Diimide

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Diimide
Ball and stick model of diazene ((E)-diazene) Trans-diazene-2D.png
Ball and stick model of diazene ((E)-diazene)
E/trans-diazene
Structural formula of diazene ((E)-diazene) Trans-diazene-3D-balls.png
Structural formula of diazene ((E)-diazene)
Structural formula of diazene ((Z)-diazene) Cis-diazene-2D.png
Structural formula of diazene ((Z)-diazene)
Z/cis-diazene
Ball and stick model of diazene ((Z)-diazene) Cis-diazene-3D-balls.png
Ball and stick model of diazene ((Z)-diazene)
Names
IUPAC name
Diazene
Other names
Diimide
Diimine
Dihydridodinitrogen
Azodihydrogen
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
KEGG
MeSH Diazene
PubChem CID
UNII
  • InChI=1S/H2N2/c1-2/h1-2H Yes check.svgY
    Key: RAABOESOVLLHRU-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/H2N2/c1-2/h1-2H
    Key: RAABOESOVLLHRU-UHFFFAOYAG
  • N=N
Properties
H2N2
Molar mass 30.030 g·mol−1
AppearanceYellow gas
Melting point −80 °C (−112 °F; 193 K)
Related compounds
Other anions
diphosphene
dinitrogen difluoride
Other cations
azo compounds
Related Binary azanes
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 ?)

Diimide, also called diazene or diimine, is a compound having the formula HN=NH. It exists as two geometric isomers, E (trans) and Z (cis). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is an example of an organic diazene.

Contents

Synthesis

A traditional route to diimide involves oxidation of hydrazine with hydrogen peroxide or air. [1]

N2H4 + H2O2 → N2H2 + 2H2O

Alternatively the hydrolysis of diethyl azodicarboxylate or azodicarbonamide affords diimide: [2]

Et−O2C−N=N−CO2−Et → HN=NH + 2 CO2 + 2 HOEt

Nowadays, diimide is generated by thermal decomposition of 2,4,6‐triisopropylbenzenesulfonylhydrazide. [3]

Because of its instability, diimide is generated and used in-situ. A mixture of both the cis (Z-) and trans (E-) isomers is produced. Both isomers are unstable, and they undergo a slow interconversion. The trans isomer is more stable, but the cis isomer is the one that reacts with unsaturated substrates, therefore the equilibrium between them shifts towards the cis isomer due to Le Chatelier's principle. Some procedures call for the addition of carboxylic acids, which catalyse the cis–trans isomerization. [4] Diimide decomposes readily. Even at low temperatures, the more stable trans isomer rapidly undergoes various disproportionation reactions, primarily forming hydrazine and nitrogen gas: [5]

2 HN=NH → H2N−NH2 + N2

Because of this competing decomposition reaction, reductions with diimide typically require a large excess of the precursor reagent.

Applications to organic synthesis

Diimide is occasionally useful as a reagent in organic synthesis. [4] It hydrogenates alkenes and alkynes with selective delivery of hydrogen from one face of the substrate resulting in the same stereoselectivity as metal-catalysed syn addition of H2. The only coproduct released is nitrogen gas. Although the method is cumbersome, the use of diimide avoids the need for high pressures or hydrogen gas and metal catalysts, which can be expensive. [6] The hydrogenation mechanism involves a six-membered C2H2N2 transition state:

DiimineReduction.png

Selectivity

Diimide is advantageous because it selectively reduces alkenes and alkynes and is unreactive toward many functional groups that would interfere with normal catalytic hydrogenation. Thus, peroxides, alkyl halides, and thiols are tolerated by diimide, but these same groups would typically be degraded by metal catalysts. The reagent preferentially reduces alkynes and unhindered or strained alkenes [1] to the corresponding alkenes and alkanes. [4]

The dicationic form, H−N+≡N+−H (diazynediium, diprotonated dinitrogen), is calculated to have the strongest known chemical bond. This ion can be thought of as a doubly protonated nitrogen molecule. The relative bond strength order (RBSO) is 3.38. [7] F−N+≡N+−H (fluorodiazynediium ion) and F−N+≡N+−F (difluorodiazynediium ion) have slightly lower strength bonds. [7]

In the presence of strong bases, diimide deprotonates to form the pernitride anion, N=N.

Related Research Articles

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In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.

<span class="mw-page-title-main">Azo compound</span> Organic compounds with a diazenyl group (–N=N–)

Azo compounds are organic compounds bearing the functional group diazenyl.

The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups. In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of activating an intermediate in a preceding step. As such, there is no obvious retron for this reaction. The reaction was reported by Nikolai Kischner in 1911 and Ludwig Wolff in 1912.

