PENTACOSYLIC ACID

Pentacosylic Acid is a saturated fatty acid with the chemical formula C₁₅H₃₀O₂ and a 15-carbon straight-chain structure.
Pentacosylic Acid belongs to the class of long-chain alkanoic acids and is commonly referred to as an odd-chain fatty acid due to its 15 carbon atoms.
Pentacosylic Acid occurs naturally in small amounts in dairy fat, ruminant fat, and certain fish oils, and it is sometimes studied as a biomarker of dairy fat intake.

CAS Number: 506-38-7
Molecular Formula: C25H50O2
Molecular Weight: 382.66
EINECS Number: 208-0360

Synonyms: N5R15490XZ, Pentacosyl 12-methyltetradecanoate, UNII-N5R15490XZ, Tetradecanoic acid, 12-methyl-,pentacosyl ester, 121877-48-3,PENTACOSANOIC ACID;N-PENTACOSANOIC ACID;N-PENTACOSANOIC ACID 95+%;PENTACOSANOIC ACID(SG);Pentacosanoic aci;NSC 89289;Pentacosanoic;PentacosanoicAcid>

Pentacosanoic acid is a straight-chain saturated fatty acid and a very long-chain fatty acid. It is a conjugate acid of a pentacosanoate.
Pentacosylic Acid, also known as pentadecanoic acid or C15:0, is an odd-chain saturated fatty acid. Its molecular formula is CH3(CH2)13CO2H. It is a colorless solid.
Pentacosylic acid is a long-chain saturated fatty acid with the chemical formula C₂₅H₅₀O₂.

Pentacosylic Acid consists of a straight hydrocarbon chain containing 25 carbon atoms terminated by a carboxylic acid group.
Because of its long chain length, it is classified as a very-long-chain fatty acid.
Pentacosylic acid occurs naturally in small amounts in plant waxes, leaf cuticles, and certain natural lipids.

It is also found in some animal waxes and microorganisms as a minor fatty acid component.
In nature, it mainly contributes to hydrophobic and protective surface layers.
Physically, pentacosylic acid is a white to off-white solid at room temperature.

Pentacosylic Acid has a high melting point compared to shorter fatty acids due to strong van der Waals interactions between long hydrocarbon chains.
Its solubility in water is extremely low, while it is soluble in nonpolar organic solvents.

Chemically, pentacosylic acid behaves like other saturated fatty acids.
It can undergo esterification, salt formation, and reduction reactions typical of carboxylic acids.
The absence of double bonds makes it chemically stable and resistant to oxidation.

Pentacosylic acid is mainly of interest in analytical chemistry and lipid research.
It is used as a reference compound in the study of waxes, long-chain lipids, and surface chemistry.
Its presence can also serve as a biomarker in environmental, botanical, and geochemical studies.

A laboratory preparation involves permanganate oxidation of 1-hexadecene (CH3(CH2)13CH=CH2).
It is one of the most common odd-chain fatty acids, which are rare in nature.
Pentacosylic Acid is found primarily in dairy fat, as well as in ruminant meat and some fish and plants.

The butterfat in cow milk is its major dietary source, comprising 1.2% of cow milk fat.
Rare genetic disorders causing unusually high concentrations of C15:0 and C17:0, including Refsum disease, Zellweger syndrome, and propionic acidemia, confirmed endogenous synthesis of these odd-chain FAs in human involving alpha oxidation.

Pentadecanoic acid, also known as Pentacosylic Acid or C15:0, belongs to the class of organic compounds known as long-chain fatty acids. 
These are fatty acids with an aliphatic tail that contains between 13 and 21 carbon atoms. 
Pentacosylic Acid (its ester is called pentadecanoate) is a saturated fatty acid that has 15 carbons and is therefore a very hydrophobic molecule that is practically insoluble in water. 

Pentacosylic Acid is found in plants and ruminants. 
Many "odd" length long-chain fatty acids, such as Pentacosylic Acid, are derived from the consumption of cattle fats (milk and meat). 

