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46-436: Unsymmetrical dimethylhydrazine (abbreviated as UDMH ; also known as 1,1-dimethylhydrazine , heptyl or Geptil ) is a chemical compound with the formula H 2 NN(CH 3 ) 2 that is primarily used as a rocket propellant . At room temperature, UDMH is a colorless liquid, with a sharp, fishy, ammonia-like smell typical of organic amines . Samples turn yellowish on exposure to air and absorb oxygen and carbon dioxide . It

92-424: A chemical compound ; the concept is most readily understood when considering pure chemical substances . It follows from their being composed of fixed proportions of two or more types of atoms that chemical compounds can be converted, via chemical reaction , into compounds or substances each having fewer atoms. A chemical formula is a way of expressing information about the proportions of atoms that constitute

138-419: A solid-state reaction , or the electron transfer reaction of reactive metals with reactive non-metals, such as halogen gases. Ionic compounds typically have high melting and boiling points , and are hard and brittle . As solids they are almost always electrically insulating , but when melted or dissolved they become highly conductive , because the ions are mobilized. An intermetallic compound

184-466: A ... white Powder ... with Sulphur it will compose a blood-red and volatile Cinaber. And yet out of all these exotick Compounds, we may recover the very same running Mercury. Boyle used the concept of "corpuscles"—or "atomes", as he also called them—to explain how a limited number of elements could combine into a vast number of compounds: If we assigne to the Corpuscles, whereof each Element consists,

230-530: A compound molecule, using the standard chemical symbols with numerical subscripts . Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service . Globally, more than 350,000 chemical compounds (including mixtures of chemicals) have been registered for production and use. The term "compound"—with a meaning similar to the modern—has been used at least since 1661 when Robert Boyle's The Sceptical Chymist

276-412: A continuous three-dimensional network, usually in a crystalline structure . Ionic compounds containing basic ions hydroxide (OH ) or oxide (O ) are classified as bases. Ionic compounds without these ions are also known as salts and can be formed by acid–base reactions . Ionic compounds can also be produced from their constituent ions by evaporation of their solvent , precipitation , freezing ,

322-585: A different chemical composition by interaction with a second chemical compound via a chemical reaction . In this process, bonds between atoms are broken in both of the interacting compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AD + CB , where A, B, C, and D are each unique atoms; and AB, AD, CD, and CB are each unique compounds. Dimethylnitrosamine Of more general concern, NDMA can be produced by water treatment by chlorination or chloramination . The question

368-548: A lifetime risk of cancer exceeding 1 in 100,000 from nitrosamines in their medicines. EU regulators first became aware of nitrosamines in medicines in mid-2018, and took regulatory actions, including recalling medicines and stopping the use of active substances from certain manufacturers. A subsequent CHMP review of sartan blood-pressure medicines in 2019, led to new requirements for the manufacture of sartans, while its 2020 review of ranitidine recommended an EU-wide suspension of ranitidine medicines. The C 2 N 2 O core of NDMA

414-471: A mixture of 50% hydrazine and 50% UDMH, called Aerozine 50 , in different stages. There is speculation that it is the fuel used in the ballistic missiles that North Korea has developed and tested in 2017. Hydrazine and its methyl derivatives are toxic but LD50 values have not been reported. It is a precursor to dimethylnitrosamine , which is carcinogenic. According to scientific data, usage of UDMH in rockets at Baikonur Cosmodrome has had adverse effects on

460-505: A mixture. UDMH is used in many European, Russian, Indian, and Chinese rocket designs. The Russian SS-11 Sego (aka 8K84) ICBM, SS-19 Stiletto (aka 15A30) ICBM, Proton , Kosmos-3M , R-29RMU2 Layner , R-36M , Rokot (based on 15A30) and the Chinese Long March 2 are the most notable users of UDMH (which is referred to as "heptyl" (codename from Soviet era ) by Russian engineers). The Titan , GSLV , and Delta rocket families use

506-651: A number of manufacturers, resulting in recalls. In April 2020, ranitidine was withdrawn from the United States market, suspended in the European Union, and suspended in Australia due to concerns about NDMA. In August 2021, a class 2 medicines recall was issued for a batch of metformin hydrochloride 500 mg/5ml Oral Solution from Rosemont Pharmaceuticals Limited, which was first distributed in December 2020, due to

