Water-formic acid mixtures

Ivanova and Fesenko have measured the heats of solution of KBr in water-formic acid mixtures from 1.2 mol per cent acid to pure acid. Data were obtained over a wide concentration range and evalu-... 

Integral Heats of Solution (AH° iJkcal mol ) of KBr in Water-Formic Acid Mixtures at 25°C ... 

The vapor is thea withdrawa from the stiH as distillate. The changing Hquid composition is most coavenieafly described by foUowiag the trajectory (or residue curve) of the overall composition of all the coexistiag Hquid phases. An exteasive amouat of valuable experimental data for the water—acetoae—chloroform mixture, including biaary and ternary LLE, VLE, and VLLE data, and both simple distillation and batch distillation residue curves are available (93,101). Experimentally determined simple distillation residue curves have also been reported for the heterogeneous system water—formic acid—1,2-dichloroethane (102). 

More Complex Mixtures. AH the sequences discussed are type I Hquid systems, ie, mixtures in which only one of the binary pairs shows Hquid—Hquid behavior. Many mixtures of commercial interest display Hquid—Hquid behavior in two of the binary pairs (type II systems), eg, secondary butyl alcohol—water—di-secondary butyl ether (SBA—water—DSBE), and water—formic acid—xylene (92). Sequences for these separations can be devised on the basis of residue curve maps. The SBA—water—DSBE separation is practiced by ARGO and is considered in detail in the Hterature (4,5,105,126). 

The membrane cast from chloroform-formic acid mixtures had an anisotropic structure with a 0.9-1.2 p active layer and a 40 p porous support layer. At a water flux of 139 1/m2 day (kg/cm2 at 20 °C), the membrane showed 99.4 % rejection of cytochrome C and 72.7% of Vitamine B12. At 3980 1/m2 day water flux level, the rejection for bovine serum hemoglobin (MW, 66000 68000), cytochrome C, and Vitamine Bl2 were, 95.6, 79.4, and 39.8%, respectively. 

According to Konovalow, the mixture water-formic acid furnishes us an example of the third kind. 

In order to determine the possible influence of additives, water, formic acid, methanol, acetone and acetic anhydride were added to the cationic polymerization of formaldehyde at —78°C with SnCl4 in toluene. These reagents were added in small amounts to the polymerization mixture prior to addition of the initiator. Conversion and DP of the polyoxymethylenes were determined after 60 min reaction time. Up to a molar ratio of 1 1 of additive to SnCl4, conversion and DP increased and went through a maximum the rate also increased. At higher levels of additives, conversion and DP decreased. 

Non-acidified methanol is the more suitable solvent to extract anthocyanins from grape reducing risks of hydrolysis of acetylated compounds 20 berry skins are extracted with 50 mL of methanol for 12h at room temperature (Revilla et al., 1998). Alternatively, the use of a methanol/water/formic acid 50 48.5 1.5 (v/v/v) mixture was reported as well (Gao et al., 1997). The volume of extract is reduced to about one-half under vacuum at 30 °C, adjusted to 100 mL with water, and 10 mL of this solution is diluted to 50 mL with water in order to further reduce the MeOH content. The resulting solution is purified by a SPE Ci8 cartridge (e.g., lg) previously activated by passage of... 

The flame ionization detector (FID) is the most widely used GC detector. Its operation is simple, sensitivity is of the order of lOpg carbon per second with a linear range of 10, the response is fast, and detector stability is excellent. The carrier gas is mixed with hydrogen, and this mixture is combusted in air at the exit of a flame jet. Ions are formed that are collected at an electrode producing a current that is proportional to the amount of sample compound in the flame. Analytes such as permanent gases, nitrogen oxides, sulfur oxides, carbon oxides, carbon disulfide, water, formic acid, formaldehyde, etc., do not provide a significant FID response. The flows of carrier and combustion gas should be set properly for optimal FID operation. Typical flow rates are 1 1 12... 

The LLE data of the ternary system composed of water + formic acid+ cumene were measured at different temperatures of 298.15, 303.15, and 308.15. The equihbrium data of the ternary mixture were also predicted by the UNIFAC method. It was found that UNIFAC with original group interaction parameters developed for LLE did not provide good prediction. The average RMSD value between the observed and calculated mole fractions with a reasonable error was 8.14% for the UNIFAC model. The solubility of water in cumene increases with amounts of formic acid added to water + cumene mixture. 

A considerable amount of the formic acid, however, still remains behind in the distilling-flask as the unhydrolysed monoformate. Therefore, if time allows, dilute the residue in the flask with about an equal volume of water, and then steam-distil, the monoformate ester being thus completely hydrolysed and the formic acid then driven over in the steam. Collect about 400 ml. of distillate. Add this distillate to that obtained by direct heating of the reaction mixture and then treat with lead carbonate as described above. Total yield of lead formate is now about 40 g. 