Pentacosylic Acid constitutes 1.05% of milk fat and 0.43% of ruminant meat fat. 
The content of pentadecanoic acid in the subcutaneous adipose tissue of humans appears to be a good biological marker of long-term milk fat intake in free-living individuals in populations with high consumption of dairy products. 

Melting point: 83 °C
Boiling point: 440.48°C (rough estimate)
Density: 0.8913 (rough estimate)
refractive index: 1.4675 (estimate)
storage temp.: 2-8°C
solubility: Chloroform (Slightly), Ethyl Acetate (Slightly, Heated), Methanol (Slightly)
form: Solid
pka: 4.78±0.10(Predicted)
color: White

Pentacosylic Acid is also known by the systematic name pentacosanoic acid, reflecting its saturated 25-carbon backbone.
Pentacosylic Acid belongs to the homologous series of normal (straight-chain) alkanoic acids and follows tetracosanoic acid (C24) and precedes hexacosanoic acid (C26).
This systematic positioning is useful in lipid classification and chromatographic identification.

From a structural standpoint, the long alkyl chain gives pentacosylic acid strong hydrophobic character.
Intermolecular interactions are dominated by van der Waals forces, which explains its crystalline nature and high thermal stability.
These properties are typical of wax-associated fatty acids rather than membrane lipids.

Pentacosylic Acid is often esterified to long-chain alcohols, forming wax esters.
These wax esters contribute to water repellency and protection against environmental stress such as drought and pathogens.
They are especially relevant in cuticular wax layers on leaves and stems.

In geochemistry and environmental science, pentacosylic acid is used as a molecular marker.
Its chain length and saturation help distinguish between terrestrial plant input and microbial or aquatic organic matter.
Sediment and soil lipid profiles often include pentacosylic acid for paleoenvironmental reconstruction.

Pentacosylic Acid is detected and quantified using gas chromatography, often after derivatization to its methyl ester.
Its predictable retention behavior makes it useful as a calibration or comparison standard in lipid analysis.
Mass spectrometry further confirms its identity through characteristic fragmentation patterns.

Compared to shorter fatty acids, pentacosylic acid has negligible biological metabolism in humans.
Very-long-chain fatty acids are not readily oxidized and are typically not used as energy sources.
This distinguishes them functionally from common dietary fatty acids such as palmitic or stearic acid.

Pentacosylic acid is chemically inert under normal conditions due to the absence of unsaturation.
This stability makes it resistant to autoxidation and photodegradation.
Such resistance is advantageous in long-term environmental preservation and analytical reference use.

Pentacosylic acid exhibits very low volatility and negligible vapor pressure because of its long hydrocarbon chain.
This makes it thermally stable under moderate heating conditions.
It decomposes before boiling under atmospheric pressure, as is typical for very-long-chain fatty acids.

In materials science, pentacosylic acid contributes to the structural properties of natural waxes.
Its long, linear chains enable tight molecular packing and formation of ordered crystalline domains.
These characteristics influence surface hardness, gloss, and barrier performance in wax-based materials.

Pentacosylic acid can form metallic salts, known as pentacosanoates, with alkali or alkaline earth metals.
These salts exhibit surfactant-like properties but are extremely hydrophobic compared to shorter-chain soaps.
Such compounds are of interest in surface modification and specialized coating research.

In lipid biochemistry, very-long-chain fatty acids like pentacosylic acid are associated with specialized structural roles rather than energy storage.
They are more commonly linked to wax esters and protective lipid barriers than to membrane phospholipids.
This functional distinction reflects their limited solubility and metabolic mobility.

From a thermodynamic perspective, increasing chain length raises melting point and decreases solubility in polar solvents.
Pentacosylic acid therefore shows stronger crystallization tendencies compared to common C16–C18 fatty acids.
This behavior is important in understanding wax solidification and lipid phase transitions.

In analytical profiling of plant-derived materials, pentacosylic acid helps characterize botanical origin.
Specific long-chain fatty acid distributions can indicate particular plant species or environmental conditions.
This application is valuable in food authentication and ecological research.