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552-566: A particular chemical compound, using chemical symbols for the chemical elements, and subscripts to indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds , the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium hydride , PdH x (0.02 < x < 0.58)]. Chemical compounds have

598-796: A peculiar size and shape ... such ... Corpuscles may be mingled in such various Proportions, and ... connected so many ... wayes, that an almost incredible number of ... Concretes may be compos’d of them. In his Logick , published in 1724, the English minister and logician Isaac Watts gave an early definition of chemical element, and contrasted element with chemical compound in clear, modern terms. Among Substances, some are called Simple, some are Compound ... Simple Substances ... are usually called Elements, of which all other Bodies are compounded: Elements are such Substances as cannot be resolved, or reduced, into two or more Substances of different Kinds. ... Followers of Aristotle made Fire, Air, Earth and Water to be

644-496: A positively charged cation . The nonmetal will gain the electrons from the metal, making the nonmetal a negatively charged anion . As outlined, ionic bonds occur between an electron donor, usually a metal, and an electron acceptor, which tends to be a nonmetal. Hydrogen bonding occurs when a hydrogen atom bonded to an electronegative atom forms an electrostatic connection with another electronegative atom through interacting dipoles or charges. A compound can be converted to

690-716: A postgraduate medical student at Fudan University , was the victim of a poisoning in Shanghai , China . Huang was poisoned by his roommate Lin Senhao, who had placed NDMA into the water cooler in their dormitory. Lin claimed that he only did this as an April Fool's joke. He received a death sentence, and was executed in 2015. In 2018, NDMA was used in an attempted poisoning at Queen's University in Kingston, Canada. In 2018, and then again in 2019, various brands of valsartan were recalled because of contamination with NDMA. In 2019, ranitidine

736-447: A solid state dependent on how low the temperature of the environment is. A covalent bond , also known as a molecular bond, involves the sharing of electrons between two atoms. Primarily, this type of bond occurs between elements that fall close to each other on the periodic table of elements , yet it is observed between some metals and nonmetals. This is due to the mechanism of this type of bond. Elements that fall close to each other on

782-469: A unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds . Chemical compounds can be molecular compounds held together by covalent bonds , salts held together by ionic bonds , intermetallic compounds held together by metallic bonds , or the subset of chemical complexes that are held together by coordinate covalent bonds . Pure chemical elements are generally not considered chemical compounds, failing

828-416: Is miscible with water, ethanol , and kerosene . At concentrations between 2.5% and 95% in air, its vapors are flammable. It is not sensitive to shock. Symmetrical dimethylhydrazine (1,2-dimethylhydrazine) also exists, but it is not as useful. UDMH can be oxidized in air to form many different substances, including toxic ones. In 1875, UDMH was first prepared by Emil Fischer , who discovered and named

874-523: Is a "potent hepatotoxin that can cause fibrosis of the liver " in rats. The induction of liver tumors in rats after chronic exposure to low doses is well documented. Its toxic effects on humans are inferred from animal experiments, but not well-established experimentally. 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

920-403: Is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. They can be classified as stoichiometric or nonstoichiometric intermetallic compounds. A coordination complex consists of a central atom or ion, which is usually metallic and is called

966-493: Is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions . These can be simple ions such as the sodium (Na ) and chloride (Cl ) in sodium chloride , or polyatomic species such as the ammonium ( NH 4 ) and carbonate ( CO 3 ) ions in ammonium carbonate . Individual ions within an ionic compound usually have multiple nearest neighbours, so are not considered to be part of molecules, but instead part of

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1012-540: Is of particular concern due to the minute concentrations at which it is harmful and the difficulty in detecting it at these concentrations. Relatively high levels of UV radiation in the 200 to 260  nm range breaks the N–N bond. Thus, it can be used to degrade NDMA. Additionally, reverse osmosis removes approximately 50% of NDMA. NDMA is found at low levels in numerous items of human consumption, including cured meat, fish, beer, as well as during use of tobacco products and

