Calcium arsenate

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Calcium arsenate
Calciumarsenaat.png
Arsenian Wapnia.jpg
Names
Other names
Calcium orthoarsenate
Cucumber dust
Tricalcium arsenate
Tricalcium ortho-arsenate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.003
EC Number
  • 233-287-8
KEGG
PubChem CID
RTECS number
  • CG0830000
Properties
Ca3(AsO4)2
Molar mass 398.072 g/mol
Appearancewhite powder
Odor odorless
Density 3.62 g/cm3, solid
Melting point 1,455 °C (2,651 °F; 1,728 K)(decomposes)
0.013 g/100 mL (25 °C) [1]
Solubility in Organic solvents insoluble
Solubility in acids soluble
Hazards
Main hazards carcinogen [2]
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeCalcium arsenate
0
4
0
Flash point noncombustible [2]
Lethal dose or concentration (LD, LC):
20 mg/kg (rat, oral)
812 mg/kg (rat, oral)
794 mg/kg (mouse, oral)
50 mg/kg (rabbit, oral)
38 mg/kg (dog, oral) [3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.010 mg/m3 [2]
REL (Recommended)
Ca C 0.002 mg/m3 [15-minute] [2]
IDLH (Immediate danger)
5 mg/m3 (as As) [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Calcium arsenate is the inorganic compound with the formula Ca3(AsO4)2. A colourless solid, it was originally used as a pesticide and as a germicide. It is highly soluble in water, as compared with lead arsenate, which makes it more toxic. The minerals Rauenthalite Ca3(AsO4)2·10H2O and Phaunouxite Ca3(AsO4)2·11H2O are hydrates of calcium arsenate. [4]

An inorganic compound is typically a chemical compound that lacks C-H bonds, that is, a compound that is not an organic compound, but the distinction is not defined or even of particular interest.

Pesticide substance used to destroy pests

Pesticides are substances that are meant to control pests, including weeds. The term pesticide includes all of the following: herbicide, insecticides nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, antimicrobial, and fungicide. The most common of these are herbicides which account for approximately 80% of all pesticide use. Most pesticides are intended to serve as plant protection products, which in general, protect plants from weeds, fungi, or insects.

Contents

Preparation

Calcium arsenate is commonly prepared from disodium hydrogen arsenate and calcium chloride:

Calcium chloride chemical compound

Calcium chloride is an inorganic compound, a salt with the chemical formula CaCl2. It is a white coloured crystalline solid at room temperature, highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide.

2 Na2H[AsO4] + 3 CaCl2 → 4 NaCl + Ca3[AsO4]2 + 2 HCl

In the 1920s, it was made in large vats by mixing calcium oxide and arsenic oxide. [5] In the United States, 1360 metric tons were produced in 1919, 4540 in 1920, and 7270 in 1922. [1] The composition of commercially available calcium arsenate varies from manufacturer to manufacturer. A typical composition is 80-85% of Ca3(AsO4)2 a basic arsenate probably with a composition of 4CaO.As2O5 together with calcium hydroxide and calcium carbonate. [4]

Use as a herbicide

It was once a common herbicide and insecticide. 38,000,000 kilograms were reported to be produced in 1942 alone, mainly for protection of cotton crops. Its high toxicity led the development of DDT. [6]

DDT Organochloride known for its insecticidal properties

Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochlorine. It was originally developed as an insecticide, then it became infamous for its environmental impacts. DDT was first synthesized in 1874 by the Austrian chemist Othmar Zeidler. DDT's insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to control malaria and typhus among civilians and troops. Müller was awarded the Nobel Prize in Physiology or Medicine in 1948 "for his discovery of the high efficiency of DDT as a contact poison against several arthropods".

Regulation

Calcium arsenate use is now banned in the UK, and its use is strictly regulated in the United States. It is currently the active ingredient in TURF-Cal manufactured by Mallinckrodt, it is one of the few herbicides – used mainly for the control of Poa annua and crabgrass- that hinders earthworm activity. Its label states that it will "reduce and inhibit earthworm activity and survival" and is only recommended against serious earthworm infestations in places such as golf course greens. [7]

<i>Poa annua</i> species of plant

Poa annua, or annual meadow grass, is a widespread low-growing turfgrass in temperate climates. Though P. annua is commonly considered a solely annual plant due to its name, perennial bio-types do exist. Poa (πόα) is Greek for "fodder". It is one of the sweetest grasses for green fodder, but less useful than hay. This grass may have originated as a hybrid between Poa supina and Poa infirma.

