Sodium hydroxide, also known as lye or caustic soda, has the molecular formula NaOH and is a highly caustic metallic base. It is a white solid available in pellets, flakes, granules, and as a 50% saturated solution.
Sodium hydroxide is soluble in water, ethanol and methanol. This alkali is deliquescent and readily absorbs moisture and carbon dioxide in air.
Sodium hydroxide is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water,soaps and detergents and as a drain cleaner. Worldwide production in 2004 was approximately 60 million tonnes, while demand was 51 million tonnes. Although molten sodium hydroxide possesses properties similar to those of the other forms, its high temperature comparatively limits its applications.
Pure sodium hydroxide is whitish solid, sold in pellets, flakes, and granular form, as well as in solution. It is highly soluble in water, with a lower solubility in ethanol and methanol, but is insoluble in ether and other non-polar solvents.
Similar to the hydration of sulfuric acid, dissolution of solid sodium hydroxide in water is a highly exothermic reaction in which a large amount of heat is liberated, posing a threat to safety through the possibility of splashing. The resulting solution is usually colourless and odorless with slippery feeling upon contact in common with other alkalis.
Reaction with acids
Sodium hydroxide reacts with protic acids to produce water and the corresponding salts. For example, when sodium hydroxide reacts withhydrochloric acid, sodium chloride is formed:
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
In general such neutralization reactions are represented by one simple net ionic equation:
OH−(aq) + H+(aq) → H2O(l)
This type of reaction with a strong acid releases heat, and hence is exothermic. Such acid-base reactions can also be used for titrations. However, sodium hydroxide is not used as a primary standard because it is hygroscopic and absorbs carbon dioxide from air.
Reaction with acidic oxides
Sodium hydroxide also reacts with acidic oxides, such as sulfur dioxide. Such reactions are often used to “scrub” harmful acidic gases (like SO2 and H2S) produced in the burning of coal and thus prevent their release into the atmosphere. For example,
2 NaOH + CO2 → Na2CO3 + H2O
Reaction with amphoteric metals and oxides
Sodium hydroxide slowly reacts with glass to form sodium silicate. Because of this, glass joints and stopcocks exposed to NaOH have a tendency to “freeze”. Flasks and glass-lined chemical reactors are damaged by long exposure to hot sodium hydroxide, which also frosts the glass. Sodium hydroxide does not attack iron since iron does not have amphoteric properties (i.e., it only dissolves in acid, not base). A few transition metals, however, may react vigorously with sodium hydroxide.
In 1986, an aluminium road tanker in the UK was mistakenly used to transport 25% sodium hydroxide solution, causing pressurization of the contents and damage to the tanker. The pressurization was due to the hydrogen gas which is produced in the reaction between sodium hydroxide and aluminium:
2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3 H2
Unlike NaOH, the hydroxides of most transition metals are insoluble, and therefore sodium hydroxide can be used to precipitate transition metal hydroxides.
Aluminium hydroxide is used as a gelatinous flocculant to filter out particulate matter in water treatment. Aluminium hydroxide is prepared at the treatment plant from aluminium sulfate by reacting it with NaOH.
Al2(SO4)3 + 6 NaOH → 2 Al(OH)3 + 3 Na2SO4
NaOH can be used for the base-driven hydrolysis of esters (as in saponification), amides and alkyl halides. However, the limited solubility of NaOH in organic solvents means that the more soluble KOH is often preferred.
In the laboratory, with carefully controlled conditions, sodium metal can be isolated from the electrolysis of the molten monohydrate in a low temperature version of the Castner process, according to the following reaction:
4 NaOH·H2O(l) → 4 Na(l) + O2(g) + 6 H2O(g)
The monohydrate does not need to be heated in order to melt, as the process produces enough heat due to ohmic heating. However, it must be initiated with a small quantity of liquid water to create an electrically conductive electrolyte. As the system’s temperature increases, the monohydrate will start to melt at about 65 °C as stated above. Only when the temperature reaches about 100 °C can sodium be isolated. Below this temperature, the water produced will react with the sodium: above this point, any water formed will be driven off in the vapour phase, creating an essentially anhydrous reaction. While this process has some advantages over other electrolytic processes, it is not preferred by most chemists because a marginal quantity of sodium produced boils at the electrode interface. The vapour thus given off consists primarily of fumed sodium oxide, which tends to settle on any surface in close proximity with corrosive consequences.
