Carbon dioxide over sodium carbonate solutions

Ethyl bromide soon distils over, and collects as heavy oily drops under the water in the receiving flask, evaporation of the very volatile distillate being thus prevented. If the mixture in the flask A froths badly, moderate the heating of the sand-bath. When no more oily drops of ethyl bromide come over, pour the contents of the receiving flask into a separating-funnel, and carefully run oflF the heavy lower layer of ethyl bromide. Discard the upper aqueous layer, and return the ethyl bromide to the funnel. Add an equal volume of 10% sodium carbonate solution, cork the funnel securely and shake cautiously. Owing to the presence of hydrobromic and sulphurous acids in the crude ethyl bromide, a brisk evolution of carbon dioxide occurs therefore release the... 

Chill the concentrated solution of the amine hydrochloride in ice-water, and then cautiously with stirring add an excess of 20% aqueous sodium hydroxide solution to liberate the amine. Pour the mixture into a separating-funnel, and rinse out the flask or basin with ether into the funnel. Extract the mixture twice with ether (2 X25 ml.). Dry the united ether extracts over flake or powdered sodium hydroxide, preferably overnight. Distil the dry filtered extract from an apparatus similar to that used for the oxime when the ether has been removed, distil the amine slowly under water-pump pressure, using a capillary tube having a soda-lime guard - tube to ensure that only dry air free from carbon dioxide passes through the liquid. Collect the amine, b.p. 59-61°/12 mm. at atmospheric pressure it has b.p. 163-164°. Yield, 18 g. 

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. 

The cooled mixture is transferred to a 3-1. separatory funnel, and the ethylene dichloride layer is removed. The aqueous phase is extracted three times with a total of about 500 ml. of ether. The ether and ethylene chloride solutions are combined and washed with three 100-ml. portions of saturated aqueous sodium carbonate solution, which is added cautiously at first to avoid too rapid evolution of carbon dioxide. The non-aqueous solution is then dried over anhydrous sodium carbonate, the solvents are distilled, and the remaining liquid is transferred to a Claisen flask and distilled from an oil bath under reduced pressure (Note 5). The aldehyde boils at 78° at 2 mm. there is very little fore-run and very little residue. The yield of crude 2-pyrrolealdehyde is 85-90 g. (89-95%), as an almost water-white liquid which soon crystallizes. A sample dried on a clay plate melts at 35 0°. The crude product is purified by dissolving in boiling petroleum ether (b.p. 40-60°), in the ratio of 1 g. of crude 2-pyrrolealdehyde to 25 ml. of solvent, and cooling the solution slowly to room temperature, followed by refrigeration for a few hours. The pure aldehyde is obtained from the crude in approximately 85% recovery. The over-all yield from pyrrole is 78-79% of pure 2-pyrrolealdehyde, m.p. 44 5°. 

The crude ester is cooled, an equal volume of benzene is added, then the free acid is neutralized by shaking with about 250 cc. of a 10 per cent solution of sodium carbonate (Note 4). The benzene solution is poured into 1300 cc. of a saturated solution of sodium bisulfite (about 60 g. of technical sodium bisulfite per 100 cc.), contained in a wide-neck bottle equipped with an efficient stirrer, and the mixture stirred for two and a half hours. The mixture soon warms up a little and becomes semi-solid. It is filtered through a 20-cm. Buchner funnel and carefully washed, first with 200 cc. of a saturated solution of sodium bisulfite, finally with two 150-cc. portions of benzene (Notes 5 and 6). The white pearly flakes of the sodium bisulfite addition product are transferred to a 3-I. round-bottom wide-neck flask equipped with a mechanical stirrer and containing 700 cc. of water, 175 cc. of concentrated sulfuric acid, and 500 cc. of benzene. The flask is heated on a steam bath under a hood, the temperature being kept at 55°, and the mixture is stirred for thirty minutes (Note 7). The solution is then poured into a separatory funnel, the benzene separated and the water layer extracted with a 200-cc. portion of benzene. The combined benzene solution is shaken with excess of 10 per cent sodium carbonate solution to remove free acid and sulfur dioxide (Note 8). The benzene is washed with a little water and then dried over anhydrous potassium carbonate (Note 9). The benzene is distilled at ordinary pressure over a free flame from a 500-cc. Claisen flask, the solution being added from a separatory funnel as fast as the benzene distils. It is advisable to distil the ester under reduced pressure although it can be done under ordinary pressure. The fraction distilling around n8°/5mm., 130710 mm., 138715 mm., 148725 mm., 155735 mm., or... 

Weak acids with weak bases. The titration of a weak acid and a weak base can be readily carried out, and frequently it is preferable to employ this procedure rather than use a strong base. Curve (c) in Fig. 13.2 is the titration curve of 0.003 M acetic acid with 0.0973 M aqueous ammonia solution. The neutralisation curve up to the equivalence point is similar to that obtained with sodium hydroxide solution, since both sodium and ammonium acetates are strong electrolytes after the equivalence point an excess of aqueous ammonia solution has little effect upon the conductance, as its dissociation is depressed by the ammonium salt present in the solution. The advantages over the use of strong alkali are that the end point is easier to detect, and in dilute solution the influence of carbon dioxide may be neglected. 

