Formaldehyde Formalin

Formalin [Formaldehyde], 55, 45 Formamide,AGV-dimethyl-, 55, 58 Free radical cychzation, 55, 57... 

Formalin (formaldehyde solution, 37%), sodium sulfite, sodium hydrogen sulfite, ethylencdiamine tetraacetate (EDTA), thymolphthalein solution, p-nitrophenol, phenolplulialein, elhaiiol. 

Formaldehyde is a colorless gas with a pungent odor. It is the simplest aldehyde and was discovered by the Russian chemist A. Butlerov in 1859. It is readily soluble in water and it is most commonly used as a 40% solution in water known as formalin. Formaldehyde is widely used to manufacture building materials and numerous household products. 

In the preparation of samples from biological materials, the time between sampling and analysis should be kept as short as possible. For storage times of a few (2 or 3) days, refrigeration at 4°C may be adequate. In favorable cases, holding times can be prolonged by the addition of chemical preservatives (e.g., formalin (formaldehyde, HCHO) and alcohol). Dehydration (by drying, combustion, and lyophili-zation) is also used. 

Of particular interest for the in situ generation of syngas are formaldehyde and paraformaldehyde. Commercial solutions of formaldehyde in water are called formal or formalin. A saturated water solution of about 40vol% or 37 mass% formaldehyde is commercialized as 100% formalin. Formaldehyde is commonly produced by the metal-catalyzed oxidation of methanol (Formox process) in several million tons per year [10]. Paraformaldehyde is the solid polymerization product (mp = 120 C) of formaldehyde with an average degree of polymerization of 8-100 units. It is depolymerized to formaldehyde upon heating. Up to now, the trimerization product of formaldehyde, 1,3,6-trioxane, does not play a role in hydroformylation. 

Fluorohydroquinone diacetate. 2-Eluoro-l,4-benzenediol diacetate, 693 Formalin. Formaldehyde solution, 733, 847, 863, 936... 

The Formaldehyde-Formic Acid Method, This method applies to primary and secondary amines, which when boiled with a formalin-formic acid mixture undergo complete methylation to the corresponding tertiary amine. This method has the advantage over the dimethyl sulphate method in that quaternary salts clearly cannot be formed. 

A 40% solution of formaldehyde in water containing about 15% of methanol is known as formalin". 

It is marketed as a 35-40 per cent, solution in water (formalin). The rpactions of formaldehyde are partly typical of aldehydes and partly peculiar to itself. By evaporating an aqueous solution paraformaldehyde or paraform (CHjO), an amorphous white solid is produced it is insoluble in most solvents. When formaldehyde is distilled from a 60 per cent, solution containing 2 per cent, of sulphuric acid, it pol5unerises to a crystalline trimeride, trioxane, which can be extracted with methylene chloride this is crystalline (m.p. 62°, b.p. 115°), readily soluble in water, alcohol and ether, and devoid of aldehydic properties ... 

Upon heating the polymers, anhydrous gaseous formaldehyde is produced (compare Section 111,17). By allowing a mixture of concentrated ammonia solution and formalin to evaporate, hexamethylenetetramine (also called hexamine, vrotropine) CjHjjNj is formed ... 

Formaldehyde is a gas, b.p. — 21°, and cannot obviously be stored as such moreover, it polymerises readily in the liquid and the gaseous state. The commercial preparation, formalin, is an aqueous solution containing 35-40 per cent, of formaldehyde and some methyl alcohol. The preparation of a solution of formaldehyde may be demonstrated by the following experiment. 

Mix 50 ml. of formalin, containing about 37 per cent, of formaldehyde, with 40 ml. of concentrated ammonia solution (sp. gr. 0- 88) in a 200 ml. round-bottomed flask. Insert a two-holed cork or rubber stopper carrying a capillary tube drawn out at the lower end (as for vacuum distillation) and reaching almost to the bottom of the flask, and also a short outlet tube connected through a filter flask to a water pump. Evaporate the contents of the flask as far as possible on a water bath under reduced pressure. Add a further 40 ml. of concentrated ammonia solution and repeat the evaporation. Attach a reflux condenser to the flask, add sufficient absolute ethyl alcohol (about 100 ml.) in small portions to dissolve most of the residue, heat under reflux for a few minutes and filter the hot alcoholic extract, preferably through a hot water fuimel (all flames in the vicinity must be extinguished). When cold, filter the hexamine, wash it with a little absolute alcohol, and dry in the air. The yield is 10 g. Treat the filtrate with an equal volume of dry ether and cool in ice. A fiulher 2 g. of hexamine is obtained. 