Sodium hydroxide is industrially produced as a 50% solution by variations of the electrolytic chloralkali process. Chlorine gas is also produced in this process. Solid sodium hydroxide is obtained from this solution by the evaporation of water. Solid sodium hydroxide is most commonly sold as flakes, prills, and cast blocks.
In 2004, world production was estimated at 60 million dry metric tonnes of sodium hydroxide, and demand was estimated at 51 million tonnes. In 1998, total world production was around 45 million tonnes. North America and Asia collectively contributed around 14 million tonnes, while Europe produced around 10 million tonnes. In the United States, the major producer of sodium hydroxide is the Dow Chemical Company, which has annual production around 3.7 million tonnes from sites at Freeport, Texas, and Plaquemine, Louisiana. Other major US producers include Oxychem, PPG, Olin, Pioneer Companies, Inc. (PIONA, which was purchased by Olin), and Formosa. All of these companies use the chloralkali process.
Historically sodium hydroxide is produced by treating sodium carbonate with calcium hydroxide in a metathesis reaction. (Sodium hydroxide is soluble while calcium carbonate is not.) This process was called causticizing.
Ca(OH)2(aq) + Na2CO3(s) → CaCO3↓ + 2 NaOH(aq)
This process was superseded by the Solvay process in the late 19th century, which was in turn supplanted by the chloralkali process which we use today.
Canister of sodium hydroxide.
Sodium hydroxide is the principal strong base used in the chemical industry. In bulk it is most often handled as an aqueous solution, since solutions are cheaper and easier to handle. Sodium hydroxide, a strong base, is responsible for most of these applications. Another strong base such as potassium hydroxide is likely to yield positive results as well.
56% of sodium hydroxide produced is used by the chemical industry, with 25% of the same total used by the paper industry. Sodium hydroxide is also used for the manufacture of sodium salts and detergents, for pH regulation, and for organic synthesis. It is used in the Bayer process of aluminiumproduction.
Sodium hydroxide is used in many scenarios where it is desirable to increase the alkalinity of a mixture, or to neutralize acids.
For example, sodium hydroxide is used as an additive in drilling mud to increase alkalinity in bentonite mud systems, to increase the mud viscosity, and to neutralise any acid gas (such as hydrogen sulfide and carbon dioxide) which may be encountered in the geological formation as drilling progresses.
In the same industry, poor quality crude oil can be treated with sodium hydroxide to remove sulfurous impurities in a process known as caustic washing. As above, sodium hydroxide reacts with weak acids such as hydrogen sulfide and mercaptans to give the non-volatile sodium salts which can be removed. The waste which is formed is toxic and difficult to deal with, and the process is banned in many countries because of this. In 2006,Trafigura used the process and then dumped the waste in Africa.
See also: hydrodesulfurization
Main article: Pulp (paper)
Sodium hydroxide is also widely used in pulping of wood for making paper or regenerated fibers. Along with sodium sulfide, NaOH is a key component of the white liquor solution used to separate lignin from cellulose fibers in the kraft process. It also plays a key role in several later stages of the process of bleaching the brown pulp resulting from the pulping process. These stages include oxygen delignification, oxidative extraction, and simple extraction, all of which require a strong alkaline environment with a pH > 10.5 at the end of the stages.
In a similar fashion, sodium hydroxide is used to digest tissues, such as in a process that was used with farm animals at one time. This process involved placing a carcass into a sealed chamber, then adding a mixture of sodium hydroxide and water (which breaks the chemical bonds that keep the flesh intact). This eventually turns the body into a coffee-like liquid, and the only solid that remains are bone hulls, which could be crushed between one’s fingertips. Sodium hydroxide is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors.
