PRODUCTS

2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID

2-hydroxy-1,2,3-propanetricarboxylic acid is used chelating agent in detergents and cleaning products
2-hydroxy-1,2,3-propanetricarboxylic acid is used pH regulator in cosmetics and pharmaceuticals
2-hydroxy-1,2,3-propanetricarboxylic acid is used component in dietary supplements

CAS Number: 77-92-9
EC number: 201-069-1
MDL Number: MFCD00011669
Molecular Formula: C6H8O7 / CH2COOH-C(OH)COOH-CH2COOH
Molecular Weight:192.13 g/mol

SYNONYMS:
citric acid, 77-92-9, Citric acid anhydrous, 2-hydroxypropane-1,2,3-tricarboxylic acid, Anhydrous citric acid, Aciletten, Citro, Citretten, Citric acid anhydrous, Chemfill, Hydrocerol A, 1,2,3-Propanetricarboxylic acid, 2-hydroxy-, Kyselina citronova, 2-hydroxy-1,2,3-propanetricarboxylic acid, 2-Hydroxytricarballylic acid, Caswell No. 221C, 3-Carboxy-3-hydroxypentane-1,5-dioic acid, FEMA No. 2306, 2-Hydroxypropanetricarboxylic acid, FEMA Number 2306, beta-Hydroxytricarballylic acid, Citric acid,anhydrous, Citricum acidum, Citric acid monoglyceride, CCRIS 3292, HSDB 911, K-Lyte, EPA Pesticide Chemical Code 021801, Kyselina citronova [Czech], K-Lyte DS, AI3-06286, NSC 30279, Citronensaeure, NSC 626579, Acidum citricum, Uro-trainer, BRN 0782061, UNII-XF417D3PSL, H3cit, EINECS 201-069-1, Suby G, XF417D3PSL, NSC-30279, NSC-626579, DTXSID3020332, CHEBI:30769, Kyselina 2-hydroxy-1,2,3-propantrikarbonova, MFCD00011669, NSC-112226, CHEMBL1261, Kyselina 2-hydroxy-1,2,3-propantrikarbonova [Czech], E330, DTXCID50332, 2-hydroxy-1,2,3-propanetricarboxyic acid, .beta.-Hydroxytricarballylic acid, EC 201-069-1, citr, 4-03-00-01272 (Beilstein Handbook Reference), NSC30279, NSC626579, 79586-22-4, Citric acid, 99%, NCGC00090954-03, Ubiquitin, E 330, CLENPIQ COMPONENT ANHYDROUS CITRIC ACID, CITRATE ANION, Acidum citricum monohydrate, C6H8O7, Citralite, ANHYDROUS CITRIC ACID (II), ANHYDROUS CITRIC ACID [II], ANHYDROUS CITRIC ACID (MART.), ANHYDROUS CITRIC ACID [MART.], Citric acid [USAN:JAN], CAS-77-92-9, 1,3-Propanetricarboxylic acid, 2-hydroxy-, ANHYDROUS CITRIC ACID (USP MONOGRAPH), ANHYDROUS CITRIC ACID [USP MONOGRAPH], CITRIC ACID, ANHYDROUS (EP IMPURITY), CITRIC ACID, ANHYDROUS [EP IMPURITY], CITRIC ACID, ANHYDROUS (USP IMPURITY), CITRIC ACID, ANHYDROUS [USP IMPURITY], 2-hydroxy-1,2,3-propane-tricarboxylic acid, B1650, Citraclean, Citronensaure, acido citrico, citric-acid, Citric Acid Anhydrous; 2-Hydroxypropane-1,2,3-tricarboxylic acid, Anhydrous citrate, 2fwp, 4aci, 4nrm, Citric acid, anhydrous [USP:JAN], Citric Acid,(S), Citric acid (8CI), K-Lyte (Salt/Mix), 1i2s, 1o4l, 1rq2, 1y4a, 2bo4, 2c4v, 2fw6, 4to8, Citraclean (Salt/Mix), Spectrum3_001850, WLN: QV1XQVQ1VQ, beta-Hydroxytricarballylate, cid_311, K-Lyte/Cl (Salt/Mix), CITRIC ACID [MI], K-Lyte DS (Salt/Mix), bmse000076, HOC(CH2COOH)2COOH, CITRIC ACID [FHFI], CITRIC ACID [HSDB], NCIStruc1_000057, NCIStruc2_000099, NCIOpen2_004062, NCIOpen2_004502, Oprea1_502996, BSPBio_003240, Citric acid anhydrous (JAN), Citric Acid, anhydrous, USP, MLS001066346, CITRIC ACID [WHO-DD], Citric acid, anhydrous (USP), CITRICUM ACIDUM [HPUS], Anhydrous citric acid (JP18), GTPL2478, Citric acid, analytical standard, BDBM14672, Citric acid, p.a., 99.5%, KBio3_002740, Citric Acid, anhydrous, granular, 4o61, Citric acid, Electrophoresis Grade, HMS1787N01, HMS2268B04, Pharmakon1600-01300013, ANHYDROUS CITRIC ACID [JAN], HY-N1428, STR12052, 1,2,3-Tricarboxy-2-hydroxypropane, Tox21_113436, Tox21_202405, Tox21_300124, BBL002530, NSC759606, s5761, STK286098, CITRIC ACID,ANHYDROUS [VANDF], AKOS000119911, BETA-HYDROXY-TRICARBOXYLIC ACID, Citric Acid, anhydrous, fine granular, Citric acid, LR, anhydrous, >=99%, USEPA/OPP Pesticide Code: 21801, 2-hydroxy-1,2,3-propanetricarboxylate, ACIDUM CITRICUM [WHO-IP LATIN], CS-6965, DB04272, 3-Carboxy-3-hydroxypentane-1,5-dioate, Citric acid, >=99.5%, FCC, FG, Citric acid, ACS reagent, >=99.5%, Citric Acid, anhydrous powder, A.C.S., 2-Hydroxy-1,3-propanetricarboxylic acid, CITRIC ACID, ANHYDROUS [WHO-IP], NCGC00090954-01, NCGC00090954-02, NCGC00090954-04, NCGC00090954-05, NCGC00090954-06, NCGC00254055-01, NCGC00259954-01, 134367-01-4, 2-hydroxypropane-1,2,3-tricarboxylicacid, BP-31028, Citric Acid, anhydrous granular, A.C.S., DA-72240, NCI60_022579, SMR000471840, SBI-0206765.P001, Citric acid, SAJ first grade, >=99.5%, 2-Hydroxy-1,2,3-propane tricarboxylic acid, C1949, Citric acid, Vetec(TM) reagent grade, 99%, NS00007335, 1,2,3-Propanetricarboxylio acid, 2-hydroxy-, EN300-16683, C00158, 1,2,3-Propanetricarboxylic acid, 2-hydroxy-, Aciletten, Citretten, Citro, 2-Hydroxy-1,2,3-propanetricarboxylic acid, β-Hydroxytricarballylic acid, Anhydrous citric acid, Citric acid, anhydrous, Kyselina citronova, Kyselina 2-hydroxy-1,2,3-propantrikarbonova, 3-Carboxy-3-hydroxypentane-1,5-dioic acid, Chemfill, F 0001 (polycarboxylic acid), Hydrocerol A, NSC 30279, NSC 626579, K-Lyte DS (Salt/Mix), K-Lyte (Salt/Mix), Citraclean (Salt/Mix), K-Lyte/Cl (Salt/Mix), BETZ 0623, BETZ 6251, Citric acid, Citric acid anhydrous, Citric acid anhydride, BUFFER CONCENTRATE, PH 9.00, BUFFER CONCENTRATE, PH 8.00, BUFFER CONCENTRATE, PH 7.00, 2-hydroxypropane-1,2,3-tricarboxylate, 2-Hydroxy-1,2,3-propanetricarboxylic acid, BORIC ACID-POTASSIUM CHLORIDE-SODIUM HYDROXIDE BUFFER, Citric acid, anhydrous, USP Grade 1,2,3-Propanetricarboxylic acid, 2 hydroxy-citric acid, anhydrous, USP Grade, Citric Acid, 2-Hydroxypropane-1,2,3-tricarboxylic Acid, β-Hydroxytricarballylic Acid, Anhydrous Citric Acid, E330, Trihydroxytricarballylic Acid, Citrate, Citric Acid Monohydrate, D00037, G91031, SBI-0206765.0002, AE-562/40806920, ANHYDROUS CITRIC ACID COMPONENT OF CLENPIQ, Citric acid, BioUltra, anhydrous, >=99.5% (T), Q159683, J-520099, 1,2,3-Propanetricarboxylic acid, 2-hydroxy- (9CI), 2-Hydroxy-1,2,3-propanetricarboxylic Acid, Anhydrous, BRD-K76792669-001-08-1, Citric acid, certified reference material, TraceCERT(R), Citric acid, meets USP testing specifications, anhydrous, F2191-0222, 8F5D336A-442D-434A-9FB0-E400FF74E343, Citrate standard for IC, 1000 mg/L, analytical standard, 1,2,3-PROPANETRICARBOXYLIC ACID,2-HYDROXY (CITRIC ACID), CITRIC ACID (CONSTITUENT OF CRANBERRY LIQUID PREPARATION), Citric acid, United States Pharmacopeia (USP) Reference Standard, CITRIC ACID (CONSTITUENT OF CRANBERRY LIQUID PREPARATION) [DSC], CITRIC ACID (CONSTITUENT OF GARCINIA CAMBOGIA AND GARCINIA INDICA), Citric acid, anhydrous, cell culture tested, plant cell culture tested, Citric acid, anhydrous, European Pharmacopoeia (EP) Reference Standard, Citric acid, anhydrous, free-flowing, Redi-Dri(TM), ACS reagent, >=99.5%, CITRIC ACID (CONSTITUENT OF GARCINIA CAMBOGIA AND GARCINIA INDICA) [DSC], Citric acid, Anhydrous, Pharmaceutical Secondary Standard; Certified Reference Material, 141633-96-7, Citric acid, meets analytical specification of Ph. Eur., BP, USP, E330, anhydrous, 99.5-100.5% (based on anhydrous substance), InChI=1/C6H8O7/c7-3(8)1-6(13,5(11)12)2-4(9)10/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)

