Solutions, formaldehyde Atmospheric pressure

In a mixture of 1.32 g of sodium acetate, 0.8 ml of sodium acetate, 40 ml of water and 200 ml of ethanol were dissolved 10 g of the colorless froth obtained, and 1.0 g of palladium black was added to the above solution. Catalytic reduction was performed for 5 hours at room temperature under atmospheric pressure in a gentle hydrogen stream. 32 ml of 37% aqueous formaldehyde solution were poured into the reaction mixture and the catalytic reduction was continued for a further 7 hours. After completion of the reaction, the catalyst was filtered off and the filtrate was concentrated under reduced pressure approximately to a quarter volume. To the concentrate were added 100 ml of water, and the mixture was adjusted to about pH 10 with an aqueous sodium carbonate solution. The mixture was extracted thoroughly with chloroform and the extract was washed with water and dried. After evaporation of the solvent in vacuo, the residue was recrystallized from a mixture of chloroform and diethyl ether, giving 6 g of crystals. 

Four milliliters of 1 AT aqueous sodium hydroxide solution is added to a mixture of 300 g. (5.2 moles) of acetone and 100 g. (0.86 mole) of aqueous 35% formaldehyde solution. The mixture is held at room temperature for 3-4 hours and then neutralized with 4 ml. oi 1 N hydrochloric acid. The excess acetone is distilled off on a water bath heated to 80-85°, and 2-4 g. of anhydrous zinc chloride is added to the residue. The mixture is distilled on an oil bath, and the distillate is collected as long as it comes over colorless. The distillate is treated with potassium carbonate, and the organic material is separated and dried over sodium sulfate. Distillation at 130 mm. pressure gives a 25-35% yield of methyl vinyl ketone boiling at 33-34°. Some decomposition occurs if the distillation is carried out at atmospheric pressure, where the product boils at 80°. 

Batchwise aldolization experiments were carried out in a 1.0 dm jacketed glass reactor operating at atmospheric pressure. Formaldehyde, either as a freshly prepared aqueous solution of paraformaldehyde or as formalin (42 wt.-%), and n-butyraldehyde, the catalyst and the solvents, water and methanol, were loaded into the reactor at room temperature. Solid paraformaldehyde was dissolved in water by the addition of alkali (NaOH). Several anionic resin catalysts were screened... 

Since formaldehyde is known to be a catalyst poison it was removed from the reagent mixture prior to hydrogenation by distillation. In order to prevent oligomerization of formaldehyde [14], water was gradually added to the mixture during distillation. The water feeding was adjusted in order to maintain a constant liquid volume in the distillation flask. Distillation was performed imder atmospheric pressure and at 100 °C using a total batch volume of 400 ml (200 ml of aldolization product mixed with 200 ml of distilled water). As the first distilled droplets from the condenser were observed, the addition of extra water was commenced. In this way, the formaldehyde content of the solution was easily suppressed below 0.5 wt.%. 

Tris[(dimethylamino)methyl]phosphine oxide 304 40% aqueous formaldehyde solution (99.8 ml) is dropped, with ice-cooling into a solution of dimethylamine (56.2 g, 1.25 moles) in ethanol (150 ml). Then white phosphorus (15 g, 0.483 mole) is added under nitrogen, and the mixture is heated under reflux for 15 h. The resulting clear yellow solution is evaporated on a rotary evaporator and the semisolid residue (165.3 g) is extracted with ether. Removing the ether gives the phosphine oxide (47.8 g, 44.6%), m.p. 154-157°. This can be further purified by sublimation at atmospheric pressure and is thus obtained as transparent needles. 

Polyoxymethylene (polyacetal) — sometimes known as polyformaldehyde — is the polymer of formaldehyde. It is obtained either by anionic or cationic solution polymerization of formaldehyde or cationic ring-opening bulk polymerization of trioxane. Highly purified formaldehyde is polymerized in the presence of an inert solvent such as hexane at atmospheric pressure and a temperature usually in the range of -50 to 70°C. The cationic bulk polymerization of trioxane is the preferred method of production of polyoxymethylene. 

