Sulfamic acid hydrolysis

At ordinary temperatures, sulfamic acid hydrolyzes slowly forming ammonium bisulfite. However, when heated it hydrolyzes rapidly forming sulfuric acid. Therefore nickel sulfamate should be prepared rapidly before any sulfamic acid hydrolysis occurs due to longer contact time with water. 

Acetamido-4-methyl-5-thiazolyl-sulfuryl chloride gives by hydrolysis the acid, which on heating with H2SO4 is reported to give the 2-sulfamic acid (337). 

Aqueous sulfamic acid solutions are quite stable at room temperature. At higher temperatures, however, acidic solutions and the ammonium salt hydroly2e to sulfates. Rates increase rapidly with temperature elevation, lower pH, and increased concentrations. These hydrolysis reactions are exothermic. Concentrated solutions heated in closed containers or in vessels having adequate venting can generate sufficient internal pressure to cause container mpture. An ammonium sulfamate, 60 wt % aqueous solution exhibits mnaway hydrolysis when heated to 200°C at pH 5 or to 130°C at pH 2. The danger is minimised in a weU-vented container, however, because the 60 wt % solution boils at 107°C (8,10). Hydrolysis reactions are ... 

Alkali metal sulfamates are stable in neutral or alkaline solutions even at boiling temperatures. Rates of hydrolysis for sulfamic acid in aqueous solutions have been measured at different conditions (Table 4) (8,10)-... 

Dilute aqueous solutions of sulfamic acid are stable for many months at room temperature but at higher temperatures hydrolysis to NH4[HS04] sets in. Alkali metal salts are stable in neutral and... 

This last reaction finds use in volumetric analysis. The use of sulfamic acid to stabilize chlorinated water depends on the equilibrium formation of A-chlorosulfamic acid, which reduces loss of chlorine by evaporation, and slowly re-releases hypochlorous acid by the reverse hydrolysis ... 

The susceptibility of the sulfamates to hydrolysis is intermediate with respect to procedures commonly used for extraction and manipulation of extracts. Quantitative hydrolysis of the pure sulfamate toxins can be accomplished (9) by heating at 100 C for 5 min in the presence of not less than 0.1 M free acid (pH 1 or below). Milder conditions appear insufficient (10). Figure 9 summarizes results from two separate experiments in which samples of nontoxic clam flesh, enriched with constant amounts of saxitoxin Cl (4), were acidified to differing final concentrations of HCl and heated for 5 min at 100 C. The difference between 0.1 M HCl, which would be sufficient for hydrolysis of the pure toxin, and the HCl concentration required to attain plateau toxicity, probably reflects the buffer capacity of... 

Wagner, W.F. and Wuellner, J.A. (1952) Homogeneous precipitation of barium sulfate by hydrolysis of sulfamic acid. Anal. Chem., 24, 1031-1032. 

These compounds contain the fragment R as an alkyl or aryl moiety. In other words, they result from the esterification of an alcohol or a phenol with nitrous acid, nitric acid, phosphoric acid, sulfuric acid, or sulfamic acid, respectively. Many of the esters to be examined in this chapter must be activated prior to eliciting their effects, e.g., the organic nitrites and nitrates, which act as donors of nitric oxide or an analogous molecule, and phosphates, which are activated by hydrolysis or even by phosphorylation (antiviral agents). Sulfates are very seldom active or used as prodrugs, but they have significance as metabolites and as industrial xenobiotics. 

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 %. 

Berglund showed that sulfamic acid derivatives are relatively stable under alkaline conditions which cause hydrolysis of A-acetamido groups. Jorpes, Bostrom and Mannson, utilizing these data, found that less than 10% of the total amino groups is liberated when a 0.2% solution of heparin in N sodium hydroxide is heated at 100° for 2 hours, whereas 55 % of that in chondroitinsulfate is released. 

Imidodisulfuric acid chloride forms colorless crystals which hydrolyze very rapidly in moist air they melt at 37°, boil at 115°/4 mm. and at 55°/0.03 mm., and have a refractive index ny> = 1.4948. The compound is readily soluble in organic solvents such as benzene or nitrobenzene. Hydrolysis in alkaline medium leads to imidodisulfate in acidic medium, sulfamic acid and sulfuric acid are formed. 

Anion or cation generation Anions can be generated slowly in solution to bring about homogeneous precipitation. Swift and Butler reviewed precipitation of the metal sulfides by use of thioacetamide or thiourea. PFHS of sulfides of cadmium, mercury, zinc, and nickel have been studied more recently by Swift and others. Phosphate can be generated by hydrolysis of triethyl phosphate, oxalate by hydrolysis of methyl oxalate, and sulfate by hydrolysis of diethyl sulfate or sulfamic acid. 

Sulfamic acid (86) can be manufactured by reaction of ammonia and sulfur trioxide followed by hydrolysis of the initially formed ammonium sulfamate (87) (Scheme 41). Sulfamic acid (86) has also been prepared by reaction of urea with... 

The structural motif 17.8 remains dominant. Acid hydrolysis of the sulfamic and... 

Hydrolysis of Sulfamate (SAM). The kinetics of hydrolysis of sulfamate ion was investigated by Maron and Berens (22) (in dilute acid at 80-98°C) and by Candlin and Wilkins (23) (in 10 3 M to 6 M perchloric acid at 95°C). A reaction mechanism involving a pre-equilibrium between sulfamate ion and sulfamic acid (Eq. 24), followed by slow hydrolysis of the acid (Eq. 25), was proposed ... 

The energies and entropies of activation determined by Maron and Berens (22) (30.5 kcal/mole and 9.7 e.u.) include the energy and entropy of formation of sulfamic acid (i.e., both reactions 24 and 25). The latter values can be estimated from the data of King and King (24) as +0.9 kcal/mole and +-9 e.u., and this will mean values for the energy and entropy of activation of hydrolysis of sulfamic acid (Eq. 25) of 29.6 kcal/mole and 0.7 e.u. 

Dissolve about a gram of the acid in 20 ml of water and divide the solution into two parts. Boil one portion for about a minute, then cool, and add barium chloride solution to both portions. Explain your observations, writing an equation for the hydrolysis of sulfamic acid. 

If liquid ammonia is not available, the ammonium sulfamate may be obtained by neutralization of sulfamic, acid with aqueous ammonia. During the process of evaporation, the solution should be kept distinctly ammoniacal to prevent hydrolysis. 

Oxidation of furfural with chlorine water or sodium hypochlorite followed by treatment of the product (see Section I.l.C,) with sulfamic acid gives 3-hydroxy-2-imino-l(2f0-pyridinesulfonic acid, which is converted to 2-amino-3-pyridinol(XI-275) on hydrolysis. ... 

Another example is provided by the precipitation of barium ions with sulfate ions generated by the hydrolysis of sulfamic acid ... 

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