Palmitic acid: Difference between revisions

{{

|Verifiedfields = changed

|Watchedfields = changed

|verifiedrevid = 415315408

|Reference = <ref>''[[Merck Index]]'', 12th Edition, '''7128'''.</ref>

|ImageFile_Ref = {{chemboximage|correct|??}}

|ImageFile = Palmitic acid.svg

|ImageSize = 250px

|ImageSize2 =

|ImageFile3 = Kyselina palmitová.jpg

|PIN = Hexadecanoic acid<!-- Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) -->

|OtherNames = Palmitic acid<br />C16:0 ([[Fatty acid#Nomenclature|Lipid numbers]])

|Section1 = {{Chembox Identifiers

|CASNo_Ref = {{cascite|correct|CAS}}

|CASNo = 57-10-3

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = 2V16EO95H1

|PubChem = 985

|ChEMBL_Ref = {{ebicite|changed|EBI}}

|ChEMBL = 82293

|IUPHAR_ligand = 1055

|ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

|ChemSpiderID = 960

|SMILES = CCCCCCCCCCCCCCCC(=O)O

|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)

|InChIKey = IPCSVZSSVZVIGE-UHFFFAOYAJ

|StdInChI_Ref = {{stdinchicite|changed|chemspider}}

|StdInChI = 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)

|StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

|StdInChIKey = IPCSVZSSVZVIGE-UHFFFAOYSA-N

}}

|Section2 = {{Chembox Properties

|C=16 | H=32 | O=2

|MolarMassUnit = g/mol

|pKa = 4.75 <ref name=pubchem>{{PubChemLink|985}}</ref>

|Appearance = White crystals

|Density = 0.852 g/cm³ (25 °C)<ref name="sigma" /><br/> 0.8527 g/cm³ (62 °C)<ref name=pubchem />

|MeltingPtC = 62.9

|MeltingPt_ref = <ref name="lexicon">{{cite journal |year=2001 |title=Lexicon of lipid nutrition (IUPAC Technical Report) |journal=Pure and Applied Chemistry |volume=73 |issue=4 |pages=685–744 |doi=10.1351/pac200173040685 |doi-access=free |last1=Beare-Rogers |first1=J. |last2=Dieffenbacher |first2=A. |last3=Holm |first3=J.V. |s2cid=84492006 }}</ref>

|BoilingPtC = 351-352

|BoilingPt_ref = <ref>[http://www.inchem.org/documents/icsc/icsc/eics0530.htm Palmitic acid] at Inchem.org</ref><br/>{{convert|271.5|C|F K}}, 100{{nbsp}}mmHg<ref name="sigma" /> <br/>{{convert|215|C|F K}}, 15{{nbsp}}mmHg

|Solubility = 4.6 mg/L (0 °C)<br/> 7.2 mg/L (20 °C)<br/> 8.3 mg/L (30 °C)<br/> 10 mg/L (45 °C)<br/> 12 mg/L (60 °C)<ref name=chemister />

|SolubleOther = Soluble in [[amyl acetate]], [[ethanol|alcohol]], [[carbon tetrachloride|CCl₄]],<ref name=chemister>{{cite web | url=http://chemister.ru/Database/properties-en.php?dbid=1&id=6488 | title=Palmitic acid}}</ref> [[benzene|C₆H₆]] <br/>Very soluble in [[chloroform|CHCl₃]]<ref name=pubchem />

|Solubility1 = 2 g/100 mL (0 °C)<br/> 2.8 g/100 mL (10 °C)<br/> 9.2 g/100 mL (20 °C)<br/> 31.9 g/100 mL (40 °C)<ref name=sioc>{{cite book|last1 = Seidell|first1 = Atherton|last2 = Linke|first2 = William F.|year = 1952|title = Solubilities of Inorganic and Organic Compounds|publisher = Van Nostrand|url = https://books.google.com/books?id=k2e5AAAAIAAJ|access-date = 2014-06-02}}</ref>

|Solvent1 = ethanol

|Solubility2 = 7.81 g/100 g<ref name=chemister />

|Solvent2 = methyl acetate

|Solubility3 = 10.7 g/100 g<ref name=chemister />

|Solvent3 = ethyl acetate

|VaporPressure = 0.051 mPa (25 °C)<ref name=pubchem>{{PubChemLink|985}}</ref><br/> 1.08 kPa (200 °C)<br/> 28.06 kPa (300 °C)<ref name=nist>{{nist|name=n-Hexadecanoic acid|id=C57103|accessdate=2014-05-11|mask=FFFF|units=SI}}</ref>