<span class="mw-page-title-main">Hydrazoic acid</span> Unstable and toxic chemical compound

Hydrazoic acid, also known as hydrogen azide, azic acid or azoimide, is a compound with the chemical formula HN3. It is a colorless, volatile, and explosive liquid at room temperature and pressure. It is a compound of nitrogen and hydrogen, and is therefore a pnictogen hydride. The oxidation state of the nitrogen atoms in hydrazoic acid is fractional and is -1/3. It was first isolated in 1890 by Theodor Curtius. The acid has few applications, but its conjugate base, the azide ion, is useful in specialized processes.

In chemistry, a trimer is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization.

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

Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas under standard conditions, whereas the other is an aqueous solution of the gas. They are interconvertible. HI is used in organic and inorganic synthesis as one of the primary sources of iodine and as a reducing agent.

<span class="mw-page-title-main">Iminium</span> Polyatomic ion of the form >C=N< and charge +1

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Hydrazides in organic chemistry are a class of organic compounds with the formula R−NR1−NR2R3 where R is acyl, sulfonyl, phosphoryl, phosphonyl and similar groups, R1, R2, R3 and R' are any groups. Unlike hydrazine and alkylhydrazines, hydrazides are nonbasic owing to the inductive influence of the acyl, sulfonyl, or phosphoryl substituent.

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

Chloroplatinic acid (also known as hexachloroplatinic acid) is an inorganic compound with the formula [H3O]2[PtCl6](H2O)x (0 ≤ x ≤ 6). A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Although often written in shorthand as H2PtCl6, it is the hydronium (H3O+) salt of the hexachloroplatinate anion (PtCl2−
6
). Hexachloroplatinic acid is highly hygroscopic.

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Benzylideneacetone is the organic compound described by the formula C6H5CH=CHC(O)CH3. Although both cis- and trans-isomers are possible for the α,β-unsaturated ketone, only the trans isomer is observed. Its original preparation demonstrated the scope of condensation reactions to construct new, complex organic compounds. Benzylideneacetone is used as a flavouring ingredient in food and perfumes.

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

An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to nitrones and participate in [3+2] cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center.

<span class="mw-page-title-main">Cyclopentadienyliron dicarbonyl dimer</span> Chemical compound

Cyclopentadienyliron dicarbonyl dimer is an organometallic compound with the formula [(η5-C5H5)Fe(CO)2]2, often abbreviated to Cp2Fe2(CO)4, [CpFe(CO)2]2 or even Fp2, with the colloquial name "fip dimer". It is a dark reddish-purple crystalline solid, which is readily soluble in moderately polar organic solvents such as chloroform and pyridine, but less soluble in carbon tetrachloride and carbon disulfide. Cp2Fe2(CO)4 is insoluble in but stable toward water. Cp2Fe2(CO)4 is reasonably stable to storage under air and serves as a convenient starting material for accessing other Fp (CpFe(CO)2) derivatives (described below).

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

Sulfur diimides are chemical compounds of the formula S(NR)2. Structurally, they are the diimine of sulfur dioxide. The parent member, S(NH)2, is of only theoretical interest. Other derivatives where R is an organic group are stable and useful reagents.

In organic chemistry, the Myers allene synthesis is a chemical reaction that converts a propargyl alcohol into an allene by way of an arenesulfonylhydrazine as a key intermediate. This name reaction is one of two discovered by Andrew Myers that are named after him; both this reaction and the Myers deoxygenation reaction involve the same type of intermediate.

Cobalt compounds are chemical compounds formed by cobalt with other elements.

References

  1. 1 2 Ohno, M.; Okamoto, M. (1973). "cis-Cyclododecene". Organic Syntheses ; Collected Volumes, vol. 5, p. 281.
  2. Wiberg, E.; Holleman, A. F. (2001). "1.2.7: Diimine, N2H2". Inorganic Chemistry. Elsevier. p. 628. ISBN   9780123526519.
  3. Chamberlin, A. Richard; Sheppeck, James E.; Somoza, Alvaro (2008). "2,4,6-Triisopropylbenzenesulfonylhydrazide". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt259.pub2. ISBN   978-0471936237.
  4. 1 2 3 Pasto, D. J. (2001). "Diimide". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rd235. ISBN   0471936235.
  5. Wiberg, Nils; Holleman, A. F.; Wiberg, Egon, eds. (2001). "1.2.7 Diimine N2H2 [1.13.17]". Inorganic Chemistry. Academic Press. pp. 628–632. ISBN   978-0123526519.
  6. Miller, C. E. (1965). "Hydrogenation with Diimide". Journal of Chemical Education. 42 (5): 254–259. Bibcode:1965JChEd..42..254M. doi:10.1021/ed042p254.
  7. 1 2 Kalescky, Robert; Kraka, Elfi; Cremer, Dieter (12 September 2013). "Identification of the Strongest Bonds in Chemistry". The Journal of Physical Chemistry A. 117 (36): 8981–8995. Bibcode:2013JPCA..117.8981K. doi:10.1021/jp406200w. PMID   23927609. S2CID   11884042.