SULFAMIC ACID

SULFAMIC ACID

CAS NO: 5329-14-6
EC NO: 226-218-8

Synonyms:

Sulfamic acid; amidosulfonic acid; amidosulfuric acid; aminosulfonic acid; sulfamidic acid; Sulphamic acid; amidosulphonic acid; amidosulphuric acid; aminosulphonic acid; sulphamidic acid; NH2SO3H; Imidosulfonic acid; Sulfamidic acid; Sulfaminic acid; Sulphamidic acid; Aminosulfuric acid; sulfuramidic acid; amidohydroxydodioxidosulfur; EINECS 226-218-8; Sulphamic-acid-; CAS-5329-14-6; NH2SO3H; NH3SO3; UN2967; UN 2967; Ammonium sulfamate; amidosulfonic acid; amido sulfuric acid; amino sulfonic acid; sulfamidicacid; Sulphamicacid; amido sulphonic acid; amido sulphuric acid; amino sulphonic acid; sulphamidic acid; amido hydroxydo dioxide osulfur; sulfamic acid; amido-sulfonic acid; amido-sulfuric acid; amino-sulfonic acid; amido-sulfonic acid; amido-sulphonic acid; amido-sulphuric acid; amino-sulphonic acid; amido-sulphonic acid; H3NSO3; H₃NO₃S; Sulphaminic acid; amidosulfonic acid; amidosulfuric acid; aminosulfonic acid; imidosulfonic acid; sulfamidic acid; sulfaminic acid; sulphamic acid; jumbo; aminosulfuric acid; sulphamidic acid; SULFAMICACID

SULFAMIC ACID

Sulfamic acid, also known as amidosulfonic acid, amidosulfuric acid, aminosulfonic acid, and sulfamidic acid, is a molecular compound with the formula H3NSO3. This colourless, water-soluble compound finds many applications. Sulfamic acid melts at 205 °C before decomposing at higher temperatures to water, sulfur trioxide, sulfur dioxide and nitrogen.

Sulfamic acid (H3NSO3) may be considered an intermediate compound between sulfuric acid (H2SO4), and sulfamide (H4N2SO2), effectively replacing a hydroxyl (–OH) group with an amine (–NH2) group at each step. This pattern can extend no further in either direction without breaking down the sulfonyl (–SO2–) moiety. Sulfamates are derivatives of sulfamic acid.

Sulfamic acid is used as an acidic cleaning agent, sometimes pure or as a component of proprietary mixtures, typically for metals and ceramics. It is frequently used for removing rust and limescale, replacing the more volatile and irritating hydrochloric acid, which is cheaper.

Harmful or fatal if swallowed. Product is an eye and skin irritant, and can cause burns. Sulfamic Acid is a respiratory tract irritant, and inhalation may cause nose irritation, sore throat, coughing, and chest tightness and possibly, ulceration and perforation of the nasal septum.

Sulfamic Acid is a strong acid (pKa =1.0) and completely dissociates in an aqueous solution. The pH at the equivalence point is determined by the dissociation of water.

The sulfamic acid solution should be neutralized by adding dilute sodium hydroxide solution (use litmus paper to determine when the solution is neutral). If you do not have any sodium hydroxide solution or litmus paper, dilute the acid with 1 L of water and then flush the neutral or diluted solution down the drain. Finally, another way to dispose is to mix your waste/extra sulfamic acid with your extra/waste sodium nitrate, stirring, and then flushing both solutions down the drain with copious amounts of water.

Sulfamic acid, the monoamide of sulfuric acid, is a strong inorganic acid. It is generally used in chemical cleaning processes like removal of nitrites, carbonate- and phosphate-containing deposits. It is used as a raw material for the preparation of a synthetic sweetener i.e, sodium cyclohexylsulfamate.

Sulfamic acid has been one of the most widely used scavengers of nitrous acid. It reacts to give nitrogen and bisulfate ion. It has the advantage of a high solubility in water, for reactions carried out in water, and is often added as the ammonium salt

Sulfamic acid is a water-soluble, moderately strong acid. An intermediate between sulfuric acid and sulfamide, it can be used as a precursor to sweet-tasting compounds, a therapeutic drug component, an acidic cleaning agent, and a catalyst for esterification.

Sulfamic acid is a relatively high melting point chemical, 205 C., and consequently presents a serious problem with respect to processing and separation of the sulfamic acid from the reaction products as well as heat transfer. Various methods have been proposed to overcome these processing problems with indifferent success. One suggestion was to use excess sulfuric acid which while it permitted the reaction to be carried out in the liquid phase did not ameliorate all the difficulties and indeed created new problems. More specifically, sulfuric acid being a reactant did not avoid the violence of the reaction and further resulted in a slurry of sulfamic acid in sulfuric acid solution from which it was most difficult to separate the sulfamic acid. Furthermore the operation was complicated by corrosion problems brought about by the many different strengths of sulfuric acid involved. In another attempt to over come theproblems, excess sulfur trioxide, also a reactant, was used as a reaction medium where again it was found difiicult'to control the reaction and also to remove residual sulfur trioxide from the product. Furthermore the use of excess sulfur trioxide necessitates pressure equipment in the desired temperature range of about 55-75 C. thereby appreciably increasing the cost of capital investment. Other solvent mediums were also tried but found wanting for one or more of the above reasons.