|Viscosity = 7.8 cP (70 °C)<ref name=pubchem />

|RefractIndex = 1.43 (70 °C)<ref name=pubchem />

|MagSus = −198.6·10⁻⁶ cm³/mol

}}

|Section3 = {{Chembox Thermochemistry

|DeltaHf = −892 kJ/mol<ref name=nist />

|DeltaHc = 10030.6 kJ/mol<ref name=pubchem />

|HeatCapacity = 463.36 J/(mol·K)<ref name=nist />

|Entropy = 452.37 J/(mol·K)<ref name=nist />

}}

|Section4 = {{Chembox Hazards

|GHSPictograms = {{GHS07}}<ref name="sigma">{{Sigma-Aldrich|id=258725|name=Palmitic acid|accessdate=2014-06-02}}</ref>

|GHSSignalWord = Warning

|HPhrases = {{H-phrases|319}}<ref name="sigma" />

|PPhrases = {{P-phrases|305+351+338}}<ref name="sigma" />

|FlashPtC = 206

|FlashPt_ref = <ref name="sigma" />

| NFPA-H = 1

| NFPA-F = 1

| NFPA-R = 0

}}

'''Palmitic acid''' ('''hexadecanoic acid''' in [[IUPAC nomenclature]]) is a [[fatty acid]] with a 16-carbon chain. It is the most common [[saturated fatty acid]] found in animals, plants and microorganisms.<ref name=lipidhb>Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The Lipid Handbook, 3rd ed. Boca Raton: CRC Press, 2007. {{ISBN|0849396883}} | {{ISBN|978-0849396885}}</ref><ref>The most common fatty acid is the monounsaturated oleic acid. See: https://pubchem.ncbi.nlm.nih.gov/compound/965#section=Top</ref> Its [[chemical formula]] is {{chem2|CH3(CH2)14COOH}}, and its C:D ratio (the total number of carbon atoms to the number of carbon-carbon double bonds) is 16:0. It is a major component of [[palm oil]] from the fruit of ''[[Elaeis guineensis]]'' ([[oil palm]]s), 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.<ref>{{cite Q|Q46799280|doi-access=free}}</ref>

'''Palmitates''' are the [[salt (chemistry)|salts]] and [[ester]]s 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.<ref>{{Cite journal |last1=Loften |first1=J.R. |last2=Linn |first2=J.G. |last3=Drackley |first3=J.K. |last4=Jenkins |first4=T.C. |last5=Soderholm |first5=C.G. |last6=Kertz |first6=A.F. |date=August 2014 |title=Invited review: Palmitic and stearic acid metabolism in lactating dairy cows |journal=Journal of Dairy Science |volume=97 |issue=8 |pages=4661–4674 |doi=10.3168/jds.2014-7919 |pmid=24913651 |issn=0022-0302|doi-access=free}}</ref>

==Occurrence and production==

Palmitic acid was discovered by [[Edmond Frémy]] (in 1840) in the [[saponification]] of palm oil, which process remains today the primary industrial route for producing the acid.<ref>{{cite journal |first=E. |last=Frémy |title=Memoire sur les produits de la saponification de l'huile de palme |journal=Journal de Pharmacie et de Chimie |volume=XII |year=1842 |pages=757 }}</ref> [[Triglyceride]]s (fats) in [[palm oil]] are [[hydrolysed]] by high-temperature water and the resulting mixture is [[fractional distillation| fractionally distilled]].<ref name=Ullmann>{{cite book |first1=David J. |last1=Anneken |first2=Sabine |last2=Both |first3=Ralf |last3=Christoph |first4=Georg |last4=Fieg |first5=Udo |last5=Steinberner |first6=Alfred |last6=Westfechtel |chapter=Fatty Acids |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2006 |publisher=Wiley-VCH |location=Weinheim |doi=10.1002/14356007.a10_245.pub2 |isbn=978-3527306732 }}</ref>

===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 [[meat]]s, as well as [[cocoa butter]], [[olive oil]], [[soybean oil]], and [[sunflower oil]], (see table).<ref>{{cite web |url=http://www.oliveoilsource.com/page/chemical-characteristics |title=Chemical Characteristics |website=Olive Oil Source |accessdate=November 11, 2021}}{{dead link|date=March 2023}}</ref> [[Karuka]]s contain 44.90% palmitic acid.<ref name="Purwanto">{{cite journal |last1=Purwanto |first1=Y. |last2=Munawaroh |first2=Esti |title=Etnobotani Jenis-Jenis Pandanaceae Sebagai Bahan Pangan di Indonesia |journal=Berkala Penelitian Hayati |date=2010 |volume=5A |pages=97–108 |url=https://berkalahayati.org/files/journals/1/articles/265/submission/265-838-1-SM.pdf |access-date=10 November 2021 |trans-title=Ethnobotany Types of Pandanaceae as Foodstuffs in Indonesia |language=id |issn=2337-389X |oclc=981032990 }}</ref> The [[cetyl alcohol|cetyl]] ester of palmitic acid, [[cetyl palmitate]], occurs in [[spermaceti]].