Dissolving amphoteric metals and compounds
Strong bases attack aluminium. Sodium hydroxide reacts with aluminium and water to release hydrogen gas. The aluminium takes the oxygen atom from sodium hydroxide (NaOH), which in turn takes the oxygen atom from the water, and releases the two hydrogen atoms, The reaction thus produces hydrogen gas and sodium aluminate. In this reaction, sodium hydroxide acts as an agent to make the solution alkaline, which aluminium can dissolve in. This reaction can be useful in etching, removing anodizing, or converting a polished surface to a satin-like finish, but without further passivation such as anodizing or alodining the surface may become degraded, either under normal use or in severe atmospheric conditions.
In the Bayer process, sodium hydroxide is used in the refining of alumina containing ores (bauxite) to produce alumina (aluminium oxide) which is the raw material used to producealuminium metal via the electrolytic Hall-Héroult process. Since the alumina is amphoteric, it dissolves in the sodium hydroxide, leaving impurities less soluble at high pH such as iron oxidesbehind in the form of a highly alkaline red mud.
See also: Ajka alumina plant accident
Other amphoteric metals are zinc and lead which dissolve in concentrated sodium hydroxide solutions to give sodium zincate and sodium plumbate respectively.
Esterification and transesterification reagent
Sodium hydroxide is traditionally used in soap making (cold process soap, saponification). It was made in the nineteenth century for a hard surface rather than liquid product because it was easier to store and transport.
For the manufacture of biodiesel, sodium hydroxide is used as a catalyst for the transesterification of methanol and triglycerides. This only works with anhydrous sodium hydroxide, because combined with water the fat would turn into soap, which would be tainted with methanol. It is used more often than potassium hydroxide because it is cheaper and a smaller quantity is needed.
Main article: Cleaning agent
Sodium hydroxide is frequently used as an industrial cleaning agent where it is often called “caustic”. It is added to water, heated, and then used to clean process equipment, storage tanks, etc. It can dissolve grease, oils, fats and protein based deposits. It is also used for cleaning waste discharge pipes under sinks and drains in domestic properties. Surfactants can be added to the sodium hydroxide solution in order to stabilize dissolved substances and thus prevent redeposition. A sodium hydroxide soak solution is used as a powerful degreaser on stainless steel and glass bakeware. It is also a common ingredient in oven cleaners.
A common use of sodium hydroxide is in the production of parts washer detergents. Parts washer detergents based on sodium hydroxide are some of the most aggressive parts washer cleaning chemicals. The sodium hydroxide based detergent include surfactants, rust inhibitors and defoamers. A parts washer heats water and the detergent in a closed cabinet and then sprays the heated sodium hydroxide and hot water at pressure against dirty parts for degreasing applications. Sodium hydroxide used in this manner replaced many solvent based systems in the early 1990s when trichloroethane was outlawed by the Montreal Protocol. Water and sodium hydroxide detergent based parts washers are considered to be an environmental improvement over the solvent based cleaning methods.
Food uses of sodium hydroxide include washing or chemical peeling of fruits and vegetables, chocolate and cocoa processing, caramel coloring production, poultry scalding, soft drinkprocessing, and thickening ice cream. Olives are often soaked in sodium hydroxide for softening; Pretzels and German lye rolls are glazed with a sodium hydroxide solution before baking to make them crisp. Owing to the difficulty in obtaining food grade sodium hydroxide in small quantities for home use, sodium carbonate is often used in place of sodium hydroxide.
Specific foods processed with sodium hydroxide include:
The Pinoy or Filipino dessert (kakanin) called kutsinta uses a bit of lye water to help give the rice flour batter a jelly like consistency.
A similar process is also used in the kakanin known as pitsi-pitsi or pichi-pichi (pit-chi-pit-chi) except that the mixture uses grated cassava instead of rice flour.
The Scandinavian delicacy known as lutefisk (from lutfisk, “lye fish”).
Hominy is dried maize (corn) kernels reconstituted by soaking in lye-water. These expand considerably in size and may be further processed by frying to make corn nuts or by drying and grinding to make grits. Nixtamal is similar, but uses calcium hydroxide instead of sodium hydroxide.
Sodium hydroxide is also the chemical that causes gelling of egg whites in the production of Century eggs.