An object of the present invention is to provide an efficient economical process for producing sulfamic acid by reaction of urea, sulfur trioxide and sulfuric acid. A further object of the present invention is to provide a simple and effective means for dissipating the heat of reaction of urea, sulfuric acid and sulfur trioxide to obtain good control of the reaction without interference to the reaction and without complication of separation of the desired sulfamic acid product. Gther objects and advantages will be apparent from the following description and accompanying drawing.

In consideration of a good practical commercial process for producing sulfamic acid several factors must be taken into account. For good economical operation the process should be conducted at substantially atmospheric pressure to avoid use of pressure equipment and at a relatively low temperature within the range of about 5575 C. Control of reaction temperature should be easily and effectively maintained within the narrow range Patented .Mar. 31, 1964 of 5575 C. without the use of indirect heat exchange contrivances which are generally uneconomical and difficult to manage and maintain within narrow limits. In addition any means for controlling the reaction should avoid the complication of the use of a medium which is reactive and should permit simple and easy recovery of the desired sulfamic acid from the reaction products.

A process for the production of sulfamic acid which comprises maintaining a mixture of urea, sulfur trioxide and sulfuric acid together with sulfuryl chloride at a temperature within the range of 5t5-75 C. in an enclosed reaction zone under substantially atmospheric pressure to effect reaction of the urea, sulfur trioxide and sulfuric acid to produce sulfamic acid and lay-product carbon dioxide, releasing generated carbon dioxide and evolved vapors of sulfuryl chloride from the reaction zone, cooling the carbon dioxide gas and sulfuryl chloride vapor to eflect condensation of the sulfuryl chloride, discharging the carbon dioxide gas, returning the sulfuryl chloride condensate to the reaction zone to maintain the temperature of reaction therein Within the range of 55-75 C., and continuing the passage of evolved sulfuryl chloride vapor from the reaction zone, cooling of the sulfuryl chloride vapor and return of the sulfuryl chloride condensate to the reaction zone until substantial completion of the reaction of urea, sulfur trioxide and sulfuric acid is effective.

A  process for the production of sulfamic acid which comprises admixing urea with sulfuric acid to form urea bisulfate, adding said urea bisulfate to a mixture of sulfur trioxide and sulfuryl chloride, maintaining a mixture of urea bisulfate and sulfur trioxide at a temperature within the range of 55-75 C. under substantially atmospheric pressure to effect reaction of the urea bisulfate and sulfur trioxide to produce sulfamic acid and by-product carbon dioxide, releasing generated carbon dioxide and evolved vapors of sulfuryl chloride from the reaction zone, cooling the carbon dioxide gas and sulfuryl chloride vapor to effect condensation of the sulfuryl chloride, discharging the carbon dioxide gas, returning the sulfuryl chloride condensate to the reaction zone to maintain the temperature of reaction therein Within the range of 55- 75 C. and continuing the passage of evolved sulfuryl chloride vapor from the reaction zone, cooling of the sulfuryl chloride vapor and return of the sulfuryl chloride condensate to the reaction zone until substantial completion of the reaction of urea bisulfate and sulfur trioxide is effective.

Sulfamic Acid inhibits pulp degradation due to temperature at the hydrochloride and chlorination stage. It allows bleaching at elevated temperature and lower pH without any loss in strength

Sulfamic acid also called as amido sulfuric acid is a white crystalline solid which is non-hygroscopic and stable. It is soluble in formamide and water, and slightly soluble in concentrated sulfuric acid, methanol, acetone, and ether. It is commercially produced from fuming sulfuric acid and urea, and classified as a strong inorganic acid. The sulfamic acid with dilute aqueous solution is stable for longer periods at room temperature. However, a rapid hydrolysis arises at high temperatures. The sulfamic acid is considered as less corrosive to metals compared to other strong acid such as hydrochloric acid. As the sulfamic acid retains a scale solubilizing capacity it is considered ideal for removal of scale from cooling towers, boilers, coils, condensers, heat exchangers and a wide range of cooling and heating systems thereby amassing the efficiency of equipment and plant.

Uses of Sulfamic Acid

As sulfamic acid is super-efficient agent for descaling, it is used for cleaning a number of domestic appliances and industrial equipment. It is used for cleaning heat exchangers, boilers, condensers, descaling toilets, jackets and coils, efflorescence other deposits of mineral deposits, removing excess grout on tiles, etc. It helps remove protein deposits, hard water scale, beer and milk stone, copper corrosion, and light rust. Some other uses of sulfamic acids are listed below.

