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Identifiers | |
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3D model (JSmol) | |
1734744 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.010.119 |
EC Number |
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239756 | |
MeSH | C081959 |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 3283 3077 |
CompTox Dashboard (EPA) | |
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Properties | |
SeC(NH2)2 | |
Molar mass | 123.028 g·mol−1 |
Appearance | White solid; pink/grey solid when impure |
Melting point | 200 °C (392 °F; 473 K) |
Boiling point | 214 °C (417 °F; 487 K) |
Hazards | |
GHS labelling: | |
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Danger | |
H301, H331, H373, H410 | |
P260, P261, P264, P270, P271, P273, P301+P310, P304+P340, P311, P314, P321, P330, P391, P403+P233, P405, P501 | |
Related compounds | |
Related compounds | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Selenourea is the organoselenium compound with the chemical formula Se=C(N H 2)2. It is a white solid. This compound features a rare example of a stable, unhindered carbon-selenium double bond. The compound is used in the synthesis of selenium heterocycles. Selenourea is a selenium analog of urea O=C(NH2)2. Few studies have been done on the compound due to the instability and toxicity of selenium compounds. [1] Selenourea is toxic if inhaled or consumed.
The compound was first synthesized in 1884 by Auguste Verneuil by the reaction of hydrogen selenide and cyanamide: [2]
While this reaction has even found use in industrial synthesis of selenourea, [3] more modern methods concern themselves with synthesis of substituted selenoureas. These can be synthesized using organic isoselenocyanates and secondary amines:
Alternatively, isocyanides react with amines in the presence of elemental selenium: [4]
X-ray crystallographic measurements on crystals at −100 °C give average C=Se bond lengths of 1.86 Å, and 1.37 Å for C−N. Both the Se−C−N and N−C−N angles were measured at 120°, as expected for an sp2-hybridized carbon. Through these same studies, the existence of Se−H hydrogen bonding in the crystal lattice—suggested from the O−H and S−H hydrogen bonding found in crystals of urea and thiourea—was confirmed. [5]
Both the shortened length of the N−C bond and the longer Se=C bond suggest a delocalization of the lone pair on the amines; the Se=C π-bonding electrons are drawn towards the selenium atom, while the nitrogen's lone pair is drawn towards the carbonyl carbon. A similar effect is observed in urea and thiourea. In going from urea to thiourea to selenourea the double bond is more delocalized and longer, while the C−N σ bond is stronger and shorter. In terms of resonance structures, the selenol form (structures II, III) is more prevalent compared to urea and thiourea analogs; however, the lone pair the nitrogen of selenourea delocalizes only slightly more than the lone pair on thiourea (in contrast to a much greater delocalization in going from urea to thiourea). [6] These minor differences suggest that the properties emergent from the delocalized nitrogen lone pair and destabilization of the C=S and C=Se π bond in thiourea and selenourea will also be similar.
Unlike urea and thiourea, which have both been researched extensively, [1] relatively few studies quantitatively characterize selenourea. While the selone tautomer (I) has been shown to be the more stable form, [7] mainly qualitative and comparative information on selenourea's tautomerization is available.
In comparable manner to ketones, selones also tautomerize:
Since the greater delocalization of the lone pair electrons correlates with the selone product, the equilibrium position of selenourea likely has an equilibrium position comparable to thiourea's (which is lies more to the right that than urea's). Thiourea has been shown to exist predominantly in its thione form at 42 °C in dilute methanol, with the thionol tautomer almost nonexistent at neutral pH. [8]
An important class of reactions of selenourea is the formation of heterocycles. Some selenium-containing heterocycles exhibit antiinflammatory and antitumor activity, among other medicinal uses. Using selenourea as a precursor is considered to be the most efficient means of selenium-containing heterocyclic synthesis. [9]
Another class of reactions is the complexation of selenourea with transition metals and metalloids. Its ability to act as an effective ligand is attributed to the electron-donating effect of the amino groups and consequent stabilization of the selenium–metal π bond. In selenourea complexes only selenium–metal bonding has been observed, unlike in the urea and thiourea counterparts, which also bond through the nitrogen atom. [10]
In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Formally, amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula R−C(=O)−NR′R″, where R, R', and R″ represent any group, typically organyl groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, as in asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid with the hydroxyl group replaced by an amine group ; or, equivalently, an acyl (alkanoyl) group joined to an amine group.
Urea, also called carbamide, is an organic compound with chemical formula CO(NH2)2. This amide has two amino groups joined by a carbonyl functional group. It is thus the simplest amide of carbamic acid.
Aniline is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starting material for fine chemical synthesis. Its main use is in the manufacture of precursors to polyurethane, dyes, and other industrial chemicals. Like most volatile amines, it has the odor of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds. It is toxic to humans.
