Formaldehyde sulfamic acid

Aldehydes form addition products with sulfamic acid salts. These are stable ia neutral or slightly alkaline solutions but are hydroly2ed ia acid and strongly alkaline solutions. With formaldehyde, the calcium salt of the methylol (hydroxymethyl) derivative [82770-57-8], Ca(02SNHCH20H)2, is obtained as a crystalline soHd. 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

Reaction of sulfamic acid, formaldehyde and nitric acid... 

This unusual process known as the W-method was discovered in Germany by Wolfram and involves the condensation of the potassium salt of sulfamic acid with formaldehyde to form the heterocycle (238) followed by treatment with nitric acid. The extreme sensitivity of (238) to hydrolysis means that nitrolysis has to be conducted under anhydrous conditions using sulfur trioxide or phosphorous pentoxide " dissolved in fuming nitric acid. The yield of RDX from the W-method is 80-90 %. 

A number of chemical treatments have been suggested to reduce the photo-yellowing of bleached and whitened wool. Tetrakishydroxymethyl phosphonium chloride, thiourea (alone or as a formaldehyde condensate) and some mercaptans and reducing agents [20,21 ] and the reaction of wool with sulfamic acid [22] have been shown to offer some protection against photo-yellowing, particularly on wet wool. 

The total world production of urea is about 100 million tons per year. By far the largest part of it is used as a nitrogen fertilizer both in solid form and in solution this consumes approximately 87% of all urea production. It is also a livestock feed additive (5%) and a raw material for urea-formaldehyde resins (6%) and melamine (1%). Other applications (1%) include its use as deicing agent, raw material for fine chemicals (cyanuric acid, sulfamic acid), formation of crystalline clathrates, and so on. 

Test solution (a) in 200 dilution of the vaccine to be examined with R is prepared as described in the pharmacopoea. Solutions containing 0.25 g/1, 0.50 g/1,1.00 g/1, and 2.00 g/1 of CH2O by dilution of formaldehyde solution R with R are prepared. To 0.5 ml of the test solution and of each of the reference solutions in test tubes, 5.0 ml of a freshly prepared 0.5 g/1 solution of methylbenzoethiazolone hydrazone hydrochloride R is added. Tubes are closed, shaken, and allowed to stand for 60 min. One ml of ferric chloride-sulfamic acid reagent R is added and allowed to stand for 15 min. The absorbance of the solutions is measured at 628 nm, and the content of formaldehyde in the vaccine to be examined is calculated from the calibration curve established using the reference solutions. The test is invalid if the correlation coefficient (r) of the calibration curve is less than 0.97. 

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