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a crystalline unsaturated fatty acid (同)elaeostearic acid
street name for lysergic acid diethylamide (同)back breaker, battery-acid, dose, dot, Elvis, loony toons, Lucy in the sky with diamonds, pane, superman, window pane, Zen
any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
having the characteristics of an acid; "an acid reaction"
of or relating to or composed of fat

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酸性の / 酸味のある,すっぱい(sour) / (言葉・態度などが)厳しい,しんらつな / 酸 / すっぱいもの / 《俗》=LSD

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/08 10:43:12」(JST)

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Stearic acid (STAIR-ik or STEER-ik) is a saturated fatty acid with an 18-carbon chain and has the IUPAC name octadecanoic acid. It is a waxy solid and its chemical formula is C₁₇H₃₅CO₂H. Its name comes from the Greek word στέαρ "stéar", which means tallow. The salts and esters of stearic acid are called stearates. As its ester, stearic acid is one of the most common saturated fatty acids found in nature following palmitic acid.^[9] The triglyceride derived from three molecules of stearic acid is called stearin.

Production

Stearic acid is obtained from fats and oils by the saponification of the triglycerides using hot water (above 200 °C). The resulting mixture is then distilled.^[3] Commercial stearic acid is often a mixture of stearic and palmitic acids, although purified stearic acid is available.

Fats and oils rich in stearic acid are more abundant in animal fat (up to 30%) than in vegetable fat (typically <5%). The important exceptions are cocoa butter and shea butter, where the stearic acid content (as a triglyceride) is 28–45%.^[10]

In terms of its biosynthesis, stearic acid is produced from carbohydrates via the fatty acid synthesis machinery wherein acetyl-CoA contributes two-carbon building blocks.

Uses

In general, applications of stearic acid exploit its bifunctional character, with a polar head group that can be attached to metal cations and a nonpolar chain that confers solubility in organic solvents. The combination leads to uses as a surfactant and softening agent. Stearic acid undergoes the typical reactions of saturated carboxylic acids, a notable one being reduction to stearyl alcohol, and esterification with a range of alcohols. This is used in a large range of manufactures, from simple to complex electronic devices.

Soaps, cosmetics, detergents

Stearic acid is mainly used in the production of detergents, soaps, and cosmetics such as shampoos and shaving cream products. Soaps are not made directly from stearic acid, but indirectly by saponification of triglycerides consisting of stearic acid esters. Esters of stearic acid with ethylene glycol, glycol stearate, and glycol distearate are used to produce a pearly effect in shampoos, soaps, and other cosmetic products. They are added to the product in molten form and allowed to crystallize under controlled conditions. Detergents are obtained from amides and quaternary alkylammonium derivatives of stearic acid.

Lubricants, softening and release agents

In view of the soft texture of the sodium salt, which is the main component of soap, other salts are also useful for their lubricating properties. Lithium stearate is an important component of grease. The stearate salts of zinc, calcium, cadmium, and lead are used to soften PVC. Stearic acid is used along with castor oil for preparing softeners in textile sizing. They are heated and mixed with caustic potash or caustic soda. Related salts are also commonly used as release agents, e.g. in the production of automobile tires.

Niche uses

Being inexpensively available and chemically benign, stearic acid finds many niche applications, for example, in making plaster castings from a plaster piece mold or waste mold and in making the mold from a shellacked clay original. In this use, powdered stearic acid is mixed in water and the suspension is brushed onto the surface to be parted after casting. This reacts with the calcium in the plaster to form a thin layer of calcium stearate, which functions as a release agent. When reacted with zinc it forms zinc stearate, which is used as a lubricant for playing cards (fanning powder) to ensure a smooth motion when fanning. In compressed confections, it is used as a lubricant to keep the tablet from sticking to the die.