In organic chemistry, a dicarbonyl is a molecule containing two carbonyl groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical or unsymmetrical.
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates.
Hydrogen peroxide–urea is a white crystalline solid chemical compound composed of equal amounts of hydrogen peroxide and urea. It contains solid and water-free hydrogen peroxide, which offers a higher stability and better controllability than liquid hydrogen peroxide when used as an oxidizing agent. Often called carbamide peroxide in dentistry, it is used as a source of hydrogen peroxide when dissolved in water for bleaching, disinfection and oxidation.
Tautomers are structural isomers of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydrogen atom within the compound. The phenomenon of tautomerization is called tautomerism, also called desmotropism. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life.
Thiourea is an organosulfur compound with the formula SC(NH2)2 and the structure H2N−C(=S)−NH2. It is structurally similar to urea, except that the oxygen atom is replaced by a sulfur atom ; however, the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. Thioureas are a broad class of compounds with the general structure R2N−C(=S)−NR2.
The cyanate ion is an anion with the chemical formula OCN−. It is a resonance of three forms: [O−−C≡N] (61%) ↔ [O=C=N−] (30%) ↔ [O+≡C−N2−] (4%).
Sulfamic acid, also known as amidosulfonic acid, amidosulfuric acid, aminosulfonic acid, sulphamic acid and sulfamidic acid, is a molecular compound with the formula H3NSO3. This colourless, water-soluble compound finds many applications. Sulfamic acid melts at 205 °C before decomposing at higher temperatures to water, sulfur trioxide, sulfur dioxide and nitrogen.
In organic chemistry, Madelung synthesis is a chemical reaction that produces indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature. The Madelung synthesis was reported in 1912 by Walter Madelung, when he observed that 2-phenylindole was synthesized using N-benzoyl-o-toluidine and two equivalents of sodium ethoxide in a heated, airless reaction. Common reaction conditions include use of sodium or potassium alkoxide as base in hexane or tetrahydrofuran solvents, at temperatures ranging between 200–400 °C. A hydrolysis step is also required in the synthesis. The Madelung synthesis is important because it is one of few known reactions that produce indoles from a base-catalyzed thermal cyclization of N-acyl-o-toluidines.
Cyanamide is an organic compound with the formula CN2H2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol-deterrent drug. The molecule features a nitrile group attached to an amino group. Derivatives of this compound are also referred to as cyanamides, the most common being calcium cyanamide (CaCN2).
Organoselenium chemistry is the science exploring the properties and reactivity of organoselenium compounds, chemical compounds containing carbon-to-selenium chemical bonds. Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are found at trace levels in ambient waters, soils and sediments.
In organic chemistry, thioureas are members of a family of organosulfur compounds with the formula S=C(NR2)2 and structure R2N−C(=S)−NR2. The parent member of this class of compounds is thiourea. Substituted thioureas are found in several commercial chemicals.
Organophosphines are organophosphorus compounds with the formula PRnH3−n, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH3).
Thiourea dioxide or thiox is an organosulfur compound that is used in the textile industry. It functions as a reducing agent. It is a white solid, and exhibits tautomerism.
In organosulfur chemistry, sulfenamides are a class of organosulfur compounds characterized by the general formula R−S−N(−R)2, where the R groups are hydrogen, alkyl, or aryl. Sulfenamides have been used extensively in the vulcanization of rubber using sulfur. They are related to the oxidized compounds known as sulfinamides and sulfonamides.
4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole is an organic compound with the formula SC2N3H(NH2)(N2H3). The compound consists of a 1,2,4-triazole heterocycle with three functional groups: amine, thioamide and hydrazyl. X-ray crystallography shows that this molecule is polar but with a C=S double bond. It is prepared by the reaction of hydrazine with thiourea:
An N-Heterocyclic silylene (NHSi) is an uncharged heterocyclic chemical compound consisting of a divalent silicon atom bonded to two nitrogen atoms. The isolation of the first stable NHSi, also the first stable dicoordinate silicon compound, was reported in 1994 by Michael Denk and Robert West three years after Anthony Arduengo first isolated an N-heterocyclic carbene, the lighter congener of NHSis. Since their first isolation, NHSis have been synthesized and studied with both saturated and unsaturated central rings ranging in size from 4 to 6 atoms. The stability of NHSis, especially 6π aromatic unsaturated five-membered examples, make them useful systems to study the structure and reactivity of silylenes and low-valent main group elements in general. Though not used outside of academic settings, complexes containing NHSis are known to be competent catalysts for industrially important reactions. This article focuses on the properties and reactivity of five-membered NHSis.
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