The reaction mixture is cooled, 250 cc. of water is added, and mixture is made acid to litmus by addition of a cooled solu-koa of 100 g. of concentrated sulfuric acid in 200 cc. of water. Chipped ice is added if necessary to keep the mixture cool. The ui >er ester layer is separated, and the aqueous layer is extracted w% 200 cc. of ether. The combined ether and ester layers are ken with 350 cc. of a saturated sodium bicarbonate solution yr til no more carbon dioxide is evolved, and then the organic layer 1S fashed with 200 cc. of water. The water layer is combined with sodium bicarbonate solution and extracted with 400 cc. of e er. The combined ether and ester layers are dried over sodium Sl)lfate. The ether is removed by distillation on the steam bath, aiM the excess ethyl benzoate and acetoacetic ester (Note 3) are t removed by distillation under reduced pressure through a l tm. fractionating column. Finally, the ethyl benzoylacetate is tilled (Note 3) at 101-106°/1 mm. (130-135°/3 mm.). The y ld of ester boiling over a 5° range is 190-210 g. (50-55 per cent theoretical amount based on the ethyl acetoacetate). 

To a flame-dried, three-neck, 1-1 flask were added, in order, p-xylene (107 g, 1.0 mol), phosphorus trichloride (412 g, 3.0 mol), and anhydrous aluminum chloride (160 g, 1.2 mol). The reaction mixture was slowly heated to reflux with stirring. After 2.5 h at reflux, the reaction was allowed to cool to room temperature and the volatile components distilled at reduced pressure. The residual oil was slowly added to cold water (1 1) with stirring, and a white solid formed. The solid was removed by filtration, washed with water, and air dried. The solid was suspended in water (1 1) to which was added 50% sodium hydroxide solution (90 ml) to cause dissolution. The solution was saturated with carbon dioxide and filtered through Celite . The basic solution was washed with methylene chloride (200 ml) and acidified with concentrated hydrochloric acid (200 ml). The white solid that separated was isolated by extraction with methylene chloride (3 x 250 ml). The extracts were dried over magnesium sulfate, filtered, and evaporated under reduced pressure to give the pure 2,5-dimethylbenzenephosphinic acid (99 g, 60%) as an oil, which slowly crystallized to a solid of mp 77-79°C. 

The oil bath is removed, and, with the stirring maintained, the reaction mixture is cooled to room temperature by running cold water over the flask. Then 150 cc. of water is added to dissolve the reaction mass, and both layers of the mixture are transferred to a separatory funnel. An ice-cold solution of 25 cc. of concentrated sulfuric acid in 200 cc. of water is added, and the mixture is shaken vigorously. The ester layer is separated and washed with 200 cc. of water it is then shaken with successive 200-cc. portions of 5 per cent sodium bicarbonate solution until the evolution of carbon dioxide ceases, after which it is washed with 200 cc. of water. The bicarbonate solution is separated and extracted with 100 cc. of ether (Note 6). The ether extract,... 

Numerous methods for the synthesis of salicyl alcohol exist. These involve the reduction of salicylaldehyde or of salicylic acid and its derivatives. The alcohol can be prepared in almost theoretical yield by the reduction of salicylaldehyde with sodium amalgam, sodium borohydride, or lithium aluminum hydride by catalytic hydrogenation over platinum black or Raney nickel or by hydrogenation over platinum and ferrous chloride in alcohol. The electrolytic reduction of salicylaldehyde in sodium bicarbonate solution at a mercury cathode with carbon dioxide passed into the mixture also yields saligenin. It is formed by the electrolytic reduction at lead electrodes of salicylic acids in aqueous alcoholic solution or sodium salicylate in the presence of boric acid and sodium sulfate. Salicylamide in aqueous alcohol solution acidified with acetic acid is reduced to salicyl alcohol by sodium amalgam in 63% yield. Salicyl alcohol forms along with -hydroxybenzyl alcohol by the action of formaldehyde on phenol in the presence of sodium hydroxide or calcium oxide. High yields of salicyl alcohol from phenol and formaldehyde in the presence of a molar equivalent of ether additives have been reported (60). Phenyl metaborate prepared from phenol and boric acid yields salicyl alcohol after treatment with formaldehyde and hydrolysis (61). 

In a 3-I. round-bottom flask, a hydrobromic add solution is made by the sulfur dioxide reduction of 480 g. of bromine in the presence of 510 g. of ice water or a mixture is made of 1000 g. of aqueous 48 per cent hydrobromic acid and 300 g. of concentrated su. furic acid. To this are added 385 cc. of aqueous allyl alcohol, which, according to bromine titration, contain 233 g. of pure allyl alcohol. The 3-I. round-bottom flask is fitted with a mechanical stirrer (Fig. 1, p. 4, see also Notes), separatory funnel, and an efficient condenser set for downward distillation. Stirring is started and 300 g. of concentrated sulfuric add are added gradually through the separatory funnel to the warm solution. The allyl bromide distils over completely in about one-half to one hour. The crude allyl bromide is washed with dilute sodium carbonate solution, is dried over calcium chloride and is distilled. The yield of product boiling at 60-72° from a number of experiments varies from 443 to 465 g. (92-96 per cent theory). A small high-boiling fraction is also obtained and examination has shown this to consist of propylene bromide. 

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