2-hydroxy-1,2,3-propanetricarboxylic acid appears as colorless, odorless crystals with an acid taste.
2-hydroxy-1,2,3-propanetricarboxylic acid is a tricarboxylic acid that is propane-1,2,3-tricarboxylic acid bearing a hydroxy substituent at position 2.

2-hydroxy-1,2,3-propanetricarboxylic acid is an important metabolite in the pathway of all aerobic organisms.
has a role as a food acidity regulator, a chelator, an antimicrobial agent and a fundamental metabolite.
2-hydroxy-1,2,3-propanetricarboxylic acid is a conjugate acid of a citrate(1-) and a citrate anion.

2-hydroxy-1,2,3-propanetricarboxylic acid is a key intermediate in metabolism.
2-hydroxy-1,2,3-propanetricarboxylic acid is an acid compound found in citrus fruits.
The salts of citric acid (citrates) can be used as anticoagulants due to their calcium-chelating ability.

2-hydroxy-1,2,3-propanetricarboxylic acid is one of the active ingredients in Phexxi, a non-hormonal contraceptive agent that was approved by the FDA on May 2020.
2-hydroxy-1,2,3-propanetricarboxylic acid is also used in combination with magnesium oxide to form magnesium citrate, an osmotic laxative.

Cosmetics, pharmaceuticals, dietary supplements, and foods 2-hydroxy-1,2,3-propanetricarboxylic acid is used as an acidulant in creams, gels, and liquids. Used in foods and dietary supplements, it may be classified as a processing aid if it was added for a technical or functional effect (e.g. acidulent, chelator, viscosifier, etc.).

If it is still present in insignificant amounts, and the technical or functional effect is no longer present, it may be exempt from labeling.
2-hydroxy-1,2,3-propanetricarboxylic acid is an alpha hydroxy acid and is an active ingredient in chemical skin peels.

2-hydroxy-1,2,3-propanetricarboxylic acid is registered under the REACH Regulation and is manufactured in and / or imported to the European Economic Area, at ≥ 100 000 tonnes per annum.
2-hydroxy-1,2,3-propanetricarboxylic acid is a metabolite found in or produced by Escherichia coli

2-hydroxy-1,2,3-propanetricarboxylic acid has been reported in Camellia sinensis, Diplachne fusca, and other organisms with data available.
2-hydroxy-1,2,3-propanetricarboxylic acid is a tricarboxylic acid found in citrus fruits.

2-hydroxy-1,2,3-propanetricarboxylic acid is a small molecule drug with a maximum clinical trial phase of IV (across all indications) that was first approved in 1982 and has 6 investigational indications.
2-hydroxy-1,2,3-propanetricarboxylic acid is a key intermediate in metabolism.

2-hydroxy-1,2,3-propanetricarboxylic acid is an acid compound found in citrus fruits.
The salts of 2-hydroxy-1,2,3-propanetricarboxylic acid can be used as anticoagulants due to their calcium chelating ability.
2-hydroxy-1,2,3-propanetricarboxylic acid is an organic compound with the formula HOC(CO2H)(CH2CO2H)2.

2-hydroxy-1,2,3-propanetricarboxylic acid is a colorless weak organic acid.
2-hydroxy-1,2,3-propanetricarboxylic acid occurs naturally in citrus fruits.
In biochemistry, 2-hydroxy-1,2,3-propanetricarboxylic acid is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms.

More than two million tons of 2-hydroxy-1,2,3-propanetricarboxylic acid are manufactured every year.
2-hydroxy-1,2,3-propanetricarboxylic acid is used widely as acidifier, flavoring, preservative, and chelating agent.
A citrate is a derivative of 2-hydroxy-1,2,3-propanetricarboxylic acid; that is, the salts, esters, and the polyatomic anion found in solutions and salts of citric acid.

An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.
When citrate trianion is part of a salt, the formula of the citrate trianion is written as C6H5O3−7 or C3H5O(COO)3−3.

2-hydroxy-1,2,3-propanetricarboxylic acid is a natural ingredient in animals and plants and an intermediate product of physiological metabolism, one of the most widely used organic acids in chemical industry and other fields.

2-hydroxy-1,2,3-propanetricarboxylic acid is colorless transparent or translucent crystals, or granular, granular powder, odorless, although there is a strong sour taste, but pleasant, slightly after astringent.
2-hydroxy-1,2,3-propanetricarboxylic acid is gradually weathered in warm air and slightly deliquescent in humid air.

USES and APPLICATIONS of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment), outdoor use, outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials), outdoor use in long-life materials with high release rate (e.g. tyres, treated wooden products, treated textile and fabric, brake pads in trucks or cars, sanding of buildings (bridges, facades) or vehicles (ships)) and indoor use in long-life materials with high release rate (e.g. release from fabrics, textiles during washing, removal of indoor paints).

2-hydroxy-1,2,3-propanetricarboxylic acid can be found in products with material based on: paper (e.g. tissues, feminine hygiene products, nappies, books, magazines, wallpaper), stone, plaster, cement, glass or ceramic (e.g. dishes, pots/pans, food storage containers, construction and isolation material), wood (e.g. floors, furniture, toys), fabrics, textiles and apparel (e.g. clothing, mattress, curtains or carpets, textile toys) and leather (e.g. gloves, shoes, purses, furniture).

2-hydroxy-1,2,3-propanetricarboxylic acid is intended to be released from scented: paper products.
Release to the environment of 2-hydroxy-1,2,3-propanetricarboxylic acid can occur from industrial use: in the production of articles.

2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following products: washing & cleaning products, polishes and waxes, coating products, fillers, putties, plasters, modelling clay, fertilisers, cosmetics and personal care products and photo-chemicals.