German pretzels are poached in a boiling sodium carbonate solution or cold sodium hydroxide solution before baking, which contributes to their unique crust.
Lye-water is an essential ingredient in the crust of the traditional baked Chinese moon cakes.
Most yellow coloured Chinese noodles are made with lye-water but are commonly mistaken for containing egg.
Some methods of preparing olives involve subjecting them to a lye-based brine.
Hardware store grade NaOH to be used as drain cleaner
Paint stripping with caustic soda
Sodium hydroxide is used in the home as a drain cleaning agent for clearing clogged drains, usually in the form of a dry crystal or as a thick liquid gel. Sodium hydroxide saponifies the triglycerides found in fat into water soluble fatty acid salts andhydrolyzes the amide bonds in protein, such as those found in hair. These reactions are sped by the heat generated when sodium hydroxide and the other chemical components of the cleaner dissolve in water. Such drain cleaners and their acidicversions are highly caustic and should be handled with care.
Sodium hydroxide is used in some relaxers to straighten hair. However, because of the high incidence and intensity of chemical burns, manufacturers of chemical relaxers use other alkaline chemicals in preparations available to average consumers. Sodium hydroxide relaxers are still available, but they are used mostly by professionals.
A solution of sodium hydroxide in water was traditionally used as the most common paint stripper on wooden objects. Its use has become less common, because it can damage the wood surface, raising the grain and staining the colour.
Sodium hydroxide has been used for detection of carbon monoxide poisoning, with blood samples of such patients turning to a vermilion color upon the addition of a few drops of sodium hydroxide. Today, carbon monoxide poisoning can be detected by CO oximetry.
Sodium hydroxide is also being used experimentally in a new technology to create synthetic petrol. 
Like other corrosive acids and alkalis, drops of sodium hydroxide solution can decompose proteins and lipids in skin, eyes or other living tissues via amide hydrolysis and ester hydrolysis which consequently causes chemical burn and may induce permanent blindness if it contacts eyes. Solid alkali may also express its corrosive nature if there is water so protective equipment such as rubber gloves, safety clothing and eye protection should always be used when handling the material or its solutions.
Moreover, dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables. It also produces heat when reacted with acids.
The standard first aid measures for alkali spills on the skin is, as for other corrosives, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes.
Sodium hydroxide is corrosive to some metals, e.g. aluminum, which produces flammable hydrogen gas on contact. Sodium hydroxide is also mildly corrosive to glass, which can cause damage to glazing or freezing of ground glass joints. Careful storage is needed.
Hydrochloric acid is a clear, colourless solution of hydrogen chloride (HCl) in water. It is a highly corrosive, strong mineral acid with many industrial uses. Hydrochloric acid is found naturally in gastric acid.
Historically called muriatic acid, and spirits of salt, hydrochloric acid was produced from vitriol (sulfuric acid) and common salt. It first appeared during the Renaissance, and then it was used by chemists such as Glauber, Priestley and Davy in their scientific research.
With major production starting in the Industrial Revolution, hydrochloric acid is used in the chemical industry as a chemical reagent in the large-scale production of vinyl chloride for PVC plastic, and MDI/TDI for polyurethane. It has numerous smaller-scale applications, including householdcleaning, production of gelatin and other food additives, descaling, and leather processing. About 20 million tonnes of hydrochloric acid are produced annually.
Spirits of salt
Colourless, transparent liquid
(S1/2), S26, S45
Supplementary data page
n, εr, etc.
Solid, liquid, gas
UV, IR, NMR, MS
Hydrochloric acid was known to European alchemists as spirits of salt or acidum salis (salt acid). Both names are still used, especially in non-English languages, such as German: Salzsäure and Dutch: Zoutzuur. Gaseous HCl was called marine acid air. The old (pre-systematic) namemuriatic acid has the same origin (muriatic means “pertaining to brine or salt”), and this name is still sometimes used.
Aqua regia, a mixture consisting of hydrochloric acid and nitric acid, prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, the 13th-century European alchemist. Other references suggest that the first mention of aqua regia is inByzantine manuscripts dating to the end of the thirteenth century. The earliest suggested discovery of hydrochloric acid is attributed to the alchemist Jābir ibn Hayyān (c. 800 AD).