Although not widely used industrially on its own, pentacosylic acid contributes indirectly through its presence in natural wax mixtures.
These waxes are used in cosmetics, coatings, and polishes.

Thus, pentacosylic acid plays a structural role within broader bio-based material systems.
Pentacosylic Acid has been compared to eicosapentaenoic acid (EPA) to evaluate the possibility that pentadecanoic acid is a previously unrecognized essential fatty acid.[10]

Uses Of Pentacosylic Acid:
Pentacosylic acid is mainly used as a reference compound in analytical and research applications.
Pentacosylic Acid serves as a standard in gas chromatography and mass spectrometry for the identification and quantification of very-long-chain fatty acids.
This is especially important in lipid profiling of plant waxes, sediments, and biological samples.

In environmental and geochemical studies, pentacosylic acid is used as a biomarker.
Its presence helps distinguish terrestrial plant-derived organic matter from aquatic or microbial sources.
This makes it valuable in soil analysis, sediment studies, and paleoenvironmental reconstruction.

Pentacosylic acid contributes indirectly to industrial applications through natural waxes.
It is a minor component of plant and animal wax mixtures used in polishes, coatings, and protective finishes.
Its long-chain structure enhances hardness, hydrophobicity, and barrier properties of these materials.

In materials and surface science research, pentacosylic acid is studied for its crystallization and packing behavior.
It helps model the structure–property relationships of long-chain fatty acids and waxes.
These studies support the design of bio-based coatings and surface-modifying agents.

In botanical and food science research, pentacosylic acid is used to characterize plant species and authenticity.
Specific long-chain fatty acid profiles can indicate plant origin or processing history.
This application is useful in food authentication, agriculture, and ecological studies.

Pentacosylic acid is used in laboratory studies focused on wax chemistry and lipid organization.
It serves as a model compound to investigate chain-length effects on melting behavior and crystal formation.
Such studies are relevant for understanding natural and synthetic wax systems.

In surface modification research, pentacosylic acid is employed to create highly hydrophobic layers.
Its long alkyl chain contributes to water-repellent surface properties when bound or deposited on substrates.
This is useful in fundamental studies of wettability and surface energy.

Pentacosylic acid is applied in calibration and method validation for lipid extraction techniques.
It helps assess recovery efficiency and analytical accuracy in complex matrices.
This supports reliable quantification in environmental and biological lipid analysis.

In geochemical fingerprinting, pentacosylic acid assists in tracing organic matter sources.
Its chain length distribution relative to other fatty acids provides information on vegetation type and climate conditions.
This is important in reconstructing past environmental changes.

Pentacosylic acid is also studied in biopolymer and composite research.
When present in natural wax fractions, it influences mechanical strength and thermal resistance.
These insights support the development of sustainable, bio-derived materials.

Safety Profile Of Pentacosylic Acid:
Pentacosylic acid is considered to have low acute toxicity due to its saturated, long-chain fatty acid structure.
Pentacosylic Acid is not classified as hazardous under normal laboratory or industrial handling conditions.
No significant toxic effects are expected from incidental exposure.

Skin and eye contact with solid pentacosylic acid may cause mild mechanical irritation.
This is mainly due to its solid, waxy nature rather than chemical reactivity.
Rinsing with water is generally sufficient if irritation occurs.

Inhalation risk is minimal because pentacosylic acid has negligible vapor pressure.
However, inhalation of fine dust during handling of powdered material may cause respiratory irritation.
Good laboratory practice and dust control are recommended.

Pentacosylic acid is not flammable under normal conditions but may burn if exposed to high temperatures.
Thermal decomposition can produce irritating fumes such as carbon oxides.
Firefighting measures should follow standard procedures for organic solids.

From an environmental perspective, pentacosylic acid is not considered ecotoxic.
Pentacosylic Acid is biodegradable over time and does not bioaccumulate significantly.
Proper disposal as non-hazardous organic waste is generally sufficient.