2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following areas: building & construction work, agriculture, forestry and fishing, health services, mining and formulation of mixtures and/or re-packaging.
2-hydroxy-1,2,3-propanetricarboxylic acid is used for the manufacture of: furniture and machinery and vehicles.

2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following products: washing & cleaning products, polishes and waxes, fertilisers, air care products, cosmetics and personal care products, photo-chemicals, coating products, adhesives and sealants and fillers, putties, plasters, modelling clay.

2-hydroxy-1,2,3-propanetricarboxylic acid can be used as an alternative to nitric acid in passivation of stainless steel.
Release to the environment of 2-hydroxy-1,2,3-propanetricarboxylic acid can occur from industrial use: formulation of mixtures, formulation in materials and in processing aids at industrial sites.

2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following products: washing & cleaning products, pH regulators and water treatment products, polishes and waxes and water treatment chemicals.
2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following areas: mining, health services, building & construction work and formulation of mixtures and/or re-packaging.

2-hydroxy-1,2,3-propanetricarboxylic acid is used for the manufacture of: chemicals, machinery and vehicles, textile, leather or fur, electrical, electronic and optical equipment, fabricated metal products and metals.
Release to the environment of 2-hydroxy-1,2,3-propanetricarboxylic acid can occur from industrial use: in processing aids at industrial sites, in the production of articles, of substances in closed systems with minimal release and as processing aid.

Release to the environment of 2-hydroxy-1,2,3-propanetricarboxylic acid can occur from industrial use: manufacturing of the substance, formulation of mixtures, formulation in materials and in processing aids at industrial sites.
2-hydroxy-1,2,3-propanetricarboxylic acid is used as an excipient in pharmaceutical preparations due to its antioxidant properties.

2-hydroxy-1,2,3-propanetricarboxylic acid is used by consumers, in articles, by professional workers (widespread uses), in formulation or re-packing, at industrial sites and in manufacturing.
2-hydroxy-1,2,3-propanetricarboxylic acid is approved for use as a biocide in the EEA and/or Switzerland, for: disinfection.

2-hydroxy-1,2,3-propanetricarboxylic acid is approved in the EEA and/or Switzerland for use in biocidal products more favourable for the environment, human or animal health.
2-hydroxy-1,2,3-propanetricarboxylic acid is used as one of the active ingredients in the production of facial tissues with antiviral properties.

2-hydroxy-1,2,3-propanetricarboxylic acid maintains stability of active ingredients and is used as a preservative.
2-hydroxy-1,2,3-propanetricarboxylic acid is used in the following products: washing & cleaning products, cosmetics and personal care products, coating products, polishes and waxes, air care products, photo-chemicals, fillers, putties, plasters, modelling clay, fertilisers and water softeners.

Other release to the environment of 2-hydroxy-1,2,3-propanetricarboxylic acid is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment), outdoor use in long-life materials with high release rate (e.g. tyres, treated wooden products, treated textile and fabric, brake pads in trucks or cars, sanding of buildings (bridges, facades) or vehicles (ships)), indoor use in long-life materials with high release rate (e.g. release from fabrics, textiles during washing, removal of indoor paints) and outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials).

The buffering properties of citrates are used to control pH in household cleaners and pharmaceuticals.
2-hydroxy-1,2,3-propanetricarboxylic acid is used as an odorless alternative to white vinegar for fabric dyeing with acid dyes.
Sodium citrate is a component of Benedict's reagent, used for both qualitative and quantitative identification of reducing sugars.

2-hydroxy-1,2,3-propanetricarboxylic acid can be used as a lower-odor stop bath as part of the process for developing photographic film.
Photographic developers are alkaline, so a mild acid is used to neutralize and stop their action quickly, but commonly used acetic acid leaves a strong vinegar odor in the darkroom.

2-hydroxy-1,2,3-propanetricarboxylic acid is an excellent soldering flux, either dry or as a concentrated solution in water.
2-hydroxy-1,2,3-propanetricarboxylic acid should be removed after soldering, especially with fine wires, as it is mildly corrosive.
2-hydroxy-1,2,3-propanetricarboxylic acid dissolves and rinses quickly in hot water.

Alkali citrate can be used as an inhibitor of kidney stones by increasing urine citrate levels, useful for prevention of calcium stones, and increasing urine pH, useful for preventing uric acid and cystine stones.
2-hydroxy-1,2,3-propanetricarboxylic acid is commonly used as a buffer to increase the solubility of brown heroin.

2-hydroxy-1,2,3-propanetricarboxylic acid is also used as an acidulant to control pH and acts as an anticoagulant by chelating calcium in blood.
2-hydroxy-1,2,3-propanetricarboxylic acid has a strong chelating effect, which can complex Fe3 + and weaken the Promoting Effect of Fe3 + on corrosion.
2-hydroxy-1,2,3-propanetricarboxylic acid can remove iron, copper and other metal oxide scale, easy to operate, safe, suitable for a variety of materials.

Since the molecule does not contain c1-it will not cause stress corrosion of the equipment, used as a cleaning agent, 2-hydroxy-1,2,3-propanetricarboxylic acid than hydrochloric acid on steel corrosion rate is small.
2-hydroxy-1,2,3-propanetricarboxylic acid is mainly used to remove rust and has poor solubility in calcium, magnesium and silicon scale, so it is mainly used for cleaning newly built large-scale devices.

2-hydroxy-1,2,3-propanetricarboxylic acid can not remove calcium and magnesium scale and silicate scale, however, 2-hydroxy-1,2,3-propanetricarboxylic acid and amino sulfonic acid, glycolic acid or formic acid mixed use, can be used to clean the rust and calcium and magnesium scale 2-hydroxy-1,2,3-propanetricarboxylic acid and EDTA mixture, can be used to clean the heat exchanger.

The corrosion inhibitor added in the 2-hydroxy-1,2,3-propanetricarboxylic acid cleaning solution is mainly thiourea, the dosage is 0. 1%, and 0.06% thiourea can also be mixed with other corrosion inhibitors.
In addition, 2-hydroxy-1,2,3-propanetricarboxylic acid can also be used in the field of medicine, sodium citrate salt can prevent blood coagulation, calcium salt can be used as the acid solution of the stomach, barium salt is toxic.

2-hydroxy-1,2,3-propanetricarboxylic acid is used as experimental reagents, chromatographic analysis reagents and biochemical reagents, also used in the preparation of buffer.
2-hydroxy-1,2,3-propanetricarboxylic acid is used in the food industry in particular as an acidifying agent, a PH buffering agent, and together with other compounds as a preservation agent.

In the detergent industry, 2-hydroxy-1,2,3-propanetricarboxylic acid is an ideal substitute for phosphate.
Boiler chemical cleaning pickling agent, boiler chemical cleaning rinsing agent.
2-hydroxy-1,2,3-propanetricarboxylic acid is mainly used as a sour agent for food, and is also used for the preparation of medical coolants and detergents.

Application in the food industry: anhydrous 2-hydroxy-1,2,3-propanetricarboxylic acid is known as the first edible acid, china's GB2760-1996 regulations for the allowed use of food acidity regulator.
In the food industry, 2-hydroxy-1,2,3-propanetricarboxylic acid is widely used as a sour agent, a solubilizer, a buffer, an antioxidant, a deodorizing agent, a chelating agent, and the like, and the specific uses thereof are numerous.

According to statistics at home and abroad, the consumption of 2-hydroxy-1,2,3-propanetricarboxylic acid in the beverage industry accounts for 75% ~ 80% of the total 2-hydroxy-1,2,3-propanetricarboxylic acid production.
2-hydroxy-1,2,3-propanetricarboxylic acid should be removed after soldering, especially with fine wires, as it is mildly corrosive.

2-hydroxy-1,2,3-propanetricarboxylic acid is one of the natural ingredients of fruit juice, not only can give fruit flavor but also solubilization, Buffering, antioxidant and other effects, so that the sugar, flavor, pigment and other ingredients in the beverage blend and coordinate to form a harmonious taste and aroma, can increase the anti-microbial antiseptic effect.