Stearic acid is also used as a negative plate additive in the manufacture of lead-acid batteries. It is added at the rate of 0.6 g per kg of the oxide while preparing the paste.^[11] It is believed to enhance the hydrophobicity of the negative plate, particularly during dry-charging process. It also reduces the extension of oxidation of the freshly formed lead (negative active material) when the plates are kept for drying in the open atmosphere after the process of tank formation. As a consequence, the charging time of a dry uncharged battery during initial filling and charging (IFC) is comparatively lower, as compared to a battery assembled with plates which do not contain stearic acid additive.

Fatty acids are classic components of candle-making. Stearic acid is used along with simple sugar or corn syrup as a hardener in candies.

Stearic acid is used to produce dietary supplements.

In fireworks, stearic acid is often used to coat metal powders such as aluminium and iron. This prevents oxidation, allowing compositions to be stored for a longer period of time.

Stearic acid is a common lubricant during injection molding and pressing of ceramic powders.^[12] It is also used as a mold release for foam latex that is baked in stone molds.

Metabolism

An isotope labeling study in humans^[13] concluded that the fraction of dietary stearic acid that oxidatively desaturates to oleic acid is 2.4 times higher than the fraction of palmitic acid analogously converted to palmitoleic acid. Also, stearic acid is less likely to be incorporated into cholesterol esters. In epidemiologic and clinical studies, stearic acid was found to be associated with lowered LDL cholesterol in comparison with other saturated fatty acids.^[14]

These findings may indicate that stearic acid is healthier than other saturated fatty acids.

References

^ Susan Budavari, ed. (1989). Merck Index (11th ed.). Rahway, New Jersey: Merck & Co., Inc. p. 8761. ISBN 978-0-911910-28-5.
^ ^a ^b ^c ^d ^e ^f ^g ^h Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
^ ^a ^b David J. Anneken, Sabine Both, Ralf Christoph, Georg Fieg, Udo Steinberner, Alfred Westfechtel "Fatty Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a10_245.pub2
^ ^a ^b ^c ^d "stearic acid". Chemister.ru. 2007-03-19. Retrieved 2014-06-15.
^ ^a ^b ^c ^d ^e Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). D. Van Nostrand Company. p. 677.
^ ^a ^b ^c Octadecanoic acid in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov (retrieved 2014-06-15)
^ Vargaftik, Natan B.; et al. (1993). Handbook of Thermal Conductivity of Liquids and Gases (illustrated ed.). CRC Press. p. 318. ISBN 0-8493-9345-0.
^ ^a ^b ^c ^d von Sydow, E. (1955). "On the structure of the crystal form B of stearic acid". Acta Crystallographica 8 (9): 557. doi:10.1107/S0365110X55001746. edit
^ Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra "The Lipid Handbook with Cd-Rom. 3rd ed. Boca Raton: CRC Press, 2007. ISBN 0849396883 | ISBN 978-0849396885
^ Beare-Rogers, J.; Dieffenbacher, A.; Holm, J.V. (2001). "Lexicon of lipid nutrition (IUPAC Technical Report)". Pure and Applied Chemistry 73 (4): 685–744. doi:10.1351/pac200173040685.
^ L.T. Lam et al. Journal of Power Sources 73 (1998) 36–46
^ Tsenga, Wenjea J.; Mo Liua, Dean; Hsub, Chung-King (1999). "Influence of stearic acid on suspension structure and green microstructure of injection-molded zirconia ceramics". Ceramics International 25 (2): 191–195. doi:10.1016/S0272-8842(98)00024-8.
^ Emken, Edward A. (1994). "Metabolism of dietary stearic acid relative to other fatty acids in human subjects". American Journal of Clinical Nutrition 60 (6): 1023S–1028S. PMID 7977144.
^ Hunter, J. E.; Zhang, J.; Kris-Etherton, P. M. (2009). "Cardiovascular disease risk of dietary stearic acid compared with trans, other saturated, and unsaturated fatty acids: A systematic review". American Journal of Clinical Nutrition 91 (1): 46–63. doi:10.3945/ajcn.2009.27661. PMID 19939984. edit

External links

NIST Chemistry WebBook Entry

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English Journal

Synthesis and characterization of novel amphiphilic copolymer stearic acid-coupled F127 nanoparticles for nano-technology based drug delivery system.