•    Descaler, rust remover, and cleaner.
•    Descaler and cleaner for dairy equipment such as milk evaporators, milkers’ pipeline.
•    Descaler and cleaner for brewery equipment such as vats, pipelines, etc.
•    Catalyst for esterification process.
•    Used in dye & pigment manufacturing
•    Used as an herbicide.
•    Effective against foot and mouth.
•    Used as an ingredient in denture tablets.
•    Ingredient in fire extinguishing media.
•    Urea-formaldehyde resins coagulator
•    Synthesis of nitrous oxide by reaction with nitric acid.
•    Chloride stabilizer and bleaching additive in pulp & paper industry.
•    Descalling Water born & Process Scales in Industrial Equipment and Process.
•    Cleaning of Metal, Floor Surface, Household Equipment, Condenser Etc.
•    Chlorine Stabilizer in Swimming Pool.
•    In Leather Dyeing Process.
•    Plastic Industries as a curing agent.
•    Silver polishing.

Sulfamic acid is used as an acidic cleaning agent, sometimes pure or as a component of proprietary mixtures, typically for metals and ceramics. It is frequently used for removing rust and limescale, replacing the more volatile and irritating hydrochloric acid, which is cheaper. It is often a component of household descaling agents, for example, Lime-A-Way Thick Gel contains up to 8% sulfamic acid and has pH 2.0–2.2, or detergents used for removal of limescale. When compared to most of the common strong mineral acids, sulfamic acid has desirable water descaling properties, low volatility, and low toxicity. It forms water-soluble salts of calcium and ferric iron.

Sulfamic acid is preferable to hydrochloric acid in household use, due to its intrinsic safety. If erroneously mixed with hypochlorite based products such as bleach, it does not form chlorine gas, whereas the most common acids would; the reaction (neutralisation) with ammonia, produces a salt, as depicted in the section above.

It also finds applications in the industrial cleaning of dairy and brewhouse equipment. Although it is considered less corrosive than hydrochloric acid, corrosion inhibitors are often added to the commercial cleansers of which it is a component. It can be used for descaling home coffee and espresso machines and in denture cleaners.

Sulfamic acid is mainly a precursor to sweet-tasting compounds. Reaction with cyclohexylamine followed by addition of NaOH gives C6H11NHSO3Na, sodium cyclamate. Related compounds are also sweeteners, see acesulfame potassium.

​Sulfamates have been used in the design of many types of therapeutic agents such as antibiotics, nucleoside/nucleotide human immunodeficiency virus (HIV) reverse transcriptase inhibitors, HIV protease inhibitors (PIs), anti-cancer drugs (steroid sulfatase and carbonic anhydrase inhibitors), anti-epileptic drugs, and weight loss drugs.

Sulfamic acid is also used as a chlorine stabilizer in cooling towers and swimming pools. The industrial applications of sulfamic acid are as follows:

Paper & pulp Industry

Sulfamic Acid inhibits pulp degradation due to temperature at the hydrochloride and chlorination stage. It allows bleaching at elevated temperature and lower pH without any loss in strength.

Dyes & Pigments Industry

Sulfamic acid takes out excess of nitrides that are used in the diazotization reactions during the manufacturing of pigments and dye stuffs. The sulfamic acid can also remove nitrides if present in process water of emissions.

Sulfamic acid is a safe and powerful acid, which is suitable for descaling applications and acid cleaning. One of the most common use of sulfamic acid is for descaling heating coils and heated vessels in the food handling premises owing to its ability to quickly dissolve hardness deposits without objectionable odors or fumes. Hence, sulfamic acid is considered as the most popular, safe, preferred acid in various industries.

Formula H₂NSO₃H H₃NO₃S (Hill)
Index-No. 016-026-00-0
EC-No. 226-218-8
Molar mass 97,08 g/mol
Form solid
Colour white
Odour odourless
pH 1,2
at 10 g/l
Melting point 205 °C (decomposition)
Relative vapour density 3,35
Density 2,13 g/cm3 at 20 °C
Water solubility 213 g/l at 20 °C
Decomposition temperature 209 °C

First aid measures

After inhalation: fresh air.

In case of skin contact: Take off immediately all contaminated clothing. Rinse skin with water/shower.

After eye contact: rinse out with plenty of water. Call in ophthalmologist. Remove contact lenses.

After swallowing: immediately make victim drink water (two glasses at most). Consult a physician.

Most important symptoms and effects, both acute and delayed
Cough, Shortness of breath, Pain, shock, Nausea irritant effects

Extinguishing media

Use extinguishing measures that are appropriate to local circumstances and the surrounding
environment.

UN number UN 2967
Proper shipping name SULPHAMIC ACID
Class 8
Packing group III
Environmentally hazardous
Tunnel restriction code E