Pantothenic Acid (79-83-4) Physical and Chemical Properties
Pantothenic Acid
Water‑soluble vitamin B5 (pantothenic acid) supplied for use as an ingredient or raw material in nutritional, pharmaceutical and cosmetic formulations, and for R&D and QC applications.
| CAS Number | 79-83-4 |
| Family | Pantothenates / Vitamins and Derivatives |
| Typical Form | Powder or crystalline solid (hygroscopic) |
| Common Grades | EP, FCC, Food Grade, Technical Grade |
Pantothenic acid is a small, water-soluble B‑vitamin (vitamin B5) belonging to the class of N‑acylated beta‑alanine derivatives. Structurally it is the amide formed between pantoic acid (a tertiary 2,4‑dihydroxy‑3,3‑dimethylbutanoic acid) and beta‑alanine; the commercially and biologically active stereoisomer is the R (D) enantiomer and the molecule contains one defined stereocenter. Key functional groups are a terminal carboxylic acid, an amide linkage, and two secondary alcohols on a highly substituted tertiary carbon. These polar functionalities give the free acid a high hydrogen‑bonding capacity (four H‑bond donors, five H‑bond acceptors) and a large topological polar surface area (\(107\,\text{Å}^2\)), which together drive strong aqueous solubility and low lipophilicity.
Electronically and chemically, pantothenic acid is amphoteric: the carboxyl group can deprotonate (forming pantothenate anion under physiological conditions) while the amide and hydroxyls remain largely neutral under typical conditions. The calculated partition coefficient (XLogP = -1.1) and the high polar surface area indicate poor passive membrane permeability and preference for transporter‑mediated uptake in biological systems. The free acid is chemically labile: it is hygroscopic and prone to degradation under strong acidic or basic conditions and by heat; more stable solid forms are typically obtained as salts (e.g., calcium or sodium pantothenate) or as the alcohol derivative panthenol for formulation uses. Biologically, pantothenic acid is the dietary precursor of coenzyme A (CoA) and acyl carrier protein prosthetic groups and is therefore central to acyl transfer, energy metabolism, and fatty acid biosynthesis.
Common commercial grades reported for this substance include: EP, FCC, Food Grade, Technical Grade.
Basic Physicochemical Properties
Density and Solid-State Form
No experimentally established numerical density value for pantothenic acid is available in the current data context. Qualitatively, the free pantothenic acid (free acid form) is reported as a viscous, extremely hygroscopic liquid/oil (described in sources as a yellow viscous oil or a viscous hygroscopic liquid) and may be isolated as hygroscopic crystals under specific conditions. Commercial, solid, and more stable forms are typically the calcium or sodium salts (e.g., calcium D‑pantothenate) which crystallize in multiple polymorphs and solvates; these salts are less hygroscopic than the free acid and are the preferred solid forms for tablets and dry mixes.
Melting Point
Reported melting/decomposition data vary with the form: - \(195\,^\circ\mathrm{C}\) (D‑Calcium Pantothenate salt) - \(170\text{–}172\,^\circ\mathrm{C}\) (/Ca salt/) - \< \(25\,^\circ\mathrm{C}\) (free acid; consistent with the free acid being viscous at ambient temperature)
Some descriptions note decomposition around \(195\text{–}196\,^\circ\mathrm{C}\) for certain preparations; thus melting or decomposition temperatures must be interpreted with respect to the specific salt/solvate or the free acid form.
Solubility and Dissolution Behavior
Solubility reports are form‑dependent and sometimes internally inconsistent in historical data; representative values and qualitative behavior include: - Described as "Very soluble in water" and "Freely soluble in water"; one reported quantitative value: \(1000.0\,\mathrm{mg}\,\mathrm{mL}^{-1}\). - Reported solubility behavior across solvents (often pertaining to specific forms): "Freely soluble in water, ethyl acetate, dioxane, glacial acetic acid; moderately soluble in ether, amyl alcohol; practically insoluble in benzene, chloroform." - A specific solubility note: \(1\,\mathrm{g}\) dissolves in \(2.8\,\mathrm{mL}\) water (reported for a salt form). Practically, the free acid and its salts are highly hygroscopic and dissolve readily in aqueous media; choice of salt (calcium, sodium, zinc complexes) markedly influences solid‑state stability and apparent solubility in formulation practice.
