Palmitic acid

Source: Wikipedia, the free encyclopedia.
Palmitic acid[1]
Names
Preferred IUPAC name
Hexadecanoic acid
Other names
Palmitic acid
C16:0 (Lipid numbers)
Identifiers
3D model (
JSmol
)
ChEMBL
ChemSpider
ECHA InfoCard
 100.000.284 Edit this at Wikidata
IUPHAR/BPS
UNII
  • InChI=1S/C16H32O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16(17)18/h2-15H2,1H3,(H,17,18) ☒N
    Key: IPCSVZSSVZVIGE-UHFFFAOYSA-N ☒N
  • InChI=1/C16H32O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16(17)18/h2-15H2,1H3,(H,17,18)
    Key: IPCSVZSSVZVIGE-UHFFFAOYAJ
  • CCCCCCCCCCCCCCCC(=O)O
Properties
C16H32O2
Molar mass 256.430 g/mol
Appearance White crystals
Density 0.852 g/cm3 (25 °C)[2]
0.8527 g/cm3 (62 °C)[3]
Melting point 62.9 °C (145.2 °F; 336.0 K)[7]
Boiling point 351–352 °C (664–666 °F; 624–625 K)[8]
271.5 °C (520.7 °F; 544.6 K), 100 mmHg[2]
215 °C (419 °F; 488 K), 15 mmHg
4.6 mg/L (0 °C)
7.2 mg/L (20 °C)
8.3 mg/L (30 °C)
10 mg/L (45 °C)
12 mg/L (60 °C)[4]
Solubility Soluble in amyl acetate, alcohol, CCl4,[4] C6H6
Very soluble in CHCl3[3]
Solubility in ethanol 2 g/100 mL (0 °C)
2.8 g/100 mL (10 °C)
9.2 g/100 mL (20 °C)
31.9 g/100 mL (40 °C)[5]
Solubility in methyl acetate 7.81 g/100 g[4]
Solubility in ethyl acetate 10.7 g/100 g[4]
Vapor pressure 0.051 mPa (25 °C)[3]
1.08 kPa (200 °C)
28.06 kPa (300 °C)[6]
Acidity (pKa) 4.75 [3]
−198.6·10−6 cm3/mol
1.43 (70 °C)[3]
Viscosity 7.8 cP (70 °C)[3]
Thermochemistry
463.36 J/(mol·K)[6]
452.37 J/(mol·K)[6]
Std enthalpy of
formation
(ΔfH⦵298)
 −892 kJ/mol[6]
Std enthalpy of
combustion
(ΔcH⦵298)
 10030.6 kJ/mol[3]
Hazards
GHS labelling:
GHS07: Exclamation mark[2]
Warning
H319[2]
P305+P351+P338[2]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point 206 °C (403 °F; 479 K)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Palmitic acid (hexadecanoic acid in

oil palms), making up to 44% of total fats. Meats, cheeses, butter, and other dairy products also contain palmitic acid, amounting to 50–60% of total fats.[11]

Palmitates are the salts and esters of palmitic acid. The palmitate anion is the observed form of palmitic acid at physiologic pH (7.4). Major sources of C16:0 are palm oil, palm kernel oil, coconut oil, and milk fat.[12]

Occurrence and production

Palmitic acid was discovered by

hydrolysed by high-temperature water and the resulting mixture is fractionally distilled.[14]

Dietary sources

Palmitic acid is produced by a wide range of plants and organisms, typically at low levels. Among common foods it is present in milk, butter, cheese, and some meats, as well as cocoa butter, olive oil, soybean oil, and sunflower oil, (see table).[15] Karukas contain 44.90% palmitic acid.[16] The cetyl ester of palmitic acid, cetyl palmitate, occurs in spermaceti.

