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To determine whether Potassium hydrogen phthalate (C8H5KO4) 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. Potassium hydrogen phthalate is a carboxylate salt, built from carboxylic acid (–COOH) and carboxylate anion (–COO⁻). As set out in the C8H5KO4 Lewis Structure Guide, C8H5KO4 has 12 heavy atoms, 1 ring system and 2 rotatable bonds.
The bond polarities follow from electronegativity. The largest differences in the structure are C–O (ΔEN ≈ 0.89), so electron density is pulled toward oxygen. In three dimensions, the oxygen centre is bent; the 2 non-bonding pairs on oxygen compress the X–O–X angle below the tetrahedral value. Because the substance separates into ions, the molecule is polar but the magnitude of its dipole is not quoted here, because the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant.
For formulation and process work, the useful consequences are these: the calculated topological polar surface area is 77.4 Ų, 1 hydrogen-bond donor and 3 hydrogen-bond acceptors and the Crippen partition coefficient is not quoted, because the parameter set does not cover every element in the molecule. PubChem’s curated experimental record adds: Potassium hydrogen phthalate is Solid;.
Potassium hydrogen phthalate (CAS 877-24-7) is a carboxylate salt, 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.
The measured physical behaviour recorded for this substance is consistent with that picture. Physical Description: Solid;. Density: 1.6 @25 °C. These are database values and should be read with the conditions (temperature, purity, pressure) that the source states.
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 species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant), and for an ionic substance the equation does not apply at all.
Structurally the reactivity sits in carboxylic acid (–COOH) and carboxylate anion (–COO⁻). That functional inventory, together with the unresolved dipole, is what predicts the solubility and adsorption behaviour: polar groups give the molecule a handle on polar solvents and on polar surfaces, while the hydrocarbon portion resists them.
PubChem’s GHS record for this substance lists H318 (41.5%): Causes serious eye damage [Danger Serious eye damage/eye irritation]. Those classifications, not the polarity of the molecule, normally determine packaging, labelling, ventilation and transport requirements.
In short, specify Potassium hydrogen phthalate 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.
The comparison below places C8H5KO4 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 |
|---|---|---|---|---|---|
| C8H5KO4 | non-zero, not quoted | — | — | Solid; | See supply listing |
| CHO3 | not applicable (ion) | — | logP ≈ -1.11 | Dissolves by dissociation; ionic hydration dominates | See supply listing |
| CHNaO3 | non-zero, not quoted | — | — | Dissolves by dissociation; ionic hydration dominates | See supply listing |
| C8H6O4 | not applicable (ion) | — | logP ≈ 1.08 | Moderate (inferred from logP) | See supply listing |
| C6H14N4O2 | ≈1.79–5.31 D (conformers) | ≈1.0136 | logP ≈ -1.55 | High (polar, H-bonding; inferred) | See supply listing |
The spread across this table is the point: composition alone does not set the polarity verdict. C8H5KO4 sits where it does because of the balance between its polar functional groups 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.
“C 8H 5KO 4 is an ionic substance, so the useful question is not "polar or nonpolar" but how the charge is distributed and how strongly the ions are hydrated. No calculated partition coefficient is quoted, because the Crippen parameter set does not cover every element in the molecule. The curated experimental record is consistent: Solid;.”
Regulatory status is specific to the substance and to the jurisdiction, and it changes. For CAS 877-24-7 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.
PubChem’s GHS record for this substance lists H318 (41.5%): Causes serious eye damage [Danger Serious eye damage/eye irritation]. These statements are the ones that must appear on the label and in section 2 of the safety data sheet; they, rather than the polarity of the molecule, drive classification, packaging group and transport documentation.
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 C8H5KO4 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.
A purchase enquiry for Potassium hydrogen phthalate (CAS 877-24-7) 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.
Looking for commercial bulk supplies or technical documentation for Potassium hydrogen phthalate (CAS 877-24-7)?
Potassium hydrogen phthalate is polar. The bond dipoles do not cancel, so the molecule is polar, but no magnitude is quoted because the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant.
The species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant. 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.
The oxygen centre is bent; the 2 non-bonding pairs on oxygen compress the X–O–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.
No permittivity is quoted: the Debye dilute-gas equation does not apply to a charged species.
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.
The curated database record states: Solid;. No calculated partition coefficient is quoted, because the Crippen parameter set does not cover every element in the molecule.
Grade, assay basis, water content, the declared impurity profile, packaging and the transport classification, plus the regulatory status required for the destination market. PubChem’s GHS record for this substance lists H318 (41.5%): Causes serious eye damage [Danger Serious eye damage/eye irritation].
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