Ethyl propane-1 1 3 3-tetracarboxylate. Cool a mixture of 320 g. (302 ml.) of redistilled diethyl malonate and 80 g. of 40 per cent, formaldehyde solution ( formalin ) contained in a 1-htre round-bottomed flask to 5° by immersion in ice, and add 5 g. (7 ml.) of diethylamine. Keep the mixture at room temperature for 15 hours and then heat under a reflux condenser on a boiling water bath for 6 hours. Separate the aqueous layer, dry the organic layer with anhydrous magnesium sulphate, and distil under reduced pressure. Collect the ethyl 1 1 3 3-tetracarboxylate at 200-215°/20 mm. The yield is 250 g. 

Urea - formaldehyde polymers. Formalin and urea (usually in the molecular proportions of 3 2) condense in the presence of ammonia, pyridine or hexamine to give urea - formaldehyde polymers, known commercially as Bedle or Plaskon, and are widely used as moulding powdens. It is believed that the intermediate products in the condensation are methylol-urea and dimethylol-urea ... 

Melamine - formaldehyde polymers. Melamine (2 4 6-triamino-1 3 5-triazine), obtained by heating dicyandiamide under pressure, condenses with formalin to give melamine - formaldehyde polymers (Beetle - Melamine), which have similar uses, but better stability to heat... 

In a 500 ml. conical flask place 50 ml. of glachtl acetic acid, 25 ml. of 40 per cent, formaldehyde solution (formalin) and 20 g. of phenol. Wrap a cloth or towel loosely around the neck and opening of the flask. Pass dry hydrogen chloride gas (Section 11,48,1) into the mixture. Within 5 minutes, a large mass of pink plastic is formed the reaction is sometimes very vigorous. The yield is 36 g. It is frequently necessary to break the flask in order to remove the product completely for this reason a beaker, or metal flask or beaker, is preferable. 

Place 250g of Ammonium Chloride and 500g of technical Formaldehyde (37%, Formalin). Rig the flask for simple distillation such that a thermometer extends into the reaction mixture, and a Liebig... 

Alkanolamides, a special subclass of substituted amides used as surfactants, are produced by three principal methods the reaction of fatty amides with formaldehyde, fatty acids with hydroxyalkylamines, and fatty esters with hydroxyalkylamines (37). A fatty amide and formalin can be heated in the presence of sodium hydroxide to yield 70—95% substituted alkanolamides (38,39). 

Aqueous formaldehyde, known as formalin, is usually 37 wt % formaldehyde, though more concentrated solutions are available. Formalin is the general-purpose formaldehyde of commerce suppHed unstabiLized or methanol-stabilized. The latter may be stored at room temperature without precipitation of soHd formaldehyde polymers because it contains 5 —10% methyl alcohol. The uiiinhibited type must be maintained at a temperature of at least 32°C to prevent the separation of soHd formaldehyde polymers. Large quantities are often suppHed in more concentrated solutions. Formalin at 44,... 

Alkylation involving formaldehyde in the presence of hydrogen chloride is known as chloromethylation (eq. 3). The reagent may be a mixture of formalin and hydrochloric acid, paraformaldehyde and hydrochloric acid, a chloromethyl ether, or a formal. Zinc chloride is commonly employed as a catalyst, although many other Lewis acids can be used. Chloromethylation of sahcyhc acids yields primarily the 5-substituted product 5-chlotomethylsahcyhc acid [10192-87-7] (4). 

This derivative is stable to TsOH/benzene at reflux and to Cr03/H. It is stable to NBS// . In the formation of this derivative formaldehyde from formalin can react with a C,-hydroxyl group to form a methoxymethyl ether. Paraformaldehyde can be used to avoid formation of the ethers. ... 

Technical formalin contains 8-10 per cent of methyl alcohol, so that it is not possible to use the table of densities (Note i of the preparation) for determining the formaldehyde content of the solutions. For example, a solution containing 37 per cent of formaldehyde and 10 per cent of methyl alcohol would have a density of 1.09 and correspond to 28 per cent of formaldehyde in pure water. In view of this, the recorded yield should probably be 64-66 per cent instead of 86-89 cent. 

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. 

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