1058-475: Is planar, as established by X-ray crystallography . The central nitrogen is bound to two methyl groups and the NO group with bond angles of 120°. The N-N and N-O distances are 1.32 and 1.26 Å, respectively. NDMA forms from a variety of dimethylamine-containing compounds, e.g. hydrolysis of dimethylformamide . Dimethylamine is susceptible to oxidation to unsymmetrical dimethylhydrazine , which air-oxidizes to NDMA. In

1104-826: Is subject to strict reporting requirements by facilities that produce, store, or use it in significant quantities. In July 2020, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) issued an opinion requiring companies to take measures to limit the presence of nitrosamines in human medicines as far as possible and to ensure levels of these impurities do not exceed set limits. Nitrosamines are classified as probable human carcinogens (substances that could cause cancer). The limits for nitrosamines in medicines have been set using internationally agreed standards (ICH M7(R1)) based on lifetime exposure. Generally, people should not be exposed to

1150-405: Is the level at which it is produced. In the U.S. state of California, the allowable level is 10 nanograms/liter. The Canadian province of Ontario set the standard at 9 ng/L. The potential problem is greater for recycled water that can contain dimethylamine . Further, NDMA can form or be leached during treatment of water by anion exchange resins . Contamination of drinking water with NDMA

1196-480: The Olin Raschig process , one method involves reaction of monochloramine with dimethylamine giving 1,1-dimethylhydrazinium chloride: In the presence of suitable catalysts, acetylhydrazine can be N-dimethylated using formaldehyde and hydrogen to give the N,N-dimethyl-N'-acetylhydrazine, which can subsequently be hydrolyzed: UDMH is often used in hypergolic rocket fuels as a bipropellant in combination with

1242-452: The coordination centre , and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those of transition metals , are coordination complexes. A coordination complex whose centre is a metal atom is called a metal complex of d block element. Compounds are held together through a variety of different types of bonding and forces. The differences in

1288-449: The oxygen molecule (O 2 ); or it may be heteronuclear , a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that still carries all the physical and chemical properties of that substance. An ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding . The compound

1334-459: The Earth. Other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. A molecule may be homonuclear , that is, it consists of atoms of one chemical element, as with two atoms in

1380-518: The OMS in the Space Shuttle or maneuvering engines , monomethylhydrazine is used instead due to its slightly higher specific impulse . In some kerosene-fueled rockets, UDMH functions as a starter fuel to start combustion and warm the rocket engine prior to switching to kerosene. UDMH has higher stability than hydrazine, especially at elevated temperatures, and can be used as its replacement or together in

1426-524: The Truth ;; tho' they are not all agreed ... Compound Substances are made up of two or more simple Substances ... So a Needle is simple Body, being made only of Steel; but a Sword or a Knife is a compound because its ... Handle is made of Materials different from the Blade. Any substance consisting of two or more different types of atoms ( chemical elements ) in a fixed stoichiometric proportion can be termed

Unsymmetrical dimethylhydrazine - Misplaced Pages Continue

1472-424: The class of hydrazines , by reducing N-Nitrosodimethylamine with zinc in boiling acetic acid . Fischer's student Edward Renouf later studied UDMH more extensively as part of his doctoral dissertation. Other historical lab routes include methylation of hydrazine , reduction of nitrodimethylamine and amination of dimethylamine with aminopersulfuric acid. UDMH is produced industrially by two routes. Based on

1518-431: The constituent atoms are bonded together. Molecular compounds are held together by covalent bonds ; ionic compounds are held together by ionic bonds ; intermetallic compounds are held together by metallic bonds ; coordination complexes are held together by coordinate covalent bonds . Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in

1564-610: The environment. Chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities ) containing atoms from more than one chemical element held together by chemical bonds . A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction , which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how

1610-400: The fixed ratios. Many solid chemical substances—for example many silicate minerals —are chemical substances, but do not have simple formulae reflecting chemically bonding of elements to one another in fixed ratios; even so, these crystalline substances are often called " non-stoichiometric compounds ". It may be argued that they are related to, rather than being chemical compounds, insofar as