Free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Other authors claim that pure hydrochloric acid was first discovered by the German benedictine monk Basil Valentine in the 15th century, by heatingcommon salt and green vitriol, whereas others claim that there is no clear reference to the preparation of pure hydrochloric acid until the end of the sixteenth century.
In the seventeenth century, Johann Rudolf Glauber from Karlstadt am Main, Germany used sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and in 1818 Humphry Davy of Penzance, England proved that the chemical composition included hydrogen andchlorine.
During the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process by Nicolas Leblanc (Issoundun, France) enabled cheap large-scale production of sodium carbonate (soda ash). In this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, the excess HCl was vented to air. After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.
In the twentieth century, the Leblanc process was effectively replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already fully settled as an important chemical in numerous applications, the commercial interest initiated other production methods, some of which are still used today. After the year 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.
Since 1988, hydrochloric acid has been listed as a Table II precursor under the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.
Hydrogen chloride (HCl) is a monoprotic acid, which means it can dissociate (i.e., ionize) only once to give up one H+ ion (a single proton). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O+:
HCl + H2O → H3O+ + Cl−
The other ion formed is Cl−, the chloride ion. Hydrochloric acid can therefore be used to prepare salts called chlorides, such as sodium chloride. Hydrochloric acid is a strong acid, since it is essentially completely dissociated in water.
Monoprotic acids have one acid dissociation constant, Ka, which indicates the level of dissociation in water. For a strong acid like HCl, the Ka is large. Theoretical attempts to assign a Ka to HCl have been made. When chloride salts such as NaCl are added to aqueous HCl they have practically no effect on pH, indicating that Cl− is an exceedingly weak conjugate base and that HCl is fully dissociated in aqueous solution. For intermediate to strong solutions of hydrochloric acid, the assumption that H+ molarity (a unit of concentration) equals HCl molarity is excellent, agreeing to four significant digits.
Of the six common strong mineral acids in chemistry, hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction. It is one of the least hazardous strong acids to handle; despite its acidity, it consists of the non-reactive and non-toxic chloride ion. Intermediate-strength hydrochloric acid solutions are quite stable upon storage, maintaining their concentrations over time. These attributes, plus the fact that it is available as a pure reagent, make hydrochloric acid an excellent acidifying reagent.
Hydrochloric acid is the preferred acid in titration for determining the amount of bases. Strong acid titrants give more precise results due to a more distinct endpoint. Azeotropic or “constant-boiling” hydrochloric acid (roughly 20.2%) can be used as a primary standard in quantitative analysis, although its exact concentration depends on the atmospheric pressure when it is prepared.
Hydrochloric acid is frequently used in chemical analysis to prepare (“digest”) samples for analysis. Concentrated hydrochloric acid dissolves many metals and forms oxidized metal chlorides and hydrogen gas, and it reacts with basic compounds such as calcium carbonate or copper(II) oxide, forming the dissolved chlorides that can be analyzed.
The reference temperature and pressure for the above table are 20 °C and 1 atmosphere (101.325 kPa).
Vapour pressure values are taken from the International Critical Tables, and refer to the total vapour pressure of the solution.
Melting temperature as a function of HCl concentration in water.
Physical properties of hydrochloric acid, such as boiling and melting points, density, and pH, depend on the concentration or molarity of HCl in the aqueous solution. They range from those of water at very low concentrations approaching 0% HCl to values for fuming hydrochloric acid at over 40% HCl.
Hydrochloric acid as the binary (two-component) mixture of HCl and H2O has a constant-boiling azeotrope at 20.2% HCl and 108.6 °C (227 °F). There are four constant-crystallization eutectic points for hydrochloric acid, between the crystal form of HCl·H2O (68% HCl), HCl·2H2O (51% HCl), HCl·3H2O (41% HCl), HCl·6H2O (25% HCl), and ice (0% HCl). There is also a metastable eutectic point at 24.8% between ice and the HCl·3H2O crystallization.
