Carbon dioxide over potassium carbonate solutions

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... 

A solution of 0-75 gm. of sodium in 18 gms. of benzyl alcohol (previously dried over potassium hydroxide and redistilled) is heated on a water bath using a calcium chloride tube on the flask, and added to 75 gms. (2 mols.) of benzaldehyde (previously dried over calcium chloride and distilled in a current of carbon dioxide). The whole is heated on a water bath for 20 hours, and acidified with 5 c.cs. of glacial acetic acid. Water is added, and the oil which separates dried over calcium chloride and distilled in a high-temperature distilling flask (see p. 19). Some unchanged benzaldehyde comes over the fraction 320°—326° is retained. 

Standardization of the Titanium Chloride Solution Drain any standing titanium chloride (TiCl3) from the feed lines and buret, and refill with fresh solution. Add 3.0 g of Ferrous Ammonium Sulfate to a wide-mouth Erlenmeyer flask followed by 200 mL of water, 25 mL of 50% sulfuric acid, 25 mL of 0.1 N Potassium Dichromate Solution (by pipet), and 2 or 3 boiling chips. Boil the solution vigorously on a hot plate for 30 s to remove dissolved air, then quickly transfer the flask to the titration apparatus, securely connect the stopper assembly, and start the carbon dioxide flow and stirrer. Pass carbon dioxide over the solution for 1 min before beginning the titration. 

Methylation of aliphatic amines to tertiary amines 1015 1 mole of a primary amine is added with cooling to a mixture of 5 moles of 90 % formic acid and 2.2 moles of 35 % formaldehyde solution. Secondary amines require only half of these amounts of formic acid and formaldehyde, but an excess is not disadvantageous. Reaction begins when the mixture is heated on a steam-bath. When the initial vigorous evolution of carbon dioxide ceases, the mixture must be heated for a further 2-4 h, in all for 8-12 h. Then somewhat more than 1 mole of hydrochloric acid is added and the formic acid and formaldehyde are distilled off. The colorless residue is dissolved in water and basified with 25 % sodium hydroxide solution, and the amine is distilled off in steam. The distillate is saturated with solid potassium hydroxide, and the oil that separates is dried over potassium hydroxide and distilled from sodium. The following tertiary amines were thus obtained in more than 80% yield iV,iV-dimethylbutyl-amine, b.p. 94° A TV-dimethylbenzylamine, b.p. 176-180° and 1-methylpiperidine, b.p. 106°. 

Preparation of carbon monoxide from formic acid 50e A round-bottomed flask (capacity 1 1) is fitted by ground-glass joints with a dropping funnel and a gas-outlet tube, filled two-thirds full with concentrated phosphoric acid, and heated in a water-bath to 80° then formic acid is dropped in slowly. For removal of impurities (carbon dioxide, air, acid vapors, water vapor), the carbon monoxide evolved is passed successively through 50% potassium hydroxide solution and an alkaline solution of sodium dithionate (25 g of dithionate in 125 ml of water containing also 20 ml of 70% potassium hydroxide solution) and over potassium hydroxide, calcium chloride, and phosphoric oxide. 

Method using potassium tricarbonatocobaltate(UI) An amino acid is poured into the green solution , and the mixture is warmed on a water-bath until the color of the solution changes from green to blue. Then 6 mol/dm acetic acid is added dropwise until the evolution of carbon dioxide ceases and the solution becomes red-violet. After filtering, the solution stands for some time in the cold. Crystals of the less soluble /ac-isomer are deposited, then the / e/--isomer separates out on evaporating the mother liquor over sulfuric acid. 

For carbon dioxide, a 25-40% solution of potassium hydroxide has been recommended. The 25% solution is least viscous and it absorbs 40ml of CO2 per milliliter. Potassium hydroxide is always preferred to sodium hydroxide, as the potassium carbonate formed is more soluble than sodium carbonate. This reagent dissolves all acid gases, which must be removed before the determination of CO2. In the presence of other water-soluble gases solid reagents must be used over mercury as the confining fluid for this determination. A typical example is ascarite (asbestos soaked with sodium hydroxide). 

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