Ammonia formamide

FORMAMIDE. Form amide (meibanamide), HCONHi. is the lirsi member of the primary amide series and is the only one liquid at room temperature. II is hygroscopic and has a faint odor of ammonia. Formamide is a colorless to pale yellowish liquid, freely miscible with water, lower alcohols and glycols, and lower esters and acetone. It is virtually immiscible in almost all aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, and ethers. By virtue of its high dielectric constant, close to that of water and unusual for an organic compound, formamide has a high solvent capacity lor many heavy-metal salts and for salts of alkali and alkalinc-carth metals. It is an important solvent, in particular for resins and plasticizers. As a chemical intermediate, formamide is especially useful in the synthesis of heterocyclic compounds, pharmaceuticals, crop protection agents, pesticides, and for the manufacture of hydrocyanic acid. 

Recent applications of this synthetic procedure include syntheses of 2,4,5-triarylimidazoles36 and the reaction of acenaphthoquinone with benzaldehydein the presence of ammonia.37 An elegant synthesis of 4,5-di- er(-butylimidazole (4)38 proceeds through reaction of an a-diketone with formaldehyde and ammonia. Formamide often proves a convenient substitute for ammonia. For example, the reaction of an... 

On heating with ammonia, formamide or primary amines, oxazoles thereby undergo a ring transformation into imidazoles. 

When starch granules are heated in an excess of water (>90 per cent w/w) or of another solvent able to form hydrogen bonding e.g. liquid ammonia, formamide, formic acid, chloroacetic acids and dimethyl sulphox-ide) starch undergoes an irreversible order-disorder transition known as gelatinization or destructuration. This... 

These debates supply a reminder that speculations about mixtures of water and other small molecules (ammonia, formamide) as solvents for extraterrestrial life are a much more subtle matter than simply looking for a low-freezing-point liquid. The interactions and partitioning of co-solvents should be expected to have a significant effect on the conformational stabilities of complex macromolecules, and in ways that are hard to predict. 

Ethyl oxalate is the only liquid ester which gives this rapid separation of the amide, which is therefore characteristic. Methyl and ethyl formate react rapidly with ammonia, but the soluble formamide does not separate methyl succinate gives crystalline succinamide after about I hour s standing, other esters only after a much longer time. The solid esters, other than methyl oxalate, are either soluble in water and remain so when treated with ammonia, or alternatively are insoluble in water and hence clearly not methyl oxalate. 

Boil 1 ml. of formamide in a test-tube and note that ammonia is freely evolved. Carbon monoxide is also produced, but cannot usually be ignited in the presence of the ammonia. 

Formamide. Commercial formamide may contain excess of formic acid. It is purified by passing ammonia gas into the mixture until a slight alkaline reaction is obtained. The ammonium formate thus formed is precipitated by the addition of acetone the filtrate, after drying over anhydrous magnesium sulphate, is distilled under reduced pressure. Pure formamide has b.p. IO571I mm. 

Iodine Acetaldehyde, acetylene, aluminum, ammonia (aqueous or anhydrous), antimony, bromine pentafluoride, carbides, cesium oxide, chlorine, ethanol, fluorine, formamide, lithium, magnesium, phosphorus, pyridine, silver azide, sulfur trioxide... 

The carbonylation of methanol [67-56-1] to methyl formate ia the presence of basic catalysts has been practiced iadustriaHy for many years. Ia older processes for formic acid utili2ing this reactioa, the methyl formate [107-31-3] reacts with ammonia to give formamide [75-12-7] which is hydroly2ed to formic acid ia the preseace of sulfuric acid ... 

Formamide decomposes thermally either to ammonia and carbon monoxide or to hydrocyanic acid and water. Temperatures around 100°C are critical for formamide, in order to maintain the quaUty requited. The lowest temperature range at which appreciable decomposition occurs is 180—190°C. Boiling formamide decomposes at atmospheric pressure at a rate of about 0.5%/min. In the absence of catalysts the reaction forming NH and CO predominates, whereas hydrocyanic acid formation is favored in the presence of suitable catalysts, eg, aluminum oxides, with yields in excess of 90% at temperatures between 400 and 600°C. 

