Guideview >  Articles >  Property  > Bromine dioxide radical Polarity

Bromine dioxide radical Polarity

Bromine dioxide radical (CAS 21255-83-4) is polar. It is polar by symmetry, but no dipole magnitude is quoted. Snyder polarity index Not conventionally assigned; XlogP3-AA -1.31 (Crippen calculated, RDKit). Maggie6 MIN READOctober 8, 2026
Reviewed by: Guidechem Scientific Editorial Board
Standards: IUPAC & PubChem Guidelines  |  Updated: 2026

Is BrO2 (Bromine dioxide radical) Polar or Nonpolar? Molecular Polarity & Structure Analysis

Bromine dioxide radical Polarity Cover
BrO2 (Bromine dioxide radical) is a polar molecule. The bromine centre carries 1 non-bonding electron pair, which makes the molecule bent rather than symmetric, so the bond dipoles add instead of cancelling. The molecule is polar but the magnitude of its dipole is not quoted here, because the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules). With 43 Ų of topological polar surface area and 1 hydrogen-bond site, it is expected to interact strongly with polar and protic media.

2D Lewis Structure of Bromine dioxide radical (BrO2)
Figure 1: 2D Lewis Structure (BrO 2; bent bromine centre)

Polarity Parameters of BrO2

CAS Registry Number 21255-83-4
Molecular Formula BrO2
Molecular Weight 111.90 g/mol
Valence Electrons 19
Lewis Structure Guide View BrO2 Lewis Structure Guide
Dipole Moment (μ) Non-zero; no magnitude is quoted because the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules)
Dielectric Constant (εr) Not quoted — the Debye estimate would inherit a dipole that this method does not deliver reliably for this class of compound
Snyder Polarity Index (P′) Not conventionally assigned
XlogP3-AA -1.31 (Crippen calculated, RDKit) (computed descriptor)
Note: Snyder P′ is a chromatographic solvent scale developed for conventional liquid solvents; no dipole magnitude is quoted: the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules), so the polarity verdict rests on symmetry and structure alone; no relative permittivity is quoted, because the Debye estimate would inherit an unreliable dipole; XlogP is a calculated partition descriptor, not a direct measure of solvent polarity.

1. Molecular Polarity Analysis of Bromine dioxide radical: Geometry & Dipole Vector

To determine whether Bromine dioxide radical (BrO2) is polar or nonpolar, the decisive question is whether the bond dipoles of the molecule cancel once its three-dimensional shape is taken into account. Bromine dioxide radical is an inorganic compound. As set out in the BrO2 Lewis Structure Guide, BrO2 has 3 heavy atoms.

The bond polarities follow from electronegativity. The largest differences in the structure are Br–O (ΔEN ≈ 0.48), so electron density is pulled toward oxygen. In three dimensions, the bromine centre is bent; the 2 non-bonding pairs on bromine compress the X–Br–X angle below the tetrahedral value. As a result, the molecule is polar but the magnitude of its dipole is not quoted here, because the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules).

For formulation and process work, the useful consequences are these: the calculated topological polar surface area is 43.0 Ų, 0 hydrogen-bond donors and 1 hydrogen-bond acceptor, the Crippen calculated partition coefficient is logP ≈ -1.31 and the calculated molar refractivity is 0.69 cm³ mol⁻¹. A negative logP indicates a net preference for the aqueous phase over octanol, which is what one expects when polar and ionisable groups dominate a small molecule.

Valence-electron check: Counting valence electrons from the formula: oxygen contributes 2 × 6 = 12 and bromine contributes 1 × 7 = 7, giving 12 + 7 = 19 valence electrons.

2. Bromine dioxide radical: Industrial Use, Handling and Specification

Bromine dioxide radical (CAS 21255-83-4) is an inorganic compound, supplied as an industrial chemical. Its polarity matters for the same reason it matters for any substance of this class: it decides which phases the material will enter, how strongly it adsorbs onto polar surfaces, and how much energy a separation will cost.

No fully curated experimental solubility or density value was retrieved for this substance from the public record used here, so the discussion below stays with calculated descriptors rather than quoting a measurement that cannot be verified. On those descriptors the compound presents 43.0 Ų of polar surface area with 1 hydrogen-bond site.

No dilute-gas permittivity is reported here: the Debye estimate would have to inherit a dipole moment that this method does not deliver reliably for this class of compound (the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules)), and for an ionic substance the equation does not apply at all.

The structure carries no strongly polar functional group, so the intermolecular forces are dominated by dispersion rather than by dipole–dipole attraction or hydrogen bonding.