Hydrochloric acid is prepared by dissolving hydrogen chloride in water. Hydrogen chloride can be generated in many ways, and thus several precursors to hydrochloric acid exist. The large-scale production of hydrochloric acid is almost always integrated with the industrial scale production of other chemicals.
Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade). Higher concentrations up to just over 40% are chemically possible, but the evaporation rate is then so high that storage and handling need extra precautions, such as pressure and low temperature. Bulk industrial-grade is therefore 30% to 34%, optimized for effective transport and limited product loss by HCl vapors. Solutions for household purposes in the US, mostly cleaning, are typically 10% to 12%, with strong recommendations to dilute before use. In the United Kingdom, where it is sold as “Spirits of Salt” for domestic cleaning, the potency is the same as the US industrial grade.
Major producers worldwide include Dow Chemical at 2 million metric tons annually (2 Mt/year), calculated as HCl gas, and FMC, Georgia Gulf Corporation, Tosoh Corporation, Akzo Nobel, and Tessenderlo at 0.5 to 1.5 Mt/year each. Total world production, for comparison purposes expressed as HCl, is estimated at 20 Mt/year, with 3 Mt/year from direct synthesis, and the rest as secondary product from organic and similar syntheses. By far, most hydrochloric acid is consumed captively by the producer. The open world market size is estimated at 5 Mt/year.
Hydrochloric acid is a strong inorganic acid that is used in many industrial processes. The application often determines the required product quality.
Pickling of steel
One of the most important applications of hydrochloric acid is in the pickling of steel, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion,rolling, galvanizing, and other techniques. Technical quality HCl at typically 18% concentration is the most commonly used pickling agent for the pickling of carbon steel grades.
Fe2O3 + Fe + 6 HCl → 3 FeCl2 + 3 H2O
The spent acid has long been re-used as iron(II) chloride (also known as ferrous chloride) solutions, but high heavy-metal levels in the pickling liquor have decreased this practice.
The steel pickling industry has developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor. The most common regeneration process is the pyrohydrolysis process, applying the following formula:
4 FeCl2 + 4 H2O + O2 → 8 HCl+ 2 Fe2O3
By recuperation of the spent acid, a closed acid loop is established. The iron(III) oxide by-product of the regeneration process is valuable, used in a variety of secondary industries.
Production of organic compounds
Another major use of hydrochloric acid is in the production of organic compounds, such as vinyl chloride and dichloroethane for PVC. This is often captive use, consuming locally produced hydrochloric acid that never actually reaches the open market. Other organic compounds produced with hydrochloric acid include bisphenol A for polycarbonate, activated carbon, andascorbic acid, as well as numerous pharmaceutical products.
Numerous products can be produced with hydrochloric acid in normal acid-base reactions, resulting in inorganic compounds. These include water treatment chemicals such as iron(III) chloride and polyaluminium chloride (PAC).
Both iron(III) chloride and PAC are used as flocculation and coagulation agents in sewage treatment, drinking water production, and paper production.
Other inorganic compounds produced with hydrochloric acid include road application salt calcium chloride, nickel(II) chloride for electroplating, and zinc chloride for the galvanizingindustry and battery production.
CaCO3 + 2 HCl → CaCl2 + CO2 + H2O (calcium chloride from limestone)
pH Control and neutralization
Hydrochloric acid can be used to regulate the acidity (pH) of solutions.
OH− + HCl → H2O + Cl−
In industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric acid is used to control the pH of process water streams. In less-demanding industry, technical quality hydrochloric acid suffices for neutralizing waste streams and swimming pool treatment.
Regeneration of ion exchangers
High-quality hydrochloric acid is used in the regeneration of ion exchange resins. Cation exchange is widely used to remove ions such as Na+ and Ca2+ from aqueous solutions, producingdemineralized water. The acid is used to rinse the cations from the resins. Na+ is replaced with H+ and Ca2+ with 2 H+.
Ion exchangers and demineralized water are used in all chemical industries, drinking water production, and many food industries.