Therefore, 2-hydroxy-1,2,3-propanetricarboxylic acid is widely used in the formulation of various fruit-type soft drinks, for example, fruit-type soft drinks generally have an acid addition of between 0.10% and 0.25%.
For non-co2-filled beverages, such as water, fruit juices, sugars, acids, colors, flavor mixtures, 2-hydroxy-1,2,3-propanetricarboxylic acid is used to adjust the pH to a certain acidity such that the titrated acidity of the product is between 0.25% and 0.40%.

For the pulp type solid beverage powder, the addition amount of 2-hydroxy-1,2,3-propanetricarboxylic acid can be increased to 1.5% ~ 5.0%.
In recent years, with the continuous improvement of living standards of urban and rural people, the demand for various beverages has increased greatly.
It can be predicted that the consumption of 2-hydroxy-1,2,3-propanetricarboxylic acid in beverage industry will increase greatly in the future.

Jam and jelly the effect of 2-hydroxy-1,2,3-propanetricarboxylic acid in jam and jelly is similar to that in beverages, mainly adjusting the pH of the product and imparting a sour taste to the product, the pH having to be adjusted to a very narrow range optimum for the coagulation of pectin.
Depending on the type of pectin used, the pH may be limited between 3.0 and 3.4.

In the production of jam, the flavor can be improved and the defects of sucrose crystallization can be prevented.
Candy 2-hydroxy-1,2,3-propanetricarboxylic acid added to the candy can increase the sour taste and prevent the oxidation of various components and the precipitation of sucrose crystals.

Generally sour candy may contain 2% 2-hydroxy-1,2,3-propanetricarboxylic acid.
After boiling the sugar, 2-hydroxy-1,2,3-propanetricarboxylic acid is added along with the color and flavor during the cooling of the sugar paste.
2-hydroxy-1,2,3-propanetricarboxylic acid can adjust the sour taste and enhance the gel strength in the production of pectin soft candy.

Anhydrous 2-hydroxy-1,2,3-propanetricarboxylic acid is used for chewing gum and powder food.
Frozen food 2-hydroxy-1,2,3-propanetricarboxylic acid has the characteristics of chelating and pH adjustment.
2-hydroxy-1,2,3-propanetricarboxylic acid can enhance the antioxidant effect and inactivate the enzyme, and can more reliably ensure the stability of frozen food.

2-hydroxy-1,2,3-propanetricarboxylic acid, alone or in combination with isoascorbic acid, helps to extend the shelf life of frozen fish and shellfish.
2-hydroxy-1,2,3-propanetricarboxylic acid can inactivate enzymes that can cause fish spoilage and shellfish deterioration and chelate trace elements.
Seafood is generally soaked in 0.25% 2-hydroxy-1,2,3-propanetricarboxylic acid and 0.2% isoascorbic acid solution before freezing, which is beneficial to the preservation and cold storage.

For fresh pork preservation, prevent corruption also has the effect.
2-hydroxy-1,2,3-propanetricarboxylic acid can also inhibit the deterioration of the color and aroma of frozen fruits, which is also a manifestation of the inhibition of the enzymes in the fruit and the prevention of the oxidation of trace elements, such: 0.1% to 0.3% 2-hydroxy-1,2,3-propanetricarboxylic acid is effective in combination with 0.001% to 0.002% isoascorbic acid.

Sodium citrate can increase the decontamination performance, accelerate the biodegradation in many household detergent products, and can be used as a substitute for phosphate, which is widely used in washing powder and detergent, sodium citrate is effective in enhancing the cleaning effect of the detergent together with the aluminosilicate.

Technical grade 50% 2-hydroxy-1,2,3-propanetricarboxylic acid solution is used as the starting material in these products.
In non-synthetic detergent solutions, 2-hydroxy-1,2,3-propanetricarboxylic acid is also used in cleaning agents for hot water extraction of carpet, baths and softeners for textiles due to its buffering effect and ability to chelate trace metals.

2-hydroxy-1,2,3-propanetricarboxylic acid is mainly used as a acidulant in food, and also used in the preparation of pharmaceutical cooling agents, detergent additives used as experimental reagents, Chromatographic Reagents and biochemical reagents, also used in the preparation of buffer.
2-hydroxy-1,2,3-propanetricarboxylic acid is used in the food industry in particular as an acidifying agent, a PH buffering agent, and together with other compounds as a preservation agent.

In the detergent industry, 2-hydroxy-1,2,3-propanetricarboxylic acid is an ideal substitute for phosphate.
2-hydroxy-1,2,3-propanetricarboxylic acid is used boiler chemical cleaning pickling agent, boiler chemical cleaning rinsing agent.
Mainly used for food acid, also used for the preparation of medicine cooling agent, detergent with 2-hydroxy-1,2,3-propanetricarboxylic acid is the most functional, the most widely used acid agent.

High solubility, strong chelating ability to metal ions, 2-hydroxy-1,2,3-propanetricarboxylic acid can be used for all kinds of food, according to the production needs of appropriate use.
In addition, 2-hydroxy-1,2,3-propanetricarboxylic acid can also be used as antioxidant Synergist, compound potato starch bleach synergist and preservative.

2-hydroxy-1,2,3-propanetricarboxylic acid is widely used as an acidulant and a pharmaceutical additive for foods and beverages.
2-hydroxy-1,2,3-propanetricarboxylic acid can also be used as cosmetics, metal cleaning agents, mordant, non-toxic plasticizer and Boiler Scale Inhibitor of raw materials and additives.

2-hydroxy-1,2,3-propanetricarboxylic acid's main salt products are sodium citrate, calcium and ammonium salts, etc., sodium citrate is blood anticoagulant, ferric ammonium citrate can be used as blood medicine.
2-hydroxy-1,2,3-propanetricarboxylic acid is used as analytical reagent with citric acid.

2-hydroxy-1,2,3-propanetricarboxylic acid is used cidulant in food and beverages
2-hydroxy-1,2,3-propanetricarboxylic acid is used preservative to prevent microbial growth

-Soilless cultivation of agronomy uses of 2-hydroxy-1,2,3-propanetricarboxylic acid:
The use of trace element plant nutrient solution in soilless culture abroad has been very common, in the domestic also began to develop.

In order to remove some excess elements such as copper, zinc, manganese and chromium in the soil, 2-hydroxy-1,2,3-propanetricarboxylic acid is generally used to chelate such elements.
The use of 2-hydroxy-1,2,3-propanetricarboxylic acid instead of phosphate can achieve satisfactory results.

-Mineral and pigment applications of 2-hydroxy-1,2,3-propanetricarboxylic acid:
2-hydroxy-1,2,3-propanetricarboxylic acid has dispersion efficiency, it can reduce the viscosity of some important slurry raw material.
In mining such as phosphate rock powder in the hydraulic transport of viscosity problems often become the main reason for the expansion of clay, the use of
2-hydroxy-1,2,3-propanetricarboxylic acid treatment can control the expansion, so that the slurry raw material easy to transport.
2-hydroxy-1,2,3-propanetricarboxylic acid can also reduce the precipitation of the concentrated raw meal of titanium dioxide, making it easy to handle and transport as a whole.

2-hydroxy-1,2,3-propanetricarboxylic acid can also be used as a dispersant for low-grade sizing, paint and textile raw material processing, and titanium dioxide.

APPLICATION OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID IN THE PHARMACEUTICAL INDUSTRY:
Effervescence is a popular drug delivery system for oral ingredients, 2-hydroxy-1,2,3-propanetricarboxylic acid reacts with sodium carbonate or aqueous sodium bicarbonate to produce large amounts of CO2 (I. E., effervescence) and sodium citrate, which allows the active ingredients in the drug to rapidly dissolve and enhance taste.

For example, laxatives and analgesics have a solubilizing effect. 2-hydroxy-1,2,3-propanetricarboxylic acid syrup is Fever patients with a cool drink, with flavor, cooling, detoxification effect.