Palmitic acid content of common foods
Food % of total calories
Palm oil 45.1%
Beef tallow
 26.5%
Butter fat
 26.2%
Cocoa butter 25.8%
Lard 24.8%
Cottonseed oil 24.7%
Chicken 23.2%
Corn oil 12.2%
Peanut oil 11.6%
Soybean oil 11%
Coconut oil 8.4%
Palm kernel oil 8%
Rapeseed oil 3.6%
Source:[17]

Biochemistry

Palmitic acid is the first fatty acid produced during fatty acid synthesis and is the precursor to longer fatty acids. As a consequence, palmitic acid is a major body component of animals. In humans, one analysis found it to make up 21–30% (molar) of human depot fat,[18] and it is a major, but highly variable, lipid component of human breast milk.[19] Palmitate negatively feeds back on acetyl-CoA carboxylase (ACC), which is responsible for converting acetyl-CoA to malonyl-CoA, which in turn is used to add to the growing acyl chain, thus preventing further palmitate generation.[20]

Some proteins are modified by the addition of a palmitoyl group in a process known as palmitoylation. Palmitoylation is important for localisation of many membrane proteins.

Applications

Surfactant

Palmitic acid is used to produce soaps, cosmetics, and industrial mold release agents. These applications use sodium palmitate, which is commonly obtained by saponification of palm oil. To this end, palm oil, rendered from palm trees (species Elaeis guineensis), is treated with sodium hydroxide (in the form of caustic soda or lye), which causes hydrolysis of the ester groups, yielding glycerol and sodium palmitate.

Foods

Because it is inexpensive and adds texture and "mouthfeel" to processed foods (convenience food), palmitic acid and its sodium salt find wide use in foodstuffs. Sodium palmitate is permitted as a natural additive in organic products.[21]

Military

Aluminium

gelling agents used with volatile petrochemicals during World War II to produce napalm. The word "napalm" is derived from the words naphthenic acid and palmitic acid.[22]

Research

It is well accepted in the medical community that palmitic acid from dietary sources raises low-density lipoprotein (LDL) and total cholesterol.[17][23][24][25] The World Health Organization have stated there is convincing evidence that palmitic acid increases cardiovascular disease risk.[26]

A 2021 review indicated that replacing dietary palmitic acid and other saturated fatty acids with

unsaturated fatty acids, such as oleic acid, could reduce several biomarkers of cardiovascular and metabolic diseases.[27]

See also

References

  1. ^ Merck Index, 12th Edition, 7128.
  2. ^ a b c d e f Sigma-Aldrich Co., Palmitic acid. Retrieved on 2014-06-02.
  3. ^ a b c d e f g CID 985 from PubChem
  4. ^ a b c d "Palmitic acid".
  5. ^ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Retrieved 2014-06-02.
  6. ^ a b c d n-Hexadecanoic acid in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-11)
  7. S2CID 84492006
    .
  8. ^ Palmitic acid at Inchem.org
  9. ISBN 978-0849396885
  10. ^ The most common fatty acid is the monounsaturated oleic acid. See: https://pubchem.ncbi.nlm.nih.gov/compound/965#section=Top
  11. Wikidata Q46799280
    .
  12. PMID 24913651
    .
  13. ^ Frémy, E. (1842). "Memoire sur les produits de la saponification de l'huile de palme". Journal de Pharmacie et de Chimie. XII: 757.
  14. ISBN 978-3527306732
    .
  15. ^ "Chemical Characteristics". Olive Oil Source. Retrieved November 11, 2021.[dead link]
  16. OCLC 981032990
    . Retrieved 10 November 2021.
  17. ^
    ISBN 978-0935315318
  18. PMID 13756126
    .
  19. PMID 352132
    .
  20. ^ "Fatty acid biosynthesis - Reference pathway". KEGG. Pathway Map 00061
  21. ^ US Soil Association standard 50.5.3
  22. doi:10.1021/ie50475a033
    .
  23. PMID 12716665
    .
  24. ^ Mensink, Ronald P. (2016). "Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis". World Health Organization. Retrieved 14 March 2023.
  25. ISBN 978-9389188301
  26. ^ "Diet, Nutrition and the Prevention of Chronic Diseases". World Health Organization. p. 82. Retrieved 16 March 2023.
  27. PMID 34849532
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Palmitic_acid&oldid=1210650570"