The mixture of 2.48 g guaiacol (0.02 mol), 3.0 g 40% aqueous formaldehyde (0.04 mol), and 3.6 g methylaminoacetaldehyde dimethyl acetal (0.03 mol) in 25 mL ethanol was stirred at room temperature for 24 h. The solvent was removed on a rotary evaporator and the resulting thick oil was dissolved in 50 mL cold 6 N HCl and washed with ether. The acidic solution was stirred at room temperature for 15 h. The last traces of ether were removed on a rotary evaporator and the solution was hydrogenated over 4 g of 5% palladium on carbon at room temperature and atmospheric pressure until no more hydrogen was absorbed (about 0.02 mol). The catalyst was removed by filtration and the solution was concentrated on a rotary evaporator to a yellow syrup. The syrup was treated with 50 mL of hot ethanol and cooled. Crystals formed and were collected to yield 1.20 g of the crude hydrochloride of 2-methyl-6-hydroxyl-7-methoxy-l,2,3,4-tetrahydroisoquinoline, in a yield of 26%, m.p. 281-284°C. The mother liquor after the removal of 2-methyl-6-hydroxyl-7-methoxy-l,2,3,4-tetrahydroisoquinoline hydrochloride was concentrated and cooled to yield 3.12 g of crystalline crude hydrochloride of 2-methyl-7-methoxy-8-hydroxyl-l,2,3,4-tetrahydroisoquinoline, in a yield of 68%, m.p. 208-212°C. 

Tetra-(chloromethyl)-phosphonium chloride (5 g) in 20 mL water was treated with 8 g sodium bicarbonate. The solution became milky and gave a strong formaldehyde reaction with fusion reagent. The phosphine was shaken out with carbon bisulfide, dried over sodium sulfate, and distilled under diminished pressure b.p. 100°C (7 mmHg). While heated at atmospheric pressure, tri-(chloromethyl)phosphine decomposes. It is a colorless, mobile liquid with a powerful, benumbing odor and with slight solubility in water. 

Synthesis of phenol-formaldehyde oligomers uses as the main raw materials phenol and formic aldehyde. Both are used in the form of aqueous solutions of 90% and 40-45% concentration, respectively [1], Since formaldehyde contains small amounts of formic acid, the condensation process can take place in the absence of catalysts, so that phenol-formaldehyde oligomers can be obtained. The reaction rate is, however, quite low when the process takes place at atmospheric pressure and a temperature around 100°C. The use of acid or basic catalysts is compulsory in industry to produce phenol-formaldehyde oligomers of desired characteristics. Novolac type oligomers are obtained in acid catalysis in basic catalysis, resol type oligomers are produced. 

Table 14. Concentration of Formaldehyde in Liquid and Gae Phase for Solutions Boiling at Approximate Atmospheric Pressure.

Toluene, formaldehyde, HC.1, calcium hydroxide, and UNO , comprise the chargestock. In step 1 of this process, the toluene is reacted with concentrated HC1 at about 70°C along with paraformaldehyde. This accomplishes chloromethylation of approximately 98% of the toluene. In step 2, saponification of the chloromethyltoluene is effected with lime and H20 under pressure and at about 125°C. The product is methylbenzyl alcohol. In step 3. the methylbenzyl alcohol is oxidized with HNO3 (dilute) under a pressure of about 20 atmospheres and at a temperature of about 170°C. The main products are o-phthalic acid in HNO3 solution and insoluble terephthalic acid. 

The oceans at this time can be thought of as the solution resulting from an acid leach of basaltic rocks, and because the neutralization of the volatile acid gases was not restricted primarily to land areas as it is today, much of this alteration may have occurred by submarine processes. The atmosphere at the time was oxygen deficient anaerobic depositional environments with internal CO2 pressures of about 10-2-5 atmospheres were prevalent, and the atmosphere itself may have had a CO2 pressure near lO-25 atmospheres. If so, the pH of early ocean water was lower than that of modern seawater, the calcium concentration was higher, and early global ocean water was probably saturated with respect to amorphous silica (—120 ppm). Hydrogen peroxide may have been an important oxidant and formaldehyde, an important reductant in rain water at this time (Holland et al., 1986). Table 10.5 is one estimate of seawater composition at this time. 

Ultra thin microporous carbon films are derived via the pyrolysis of phenolic precursors. The latter can be prepared from resorcinol-formaldehyde resins using a base catalyst. After several hours at 50°C of curing, the solution forms a stable polymeric film. Followed by a solvent exchange and ambient pressure drying, the film is pyrolysed in argon atmosphere at temperatures above 800°C. The result is an electrically conducting polymeric carbon film, the structure of which resembles the organic precursor, but shows microporosity in addition. Hereby, films with thicknesses of > 5 microns and sufficient mechanical stability can be made. 

According to Ke -ssner s patents, the i-eaction of acetylene and formaldehyde is best carried out under pri sure. For this purpose the acetylene is mixed ith nitrogen in a 2. 1 ratio and charged into an autoclave containing the hot 30 to 40 per cent formaldel vde solution and catalyst until a total pressure of 15 to as high as 30 atmospheres is obtained. Butinediol yield. of 90 per cent or better are reported when the reaction is carried out at SO to 100 °C. 

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