Early in the twentieth century, the first attempts to manufacture formamide directiy from ammonia and carbon monoxide under high temperature and pressure encountered difficult technical problems and low yields (23). Only the introduction of alkaU alkoxides in alcohoHc solution, ie, the presence of alcoholate as a catalyst, led to the development of satisfactory large-scale formamide processes (24). 

However, BASF developed a two-step process (25). After methyl formate [107-31-3] became available in satisfactory yields at high pressure and low temperatures, its conversion to formamide by reaction with ammonia gave a product of improved quaUty and yield in comparison with the earlier direct synthesis. 

Two-Step Process. The significant advantage of the two-step process is that it only requkes commercial-grade methyl formate and ammonia. Thus the cmde product leaving the reactor comprises, in addition to excess starting materials, only low boiling substances, which are easily separated off by distillation. The formamide obtained is of sufficient purity to meet all quaUty requkements without recourse to the costiy overhead distillation that is necessary after the dkect synthesis from carbon monoxide and ammonia. 

In addition to the processes mentioned above, there are also ongoing efforts to synthesize formamide direcdy from carbon dioxide [124-38-9J, hydrogen [1333-74-0] and ammonia [7664-41-7] (29—32). Catalysts that have been proposed are Group VIII transition-metal coordination compounds. Under moderate reaction conditions, ie, 100—180°C, 1—10 MPa (10—100 bar), turnovers of up to 1000 mole formamide per mole catalyst have been achieved. However, since expensive noble metal catalysts are needed, further work is required prior to the technical realization of an industrial process for formamide synthesis based on carbon dioxide. 

The estimated capacity of formamide was approximately 100,000 t/yr worldwide in 1990. In 1993, there are only three significant producers BASE in Germany is the leading manufacturer. Smaller quantities of formamide are produced in the former Czechoslovakia (Sokolov) and Japan (Nitto) by direct synthesis from carbon monoxide and ammonia. Most of the formamide produced is utilized direcdy by the manufacturers. The market price for formamide (ca 1993) is about 2.00/kg. 

Eor the purpose of quantitative analysis, formamide can be hydrolyzed under basic conditions to alkaU formate and ammonia that can be deterruined by conventional methods. 

Methanol can be converted to a dye after oxidation to formaldehyde and subsequent reaction with chromatropic acid [148-25-4]. The dye formed can be deterruined photometrically. However, gc methods are more convenient. Ammonium formate [540-69-2] is converted thermally to formic acid and ammonia. The latter is trapped by formaldehyde, which makes it possible to titrate the residual acid by conventional methods. The water content can be determined by standard Kad Eischer titration. In order to determine iron, it has to be reduced to the iron(II) form and converted to its bipyridyl complex. This compound is red and can be determined photometrically. Contamination with iron and impurities with polymeric hydrocyanic acid are mainly responsible for the color number of the merchandized formamide (<20 APHA). Hydrocyanic acid is detected by converting it to a blue dye that is analyzed and deterruined photometrically. 

Sodium cyanide is soluble in Hquid ammonia. At temperatures below —31°C, sodium cyanide pentaammoniate [69331-34-6] NaCN-5NH3, separates in large flat crystals. At 15°C, 100 g anhydrous methanol dissolves 6.44 g anhydrous sodium cyanide at 67.4°C, it dissolves 4.10 g. Sodium cyanide hemihydrate [69331 -35-7] NaCNO.5 H2O, has been obtained by recrystaUization from cold 85% alcohol. The system NaCN—NaOH—H20 has been studied (48,49). Sodium cyanide is slightly soluble in formamide, ethanol, methanol, SO2, furfural, and dimethylformamide. 

Instead of Hquid ammonia, aqueous ammonia is also used together with a polar aprotic solvent such as formamide (48). It is also prepared by sulfonating... 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

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