2-hydroxy-1,2,3-propanetricarboxylic acid is widely used in various nutritional oral liquids, etc., buffering pH 3.5~4.5, maintaining the stability of active ingredients, strengthening the effect of preservatives.

The combination of 2-hydroxy-1,2,3-propanetricarboxylic acid and fruit flavor gives people a favorite flavor to mask the bitter taste of drugs, especially traditional Chinese medicine.

Adding 0.02% 2-hydroxy-1,2,3-propanetricarboxylic acid in liquid ingredients can form a complex of trace iron and copper, delay the degradation of active ingredients.
The use of 0.1% ~ 0.2% 2-hydroxy-1,2,3-propanetricarboxylic acid in the chewing tablet can improve the flavor of the tablet and make it have a lemon flavor.

METAL PURIFICATION USES OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
The 2-hydroxy-1,2,3-propanetricarboxylic acid-based metal purification formula can effectively remove the oxides formed on the surface of ferrous and non-ferrous metals, as a weak organic acid, it can cause slight damage to the metal surface layer, however, as a metal ion chelating agent, it accelerates the migration of metal oxides.

In many steel pickling systems, in order to eliminate metal oxide stress cracks and to minimize the corrosion brittleness of high strength steel, 2-hydroxy-1,2,3-propanetricarboxylic acid is used to remove rust instead of inorganic strong acid.
in boilers, heaters, superheater tubes and non-clean reactors and stainless steel equipment, 2-hydroxy-1,2,3-propanetricarboxylic acid is generally used for pre-washing and purification to remove iron and copper oxides, especially where the presence of chloride is not permitted.

The purification reaction of 2-hydroxy-1,2,3-propanetricarboxylic acid solution should be carried out under the condition of higher than 37.8 ℃, and the purification time below 37.8 ℃ should be correspondingly prolonged, and the amount of 2-hydroxy-1,2,3-propanetricarboxylic acid used and the working conditions should be adjusted by increasing or decreasing the estimated amount of precipitation.

2-hydroxy-1,2,3-propanetricarboxylic acid is a highly efficient chelating cleaning agent, which is effective for calcium, magnesium, iron, chromium, copper and other dirt.
It is widely used in the cleaning of various metal surfaces.

In recent years, 2-hydroxy-1,2,3-propanetricarboxylic acid is suitable for the chemical treatment of metal purification, and is also suitable for the pollution-free ashing of waste solvents, the 2-hydroxy-1,2,3-propanetricarboxylic acid molecules are burned into CO2 and water vapor in the ash and the valuable metals can be recovered from the ash, and the toxic or radioactive elements can be fully enclosed for chemical treatment.

APPLICATIONS OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID FOR FOOD AND DRINK:
Because it is one of the stronger edible acids, the dominant use of 2-hydroxy-1,2,3-propanetricarboxylic acid is as a flavoring and preservative in food and beverages, especially soft drinks and candies.
Within the European Union 2-hydroxy-1,2,3-propanetricarboxylic acid is denoted by E number E330.

Citrate salts of various metals are used to deliver those minerals in a biologically available form in many dietary supplements.
2-hydroxy-1,2,3-propanetricarboxylic acid has 247 kcal per 100 g.

In the United States the purity requirements for 2-hydroxy-1,2,3-propanetricarboxylic acid as a food additive are defined by the Food Chemicals Codex, which is published by the United States Pharmacopoeia (USP).

2-hydroxy-1,2,3-propanetricarboxylic acid can be added to ice cream as an emulsifying agent to keep fats from separating, to caramel to prevent sucrose crystallization, or in recipes in place of fresh lemon juice.

2-hydroxy-1,2,3-propanetricarboxylic acid is used with sodium bicarbonate in a wide range of effervescent formulae, both for ingestion (e.g., powders and tablets) and for personal care (e.g., bath salts, bath bombs, and cleaning of grease).

2-hydroxy-1,2,3-propanetricarboxylic acid sold in a dry powdered form is commonly sold in markets and groceries as "sour salt", due to its physical resemblance to table salt.

2-hydroxy-1,2,3-propanetricarboxylic acid has use in culinary applications, as an alternative to vinegar or lemon juice, where a pure acid is needed.
2-hydroxy-1,2,3-propanetricarboxylic acid can be used in food coloring to balance the pH level of a normally basic dye.

CLEANING AND CHELATING AGENT OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid is an excellent chelating agent, binding metals by making them soluble.
2-hydroxy-1,2,3-propanetricarboxylic acid is used to remove and discourage the buildup of limescale from boilers and evaporators.
2-hydroxy-1,2,3-propanetricarboxylic acid can be used to treat water, which makes it useful in improving the effectiveness of soaps and laundry detergents.

By chelating the metals in hard water, 2-hydroxy-1,2,3-propanetricarboxylic acid lets these cleaners produce foam and work better without need for water softening.
2-hydroxy-1,2,3-propanetricarboxylic acid is the active ingredient in some bathroom and kitchen cleaning solutions.

A solution with a six percent concentration of 2-hydroxy-1,2,3-propanetricarboxylic acid will remove hard water stains from glass without scrubbing.
2-hydroxy-1,2,3-propanetricarboxylic acid can be used in shampoo to wash out wax and coloring from the hair.

Illustrative of its chelating abilities, 2-hydroxy-1,2,3-propanetricarboxylic acid was the first successful eluant used for total ion-exchange separation of the lanthanides, during the Manhattan Project in the 1940s.

In the 1950s, 2-hydroxy-1,2,3-propanetricarboxylic acid was replaced by the far more efficient EDTA.
In industry, 2-hydroxy-1,2,3-propanetricarboxylic acid is used to dissolve rust from steel, and to passivate stainless steels

PROPERTIES OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
*Non-toxic and biodegradable
*Highly soluble in water
*2-hydroxy-1,2,3-propanetricarboxylic acid acts as a natural antioxidant
*Excellent buffering capacity

BENEFITS OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
*2-hydroxy-1,2,3-propanetricarboxylic acid improves shelf life of food products
*2-hydroxy-1,2,3-propanetricarboxylic acid enhances flavor in beverages
*2-hydroxy-1,2,3-propanetricarboxylic acid aids in removing scale and stains
*Eco-friendly alternative to synthetic chelating agents
*Safe for human consumption

PRODUCTION METHOD OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid is mainly produced by fermentation, and its raw materials can be molasses, sucrose, sweet potato, petroleum hydrocarbons and other carbohydrates.

Generally, fungi are used for fermentation production, and can be divided into two categories: surface fermentation and submerged fermentation according to the fermentation method.

Surface fermentation is an early production method, and some Penicillium or Aspergillus niger is used as the strain; the submerged fermentation method also uses Aspergillus niger as the strain to generate small spherical filamentous aggregates during the fermentation process.

The growing and thin filamentous cells should be avoided, and the fermentation condition is pH 1.5-2.8, at the same time, sterile air should be introduced and stirred, and the fermentation is completed to remove Silk cells and residual solid waste.

The filtrate is neutralized with calcium carbonate to obtain calcium citrate, and then neutralized with concentrated sulfuric acid to obtain crude citric acid, 2-hydroxy-1,2,3-propanetricarboxylic acid is refined, concentrated and crystallized by ion exchange resin.
The yield of submerged fermentation was about 80%.

2-hydroxy-1,2,3-propanetricarboxylic acid can be extracted from fruits such as lemon and orange, and can also be synthesized by using oxaloacetic acid and ketene as raw materials.
However, the current industrial production method at home and abroad is fermentation.

The fermentation methods include solid fermentation, shallow fermentation and submerged fermentation.
In China, more than 80% of 2-hydroxy-1,2,3-propanetricarboxylic acid is made from dry potato powder by submerged fermentation with Aspergillus niger, neutralization of calcium carbonate, acidolysis with sulfuric acid, refining, concentration, crystallization and drying.

(1) fermentation the sweet potato powder is prepared into 18% ~ 22% slurry, and the fermentation tank which has been steam sterilized (0.2MPa,40~60min) is given.
Heat to 110 °c for 20min with steam, Liquefaction was performed with 0.05% amylase.
Fermentation was carried out by inoculation with Aspergillus Niger after cooling to 35 °c.