<i>Digitaria</i> genus of plants

Digitaria is a genus of plants in the grass family native to tropical and warm temperate regions. Common names include crabgrass, finger-grass, and fonio. They are slender monocotyledonous annual and perennial lawn, pasture, and forage plants; some are often considered lawn pests. Digitus is the Latin word for "finger", and they are distinguished by the long, finger-like inflorescences they produce.

Toxicity and regulation

Calcium arsenate is highly toxic, having both carcinogenic and systemic health effects. [8] The Occupational Safety and Health Administration has set a permissible exposure limit at 0.01 mg/m3 over an eight-hour time-weighted average, while the National Institute for Occupational Safety and Health recommends a limit five times less (0.002 mg/m3). [9]

A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise in both natural and synthetic substances. Carcinogens are not necessarily immediately toxic; thus, their effect can be insidious.

The Occupational Safety and Health Administration (OSHA) is an agency of the United States Department of Labor. Congress established the agency under the Occupational Safety and Health Act, which President Richard M. Nixon signed into law on December 29, 1970. OSHA's mission is to "assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance". The agency is also charged with enforcing a variety of whistleblower statutes and regulations. OSHA is currently headed by Acting Assistant Secretary of Labor Loren Sweatt. OSHA's workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects to employment, sales, credit ratings, or firm survival.

The permissible exposure limit is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational Safety and Health Administration (OSHA). Most of OSHA’s PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970.

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. [10]

Related Research Articles

Arsenic Chemical element with atomic number 33

Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry.

Hydrazine A colorless flammable liquid with an ammonia-like odor

Hydrazine is an inorganic compound with the chemical formula N
2
H
4
. It is a simple pnictogen hydride, and is a colorless and flammable liquid with an ammonia-like odor.

Parathion chemical compound

Parathion, also called parathion-ethyl or diethyl parathion and locally known as "Folidol", is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans, so its use has been banned or restricted in most countries. The basic structure is shared by parathion methyl.

1,4-Dioxane chemical compound

1,4-Dioxane is a heterocyclic organic compound, classified as an ether. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. The compound is often called simply dioxane because the other dioxane isomers are rarely encountered.

Phosphorus trichloride chemical compound

Phosphorus trichloride is a chemical compound of phosphorus and chlorine, having the chemical formula PCl3. It has a trigonal pyramidal shape. It is the most important of the three phosphorus chlorides. It is an important industrial chemical, being used for the manufacture of organophosphorus compounds for a wide variety of applications. It has a 31P NMR signal at around +220 ppm with reference to a phosphoric acid standard.

Vanadium(V) oxide chemical compound

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V2O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

<i>tert</i>-Butyl alcohol chemical compound

tert-Butyl alcohol (TBA), also called tert-butanol or t-butanol, is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). It is one of the four isomers of butanol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

Arsenic trioxide pharmaceutical drug

Arsenic trioxide is an inorganic compound with the formula As
2
O
3
. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds. Approximately 50,000 tonnes are produced annually. Many applications are controversial given the high toxicity of arsenic compounds.

Arsenous acid chemical compound

Arsenous acid (or arsenious acid) is the inorganic compound with the formula H3AsO3. It is known to occur in aqueous solutions, but it has not been isolated as a pure material, although this fact does not detract from the significance of As(OH)3.

Cacodylic acid chemical compound

Cacodylic acid is the organoarsenic compound with the formula (CH3)2AsO2H. With the formula R2As(O)OH, it is the simplest of the organoarsinic acids. It is a colorless solid that is soluble in water.

2,4-Dinitrotoluene chemical compound

2,4-Dinitrotoluene (DNT) or dinitro is an organic compound with the formula C7H6N2O4. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene (TNT) but is mainly produced as a precursor to toluene diisocyanate.

Arsenic pentoxide chemical compound

Arsenic pentoxide is the inorganic compound with the formula As2O5. This glassy, white, deliquescent solid is relatively unstable, consistent with the rarity of the As(V) oxidation state. More common, and far more important commercially, is arsenic(III) oxide (As2O3). All arsenic compounds are highly toxic and thus find only limited commercial applications.