No GHS hazard statements were retrieved for this substance from the public record used here, so no classification is asserted. The applicable classification must be taken from the supplier’s safety data sheet and from the ECHA or OSHA/NIOSH tables for CAS 21255-83-4.

Industrial Sourcing & Compliance Insight: For Bromine dioxide radical, the commercially relevant specification is assay, grade, water content and the impurity profile declared on the certificate of analysis, together with the packaging and transport class required for the destination market. Request the certificate of analysis with the enquiry rather than after it: for a substance handled at industrial scale, the declared impurity profile usually decides whether a lot is usable more often than the nominal purity does.

Recommended Analytical Quality-Control Strategy

  • Identity confirmation: FTIR or Raman against a reference spectrum, supported by GC–MS or LC–MS where the compound is amenable; this is the fastest way to catch a mis-labelled lot.
  • Assay / purity: GC-FID or GC-MS for volatile material, HPLC with a validated detector for non-volatile or thermally labile material; state the basis (area %, assay on dried substance, or titrimetric) on the certificate of analysis.
  • Water content: Karl Fischer titration is the default for a substance whose polarity and hydrogen-bonding capacity make it hygroscopic; moisture is the single most common cause of out-of-specification lots.
  • Related substances: a gradient HPLC or GC method capable of resolving the synthesis by-products and the isomeric impurities typical of this structure.
  • Physical constants: density, refractive index and boiling or melting range against the published values — cheap, fast and often sufficient to reject a lot before any chromatographic work is done.

In short, specify Bromine dioxide radical by assay, water content, impurity profile, packaging and transport class, and state the intended application on the enquiry. The polarity analysis above explains behaviour in use; it does not replace a specification.

3. Polarity Comparison: BrO2 and Related Industrial Fluids

The comparison below places BrO2 next to structurally related substances from the same catalogue. Dipole moments come from one consistent protocol (GFN2-xTB//MMFF94, gas phase, single conformer) and are quoted only where that protocol has been validated; where it has not, the cell says so instead of giving a number. Permittivities are dilute-gas estimates from the Debye equation, logP values are Crippen calculations, and the solubility column is a qualitative inference from the calculated descriptors rather than a measurement.

Compound Dipole Moment Approx. Gas εr log P / XlogP Water Solubility Behavior Industrial Sourcing
BrO2 non-zero, not quoted — logP ≈ -1.31 Moderate to high (inferred from logP < 0) See supply listing
Br2O non-zero, not quoted — logP ≈ 1.62 Moderate (inferred from logP) See supply listing
HBrO2 ≈3.51–5.46 D (conformers) — logP ≈ -1.75 High (polar, H-bonding; inferred) See supply listing
BrNO non-zero, not quoted — logP ≈ 1.06 Moderate (inferred from logP) See supply listing
Br2OSe non-zero, not quoted — — Not predicted here See supply listing

The spread across this table is the point: composition alone does not set the polarity verdict. BrO2 sits where it does because of the balance between weak dispersion forces and the asymmetry of its shape, and any of the neighbouring entries can be the better choice once the temperature, the phase and the required polarity window are fixed.

4. Expert R&D Commentary

Expert Chemical Commentary
“BrO 2 is polar, but no magnitude is quoted: the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules). A calculated logP of -1.31 tells you where it will partition.”

5. Regulatory, Safety & Sustainability Trends

Regulatory status is specific to the substance and to the jurisdiction, and it changes. For CAS 21255-83-4 the authoritative public sources are the ECHA registered-substance database for the EU, and the OSHA and NIOSH tables for occupational exposure in the United States.

No GHS hazard statements for this substance were retrieved from the public database used to build this article, so none are asserted here. Treat the absence of a quoted classification as an instruction to check the supplier’s safety data sheet, not as evidence that the substance is harmless.

No occupational exposure limit for this substance is quoted in this article, because none was present in the database record used here. Publishing a limit that is not on the record would be worse than publishing none: obtain the applicable value from the OSHA Z-table, the NIOSH pocket guide or the equivalent national instrument before designing the ventilation or monitoring programme.

From a compliance and sustainability standpoint, the polarity of BrO2 is a means rather than an end. It determines which solvent can replace another, how completely the substance can be recovered from a stream, and how much energy the separation will cost — so it belongs in the process justification, while the hazard classification and the exposure limits belong in the safety case.

6. Guidechem's Procurement Tips: What to Specify for Bromine dioxide radical

A purchase enquiry for Bromine dioxide radical (CAS 21255-83-4) should state the grade, assay basis, permitted impurity limits, water content, packaging, and the transport and regulatory status required for the destination market. Where the substance is used as a reagent or intermediate, the impurity profile usually matters more than the nominal percentage.