Hydrochloric acid is used for a large number of small-scale applications, such as leather processing, purification of common salt, household cleaning, and building construction. Oil production may be stimulated by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure. Oil well acidizing is a common process in the North Sea oil production industry.
Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives. Typical products include aspartame, fructose, citric acid,lysine, hydrolyzed vegetable protein as food enhancer, and in gelatin production. Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product.
Presence in living organisms
Diagram of alkaline mucous layerin stomach with mucosal defense mechanisms
Gastric acid is one of the main secretions of the stomach. It consists mainly of hydrochloric acid and acidifies the stomach content to a pH of 1 to 2.
Chloride (Cl−) and hydrogen (H+) ions are secreted separately in the stomach fundus region at the top of the stomach by parietal cells of the gastric mucosa into a secretory network called canaliculi before it enters the stomach lumen.
Gastric acid acts as a barrier against microorganisms to prevent infections and is important for the digestion of food. Its low pH denatures proteins and thereby makes them susceptible to degradation by digestive enzymes such as pepsin. The low pH also activates the enzyme precursor pepsinogeninto the active enzyme pepsin by self-cleavage. After leaving the stomach, the hydrochloric acid of the chyme is neutralized in the duodenum bysodium bicarbonate.
The stomach itself is protected from the strong acid by the secretion of a thick mucus layer, and by secretin induced buffering with sodium bicarbonate. Heartburn or peptic ulcers can develop when these mechanisms fail. Drugs of the antihistaminic and proton pump inhibitor classes can inhibit the production of acid in the stomach, and antacids are used to neutralize existing acid.
Concentrated hydrochloric acid (fuming hydrochloric acid) forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. Upon mixing hydrochloric acid with common oxidizing chemicals, such as sodium hypochlorite (bleach, NaClO) or potassium permanganate (KMnO4), the toxic gas chlorine is produced.
Personal protective equipment such as rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing and shoes are used to minimize risks when handling hydrochloric acid. The United States Environmental Protection Agency rates and regulates hydrochloric acid as atoxic substance.
The UN number or DOT number is 1789. This number will be displayed on a placard on the container.
Chiral amino alcohol possessing both amine and alcohol is a structural motif for the compounds which have important biological and pharmacological functions within the body as inhibitor of aspartyl proteases, aldose reductase, b-amyloid peptide formation, and dopamine D4 antagonists. The chiral amino alcohol also exhibits anti-inflammatory, anesthetic, antipasmodic, hepatotoxic, anti-diabetic, anti-obesity,and anti-depressant activities. Chiral amino alcohols and their N-protected derivatives (Cbz, t-Boc, and Fmoc) are versatile building blocks, auxiliaries, ligand or resolving agent in asymmetric synthesis for biological and pharmaceutical researches. applications are present in the field of antitumor, anesthetic, antipasmodic, hepatotoxic, antiinflammatory or anti-HIV activities. Their derivatives include the forms of;
Amphiphylic antibacterial peptides
Analogs of peptides
Aziridines, Halogen aminoalkyls
Enantiomerical alpha-alkyl mono and diamines
Enantiomerical beta-substituted amines
Enantiomerical beta-amino acids beta-amino sulfoxides, beta-amino sulfides and
The precursors of diverse compounds such as statines, sphingolipides and peptide isosteres.
Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Never give anything by mouth to an unconscious person. Get medical aid immediately.
Get medical aid immediately. Remove from exposure to fresh air immediately. If breathing is difficult, give oxygen. DO NOT use mouth-to-mouth respiration. If breathing has ceased apply artificial respiration using oxygen and a suitable mechanical device such as a bag and a mask.
Get medical aid immediately. Immediately flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse. Destroy contaminated shoes.
Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid immediately. Do NOT allow victim to rub or keep eyes closed. Extensive irrigation is required (at least 30 minutes).
Handling and Storage
Keep away from heat, sparks, and flame. Keep away from sources of ignition. Keep container closed when not in use. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Corrosives area.
Wash thoroughly after handling. Use only in a well ventilated area. Avoid breathing dust, vapor, mist, or gas. Do not get in eyes, on skin, or on clothing. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Take precautionary measures against static discharges. Keep container tightly closed. Avoid contact with heat, sparks and flame. Do not ingest or inhale. Discard contaminated shoes. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames.
