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'''Lithium soap''', often loosely referred to as "'''lithium grease'''" or "'''white lithium'''", is a [[soap]] that is a [[lithium]] derivative. Lithium soaps are primarily used as components of certain [[lubricant]] [[Grease (lubricant)|grease]]s.
|- border="0" class="backgroundcolor6" align="center"
| Examples of Lithium salts of fatty acids
|-
| [[File:Oelic Acid Lithium Salt Structural Formula V.4.svg|center|200px]] [[Lithium oleate]], the lithium salt of [[oleic acid]].
|-
| [[File:Palmitic Acid Lithium Salt Structural Formula V.2.svg|center|200px]] [[Lithium palmitate]], the lithium salt of [[palmitic acid]].
|-
| [[File:Stearic Acid Lithium Salt Structural Formula V.2.svg|center|200px]] [[Lithium stearate]], the lithium salt of [[stearic acid]].
|}
[[File:Литол.jpg|thumb|Lithium grease in use]]
'''Lithium soap''' is a [[soap]] consisting of a [[lithium]] salt of a [[fatty acid]].<ref name="Tadros2014">{{cite book|author=Tharwat F. Tadros|title=An Introduction to Surfactants|url=https://books.google.com/books?id=CWznBQAAQBAJ&pg=PA6|date=1 April 2014|publisher=De Gruyter|isbn=978-3-11-031213-3|pages=6–}}</ref><ref name="Cahn2003">{{cite book|author=Arno Cahn|title=5th World Conference on Detergents: Reinventing the Industry : Opportunities and Challenges|url=https://books.google.com/books?id=VMqSJROG_WYC&pg=PA182|date=30 May 2003|publisher=The American Oil Chemists Society|isbn=978-1-893997-40-0|pages=182–}}</ref> Sodium-based and potassium-based soaps are used as cleaning agents in domestic and industrial applications, whereas lithium soaps are used as components of lithium grease (white lithium).


Lithium soaps are produced by [[saponification]] of triglycerides, using [[lithium hydroxide]] or [[lithium carbonate]] as the saponification agent. Lithium soaps are used as [[lubricant]] components and form-release agents at relatively high temperatures.<ref>{{cite book|title=The Significance of Tests of Petroleum Products: A Report|url=https://books.google.com/books?id=3FkMrP4Hlw0C&pg=PA152|year=1934|publisher=ASTM International|pages=152–|id=GGKEY:FWTS3ZUUWJL}}</ref>
Soaps are [[salts]] of [[fatty acid]]s.<ref name="Cahn2003">{{cite book|author=Arno Cahn|title=5th World Conference on Detergents: Reinventing the Industry : Opportunities and Challenges|url=https://books.google.com/books?id=VMqSJROG_WYC&pg=PA182|date=30 May 2003|publisher=The American Oil Chemists Society|isbn=978-1-893997-40-0|pages=182–}}</ref> In the domestic setting, sodium-based and potassium-based soaps are commonly used as natural cleaning [[surfactant|surfactants]]. The most useful of the non-detergent soaps are those based on lithium, as they are free of corrosive properties. For lubrication, and as form-release agents, soaps derived from lithium are used due to their higher melting points.<ref>{{cite book|title=The Significance of Tests of Petroleum Products: A Report|url=https://books.google.com/books?id=3FkMrP4Hlw0C&pg=PA152|year=1934|publisher=ASTM International|pages=152–|id=GGKEY:FWTS3ZUUWJL}}</ref> The main components of lithium soaps are [[lithium stearate]] and [[lithium 12-hydroxystearate]].<ref name="Chaudhuri2016">{{cite book|author=Uttam Ray Chaudhuri|title=Fundamentals of Petroleum and Petrochemical Engineering|url=https://books.google.com/books?id=mKQnDet5IUoC&pg=PA89|date=19 April 2016|publisher=CRC Press|isbn=978-1-4398-5161-6|pages=89–}}</ref> In addition to soap, soap-based lubricating greases also contain hydrocarbon oils and other components.<ref name=Ullmann>Angelo Nora, Alfred Szczepanek, Gunther Koenen, "Metallic Soaps" in Ullmann’s Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a16_361}}</ref>
The main components of lithium soaps are [[lithium stearate]] and [[lithium 12-hydroxystearate]].<ref name="Chaudhuri2016">{{cite book|author=Uttam Ray Chaudhuri|title=Fundamentals of Petroleum and Petrochemical Engineering|url=https://books.google.com/books?id=mKQnDet5IUoC&pg=PA89|date=19 April 2016|publisher=CRC Press|isbn=978-1-4398-5161-6|pages=89–}}</ref>


==Lithium grease==
==Lithium grease==
[[File:LithiumGrease.jpg|thumb|left|360 px|Tube of grease ("Fett" in German) made from lithium soap.]]
{{unreferenced section}}
[[Grease (lubricant)|Lubricating greases]] are commonly formulated as mixtures of an oil and a lithium soap thickener.<ref name=Ullmann>Angelo Nora, Alfred Szczepanek, Gunther Koenen, "Metallic Soaps" in Ullmann’s Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a16_361}}</ref> Some formulations include [[Polytetrafluoroethylene|PTFE]] or other substances, such as [[molybdenum disulfide]].
Most [[Grease (lubricant)|lubricating greases]] are mixtures of an oil and a soap. The soap is dispersed into the oil to form a stable, viscous gel that is called a grease. Grease made with lithium soap ("lithium grease") adheres particularly well to [[metal]], is non-[[corrosion|corrosive]], may be used under heavy loads, and exhibits good temperature tolerance. It has a [[drip temperature]] of {{convert|190|to|220|°C|°F|-1}} and resists moisture, so it is commonly used as lubricant in household products, such as electric garage doors, as well as in automotive applications, such as [[CV joints]]. Lithium-containing greases first appeared during World War II and were perhaps the first large-scale commercial application of lithium compounds.