Chemical Properties
Acid–Base Behavior and Qualitative pKa
No experimentally established numeric pKa value for pantothenic acid is available in the current data context. Qualitatively, the molecule is amphoteric: the terminal carboxyl group is acidic and will deprotonate to give the pantothenate anion at neutral to basic pH, while the amide nitrogen is not strongly basic. Reported pH behavior for salt formulations includes: pH of a 5% aqueous solution in the range 7.2–8.0 and pH in CO2‑free water reported as 8.7 (reported for calcium salt preparations). In physiological media pantothenic acid exists predominantly as the pantothenate anion, which is the substrate for cellular uptake systems and for enzymatic conversion to CoA.
Reactivity and Stability
Pantothenic acid is chemically unstable under strongly acidic or basic conditions and is heat‑labile; descriptions indicate it is "unstable … easily destroyed by acids, bases, heat." The free acid is extremely hygroscopic, complicating handling and storage; decomposition on heating can release toxic gases (a reported note indicates emission of nitrogen oxides on decomposition). Conversion to more stable forms (calcium or sodium pantothenate, or the alcohol panthenol) is standard industrial practice to improve shelf life and handling. In formulation contexts, panthenol (the alcohol analog) is favored for liquid products because of superior stability; calcium pantothenate shows improved stability in dry mixes and multivitamin tablets.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: C9H17NO5
- Molecular weight (reported): \(219.23\,\mathrm{g}\,\mathrm{mol}^{-1}\)
- Exact mass / Monoisotopic mass: 219.11067264
Additional computed descriptors available for structure‑based evaluations include heavy atom count 15, complexity 239, and one defined stereocenter.
LogP and Structural Features
- XLogP (computed): -1.1
- Topological polar surface area: \(107\,\text{Å}^2\)
- Hydrogen bond donors: 4
- Hydrogen bond acceptors: 5
- Rotatable bond count: 6
These parameters indicate a highly polar, hydrogen‑bonding molecule with low lipophilicity (negative XLogP) and limited passive membrane permeability; biological transport is consequently dominated by carrier systems. The single stereocenter (R configuration for the biologically active isomer) is critical for enzymatic recognition.
Structural Identifiers (SMILES, InChI)
- SMILES: CC(C)(CO)C@HO
- InChI: InChI=1S/C9H17NO5/c1-9(2,5-11)7(14)8(15)10-4-3-6(12)13/h7,11,14H,3-5H2,1-2H3,(H,10,15)(H,12,13)/t7-/m0/s1
- InChIKey: GHOKWGTUZJEAQD-ZETCQYMHSA-N
All three identifiers correspond to the R/D enantiomer often reported as the biologically active pantothenic acid.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS Registry Number: 79-83-4
- European Community (EC) Number: 201-229-0
- UNII: 19F5HK2737
- ChEBI: CHEBI:46905
- ChEMBL: CHEMBL1594
- DrugBank: DB01783
- HMDB: HMDB0000210
- KEGG: C00864 / D07413
- DSSTox Substance ID: DTXSID9023417
- Other vendor and registry cross‑references exist for salts and derivatives (e.g., calcium pantothenate, sodium pantothenate).
Synonyms and Brand‑Independent Names
Common synonyms and systematic names recorded for this substance include: - Pantothenic acid - Pantothenate - Vitamin B5 - D‑pantothenic acid; (R)‑pantothenic acid - beta‑Alanine, N‑[(2R)‑2,4‑dihydroxy‑3,3‑dimethyl‑1‑oxobutyl]‑ - 3‑[[(2R)‑2,4‑dihydroxy‑3,3‑dimethylbutanoyl]amino]propanoic acid - Panthenol (alcohol analog; provitamin)
These synonyms cover free acid, salt, and derivative nomenclature commonly used in industrial, nutritional, and pharmacological contexts.
