Hydrochloric acid partial pressure

The rings in l,4 3,6-dianhydro-D-sorbitol have different stabilities. Montgomery and Wiggins66 treated the anhydride with hydrochloric acid under pressure and isolated some l,6-dichloro-l,6-didesoxy-D-sorbitol and much 6-chloro-6-desoxy-l,4-anhydro-D-sorbitol, both isolated as their benzylidene derivatives. No l-chloro-l-desoxy-3,6-anhydro-D-sorbitol was found. This experiment demonstrates that the 1,4-anhydro ring is more stable than the 3,6-ring in this substance. This is in agreement with the fact that partial dehydration of D-sorbitol in the 1,4-position can be preferentially effected and 1,4-anhydro-D-sorbitol isolated. 

On heating ephedrine hydrochloride with 5% hydrochloric acid, under pressure, at 170-180° (248) or with 25% acid, at 100°, the compound is partially converted to iZ -ephedrine (20, 32,40). The conversion is reversible and an equilibrium is established. According to Emde (39), the rearrangement takes place by replacement of the hydroxyl group by chlorine, followed by hydrolysis. Oxidation of ephedrine or Ephedrine, gives benzaldehyde or benzoic acid. 

The corrosion rate of steel in carbonic acid is faster than in hydrochloric acid Correlations are available to predict the rate of steel corrosion for different partial pressures of CO2 and different temperatures. At high temperatures the iron carbonate forms a film of protective scale on the steel s surface, but this is easily washed away at lower temperatures (again a corrosion nomogram is available to predict the impact of the scale on the corrosion rate at various CO2 partial pressures and temperatures). 

Make a thin paste of 21 5 g. of finely-powdered o-tolidine (a commercial product) with 300 ml. of water in a 1-litre beaker, add 25 g. (21 ml.) of concentrated hydrochloric acid, and warm until dissolved. Cool the solution to 10° with ice, stir mechanically, and add a further 25 g. (21 ml.) of concentrated hydrochloric acid (1) partial separation of o tolidine dihydrochloride will occur. Add a solution of 15 g, of sodium nitrite in 30 ml. of water as rapidly as possible, but keep the temperature below 15° a slight excess of nitrous acid is not harmful in this preparation. Add the clear, orange tetrazonium solution to 175 ml. of 30 per cent, hypophosphorous acid (2), and allow the mixture to stand, loosely stoppered, at room temperature for 16-18 hours. Transfer to a separatory funnel, and remove the upper red oily layer. Extract the aqueous layer with 50 ml, of benzene. Dry the combined upper layer and benzene extract with anhydrous magnesium sulphate, and remove the benzene by distillation (compare Fig. II, 13, 4) from a Widmer or similar flask (Figs. II, 24, 3-5) heat in an oil bath to 150° to ensure the removal of the last traces of benzene. Distil the residue at ca. 3 mm. pressure and a temperature of 155°. Collect the 3 3 -dimethyldiphenyl as a pale yellow liquid at 114-115°/3 mm. raise the bath temperature to about 170° when the temperature of the thermometer in the flask commences to fall. The yield is 14 g. 

Chlorine. The solubiUty of chlorine [7782-50-5] in hydrochloric acid is an important factor in the purification of by-product hydrochloric acid. The concentration of chlorine in solution, S, is proportional to the partial pressure of chlorine, p, in the gas phase and follows Henry s law, S = i/p, in the... 

Hydrochloric acid [7647-01-0], which is formed as by-product from unreacted chloroacetic acid, is fed into an absorption column. After the addition of acid and alcohol is complete, the mixture is heated at reflux for 6—8 h, whereby the intermediate malonic acid ester monoamide is hydroly2ed to a dialkyl malonate. The pure ester is obtained from the mixture of cmde esters by extraction with ben2ene [71-43-2], toluene [108-88-3], or xylene [1330-20-7]. The organic phase is washed with dilute sodium hydroxide [1310-73-2] to remove small amounts of the monoester. The diester is then separated from solvent by distillation at atmospheric pressure, and the malonic ester obtained by redistillation under vacuum as a colorless Hquid with a minimum assay of 99%. The aqueous phase contains considerable amounts of mineral acid and salts and must be treated before being fed to the waste treatment plant. The process is suitable for both the dimethyl and diethyl esters. The yield based on sodium chloroacetate is 75—85%. Various low molecular mass hydrocarbons, some of them partially chlorinated, are formed as by-products. Although a relatively simple plant is sufficient for the reaction itself, a si2eable investment is required for treatment of the wastewater and exhaust gas. 