The fermentation temperature was 36~38 ℃ in the early stage and 34~36 ℃ in the late stage.
The aeration rate was 1:(0.1~0.2); The pH value was not less than 2.5; The fermentation period was 96H.
The acid production level was 10% ~ 14%, and the conversion rate was 95%.

(2) after completion of neutralization and fermentation, the fermentation broth was heated to 80 ° C.
To kill mold, and then submitted to plate-and-frame pressure filtration to obtain a clear solution.

The filtrate was neutralized to pH 5.0-5.5 by adding calcium carbonate powder at 80 ° C.
And incubated for 0.5 hours.
The calcium citrate is then obtained by vacuum suction filtration and washing with hot water at 80 °c.

(3) acid hydrolysis and refining under constant stirring, calcium citrate is added to water or dilute acid, and then sulfuric acid is slowly added until the pH value is 1.8, heated to 90 ° C., and the end point is determined by double tube method.

Then add the amount of 2-hydroxy-1,2,3-propanetricarboxylic acid 1%~ 3% of the activated carbon, insulation 0.5h, put the suction filter barrel to dry, and 90 deg C hot water to the residual acid below 0.5%, washing water (ie dilute acid) for the next acid solution.
Finally, ion exchange was carried out with a 732 cation resin to remove various cations.

(4) concentration, crystallization and drying the clear liquid after ion exchange contains about 15% to 20% of 2-hydroxy-1,2,3-propanetricarboxylic acid.
At 55~60 0C: vacuum concentration to a relative density of 1.335~1.340, put into the crystallization pot.

Aqueous crystals were precipitated by cooling to 36.6 ° C.
Or lower with frozen brine.

After the crystals were separated, they were washed with a small amount of distilled water until the content of sulfuric acid was below 200 × 10 ° C., and finally dried by hot air at 35 ° C. To obtain a finished product.

NATURAL DISTRIBUTION OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid is widely distributed in nature, existing in plants such as lemon, citrus, pineapple, gooseberry, raspberry, grape juice and other fruits and animal bones, muscles, blood.

Synthetic 2-hydroxy-1,2,3-propanetricarboxylic acid is sugar, molasses, starch, grape and other sugar-containing substances produced by fermentation, can be divided into anhydrous and hydrate two.

Pure 2-hydroxy-1,2,3-propanetricarboxylic acid is colorless transparent crystal or white powder, odorless, has an attractive sour taste.
The translucent colorless crystals obtained from the hot concentrated aqueous solution were anhydrous and had a melting point of 153 °c.

The translucent colorless crystals obtained from the cold water solution were monohydrate with a density of 1.542.
Softening at 75 °c and melting at about 100 °c.

A water substance may lose water in dry air.
Is a strong organic acid. Soluble in water, ethanol and ether.

2-hydroxy-1,2,3-propanetricarboxylic acid is used in the manufacture of drugs, soda, candy, etc., but also used as a metal detergent, mordant, etc.
A wide variety of fruits and vegetables, especially citrus fruits, contain more 2-hydroxy-1,2,3-propanetricarboxylic acid, especially lemon and lime-they contain a lot of 2-hydroxy-1,2,3-propanetricarboxylic acid, after drying, the content can reach 8% (about 47g/L in fruit juice).

In citrus fruits, the content of 2-hydroxy-1,2,3-propanetricarboxylic acid is between 0.005 mol/L for Orange and grape and 0.30 mol/L for lemon and lime.
This content varies with the growth of different cultivars and plants.

SYNTHESIS OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid is a versatile precursor to many other organic compounds.
Dehydration routes give itaconic acid and its anhydride.
Citraconic acid can be produced via thermal isomerization of itaconic acid anhydride.

The required itaconic acid anhydride is obtained by dry distillation of 2-hydroxy-1,2,3-propanetricarboxylic acid.
Aconitic acid can be synthesized by dehydration of 2-hydroxy-1,2,3-propanetricarboxylic acid using sulfuric acid:

(HO2CCH2)2C(OH)CO2H → HO2CCH=C(CO2H)CH2CO2H + H2O
Acetonedicarboxylic acid can also be prepared by decarboxylation of 2-hydroxy-1,2,3-propanetricarboxylic acid in fuming sulfuric acid

NATURE OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid is divided into two types: anhydrous and monohydrate.
2-hydroxy-1,2,3-propanetricarboxylic acid is a translucent crystals or white fine powder crystals.
2-hydroxy-1,2,3-propanetricarboxylic acid is Odorless, with strong sour taste.

Dry or heated to 40~50 ℃ to become anhydrous, anhydrous weathering in dry air, micro deliquescence. 75 ℃ soft. 100 ℃ melting.
Relative densities were 542(-hydrate) and 1.67 (anhydrous).
Readily soluble in water (monohydrate 209g]lOOmL,25 °c; Anhydrous 59. 2G/lOOmL,20 °c; 1% solution pH 2.31) and ethanol, soluble in ether.

Natural products are found in citrus fruits such as lemon.
The powder and air can form an explosive mixture.
In case of open flame, high heat or contact with oxidant, there is a risk of combustion explosion.

PREPARATION METHOD OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
sugar, molasses, starch, starch residue or glucose as raw material, through fermentation, separation, purification.

BIOCHEMISTRY OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid cycle
Citrate is an intermediate in the 2-hydroxy-1,2,3-propanetricarboxylic acid cycle, also known as the TCA (TriCarboxylic Acid) cycle or the Krebs cycle, a central metabolic pathway for animals, plants, and bacteria.

In the Krebs cycle, citrate synthase catalyzes the condensation of oxaloacetate with acetyl CoA to form citrate.
Citrate then acts as the substrate for aconitase and is converted into aconitic acid.
The cycle ends with regeneration of oxaloacetate.

This series of chemical reactions is the source of two-thirds of the food-derived energy in higher organisms.
The chemical energy released is available under the form of Adenosine triphosphate (ATP).
Hans Adolf Krebs received the 1953 Nobel Prize in Physiology or Medicine for the discovery.

OTHER BIOLOGICAL ROLES OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
Citrate can be transported out of the mitochondria and into the cytoplasm, then broken down into acetyl-CoA for fatty acid synthesis, and into oxaloacetate.
Citrate is a positive modulator of this conversion, and allosterically regulates the enzyme acetyl-CoA carboxylase, which is the regulating enzyme in the conversion of acetyl-CoA into malonyl-CoA (the commitment step in fatty acid synthesis).

In short, citrate is transported into the cytoplasm, converted into acetyl-CoA, which is then converted into malonyl-CoA by acetyl-CoA carboxylase, which is allosterically modulated by citrate.

High concentrations of cytosolic citrate can inhibit phosphofructokinase, the catalyst of a rate-limiting step of glycolysis.
This effect is advantageous: high concentrations of citrate indicate that there is a large supply of biosynthetic precursor molecules, so there is no need for phosphofructokinase to continue to send molecules of its substrate, fructose 6-phosphate, into glycolysis.

Citrate acts by augmenting the inhibitory effect of high concentrations of ATP, another sign that there is no need to carry out glycolysis.
Citrate is a vital component of bone, helping to regulate the size of apatite crystals

PHYSICAL AND CHEMICAL PROPERTIES OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
Relative density of 2-hydroxy-1,2,3-propanetricarboxylic acid is 1.542, melting point 153 ℃ (water loss), refractive index 1.493~1.509
2-hydroxy-1,2,3-propanetricarboxylic acid is a colorless translucent crystals or white particles, or white crystalline powder, often containing a molecule of crystal water, odorless, extremely sour taste, soluble in water, alcohol and ether.

Its calcium salt is more soluble in cold water than hot water, and this property is often used to identify and isolate 2-hydroxy-1,2,3-propanetricarboxylic acid.
Anhydrous 2-hydroxy-1,2,3-propanetricarboxylic acid can be obtained by controlling the appropriate temperature during crystallization.