Gao Q, Liang Q, Yu F, Xu J, Zhao Q, Sun B.SourceSoutheast University, School of Chemistry and Chemical Engineering, Nanjing 210000, China.
Colloids and surfaces. B, Biointerfaces.Colloids Surf B Biointerfaces.2011 Dec 1;88(2):741-8. Epub 2011 Aug 18.
Pluronic, F127, amphiphilic block copolymers, are used for several applications, including drug delivery systems. The critical micelle concentration (CMC) of F127 is about 0.26-0.8wt% so that the utility of F127 in nano-technology based drug delivery system is limited since the nano-sized micelles c
PMID 21906917

Japanese Journal

LB膜味覚センサによる甘味濃度測定 (有機エレクトロニクス)

長谷川有貴,立野靖大,浅見哲也 [他]
電子情報通信学会技術研究報告 110(409), 33-36, 2011-02-07
NAID 40018715235

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★リンクテーブル★

リンク元	「stearate」「aluminum monostearate」「magnesium stearate」「calcium stearate」「octadecanoic acid」

「stearate」

Stearic acid^[1]
Names
	IUPAC name Octadecanoic acid
	Other names C18:0 (Lipid numbers)
Identifiers
CAS Registry Number	57-11-4
ChEMBL	ChEMBL46403
ChemSpider	5091
DrugBank	DB03193
EC number	200-313-4
Jmol-3D images	Image
PubChem	5281
RTECS number	WI2800000
	SMILES CCCCCCCCCCCCCCCCCC(=O)O ;
Properties
Molecular formula	C18H36O2
Molar mass	284.48 g·mol−1
Appearance	White solid
Odor	Pungent, oily
Density	0.9408 g/cm3 (20 °C); 0.847 g/cm3 (70 °C)
Melting point	69.3 °C (156.7 °F; 342.4 K)
Boiling point	361 °C (682 °F; 634 K); decomposes; 232 °C (450 °F; 505 K); at 15 mmHg
Solubility in water	0.003 g/L (20 °C); 0.34 g/L (25 °C); 9.93 g/L (37 °C)
Solubility	Soluble in alkyl acetates, alcohols, HCOOCH3, phenyls, CS2, CCl4
Solubility in dichloromethane	3.58 g/100 g (25 °C); 8.85 g/100 g (30 °C); 18.3 g/100 g (35 °C)
Solubility in ethanol	0.9 g/100 mL (10 °C); 2 g/100 mL (20 °C); 4.5 g/100 mL (30 °C); 13.8 g/100 mL (40 °C)
Solubility in acetone	4.96 g/100 g
Solubility in chloroform	18.4 g/100 g
Solubility in toluene	15.75 g/100 g
Vapor pressure	0.01 kPa (158 °C); 0.46 kPa (200 °C); 16.9 kPa (300 °C)
Thermal conductivity	0.173 W/m·K (70 °C); 0.166 W/m·K (100 °C)
Refractive index (nD)	1.4299 (80 °C)
Structure
Crystal structure	B-form = Monoclinic
Space group	B-form = P21/a
Point group	B-form = Cs; 2h
Lattice constant	a = 5.591 Å, b = 7.404 Å, c = 49.38 Å (B-form)
Lattice constant	α = 90°, β = 117.37°, γ = 90°
Thermochemistry
Specific; heat capacity (C)	501.5 J/mol·K
Std molar; entropy (So298)	435.6 J/mol·K
Std enthalpy of; formation (ΔfHo298)	−947.7 kJ/mol
Std enthalpy of; combustion (ΔcHo298)	11290.79 kJ/mol
Hazards
NFPA 704	1 1 0
Flash point	113 °C (235 °F; 386 K)
LD50 (Median lethal dose)	21.5 mg/kg (rats, intravenous)
	Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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