flask, fitted with an efficient reflux condenser. Reflux the mixture, which soon separates into Wo layers, gently for 8 hoius, cool and pour into 350 ml. of water. 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 anh3 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 Claisen flask under diminished pressm (Fig. II, 20, 1) collect the ester at 116-lI8°/20 mm. 

In a 250 ml. conical flask, fitted with an air condenser of wide bore, place 50 g. (51 -5 ml.) of acetonylacetone (see Section V,9, Note 2) and 100 g. of ammonium carbonate (lump form). Heat the mixture in an oil bath at 100° until effervescence stops (60-90 minutes) some ammonium carbonate (or carbamate) sublimes into the condenser and this must be pushed back into the reaction mixture by means of a stout glass rod. Replace the air condenser by a Liebig s condenser with wide bore inner tube and reflux the mixture gently (bath temperature, 115°) for a further 30 minutes dissolve the solid which has sublimed into the condenser in about 5 ml. of hot water and return the solution to the reaction mixture. 

Methyl crotonate. Purify commercial crotonic acid by distiUing 100 g. from a 100 ml. Claisen flask attached to an air condenser use an air bath (Fig. II, 5, 3). The pure acid passes over at 180-182° and crystallises out on cooling, m.p. 72-73° the recovery is about 90 per cent. Place 75 g. of absolute methyl alcohol, 5 g. (2 -7 ml.) of concentrated sulphuric acid and 50 g. of pure crotonic acid in a 500 ml. round-bottomed flask and heat under reflux for 12 hours. Add water, separate the precipitated ester and dissolve it in ether wash with dilute sodium carbonate solution until effervescence ceases, dry with anhydrous magnesium sulphate, and remove the ether on a water bath. Distil and collect the methyl crotoiiato at 118-120° the yield is 40 g. 

The effervescence may become quite brisk this is the reason for using a large container. 

Girard s reagent P , C5H5NCH2C0NHNH2 C1. In a 1-htre threenecked flask, equipped as in the previous preparation, place 200 ml. of absolute ethyl alcohol, 63 g. (64 -5 ml.) of pure anhydrous pyridine and 98 - 5 g. (84 5 ml.) of ethyl chloroacetate. Heat the mixture under reflux for 2-3 hours until the formation of the quaternary salt is complete acidify a small test-portion with dilute sulphuric acid it should dissolve completely and no odour of ethyl chloroacetate should be apparent. Cool the mixture in ice and salt. Replace the thermometer by a dropping funnel, and add a solution of 40 g. of 100 per cent, hydrazine hydrate in 60 ml. of absolute ethanol all at once. A vigorous exothermic reaction soon develops and is accompanied by vigorous effervescence. The pro duct separates almost immediately. When cold, filter with suction, wash... 

In a 500 ml. bolt-head flask provided with a thermometer (reaching almost to the bottom) and a calcium chloride (or cotton wool) guard tube, place 100 g. of a-bromo-wo-valerj l bromide and 50 g. of dry, finely-divided urea. Start the reaction by warming the flask on a water bath the temperature soon rises to about 80°. Maintain this temperature for about 3 horns the mass will liquefy and then resolidify. Transfer the sticky reaction product to a large beaker containing saturated sodium bicarbonate solution, stir mechanically and add more saturated sodium bicarbonate solution in small quantities until effervescence ceases. Filter at the pump, suck as dry as possible and dry the crude bromural upon filter paper in the air. RecrystaUise the dry product from toluene. Alternatively, recrystaUise the moist product from hot water (ca. 700 ml.). The yield of pure brommal, m.p. 154-155°, is 28 g. 

Effectiveness factor Effervescent tablets Effexor Effluents Effluent treatment Efflux viscometers... 

Wines can be made effervescent by carbonation rather than refermentation in a closed system, but that must be stated on the label. Even though... 

Precipitated Calcium Carbonate. Calcium carbonate [471-34-1] (Turns), CaCO, is a fine white microcrystaUine powder without odor or taste. It is stable in air. An aqueous suspension is close to neutrality. It is practically insoluble in water, insoluble in alcohol, and dissolves with effervescence in dilute acetic, hydrochloric, and nitric acids (see Calcium compounds, calcium carbonate). 

Sodium bicarbonate is a gastric antacid that may cause systemic alkalosis on overdose and may contribute to edema owing to sodium retention. It is useful for systemic acidosis because both deficient ions are present in the same molecule, and it can be used topically as a moist paste or in solution as an antipmritic. Sodium bicarbonate also is an ingredient of many effervescent mixtures, alkaline solutions, etc. One gram of NaHCO neutralizes 115 mL 0.1 NHCl. 

Pha.rma.ceutica.ls. Tartaric acid is used ia the manufacture of fine dmg salts, as ia effervescent salts. Tartar emetic [28300-74-5] is used ia small doses as an expectorant ia cough symps. It can be used to treat infections caused by Schistosomajaponium. 

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