The aqueous solution of 2-hydroxy-1,2,3-propanetricarboxylic acid was acidic.
2-hydroxy-1,2,3-propanetricarboxylic acid is slightly weathered in dry air and deliquescent in moist air.
Above 175 deg C and carbon dioxide free water.

CHEMICAL CHARACTERISTICS OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid can be obtained as an anhydrous (water-free) form or as a monohydrate.
The anhydrous form crystallizes from hot water, while the monohydrate forms when 2-hydroxy-1,2,3-propanetricarboxylic acid is crystallized from cold water.
The monohydrate can be converted to the anhydrous form at about 78 °C.

2-hydroxy-1,2,3-propanetricarboxylic acid also dissolves in absolute (anhydrous) ethanol (76 parts of 2-hydroxy-1,2,3-propanetricarboxylic acid per 100 parts of ethanol) at 15 °C.
It decomposes with loss of carbon dioxide above about 175 °C.

2-hydroxy-1,2,3-propanetricarboxylic acid is a triprotic acid, with pKa values, extrapolated to zero ionic strength, of 3.128, 4.761, and 6.396 at 25 °C.
The pKa of the hydroxyl group has been found, by means of 13C NMR spectroscopy, to be 14.4.
The speciation diagram shows that solutions of 2-hydroxy-1,2,3-propanetricarboxylic acid are buffer solutions between about pH 2 and pH 8.

In biological systems around pH 7, the two species present are the citrate ion and mono-hydrogen citrate ion.
The SSC 20X hybridization buffer is an example in common use. Tables compiled for biochemical studies are available.

Conversely, the pH of a 1 mM solution of 2-hydroxy-1,2,3-propanetricarboxylic acid will be about 3.2.
The pH of fruit juices from citrus fruits like oranges and lemons depends on the 2-hydroxy-1,2,3-propanetricarboxylic acid concentration, with a higher concentration of 2-hydroxy-1,2,3-propanetricarboxylic acid resulting in a lower pH.

Acid salts of 2-hydroxy-1,2,3-propanetricarboxylic acid can be prepared by careful adjustment of the pH before crystallizing the compound.
The citrate ion forms complexes with metallic cations.
The stability constants for the formation of these complexes are quite large because of the chelate effect.

Consequently, 2-hydroxy-1,2,3-propanetricarboxylic acid forms complexes even with alkali metal cations.
However, when a chelate complex is formed using all three carboxylate groups, the chelate rings have 7 and 8 members, which are generally less stable thermodynamically than smaller chelate rings.

In consequence, the hydroxyl group can be deprotonated, forming part of a more stable 5-membered ring, as in ammonium ferric citrate, [NH+4]5Fe3+(C6H4O4−7)2•2H2O.
2-hydroxy-1,2,3-propanetricarboxylic acid can be esterified at one or more of its three carboxylic acid groups to form any of a variety of mono-, di-, tri-, and mixed esters.

NATURAL ACCURRENCE AND INDUSTRIAL PRODUCTION OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
2-hydroxy-1,2,3-propanetricarboxylic acid occurs in a variety of fruits and vegetables, most notably citrus fruits.
Lemons and limes have particularly high concentrations of the acid; 2-hydroxy-1,2,3-propanetricarboxylic acid can constitute as much as 8% of the dry weight of these fruits (about 47 g/L in the juices).

The concentrations of 2-hydroxy-1,2,3-propanetricarboxylic acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons and limes; these values vary within species depending upon the cultivar and the circumstances under which the fruit was grown.
2-hydroxy-1,2,3-propanetricarboxylic acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice.

Industrial-scale 2-hydroxy-1,2,3-propanetricarboxylic acid production first began in 1890 based on the Italian citrus fruit industry, where the juice was treated with hydrated lime (calcium hydroxide) to precipitate calcium citrate, which was isolated and converted back to the acid using diluted sulfuric acid.

In 1893, C. Wehmer discovered Penicillium mold could produce 2-hydroxy-1,2,3-propanetricarboxylic acid from sugar.
However, microbial production of 2-hydroxy-1,2,3-propanetricarboxylic acid did not become industrially important until World War I disrupted Italian citrus exports.

In 1917, American food chemist James Currie discovered that certain strains of the mold Aspergillus niger could be efficient 2-hydroxy-1,2,3-propanetricarboxylic acid producers, and the pharmaceutical company Pfizer began industrial-level production using this technique two years later, followed by Citrique Belge in 1929.

In this production technique, which is still the major industrial route to 2-hydroxy-1,2,3-propanetricarboxylic acid used today, cultures of Aspergillus niger are fed on a sucrose or glucose-containing medium to produce 2-hydroxy-1,2,3-propanetricarboxylic acid.
The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch, or other inexpensive, carbohydrate solution.

After the mold is filtered out of the resulting suspension, 2-hydroxy-1,2,3-propanetricarboxylic acid is isolated by precipitating it with calcium hydroxide to yield calcium citrate salt, from which 2-hydroxy-1,2,3-propanetricarboxylic acid is regenerated by treatment with sulfuric acid, as in the direct extraction from citrus fruit juice.

In 1977, a patent was granted to Lever Brothers for the chemical synthesis of 2-hydroxy-1,2,3-propanetricarboxylic acid starting either from aconitic or isocitrate (also called alloisocitrate) calcium salts under high pressure conditions; this produced 2-hydroxy-1,2,3-propanetricarboxylic acid in near quantitative conversion under what appeared to be a reverse, non-enzymatic Krebs cycle reaction.

Global production of 2-hydroxy-1,2,3-propanetricarboxylic acid was in excess of 2,000,000 tons in 2018.
More than 50% of this volume was produced in China.

More than 50% was used as an acidity regulator in beverages, some 20% in other food applications, 20% for detergent applications, and 10% for applications other than food, such as cosmetics, pharmaceuticals, and in the chemical industry.

HISTORY OF DISCOVERY OF 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
The Discovery of 2-hydroxy-1,2,3-propanetricarboxylic acid began in the 8th-century with the Iranian aldrant Jabier.
1784 C.W. Scheler first isolated 2-hydroxy-1,2,3-propanetricarboxylic acid by crystallization from lemon juice.

It is prepared by adding milk of lime to the juice of fruit to form a calcium citrate precipitate.
natural 2-hydroxy-1,2,3-propanetricarboxylic acid is widely distributed in nature, in plants such as lemon, citrus, pineapple and other fruits and animal bones, muscle, blood are contained.
Originally found in California, Italy, and the West Indies.

Italy ranks first in production.
The production of 2-hydroxy-1,2,3-propanetricarboxylic acid by fermentation began at the end of the 19th century.
In 1893, Weemer discovered that Penicillium can produce 2-hydroxy-1,2,3-propanetricarboxylic acid from sugars.

However, the industrial use of microorganisms to produce 2-hydroxy-1,2,3-propanetricarboxylic acid was not on the agenda until the First World War hindered the export of lemon in Italy.
1913b. Zahosky reported that Aspergillus niger could produce 2-hydroxy-1,2,3-propanetricarboxylic acid.

In 1916, Tom and Corey were tested with Aspergillus, and it was confirmed that most Aspergillus such as Aspergillus sojae, Aspergillus oryzae, Aspergillus Wenshi, Trichoderma viride and Aspergillus Niger have the ability to produce 2-hydroxy-1,2,3-propanetricarboxylic acid, and the acid production ability of Aspergillus niger is stronger.
For example, Aspergillus niger was used as the test strain to ferment in 15% sucrose medium, and the absorption rate of sugar reached 55%.

The first plant in the world for the production of 2-hydroxy-1,2,3-propanetricarboxylic acid by Aspergillus niger shallow-dish fermentation was built by fizea Co.
Then Belgium, Britain, Germany, the Soviet Union and so on have studied the successful fermentation production of 2-hydroxy-1,2,3-propanetricarboxylic acid.