May cause severe and permanent damage to the digestive tract. Causes gastrointestinal tract burns.
Causes chemical burns to the respiratory tract. Inhalation may be fatal as a result of spasm, inflammation, edema of the larynx and bronchi, chemical pneumonitis and pulmonary edema.
Causes skin burns.
Causes eye burns.
When heated, vapors may form explosive mixtures with air: indoors, outdoors, and sewers explosion hazards.
【EC Risk Phrase】
R 21/22 34
【EC Safety Phrase】
S 26 36/37/39 45
Exposure Controls/Personal Protection
Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA’s eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear appropriate protective gloves to prevent skin exposure. Clothing: Wear appropriate protective clothing to prevent skin exposure.
Follow the OSHA respirator regulations found in 29CFR 1910.134 or European Standard EN 149. Always use a NIOSH or European Standard EN 149 approved respirator when necessary.
4 (Substances and products that must be considered harmful)
Fire Fighting Measures
Wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. During a fire, irritating and highly toxic gases may be generated by thermal decomposition or combustion. Will burn if involved in a fire. Use water spray to keep fire-exposed containers cool. Combustible Liquid. Containers may explode when heated. To extinguish fire, use water, dry chemical, chemical foam, or alcohol-resistant foam. Use water spray to cool fire-exposed containers.
Combustible material: may burn but does not ignite readily.
Accidental Release Measures
Absorb spill with inert material, (e.g., dry sand or earth), then place into a chemical waste container. Clean up spills immediately, using the appropriate protective equipment. Remove all sources of ignition. Provide ventilation.
Stability and Reactivity
Stable under normal temperatures and pressures. Absorbs carbon dioxide from the air.
Strong oxidizing agents, acids, methanoic acid, oxalic acid), aldehydes (e.g. acetaldehyde, acrolein, chloral hydrate, formaldehyde), dithiocarbamates (e.g. ferbam, maneb, metham, thiram), halogenated organics (e.g. dibromoethane, hexachlorobenzene, methyl chloride, trichloroethylene), isocyanates (e.g. methyl isocyanate), metals (alkali and alkaline, e.g. cesium, potassium, sodium), metals and metal compounds (toxic, e.g. beryllium, lead acetate, nickel carbonyl, tetraethyl lead), peroxides and hydroperoxides (organic, e.g. acetyl peroxide, benzoyl peroxide, butyl peroxide, methyl ethyl ketone peroxide), epoxides (e.g. butyl glycidyl ether), oxidizing agents (strong, e.g. bromine, hydrogen per
Nitrogen oxides, carbon monoxide, carbon dioxide.
Fire may produce irritating, corrosive and/or toxic gases.
4′-Methyl-α-pyrrolidinobutiophenone or MPBP is a stimulant compound which has been reported as a novel designer drug. It is closely related to pyrovalerone, being simply its chain-shortened homologue.
TIMTEC-BB SBB007812;4,4′-DI-T-BUTYLBIPHENYL;4,4′-Di-t-butylbiphenyl;4,4′-DI-TERT-BUTYLBIPHENYL;4,4′-Ditert-butyl-1,1′-biphenyl;4,4′-Di-tert-butylbiphenyl, 99+%;4,4′-Di-tert-butylbiphenyl Zone Refined;1,1′-Biphenyl, 4,4′-bis(1,1-dimethylethyl)-;4,4′-Di-tert-butylbiphenyl Zone Refined (number of passes:30)
Thus, the two substrates of this enzyme are S-adenosyl methionine and m7G(5′)pppR-RNA, whereas its two products are S-adenosylhomocysteineand m7G(5′)pppRm-RNA (mRNA containing a 2′-O-methylpurine cap).
This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:mRNA (nucleoside-2′-O-)-methyltransferase. Other names in common use include messenger ribonucleate nucleoside 2′-methyltransferase, and messenger RNA (nucleoside-2′-)-methyltransferase.
RCSB PDB PDBe PDBsum
AmiGO / EGO
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2GA9 and 2GAF.