Industrial and Pharmaceutical Applications
Role as Active Ingredient or Intermediate
Pantothenic acid and its salts are widely used as nutritional supplements and active pharmaceutical ingredients in multivitamin and parenteral/enteral nutrition products. The compound is the dietary precursor for coenzyme A biosynthesis and thus is essential in metabolic pathways; it is included as an active ingredient in formulations to prevent deficiency and is investigated in diverse therapeutic contexts (wound healing, dermatological uses, peripheral neuropathy, and metabolic studies). In industrial production the more stable calcium or sodium salts serve as bulk ingredients and intermediates for formulation into solid dosage forms.
Formulation and Development Contexts
Formulation practice exploits the higher stability and lower hygroscopicity of salt forms (calcium, sodium) versus the free acid, and panthenol is used when liquid stability is required. Calcium pantothenate is commonly used in tablets and dry mixes because of superior stability. Typical finished formulations include oral tablets (10–545 mg ranges reported for calcium pantothenate products), injectable dexpanthenol solutions for parenteral use, and cosmetic formulations where pantothenic acid/panthenol are used as skin‑ and hair‑conditioning agents.
If a concise application summary is required beyond these generalities, product‑specific technical literature or formulation records should be consulted.
Specifications and Grades
Typical Grade Types (Pharmaceutical, Analytical, Technical)
Commercially available grades and grade concepts for pantothenic acid include pharmaceutical‑grade (for medicinal use), analytical‑grade (for laboratory standards), and technical/food grades for dietary supplements and food fortification. Common commercial grades reported for this substance include: EP, FCC, Food Grade, Technical Grade.
General Quality Attributes (Qualitative Description)
Quality attributes that are controlled or considered during specification include optical purity (R/D enantiomer content), moisture/hygroscopicity (critical due to extreme hygroscopic nature), residual solvent content for solvates, polymorphic form for crystalline salts, and assay/purity by suitable analytical methods (HPLC, titrimetric or microbiological assays). For salts and drug‑substance manufacturing, control of residual beta‑alanine and lactone precursors, and prevention of racemization are typical quality considerations. Specific assay limits and impurity criteria are set by the purchasing specification and regulatory requirements and are not provided here.
Safety and Handling Overview
Toxicological Profile and Exposure Considerations
Pantothenic acid is generally regarded as of low toxicity in typical dietary and supplement exposures, and it is not classified under many GHS submissions (reported as "Not Classified" in aggregated supplier notifications). Adverse effects at very high oral intakes may include gastrointestinal upset (diarrhea) and, rarely, hypersensitivity reactions. Reported non‑human acute toxicity values include: - LD50 (mouse, intraperitoneal): \(1{,}443\,\mathrm{mg}\,\mathrm{kg}^{-1}\) - LD50 (mouse, subcutaneous): \(2{,}500\,\mathrm{mg}\,\mathrm{kg}^{-1}\) - LD50 (rat, subcutaneous): \(3{,}500\,\mathrm{mg}\,\mathrm{kg}^{-1}\)
Clinical and case reports note that hypersensitivity reactions, including rare eosinophilic pleuropericarditis, have been associated with combined vitamin use in isolated cases. High supplemental doses (multi‑gram daily) can cause mild gastrointestinal effects; one summary indicates potential symptoms at very large daily doses (on the order of \(10{,}000\,\mathrm{mg}\) daily). In industrial and laboratory settings, inhalation exposure is unlikely to be significant for the free oil/acids but dust or aerosols of salt forms should be controlled. Eye and skin irritation may occur on direct contact in sensitive individuals.
This compound is a biologically active vitamin and will be readily absorbed via intestinal transport mechanisms when ingested; excretion is primarily renal with urinary pantothenate proportional to intake.
Storage and Handling Guidelines
- Store in tightly sealed, moisture‑proof containers in a cool, dry place protected from heat and strong acids or bases; the free acid and many salts are extremely hygroscopic and will absorb water from air.
- Use appropriate personal protective equipment (gloves, eye protection) to avoid skin and eye contact; minimize dust generation when handling solid salts.
- Avoid exposure to strong acidic or basic conditions and elevated temperatures to limit decomposition.
- For transport, storage limits, and disposal follow the product‑specific Safety Data Sheet (SDS) and applicable local regulations; do not assume uniform regulatory classification across jurisdictions. For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.