1656-508: The four Elements, of which all earthly Things were compounded; and they suppos'd the Heavens to be a Quintessence, or fifth sort of Body, distinct from all these : But, since experimental Philosophy ... have been better understood, this Doctrine has been abundantly refuted. The Chymists make Spirit, Salt, Sulphur, Water and Earth to be their five Elements, because they can reduce all terrestrial Things to these five : This seems to come nearer

1702-522: The inhalation of tobacco smoke. Unsymmetrical dimethylhydrazine , a rocket fuel, is a highly effective precursor to NDMA: Groundwater near rocket launch sites often has high levels of NDMA. The United States Environmental Protection Agency (EPA) determined that the maximal admissible concentration of NDMA in drinking water is 7 ng/L. As of July 2020, the EPA has not set a regulatory maximal contaminant level (MCL) for drinking water. At high doses, it

1748-558: The laboratory, NDMA can be synthesised by the reaction of nitrous acid with dimethylamine : The mechanism of its carcinogenicity involves metabolic activation steps resulting in the formation of methyldiazonium , an alkylating agent . Several incidents in which NDMA was used intentionally to poison another person have garnered media attention. In 1978, a teacher in Ulm, Germany, was sentenced to life in prison for trying to murder his wife by poisoning jam with NDMA and feeding it to her. Both

1794-477: The oxidizer nitrogen tetroxide and less frequently with IRFNA (inhibited red fuming nitric acid) or liquid oxygen . UDMH is a derivative of hydrazine and is sometimes referred to as a hydrazine. As a fuel, it is described in specification MIL-PRF-25604 in the United States. UDMH is stable and can be kept loaded in rocket fuel systems for long periods, which makes it appealing for use in many liquid rocket engines, despite its cost. In some applications, such as

1840-536: The periodic table tend to have similar electronegativities , which means they have a similar affinity for electrons. Since neither element has a stronger affinity to donate or gain electrons, it causes the elements to share electrons so both elements have a more stable octet . Ionic bonding occurs when valence electrons are completely transferred between elements. Opposite to covalent bonding, this chemical bond creates two oppositely charged ions. The metals in ionic bonding usually lose their valence electrons, becoming

1886-494: The two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H 2 , or the polyatomic molecule S 8 , etc.). Many chemical compounds have a unique numerical identifier assigned by the Chemical Abstracts Service (CAS): its CAS number . There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, which require

Unsymmetrical dimethylhydrazine - Misplaced Pages Continue

1932-455: The types of bonds in compounds differ based on the types of elements present in the compound. London dispersion forces are the weakest force of all intermolecular forces . They are temporary attractive forces that form when the electrons in two adjacent atoms are positioned so that they create a temporary dipole . Additionally, London dispersion forces are responsible for condensing non polar substances to liquids, and to further freeze to

1978-421: The variability in their compositions is often due to either the presence of foreign elements trapped within the crystal structure of an otherwise known true chemical compound , or due to perturbations in structure relative to the known compound that arise because of an excess of deficit of the constituent elements at places in its structure; such non-stoichiometric substances form most of the crust and mantle of

2024-536: The wife and the teacher later died from liver failure. That same year, Steven Roy Harper spiked lemonade with NDMA at the Johnson family home in Omaha , Nebraska . The incident resulted in the deaths of 30-year-old Duane Johnson and 11-month-old Chad Shelton. For his crime, Harper was sentenced to death, but committed suicide in prison before his execution could be carried out. In the 2013 Fudan poisoning case , Huang Yang,

2070-409: Was published. In this book, Boyle variously used the terms "compound", "compounded body", "perfectly mixt body", and "concrete". "Perfectly mixt bodies" included for example gold, lead, mercury, and wine. While the distinction between compound and mixture is not so clear, the distinction between element and compound is a central theme. Quicksilver ... with Aqua fortis will be brought into

2116-575: Was recalled around the world due to contamination with NDMA. In December 2019, the FDA began testing samples of the diabetes drug metformin for NDMA. The FDA announcement followed a recall of three versions of metformin in Singapore, and the European Medicines Agency's request that manufacturers test for NDMA. In September 2019, N -nitrosodimethylamine was discovered in ranitidine products from

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