Selenourea

Last updated
Selenourea
Selenourea.svg
Selenourea-3D-spacefill.png
   Carbon, C
   Hydrogen, H
   Nitrogen, N
   Selenium
Identifiers
3D model (JSmol)
1734744
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.010.119 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 211-129-9
239756
MeSH C081959
PubChem CID
RTECS number
  • YU1820000
UNII
UN number 3283 3077
  • InChI=1S/CH4N2Se/c2-1(3)4/h(H4,2,3,4) X mark.svgN
    Key: IYKVLICPFCEZOF-UHFFFAOYSA-N X mark.svgN
  • InChI=1/CH4N2Se/c2-1(3)4/h(H4,2,3,4)
    Key: IYKVLICPFCEZOF-UHFFFAOYAJ
  • NC(N)=[Se]
Properties
SeC(NH2)2
Molar mass 123.028 g·mol−1
AppearanceWhite 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:
GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
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).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

Synthesis

The compound was first synthesized in 1884 by Auguste Verneuil by the reaction of hydrogen selenide and cyanamide: [2]

H2Se + N≡C−NH2 → Se=C(NH2)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:

R−N=C=Se + NHR′R″ → Se=C(−NHR)(−NR′R″)

Alternatively, isocyanides react with amines in the presence of elemental selenium: [4]

RN≡C + R'2NH + Se → R(H)NC(Se)NR'2

Properties

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.

Resonance.gif

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:

Selenourea Tautomers.gif

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]

Reactivity

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]

Related Research Articles

<span class="mw-page-title-main">Amine</span> Chemical compounds and groups containing nitrogen with a lone pair (:N)

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.

<span class="mw-page-title-main">Amide</span> Organic compounds of the form RC(=O)NR′R″

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.

<span class="mw-page-title-main">Aniline</span> Organic compound (C₆H₅NH₂); simplest aromatic amine

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.

<span class="mw-page-title-main">Dicarbonyl</span> Molecule containing two adjacent C=O groups

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.

<span class="mw-page-title-main">Enamine</span> Class of chemical compounds

An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates.

<span class="mw-page-title-main">Hydrogen peroxide–urea</span> Chemical compound

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.

<span class="mw-page-title-main">Tautomer</span> Isomers of chemical compounds that interconvert

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.

<span class="mw-page-title-main">Thiourea</span> Organosulfur compound (S=C(NH2)2)

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.

<span class="mw-page-title-main">Sulfamic acid</span> Chemical compound

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.

<span class="mw-page-title-main">Tetrasulfur tetranitride</span> Chemical compound

Tetrasulfur tetranitride is an inorganic compound with the formula S4N4. This vivid orange, opaque, crystalline explosive is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen. It is a precursor to many S-N compounds and has attracted wide interest for its unusual structure and bonding.

<span class="mw-page-title-main">Cyanamide</span> Chemical compound featuring a nitrile group attached to an amino group

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).

<span class="mw-page-title-main">Ethylenediamine</span> Chemical compound

Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a basic amine. It is a widely used building block in chemical synthesis, with approximately 500,000 tonnes produced in 1998. Ethylenediamine is the first member of the so-called polyethylene amines.

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.

<span class="mw-page-title-main">Thioureas</span> Organosulfur compounds with an >NC(=S)N< structure

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).

<span class="mw-page-title-main">Thiourea dioxide</span> Chemical compound

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.

<span class="mw-page-title-main">Sulfenamide</span> Molecules of the form >N–S–

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.

<span class="mw-page-title-main">4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole</span> Chemical compound

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:

<i>N</i>-heterocyclic silylene Chemical compound

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.

References

  1. 1 2 Koketsu, M.; Ishihara, H. (2006). "Thiourea and selenourea and their applications". Current Organic Synthesis. 3 (4): 439–455. doi:10.2174/157017906778699521.
  2. ↑ Hope, H. (1964). "Synthesis of selenourea". Acta Chemica Scandinavica. 18: 1800. doi: 10.3891/acta.chem.scand.18-1800 .
  3. ↑ Suvorov, V.; et al. (1996). "Production of selenourea of high purity". Vysokochistye Veshchestva. 3: 17–23.
  4. ↑ Campos, Michael P.; Hendricks, Mark P.; Beecher, Alexander N.; Walravens, Willem; Swain, Robert A.; Cleveland, Gregory T.; Hens, Zeger; Sfeir, Matthew Y.; Owen, Jonathan S. (2017). "A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit". Journal of the American Chemical Society. 139 (6): 2296–2305. doi:10.1021/jacs.6b11021. OSTI   1437942. PMID   28103035.
  5. ↑ Rutherford, J. S.; Calvo, C. (1969). "The crystal structure of selenourea". Zeitschrift für Kristallographie. 128 (3–6): 229–258. Bibcode:1969ZK....128..229R. doi:10.1524/zkri.1969.128.3-6.229. S2CID   98443594.
  6. ↑ Hampson, P.; Mathias, A. (1968). "Nitrogen-14 chemical shifts in ureas". Journal of the Chemical Society B. 1968: 673–675. doi:10.1039/J29680000673..
  7. ↑ Rostkowska, H.; et al. (2004). "Proton transfer processes in selenourea: UV-induced selenone → selenol photoreaction and ground state selenol → selone proton tunneling". Chemical Physics. 298 (1–3): 223–232. Bibcode:2004CP....298..223R. doi:10.1016/j.chemphys.2003.11.024.
  8. ↑ Pramanick, D.; Chatterjee, A. K. (1980). "Thiourea as a transfer agent in the radical polymerization of methyl methacrylate in aqueous solution at 42°". European Polymer Journal. 16 (9): 895–899. Bibcode:1980EurPJ..16..895P. doi:10.1016/0014-3057(80)90122-6.
  9. ↑ Ninomiya, M.; et al. (2010). "Selenium-containing heterocycles using selenoamides, selenoureas, selenazadienes, and isoselenocyanates". Heterocycles. 81 (9): 2027–2055. doi: 10.3987/REV-10-677 .
  10. ↑ Jones, P. G.; Thöne, C. (1991). "Preparation, crystal structures and reactions of phosphine(selenourea)gold(I) complexes". Chemische Berichte. 124: 2725–2729. doi:10.1002/cber.19911241213.
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