Dinitrogen tetroxide
chemical compound
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russian rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium mixture with nitrogen dioxide. Its molar mass is 92.011 g/mol.
Dinitrogen tetroxide is a powerful oxidizer that is hypergolic (spontaneously ignites) upon contact with various forms of hydrazine, which has made the pair a common bipropellant for rockets.
Structure and properties
Dinitrogen tetroxide could be regarded as two nitro groups (-NO2) bonded together. It forms an equilibrium mixture with nitrogen dioxide. The molecule is planar with an N-N bond distance of 1.78 Å and N-O distances of 1.19 Å. The N-N distance corresponds to a weak bond, since it is significantly longer than the average N-N single bond length of 1.45 Å. This exceptionally weak σ bond (amounting to overlapping of the sp2 hybrid orbitals of the two NO2 units) results from the simultaneous delocalization of the bonding electron pair across the whole N2O4 molecule, and the considerable electrostatic repulsion of the doubly occupied molecular orbitals of each NO2 unit.
Unlike NO2, N2O4 is diamagnetic since it has no unpaired electrons. The liquid is also colorless but can appear as a brownish-yellow liquid due to the presence of NO2 according to the following equilibrium:
N2O4 ⇌ 2 NO2 (ΔH = +57.23 kJ/mol)
Higher temperatures push the equilibrium towards nitrogen dioxide.
The public source identifies “Dinitrogen tetroxide” as chemical compound. This brief keeps that definition visible, then builds a research path around Dinitrogen, tetroxide and chemical.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Dinitrogen tetroxide”, the useful work is to connect “chemical compound” to the records capable of establishing context and consequence.
Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Sep 3, 2026. The linked authority identifier is Q382984. The Library of Congress control number is sh2001002918. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
Scientific names, classifications and consensus can change while older terminology persists in catalogues and historical literature. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Check terminology, classification and the date of the cited evidence. Scientific names and technical consensus can change while older records retain historical value.
- Current terminology
- Classification context
- Finding cited technical literature
Primary datasets, specimen catalogues, standards bodies and the most recent peer-reviewed literature.
Three-step research path
- Establish the record: confirm the title “Dinitrogen tetroxide”, its source revision and the description used here.
- Expand the search: follow Dinitrogen tetroxide primary sources, Dinitrogen tetroxide archive and Dinitrogen research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Dinitrogen tetroxide”?
- Which observation, specimen, dataset or publication supports the account?
- Has classification or technical consensus changed since the cited source?
Search terms from this dossier
This entry incorporates text from “Dinitrogen tetroxide” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.