If the reaction mixture used in the above preparation of formic acid is heated to 190-200°, the glyceryl monoformate which has escaped hydrolysis undergoes decomposition, with the loss of carbon dioxide and water, and the... 

Place 27 g. of o-phenylenediamine (Section IV,92) in a 250 ml. round-bottomed flask and add 17 -5 g. (16 ml.) of 90 per cent, formic acid (1). Heat the mixture on a water bath at 100° for 2 hours. Cool, add 10 per cent sodium hydroxide solution slowly, with constant rotation of the flask, until the mixture is just alkaline to litmus. Filter off the crude benzimidazole at the pump, wash with ice-cold water, drain well and wash again with 25 ml. of cold water. Dissolve the crude product in 400 ml. of boiling water, add 2 g. of decolourising carbon, and digest for 16 minutes. Filter rapidly at the pump through a pre heated Buchner funnel and flask. Cool the filtrate to about 10°, filter off the benzimidazole, wash with 25 ml. of cold water, and dry at 100°. The yield of pure benzimidazole, m.p. 171-172°, is 26 g. 

In a 500 ml. three-necked flask, equipped with a mechanical stirrer, thermometer and dropping funnel, place 300 ml. of 88-90 per cent, formic acid and add 70 ml. of 30 per cent, hydrogen peroxide. Then introduce slowly 41 g. (51 ml.) of freshly distilled cyclohexene (Section 111,12) over a period of 20-30 minutes maintain the temperature of the reaction mixture between 40° and 45° by cooling with an ice bath and controlling the rate of addition. Keep the reaction mixture at 40° for 1 hour after all the cyclohexene has been added and then allow to stand overnight at room temperature. Remove most of the formic acid and water by distillation from a water bath under reduced pressure. Add an ice-cold solution of 40 g. of sodium hydroxide in 75 ml. of water in small portions to the residual mixture of the diol and its formate take care that the tempera... 

Although acetic acid and water are not beheved to form an azeotrope, acetic acid is hard to separate from aqueous mixtures. Because a number of common hydrocarbons such as heptane or isooctane form azeotropes with formic acid, one of these hydrocarbons can be added to the reactor oxidate permitting separation of formic acid. Water is decanted in a separator from the condensate. Much greater quantities of formic acid are produced from naphtha than from butane, hence formic acid recovery is more extensive in such plants. Through judicious recycling of the less desirable oxygenates, nearly all major impurities can be oxidized to acetic acid. Final acetic acid purification follows much the same treatments as are used in acetaldehyde oxidation. Acid quahty equivalent to the best analytical grade can be produced in tank car quantities without difficulties. 

Methyl Vinyl Ketone. Methyl vinyl ketone [78-94-4] (3-buten-2-one) is a colorless Hquid with a pungent odor. It is stable only below 0°C, and readily polymerizes on standing at room temperature. It can be inhibited for storage and transportation by a mixture of acetic or formic acid and hydroquinone or catechol (266). This ketone is completely soluble in water, and forms a binary azeotrope with water (85 MVK 15 H2O vol %) at 75.8°C. 

To the white residue (Note 1) are added 25 g. of 98-100% formic acid and 2-3 drops of concentrated nitric acid. The mixture is heated for 24 hours on a steam bath. The resulting syrup is dissolved in 100 ml. of water and, with the temperature at 50°, is carefully treated with 25 g. of anhydrous sodium carbonate. The solution is then placed in an evaporating dish and evaporated to dryness on the steam bath. The residue is extracted twice by boiling it with 200-ml. portions of absolute ethanol, and the alcohol solutions are filtered. The alcohol is removed by evaporation and the residue triturated with 100 ml. of a mixture of equal... 

Although less common, azeotropic mixtures are known which have higher boiling points than their components. These include water with most of the mineral acids (hydrofluoric, hydrochloric, hydrobromic, perchloric, nitric and sulfuric) and formic acid. Other examples are acetic acid-pyridine, acetone-chloroform, aniline-phenol, and chloroform-methyl acetate. 

A. Ethyl N- p-tolylsulfonylmethyl)carhamate,[Carbamic acid, (4 -methyl-phenylsulfonylmethyl)-, ethyl ester]. A solution of 178 g. (1.0 mole) of sodium p-toluenesulfinate (Note 1) in 1 1. of water is placed in a 3-1., three-necked daak, equipped with a condenser, an efficient mechanical stirrer, and a thermometer. After addition of 100 ml. (108 g.) of a 34—37% solution of formaldehyde ca. 1.2-1.4 moles) (Note 2), 107 g. (1.2 moles) of ethyl carbamate (Note 3), and 250 ml. of formic acid (Note 4), the stirred solution is heated to 70°. Soon after this temperature is reached, the reaction mixture becomes turbid by separation of the... 

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