Because polarity governs phase behaviour, it also governs recovery: a polar molecule is easier to strip from a non-polar stream and harder to dry than a non-polar one, and vice versa. Confirm the Guidechem supply listing for current availability and compare lots on the certificate of analysis rather than on the label alone.

Industrial Engineering & Sourcing Specifications

Looking for commercial bulk supplies or technical documentation for Bromine dioxide radical (CAS 21255-83-4)?

Frequently Asked Questions (FAQs)

Is Bromine dioxide radical polar or nonpolar?

Bromine dioxide radical is polar. The bond dipoles do not cancel, so the molecule is polar, but no magnitude is quoted because the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules).

Why is no dipole moment quoted for Bromine dioxide radical?

The method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules). Rather than publish a number that would be misleading, the article argues the polarity from structure and symmetry; the literature value can be looked up in the NIST or CRC tables if a number is required.

How does the molecular geometry decide the answer?

The bromine centre is bent; the 2 non-bonding pairs on bromine compress the X–Br–X angle below the tetrahedral value. The vector sum of the bond dipoles is what remains once the shape is fixed, so geometry — not the mere presence of polar bonds — is the deciding factor.

What is the dielectric constant of Bromine dioxide radical?

No permittivity is quoted: the estimate would have to inherit a dipole that this method does not deliver reliably for this class of compound.

Does Bromine dioxide radical have a Snyder polarity index?

Not in routine tabulations. Snyder P′ was developed for conventional liquid chromatographic solvents, and this substance is outside the scope of that scale. Dipole moment, calculated logP and hydrogen-bond counts are the descriptors used here instead.

How does Bromine dioxide radical behave toward water?

No measured solubility value was retrieved for this substance, so only an inference is offered: with a calculated logP of -1.31, 0 hydrogen-bond donors and 1 acceptor, the expected behaviour is Moderate to high (inferred from logP < 0).

What should be checked before buying Bromine dioxide radical?

Grade, assay basis, water content, the declared impurity profile, packaging and the transport classification, plus the regulatory status required for the destination market. Confirm the hazard classification from the supplier’s safety data sheet, since none is asserted here.

References & Academic Databases

  1. PubChem Compound Summary: Bromine dioxide radical, CAS RN 21255-83-4, CID 5460629. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov
  2. ECHA Substance Information: Bromine dioxide radical, CAS 21255-83-4 — REACH registration status, harmonised classification and regulatory context. European Chemicals Agency.
  3. NIST Chemistry WebBook / CCCBDB: experimental geometry, vibrational data and dipole-moment compilations for Bromine dioxide radical. National Institute of Standards and Technology.
  4. CRC Handbook of Chemistry and Physics, 92nd ed. (Haynes, W. M., ed.), CRC Press, 2011 — electronegativity, dielectric constant and dipole-moment tables.
  5. Nelson, R. D.; Lide, D. R.; Maryott, A. A.: Selected Values of Electric Dipole Moments for Molecules in the Gas Phase, NSRDS-NBS 10, National Bureau of Standards, 1967.
  6. Snyder, L. R.: solvent-polarity classification and the P′ scale for liquid chromatographic solvents. The P′ scale is defined only for conventional liquid solvents and is not assigned to substances outside that scope.
  7. Bannwarth, C.; Ehlert, S.; Grimme, S.: GFN2-xTB — an accurate and broadly parametrised self-consistent tight-binding quantum chemical method with multipole electrostatics and density-dependent dispersion contributions. J. Chem. Theory Comput. 2019, 15 (3), 1652–1671.
  8. RDKit / Halgren, T. A.: MMFF94 force field for geometry generation (J. Comput. Chem. 1996, 17, 490–519) and the RDKit cheminformatics toolkit used for the Crippen logP, TPSA and hydrogen-bond descriptors quoted here.
Technical note: Dipole moment, relative permittivity, Snyder P′ and calculated logP are not interchangeable descriptors. For BrO 2 no dipole magnitude is reported: the method over-estimates the polarity of O–Br bonds (measured on C–Br bonds: mean error +1.00 D over 16 benchmark molecules). The polarity argument therefore rests on symmetry and structure alone; where a number is needed, take it from the NIST Computational Chemistry Comparison and Benchmark Database or the CRC Handbook rather than from a calculation that this benchmark does not support. Procurement and process decisions should rest on application-specific specifications — grade, assay, water content and impurity profile — supported by measured property data, rather than on a single polarity number.
Make Guideview Preferred Source on Google
Related News