Formic acid boiling point

Formic acid Boiling point Maleic anhydride... 

Benzoic acid (C6H5COOH, phenyl formic acid, melting point 121.7°C, boiling point 249.2°C, density 1.266) is a white crystalline solid that sublimes readily at 100°C and is volatile in steam. Benzoic acid is insoluble in cold water but is readily soluble in hot water or in alcohol or ether. 

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. 

Formaldehyde is a gas with a boiling point of -21 °C. It is usually supplied as a stabilised aqueous solution ( 40% formaldehyde) known as formalin. When formalin is used as the source of the aldehyde, impurities present generally include water, methanol, formic acid, methylal, methyl formate and carbon dioxide. The first three of these impurities interfere with polymerisation reactions and need to be removed as much as possible. In commercial polymerisation the low polymers trioxane and paraformaldehyde are convenient sources of formaldehyde since they can be obtained in a greater state of purity. 

Schimmel Co. attempted to acetylise the alcohol by means of acetic anhydride, but the reaction product only showed 5 per cent, of ester, which was not submitted to further examination. The bulk of the alcohol had been converted into a hydrocarbon, with loss of water. Ninety per cent, formic acid is most suitable for splitting off water. Gne hundred grams of the sesquiterpene alcohol were heated to boiling-point with three times the quantity of formic acid, well shaken, and, after cooling, mixed with water. The layer of oil removed from the liquid was freed fi-om resinous impurities by steam-distillation, and then fractionated at atmo.spheric pressure. It was then found to consist of a mixture of dextro-rotatory and laevo-rotatory hydrocarbons. By repeated fractional distillation, partly in vacuo, partly at ordinary pressure, it was possible to separate two isomeric sesquiterpenes, which, after treatment with aqueous alkali, and distillation over metallic sodium, showed the following physical constants —... 

A mixture of 49 g of this ester compound, 76 g of 9B% formic acid and 6B ml of formalin solution is heated under reflux for B hours. The solvents are then removed in vacuo on the steam bath, the residue dissolved in water, made alkaline with ammonium hydroxide and extracted with chloroform. Removal of the solvent and distillation in vacuo yieids ethyl 4-di-methylaminocyclohexylcarboxylate, boiling point 122°C to 125°C/10 mm. 

In a 3-I. round-bottomed flask fitted with a 3-ft. indented column to which is attached a condenser set for downward distillation are placed 321 g. (3 moles) of methylaniline, 300 g. of formic acid (85-90 per cent), and 1800 cc. of toluene (Note 1). The solution is distilled slowly. As long as the azeotrope containing water is present, the temperature of the vapor is 87-88° when the water has been removed, the temperature rises to 108-110° (Note 2). The distillation is continued until approximately 1500 cc. of toluene has been collected (five to six hours). The residue is then transferred to a modified Claisen flask (Org. Syn. Coll. Vol. 1, 125) and distilled in vacuo, the portion boiling at 114-121° at 8 mm. being collected. This has a freezing point of 13.6-13.7° d i-5S3 I SSS- The yield is 380-393 g. (93-97 per cent of the theoretical amount). This product is satisfactory for the preparation of aldehydes (p. 11). Upon redistillation it boils at 117-121° at 8 mm., 130-132° at 22 mm. The freezing point and refractive index are unchanged. 

Chemical species which can be used as buffers and, due to their volatile nature (te., relatively low boiling points), can be readily removed from a system (e.g., by evaporation). Such buffers have proved to be quite useful in procedures which later require ion-exchange chromatography or electrophoresis (particularly high voltage electrophoresis). Examples of some common components of volatile buffer systems (with their corresponding boiling points and pK values [at 25°C]) would be formic acid (100.5°C 3.75), acetic acid (118°C 4.76), pyridine (115.5°C 5.23), triethanolamine (335.4°C 7.76), ammo-... 

An azeotrope is a mixture of two or more substances that boils at a constant temperature, either higher or lower than any of its constituents. Thus an 8.5 1 mole mixture of ethanol and water boils like a pure substance, distilling at 78.2°, which is lower than the boiling point of ethanol (78.5°) or of water (100°). In contrast, a 1.35 1 mole mixture of methanoic (formic) acid and water boils at 107.1°, which is higher than the boiling points of either methanoic acid (100.7°) or water (100°). 

HCOOH (g), (HCOOH)2 (g). Ramsperger and Porter2 and Coo-lidge1 studied the equilibrium, (HCOOH) 2 (g) =2HCOOH (g), and their data yield —14.13 for the heat of this reaction. The equilibrium concentrations in mole fraction are, for (HCOOH) 2 (g) and HCOOH (g), respectively, about 0.80 and 0.20 at 18°, and about 0.52 and 0.48 at the boiling point, 100.8°. Data on the heat of vaporization of liquid formic acid to form the equilibrium mixture of (HCOOH) 2 (g) and HCOOH (g)... 

This reagent is particularly convenient as the by-products of the reaction do not contaminate the product, and excess thionyl chloride is usually separable by fractional distillation. If the boiling point of the acyl chloride is too near to that of thionyl chloride the excess of the latter can be destroyed by the addition of pure formic acid. 

A mixture of 61 grams l-phenyl-l-oxo-2-(N-methyl-N-ethanolamino)-propane hydrochloride and 100 cc 98-100% formic acid was refluxed at the boiling point at atmospheric pressure for 45 minutes on an oil bath. Thereafter, the oil bath temperature was increased to 180°C and as much of the excess unreacted formic acid as possible was distilled off. A vigorous evolution of carbon dioxide developed during the distillation, which ceased after approximately 45 additional minutes. The honey-yellow syrup which remained as the distillation residue was worked up by admixing it with about six volumes of water and adjusting the aqueous mixture to alkaline reaction with concentrated sodium hydroxide. An oily phase separated out which was extracted with ether. The ether extract was washed with water and dried over potassium carbonate. The solvent was distilled off and the distillation residue was fractionally distilled in vacuo. The base boils at 132°-133°C at 12 mm. The yield was 93% of theory. Reaction with tartaric acid gave the final product. 

A mixture of 20.0 g of 3-hydrazino-4-methyl-6-piperidinopyridazine in 100 ml of aqueous 99% formic acid was heated at the boiling temperature under reflux for 3 h and then evaporated to dryness. The residue, containing 8-methyl-6-piperidino-s-triazolo[4,3-b]pyridazine formate was taken up in excess aqueous sodium carbonate and extracted with chloroform. After evaporation of the chloroform solvent the 8-methyl-6-piperidino-s-triazolo[4,3-b]pyridazine was crystallized from ethyl acetate. Yield 4.4 g, melting point 118-120°C. 

In the third case it is necessary to distinguish whether the liquid has a composition that lies to the left or the right of the pressure minimum in the one case the liquid on the left—here formic acid—distils, in the other water in both a mixture corresponding to the minimum vapour pressure remains behind. This agrees, therefore, with the first case, in the impossibility of complete separation but here the unfractionated mixture has the highest boiling point, in tlie other case the lowest. 

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