Lithium grease adheres particularly well to [[metal]], is non-[[corrosion|corrosive]], may be used under heavy loads, and exhibits good temperature tolerance. It has a [[dropping point]] of {{convert|190|to|220|°C|°F|-1}} and resists moisture, so it is commonly used as lubricant in household products, such as electric garage doors, as well as in automotive applications, such as [[constant-velocity joint]]s. Lithium greases using a thickener formed by reacting a simple lithium soap with an acid are known as lithium complex greases and have higher [[Dropping point|dropping points]] as well as improvements to other properties.<ref>{{cite web |url=https://www.machinerylubrication.com/Read/28381/grease-lithium-production-resistance |title=Grease Selection: Lithium vs. Lithium Complex |author=David Turner |website=Machinery Lubrication |accessdate=2020-11-26 }}</ref>
Some formulations also include [[Polytetrafluoroethylene|PTFE]] or other substances, such as [[molybdenum disulfide]]. For high-performance and higher-temperature applications, lithium greases have been superseded by other types of lubricants.{{clarify|date=January 2013}}{{cn|date=January 2013}}

==Production==
Lithium soaps are produced in a manner similar to [[saponification]] of triglycerides.<ref name="Tadros2014">{{cite book|author=Tharwat F. Tadros|title=An Introduction to Surfactants|url=https://books.google.com/books?id=CWznBQAAQBAJ&pg=PA6|date=1 April 2014|publisher=De Gruyter|isbn=978-3-11-031213-3|pages=6–}}</ref> However, instead of sodium hydroxide, the fatty acids are treated with [[lithium hydroxide]] or [[lithium carbonate]] to form lithium salts of fatty acids. The lithium salts are colourless solids that melt near {{convert|200|°C|°F|-1}}.<ref name=Ullmann/>


==References==
==References==
{{Reflist}}
{{Reflist}}

{{Lithium compounds}}


{{DEFAULTSORT:Lithium-Based Grease}}
{{DEFAULTSORT:Lithium-Based Grease}}
[[Category:Greases]]
[[Category:Greases]]
[[Category:Lithium salts|*]]
[[Category:Organolithium compounds]]

Latest revision as of 04:15, 19 January 2024

Examples of Lithium salts of fatty acids
Lithium oleate, the lithium salt of oleic acid.
Lithium palmitate, the lithium salt of palmitic acid.
Lithium stearate, the lithium salt of stearic acid.
Lithium grease in use

Lithium soap is a soap consisting of a lithium salt of a fatty acid.[1][2] Sodium-based and potassium-based soaps are used as cleaning agents in domestic and industrial applications, whereas lithium soaps are used as components of lithium grease (white lithium).

Lithium soaps are produced by saponification of triglycerides, using lithium hydroxide or lithium carbonate as the saponification agent. Lithium soaps are used as lubricant components and form-release agents at relatively high temperatures.[3] The main components of lithium soaps are lithium stearate and lithium 12-hydroxystearate.[4]

Lithium grease

[edit]
Tube of grease ("Fett" in German) made from lithium soap.

Lubricating greases are commonly formulated as mixtures of an oil and a lithium soap thickener.[5] Some formulations include PTFE or other substances, such as molybdenum disulfide.

Lithium grease adheres particularly well to metal, is non-corrosive, may be used under heavy loads, and exhibits good temperature tolerance. It has a dropping point of 190 to 220 °C (370 to 430 °F) and resists moisture, so it is commonly used as lubricant in household products, such as electric garage doors, as well as in automotive applications, such as constant-velocity joints. Lithium greases using a thickener formed by reacting a simple lithium soap with an acid are known as lithium complex greases and have higher dropping points as well as improvements to other properties.[6]

References

[edit]
  1. ^ Tharwat F. Tadros (1 April 2014). An Introduction to Surfactants. De Gruyter. pp. 6–. ISBN 978-3-11-031213-3.
  2. ^ Arno Cahn (30 May 2003). 5th World Conference on Detergents: Reinventing the Industry : Opportunities and Challenges. The American Oil Chemists Society. pp. 182–. ISBN 978-1-893997-40-0.
  3. ^ The Significance of Tests of Petroleum Products: A Report. ASTM International. 1934. pp. 152–. GGKEY:FWTS3ZUUWJL.
  4. ^ Uttam Ray Chaudhuri (19 April 2016). Fundamentals of Petroleum and Petrochemical Engineering. CRC Press. pp. 89–. ISBN 978-1-4398-5161-6.
  5. ^ Angelo Nora, Alfred Szczepanek, Gunther Koenen, "Metallic Soaps" in Ullmann’s Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_361
  6. ^ David Turner. "Grease Selection: Lithium vs. Lithium Complex". Machinery Lubrication. Retrieved 2020-11-26.
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