In consequences of the great differences in vapor pressures of the heptoxides and acids at low temperatures, technetium may be partially separated from rhenium by repeated alternating evaporation with nitric acid and hydrochloric acid ]... 

Fischer and Bergmann 75 adapted the method of Hinsberg 76 for the N-methylation of benzenesulfonamides in the synthesis of Sar, 5-aminopentanoic acid, and racemic Orn. Two years later Fischer and Lipschitz 73 succeeded in the synthesis of optically active, N-methylated derivatives of Ala, Leu, Phe, and Tyr. TV-Tosyl amino acids were N-methylated with two equivalents of iodomethane at 65-68 °C in a sealed pressure tube. The tosyl group was then deprotected either with sodium in liquid ammonia or with hot hydrochloric acid, but partially racemic products were obtained that were purified by crystallization with optically active bases. 77 Cheung and Benoiton did not observe racemization during deprotection with sodium in liquid ammonia. 78 ... 

The flask is now disconnected from the stirrer and column, and the contents distilled off as completely as possible on the steam bath under reduced pressure. The remaining solid is freed from residual moisture and hydrochloric acid by allowing a slow current of dry air to pass over it, while still heating on the steam balh and maintaining a partial vacuum (Note 3). It is then redissolved in distilled water, and the solution filtered with... 

Butyl lithium (10 ml, 1.64 mol in hexane) was added under nitrogen to a stirred suspension of triphenyl-2-pyrrolidinoethylphosphonium bromide (7.2 g) in dry toluene (75 ml). After 0.5 h, ((E)-3-(6-(4-toluoyl)-2-pyridyl)acrylate, vide supra, (4.8 g) in toluene (50 ml) was added. The suspension, initially orange, became deep purple, then slowly faded to yellow during 2 h heating at 75°C. The cooled solution was diluted with ether (150 ml) and treated with hydrochloric acid (50 ml, 2 mol). The aqueous phase was separated, washed with ether, and basified with potassium carbonate (ice) and extracted with ether. The mixture of isomeric esters obtained by evaporation was dissolved in ethanol (100 ml) containing sodium hydroxide solution (20 ml, 1 mol) and partially evaporated on the steam bath under reduced pressure for 5 min. The residual aqueous solution was neutralized with sulfuric acid (20 ml, 0.5 mol) and evaporated to dryness. The solid residue was extracted with hot isopropanol (3x50 ml) and the extracts were concentrated until crystallization commenced. The (E)-3-(6-(3-pyrrolidino-l-(4-tolyl)prop-l-(E)-enyl)-2-pyridyl)acrylic acid, melting point 222°C (dec. recrystallization from isopropanol) was obtained. 

To solution of 16.7 g 1-morpholinocyclohex-l-ene in 45 ml chloroform, 10.1 g of triethylamine are added. Over a period of one hour a solution of 1 mole-equivalent of isobutyroyl chloride in 15 ml chloroform is added, with stirring. The mixture is stirred for two hours at room temperature and is thereafter heated at 60°C for 3 hours. It is kept aside for a night, then 150 ml hydrochloric acid are added. The mixture is shaken and is then allowed to settle. The chloroformic phase is discarded. The aqueous phase is partially neutralized with sodium carbonate until the pH value reaches 6 and is then extracted with chloroform three times. The organic phases are united, washed with water, dried over sodium sulfate, filtered and evaporated to dryness. The crude residue is purified by distillation under reduced pressure to give 2-(isobutyroyl)cyclohexanone. 

A given amount of liquid can absorb gas only up to the concentration at which the partial pressure of the gas from the solution formed by absorption is equal to its partial pressure in the gas phase. If the partial pressure of the gas from the solution is lower than in the vapour phase, absorption sets in and the rate of absorption, at a given total absorption coefficient, depends on the difference in the partial pressures in the two phases and on the size of the contact surface. From the dependence of the partial pressures of hydrogen chloride on the composition of the hydrochloric acid it follows that the vapour pressure of HC1 from diluted solutions is relatively very low. Therefore, praotically all the hydrogen chloride from the gas phase can be absorbed, as... 

As the equilibrium partial pressure of hydrogen chloride over a 35.2 per cent hydrochloric acid is only pxHci = 135 mm Hg the gas under partial pressure Phci = 228 mm Hg will be readily absorbed in the acid (the difference in pressures pHci — Pan — AB determines the absorption rate). 

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