{|class="wikitable"

|+ Palmitic acid content of common foods

! scope="col" | Food

! scope="col" | % 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 as food|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%

|-

|colspan=2 style="text-align:center;"|<small>Source:<ref name="Nelson 1991">Nelson, Gary J. (1991). ''Health Effects of Dietary Fatty Acids''. American Oil Chemists' Society. pp. 84-86. {{ISBN|978-0935315318}}</ref></small>

|}

Palmitic acid is the first fatty acid produced during [[fatty acid synthesis and longer fatty acids . 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.<ref>[http://www.genome.jp/pathway/map00061 </ref>

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 protein]]s.

==Applications==

=== Surfactant ===

Palmitic acid is used to produce [[soap]]s, [[cosmetics]], and industrial mold [[release agent]]s. 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 certification|organic]] products.<ref>US Soil Association standard 50.5.3</ref>

======

Aluminium [[salt (chemistry)|salts]] of palmitic acid and [[naphthenic acid]] were the [[gelling agent]]s used with volatile petrochemicals during [[World War II]] to produce [[napalm]]. The word "napalm" is derived from the words naphthenic acid and palmitic acid.<ref>{{Cite journal|url=https://pubs.acs.org/doi/pdf/10.1021/ie50475a033|doi=10.1021/ie50475a033|title=Napalm. Mixture of Aluminum Disoaps|year=1949|last1=Mysels|first1=Karol J.|journal=Industrial & Engineering Chemistry|volume=41|issue=7|pages=1435–1438}}</ref>

====

It is well accepted in the medical community that palmitic acid from dietary sources raises [[low-density lipoprotein]] (LDL) and total cholesterol.<ref name="Nelson 1991"/><ref>{{cite journal|vauthors=Mensink RP, Zock PL, Kester AD, Katan MB|year=2003|title=Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials|journal=Am J Clin Nutr|volume=77|issue=5|pages=1146–1155|doi=10.1093/ajcn/77.5.1146|pmid=12716665|doi-access=free}}</ref><ref>Mensink, Ronald P. (2016). [https://apps.who.int/iris/bitstream/handle/10665/246104/9789241565349-eng.pdf "Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis"]. World Health Organization. Retrieved 14 March 2023.</ref><ref>Rao, Gundu HR. (2020). ''Clinical Handbook of Coronary Artery Disease''. Jaypee Brothers Medical Publishers. pp. 186-187. {{ISBN|978-9389188301}}</ref> The [[World Health Organization]] have stated there is convincing evidence that palmitic acid increases [[cardiovascular disease]] risk.<ref>[https://web.archive.org/web/20220901225923/https://apps.who.int/iris/bitstream/handle/10665/42665/WHO_TRS_916.pdf "Diet, Nutrition and the Prevention of Chronic Diseases"]. World Health Organization. p. 82. Retrieved 16 March 2023.</ref>

A 2021 review indicated that replacing dietary palmitic acid and other saturated fatty acids with [[unsaturated fatty acid]]s, such as [[oleic acid]], could reduce several [[biomarker]]s of cardiovascular and [[metabolic syndrome|metabolic]] diseases.<ref name="Sellem">{{cite journal | last1=Sellem | first1=Laury | last2=Flourakis | first2=Matthieu | last3=Jackson | first3=Kim G | last4=Joris | first4=Peter J | last5=Lumley | first5=James | last6=Lohner | first6=Szimonetta | last7=Mensink | first7=Ronald P | last8=Soedamah-Muthu | first8=Sabita S | last9=Lovegrove | first9=Julie A | title=Impact of Replacement of Individual Dietary SFAs on Circulating Lipids and Other Biomarkers of Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Humans | journal=Advances in Nutrition | date=2021-11-25 | volume=13 | issue=4 | pages=1200–1225 | issn=2161-8313 | doi=10.1093/advances/nmab143 | pmid=34849532| pmc=9340975 | doi-access=free }}</ref>

== See also ==

* [[]]

* [[SN2 Palmitate]]

* [[Juniperic acid]] (16-hydroxypalmitic acid)

{{Reflist}}

==External links==

*{{Commons category-inline|Palmitic acid}}

*{{Cite EB1911|wstitle=Palmitic Acid|short=x}}

{{Palm oil}}

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