In this way, the method of extracting natural 2-hydroxy-1,2,3-propanetricarboxylic acid from citrus is gradually replaced by fermentation.
2-hydroxy-1,2,3-propanetricarboxylic acid was produced by shallow-dish fermentation before 1950. A large-scale production of 2-hydroxy-1,2,3-propanetricarboxylic acid by submerged fermentation was carried out in the laboratory of Myers, USA in 1952.

Since then, the submerged fermentation method was gradually established.
Submerged Fermentation has the advantages of short cycle, high yield, labor saving, small footprint, easy to achieve instrument control and continuous, this manufacturing technology is still the most important manufacturing method.

In this technique, Aspergillus niger is cultured in a medium containing sucrose or glucose to produce 2-hydroxy-1,2,3-propanetricarboxylic acid.
Sources of sugars include corn steep liquor, molasses fermentation broth, hydrolysates of corn flour, or other inexpensive sugar solutions.

After the mold is removed, calcium hydroxide is added to the remaining solution to react the 2-hydroxy-1,2,3-propanetricarboxylic acid to form a calcium citrate precipitate.
After the precipitate is separated, sulfuric acid is added to obtain 2-hydroxy-1,2,3-propanetricarboxylic acid.

PHYSICAL and CHEMICAL PROPERTIES of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
Systematic Name:1,2,3-Propanetricarboxylic acid, 2-hydroxy-
EPA Registry Name:Citric acid
CAS Number:77-92-9
Substance Type:Chemical Substance
Molecular Formula:C6H8O7
Molecular Weight:192.13 g/mol
Molecular Weight: 192.12 g/mol
XLogP3: -1.7
Hydrogen Bond Donor Count: 4
Hydrogen Bond Acceptor Count: 7

Rotatable Bond Count: 5
Exact Mass: 192.02700259 Da
Monoisotopic Mass: 192.02700259 Da
Topological Polar Surface Area: 132 Å²
Heavy Atom Count: 13
Formal Charge: 0
Complexity: 227
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0

Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
Physical State: Small beads
Color: Colorless, or, white
Odor: Odorless
Melting Point/Freezing Point:
Melting point/range: 153 - 159 °C
Initial Boiling Point and Boiling Range:
200 °C at 1.013 hPa - (decomposition)

Flammability (Solid, Gas): No data available
Upper/Lower Flammability or Explosive Limits: No data available
Flash Point: Not applicable
Autoignition Temperature: No data available
Decomposition Temperature: No data available
pH: ca. 1.7 at 100 g/l at 20 °C
Viscosity:
Viscosity, kinematic: No data available
Viscosity, dynamic: No data available
Water Solubility: 1.330 g/l at 20 °C
Partition Coefficient:

n-octanol/water log Pow: -1.72 at 20 °C -
Bioaccumulation is not expected.
Vapor Pressure: < 0.1 hPa at 25 °C
Density: 1.67 g/cm³ at 20 °C
Relative Density: 1.67 at 20 °C
Relative Vapor Density: No data available
Particle Characteristics: No data available
Explosive Properties: No data available
Oxidizing Properties: None
Other Safety Information:
Dissociation Constant: 3.13 at 25 °C

CAS: 77-92-9
EINECS: 201-069-1
InChI: InChI=1/C6H8O7/c7-3(8)1-6(13,5(11)12)2-4(9)10/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)/p-3
InChIKey: KRKNYBCHXYNGOX-UHFFFAOYSA-N
Molecular Formula: C6H8O7
Molar Mass: 192.12
Density: 1.67 g/cm³ at 20 °C
Melting Point: 153-159 °C (lit.)
Boiling Point: 248.08°C (rough estimate)
Flash Point: 100 °C

JECFA Number: 218
Water Solubility: Soluble in water
(1174 g/L at 10°C, 1809 g/L at 30°C, 3825 g/L at 80°C)
Solubility: Soluble in water 750 g/L (20°C), ethanol, ether,
insoluble in benzene, slightly soluble in chloroform
Vapor Pressure: <0.1 hPa (20 °C)
Vapor Density: 7.26 (vs air)
Appearance: White crystalline powder
Color: White
Odor: Odorless

Maximum Wavelength (λmax): ['λ: 260 nm Amax: 0.20',
'λ: 280 nm Amax: 0.10']
Merck: 14,2326
BRN: 782061
pKa: 3.14 (at 20℃)
pH: 3.24 (1 mM solution); 2.62 (10 mM solution);
2.08 (100 mM solution)
Storage Condition: 2-8°C
Stability: Stable.
Incompatible with bases, strong oxidizing agents,
reducing agents, metal nitrates.

Sensitive: Hygroscopic
Explosive Limit: 8%, 65°F
Refractive Index: 1.493~1.509
MDL: MFCD00011669
Chemical Formula: C₆H₈O₇
Molecular Weight: 192.12 g/mol
Appearance: Colorless or white crystalline powder
Density: 1.665 g/cm³
Melting Point: 153°C
Boiling Point: Decomposes before boiling
Solubility: Soluble in water, slightly soluble in ethanol

pH (5% Solution): ~2.2
Flash Point: Non-flammable
Identifiers:
EC Number: 201-069-1
CAS Number: 77-92-9
CAS Number: 77-92-9
EC Number: 201-069-1
Hill Formula: C₆H₈O₇
Chemical Formula: (HOOCCH₂)₂C(OH)COOH
Molar Mass: 192.12 g/mol
HS Code: 2918 14 00
Boiling Point: 200 °C (1013 hPa) (decomposition)
Density: 1.67 g/cm³ (20 °C)

Melting Point: 153 °C (decomposition)
pH Value: 1.7 (100 g/l, H₂O, 20 °C)
Vapor Pressure: <0.1 hPa (25 °C)
Bulk Density: 560 kg/m³
Solubility: 1330 g/l
Molecular Formula / Molecular Weight: C6H8O7 = 192.12
Physical State (20°C): Solid
Storage Temperature: Room Temperature
(Recommended in a cool and dark place, <15°C)
CAS RN: 77-92-9
Reaxys Registry Number: 782061
PubChem Substance ID: 87558243
Merck Index (14): 2326

FIRST AID MEASURES of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Description of first-aid measures
*General advice:
Show this material safety data sheet to the doctor in attendance.
*If inhaled:
After inhalation:
Fresh air.
*In case of skin contact:
Take off immediately all contaminated clothing.
Rinse skin with
water/ shower.
*In case of eye contact:
After eye contact:
Rinse out with plenty of water.
Call in ophthalmologist.
Remove contact lenses.
*If swallowed:
After swallowing:
Immediately make victim drink water (two glasses at most).
Consult a physician.
-Indication of any immediate medical attention and special treatment needed.
No data available

ACCIDENTAL RELEASE MEASURES of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Environmental precautions:
Do not let product enter drains.
-Methods and materials for containment and cleaning up:
Cover drains.
Collect, bind, and pump off spills.
Observe possible material restrictions.
Take up dry.
Dispose of properly.
Clean up affected area.

FIRE FIGHTING MEASURES of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Extinguishing media:
*Suitable extinguishing media:
Carbon dioxide (CO2)
Foam
Dry powder
*Unsuitable extinguishing media:
For this substance/mixture no limitations of extinguishing agents are given.
-Further information:
Prevent fire extinguishing water from contaminating surface water or the ground water system.

EXPOSURE CONTROLS/PERSONAL PROTECTION of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Control parameters:
--Ingredients with workplace control parameters:
-Exposure controls:
--Personal protective equipment:
*Eye/face protection:
Use equipment for eye protection.
Safety glasses
*Body Protection:
protective clothing
*Respiratory protection:
Recommended Filter type: Filter A
-Control of environmental exposure:
Do not let product enter drains.

HANDLING and STORAGE of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Conditions for safe storage, including any incompatibilities:
*Storage conditions:
Tightly closed.
Dry.

STABILITY and REACTIVITY of 2-HYDROXY-1,2,3-PROPANETRICARBOXYLIC ACID:
-Chemical stability:
The product is chemically stable under standard ambient conditions (room temperature) .
-Possibility of hazardous reactions:
No data available