Palmitic acid

Structural formula
General
Surname	Palmitic acid
other names	Hexadecanoic acid ( IUPAC ); Cetylic acid; PALMITIC ACID ( INCI ) ;
Molecular formula	C 16 H 32 O 2
Brief description	colorless, crystalline platelets
External identifiers / databases
EC number	200-312-9
ECHA InfoCard	100,000,284
PubChem	985
ChemSpider	960
DrugBank	DB03796
Wikidata	Q209727
properties
Molar mass	256.43 g mol −1
Physical state	firmly
density	0.8577 g cm −3
Melting point	62.5-63 ° C
boiling point	351 ° C
Vapor pressure	1.3 · 10 −7 Pa (298 K)
solubility	almost insoluble in water (7.2 mg l −1 ); bad in cold ethanol or petroleum ether ; good in hot ethanol, diethyl ether , propanol, and chloroform ;
Refractive index	1.4335
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
MAK	not forgiven
Toxicological data	> 10000 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Palmitic acid (hexadecanoic acid) is a saturated organic acid and is a fatty acid (= higher carboxylic acid ). Palmitates (systematically also hexadecanoates ) are the salts and esters of palmitic acid. Palmitic acid is a colorless solid at room temperature.

In many living organisms, palmitate is a main intermediate product of the metabolism , from which all other fatty acids are made in the form of glycerides for building up fat reserves . The biosynthesis of palmitate takes place in lipogenesis from small molecular precursors in a repetitive process in which two carbon molecules are attached to the molecular chain with each step.

The name comes from the first palmitic acid, obtained by hydrolysis of palm oil by Edmond Frémy (1840).

Occurrence

The pulp of the oil palm provides palm oil, the triglycerides of which are rich in palmitic acid residues.

The palmitic acid residue is the saturated fatty acid residue most frequently found in many vegetable and animal fats and fatty oils as glycerine esters :

product	Palmitic acid content
Stillingia oil	60-70%
Palm oil	41-46%
Butterfat	24-32%
Lard	24-30%
Cocoa butter	23-30%
Beef tallow	23-29%
Cottonseed oil	21-27%
Avocado oil	10-26%

Contrary to popular belief, natural fats and oils do not contain free palmitic acid, but its glycerol esters .

Physical Properties

The flash point is> 160 ° C, the ignition temperature is 240 ° C and the lower explosion limit is 0.42% by volume.

Analytics

The reliable qualitative and quantitative determination of palmitic acid in a wide variety of test materials is possible after adequate sample preparation and transesterification to the methyl ester by coupling capillary gas chromatography with mass spectrometry .

use

Palmitates are widely used in cosmetics .

The aluminum salt of palmitic acid forms, together with the aluminum salt of naphthenic acid, the thickening agent of the fire weapon Napalm whose name is composed of the initial syllables of the acids ( Na phthensäure, Palm itinsäure).

An alcoholic potassium palmitate solution (standardized soft soap ) is used to determine the total hardness in water.

Web links

Wiktionary: Palmitic acid - explanations of meanings, word origins, synonyms, translations

Wikibooks: Saturated Fatty Acids Biosynthesis - Learning and Teaching Materials

Gopinathrao, reactome.org: Palmitate synthesis

Individual evidence

↑ Entry on PALMITIC ACID in the CosIng database of the EU Commission, accessed on December 28, 2019.
↑ ^a ^b ^c ^d ^e ^f ^g Entry on palmitic acid. In: Römpp Online . Georg Thieme Verlag, accessed on June 20, 2014.
↑ ^a ^b David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 96th edition. (Internet version :), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-294.
↑ ^a ^b ^c ^d ^e ^f Entry for CAS no. 57-10-3 in the GESTIS substance database of the IFA , accessed on December 20, 2019 (JavaScript required)
↑ CD Cappa, ER Lovejoy, AR Ravishankara: Evaporation Rates and Vapor Pressures of the Even-Numbered C ₈ −C ₁₈ Monocarboxylic Acids. In: J. Phys. Chem. A 112, 2008, pp. 3959-3964. doi: 10.1021 / jp710586m
^ DM Cassidy, DA Pratt, R. Taylor, KG Alberti, MF Laker: Capillary column gas chromatography-mass spectrometry for the determination of the fatty acid composition of human adipose tissue. In: J Chromatogr. 491 (1), Jun 30, 1989, pp. 1-13. PMID 2793965
↑ NN Ahmad Nizar, JM Nazrim Marikkar, DM Hashim: Differentiation of lard, chicken fat, beef fat and mutton fat by GCMS and EA-IRMS techniques. In: J Oleo Sci. 62 (7), 2013, pp. 459-464. PMID 23823911
^ X. Dong, Y. Gao, M. Zeng, M. Liu, W. Li, Q. Liu, B. Wang: Analysis of meibum by gas chromatography-mass spectrometry. In: Zhonghua Yan Ke Za Zhi. 51 (9), Sep 2015, pp. 668-672. (Chinese) PMID 26693651

[CosIng-1] Entry on PALMITIC ACID in the CosIng database of the EU Commission, accessed on December 28, 2019.

[roempp-2] ↑ ^a ^b ^c ^d ^e ^f ^g Entry on palmitic acid. In: Römpp Online . Georg Thieme Verlag, accessed on June 20, 2014.

[CRC-3] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 96th edition. (Internet version :), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-294.

[GESTIS-4] ↑ ^a ^b ^c ^d ^e ^f Entry for CAS no. 57-10-3 in the GESTIS substance database of the IFA , accessed on December 20, 2019 (JavaScript required)

[Cappa-5] CD Cappa, ER Lovejoy, AR Ravishankara: Evaporation Rates and Vapor Pressures of the Even-Numbered C ₈ −C ₁₈ Monocarboxylic Acids. In: J. Phys. Chem. A 112, 2008, pp. 3959-3964. doi: 10.1021 / jp710586m

[6] DM Cassidy, DA Pratt, R. Taylor, KG Alberti, MF Laker: Capillary column gas chromatography-mass spectrometry for the determination of the fatty acid composition of human adipose tissue. In: J Chromatogr. 491 (1), Jun 30, 1989, pp. 1-13. PMID 2793965

[7] NN Ahmad Nizar, JM Nazrim Marikkar, DM Hashim: Differentiation of lard, chicken fat, beef fat and mutton fat by GCMS and EA-IRMS techniques. In: J Oleo Sci. 62 (7), 2013, pp. 459-464. PMID 23823911

[8] X. Dong, Y. Gao, M. Zeng, M. Liu, W. Li, Q. Liu, B. Wang: Analysis of meibum by gas chromatography-mass spectrometry. In: Zhonghua Yan Ke Za Zhi. 51 (9), Sep 2015, pp. 668-672. (Chinese) PMID 26693651