Copper(II) arsenate an insecticide, herbicide, fungicide, and rodenticide

Copper arsenate (Cu3(AsO4)2.4H2O, or Cu5H2(AsO4)4.2H2O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous ammonium and dilute acids. Its CAS number is 7778-41-8 or 10103-61-4.

Monosodium methyl arsonate chemical compound

Monosodium methyl arsenate (MSMA) is an arsenic-based herbicide. It is an organo-arsenate; less toxic than the inorganic form of arsenates. However, the EPA states that all forms of arsenic are a serious risk to human health and the United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites.

Arsenic trichloride chemical compound

Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.

Hexachloroethane chemical compound

Hexachloroethane, also known as perchloroethane (PCA), C2Cl6, is a white crystalline solid at room temperature with a camphor-like odor. It has been used by the military in smoke compositions, such as base-eject smoke munitions (smoke grenades).

Potassium arsenite (KAsO2) is an inorganic compound that exists in two forms, potassium meta-arsenite (KAsO2) and potassium ortho-arsenite (K3AsO3). It is composed of arsenite ions (AsO33− or AsO2) with arsenic always existing in the +3 oxidation state, and potassium existing in the +1 oxidation state. Like many other arsenic containing compounds, potassium arsenite is highly toxic and carcinogenic to humans. Potassium arsenite forms the basis of Fowler’s solution, which was historically used as a medicinal tonic, but due to its toxic nature its use was discontinued. Potassium arsenite is still, however, used as a rodenticide.

<i>o</i>-Anisidine chemical compound

o-Anisidine (2-anisidine) is an organic compound with the formula CH3OC6H4NH2. A colorless liquid, commercial samples can appear yellow owing to air oxidation. It is one of three isomers of the methoxy-containing aniline derivative.

Disodium methyl arsonate chemical compound

Disodium methyl arsonate (DSMA) is the organoarsenic compound with the formula CH3AsO3Na2. It is a colorless, water-soluble solid derived from methanearsonic acid. It is used as a herbicide. Tradenames include Metharsinat, Arrhenal, Disomear, Metharsan, Stenosine, Tonarsan, Tonarsin, Arsinyl, Arsynal, and Diarsen.

4-Nitrochlorobenzene chemical compound

4-Nitrochlorobenzene is the organic compound with the formula ClC6H4NO2. It is a pale yellow solid. 4-Nitrochlorobenzene is a common intermediate in the production of a number of industrially useful compounds, including common antioxidants found in rubber. Other isomers with the formula ClC6H4NO2 include 2-nitrochlorobenzene and 3-nitrochlorobenzene.

References

  1. 1 2 Tartar, H.V.; Wood, L; Hiner, E; A Basic Arsenate of Calcium. J. Am. Chem. Soc. 1924, vol. 46, 809-813.
  2. 1 2 3 4 5 NIOSH Pocket Guide to Chemical Hazards. "#0089". National Institute for Occupational Safety and Health (NIOSH).
  3. "Calcium arsenate (as As)". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 Ropp, Richard (2012). Encyclopedia of the Alkaline Earth Compounds. Newnes. p. 76. ISBN   0444595538.
  5. Smith, C.M.; Murray, C.W.; The Composition of Commercial Calcium Arsenate. Journal of Industrial and Engineering Chemistry; 1931, 23
  6. Robert L. Metcalf "Insect Control" in Ullmann’s Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2002. doi : 10.1002/14356007.a14_263
  7. Koval, C.F. "Turf insect pest control guide: Urban Phytonarian Series" (PDF). College of Agricultural and Life Sciences - University of Wisconsin-Madison. Retrieved 9 November 2018.
  8. Tchounwou, P.B.; Patlolla, A.K.; Centeno, J.A.; Carcinogenic and Systematic Health Effects Associated with Arsenic – A Critical Review. Toxicologic Pathology; 2003, 31, 575-588
  9. "Calcium Arsenate". NIOSH Pocket Guide to Chemical Hazards. Centers for Disease Control and Prevention. 4 April 2011. Retrieved 18 November 2013.
  10. "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (1 July 2008 ed.). Government Printing Office. Archived from the original (PDF) on 25 February 2012. Retrieved 29 October 2011.Cite journal requires |journal= (help)