Editing Soxhlet extractor

{{short description|Laboratory apparatus}}
[[Image:Soxhlet extractor.svg|thumb|A schematic representation of a Soxhlet extractor: {{image key|list type=ordered|thumb size=narrow
| Stirrer bar
| Still pot (the still pot should not be overfilled and the volume of solvent in the still pot should be 3 to 4 times the volume of the Soxhlet chamber)
| Distillation path
| Thimble
| Solid
| Siphon top
| Siphon exit
| Expansion adapter
| Condenser
| Cooling water out
| Cooling water in
}}]]A '''Soxhlet extractor''' is a piece of [[laboratory]] apparatus<ref name=HarwoodMoodyEOCPAP>{{cite book
 |first1 = Laurence M.
 |last1 = Harwood
 |first2 = Christopher J.
 |last2 = Moody
 |title = Experimental organic chemistry: Principles and Practice
 |edition = Illustrated
 |pages = [https://archive.org/details/experimentalorga00harw/page/122 122–125]
 |isbn = 978-0-632-02017-1
 |date = 13 Jun 1989
 |publisher = [[Wiley-Blackwell]]
 |url = https://archive.org/details/experimentalorga00harw/page/122
}}</ref> invented in 1879 by [[Franz von Soxhlet]].<ref>{{cite journal |last=Soxhlet |first=F. |title=Die gewichtsanalytische Bestimmung des Milchfettes |journal= Dingler's Polytechnisches Journal |date=1879 |volume=232 |pages=461–465 |url=http://dingler.culture.hu-berlin.de/article/pj232/ar232136 |language= German}}</ref>  It was originally designed for the extraction of a [[lipid]] from a solid  material. Typically, Soxhlet extraction is used when the desired compound has a ''limited'' [[solubility]] in a [[solvent]], and the impurity is [[insoluble]] in that solvent. It allows for unmonitored and unmanaged operation while efficiently recycling a small amount of solvent to dissolve a larger amount of material.

==Description==
A Soxhlet extractor has three main sections: a percolator (boiler and reflux) which circulates the solvent, a thimble (usually made of thick filter paper) which retains the solid to be extracted, and a siphon mechanism, which periodically empties the condensed solvent from the thimble back into the percolator.

==Assembly==

* The source material containing the compound to be extracted is placed inside the thimble.

* The thimble is loaded into the main chamber of the Soxhlet extractor.
* The extraction [[solvent]] to be used is placed in a distillation [[round bottomed flask|flask]].
* The flask is placed on the [[heating element]].
* The Soxhlet extractor is placed atop the flask.
* A reflux [[condenser (laboratory)|condenser]] is placed atop the extractor.

==Operation==
The solvent is heated to [[reflux]]. The solvent vapour travels up a [[distillation]] arm, and floods into the chamber housing the thimble of solid. The condenser ensures that any solvent vapour cools, and drips back down into the chamber housing the solid material. The chamber containing the solid material slowly fills with warm solvent. Some of the desired compound [[solvation|dissolves]] in the cold solvent. When the Soxhlet chamber is almost full, the chamber is emptied by the [[siphon]]. The solvent is returned to the [[distillation]] flask.  The thimble ensures that the rapid motion of the solvent does not transport any solid material to the still pot.  This cycle may be allowed to repeat many times, over hours or days.

During each cycle, a portion of the non-[[Volatility (chemistry)|volatile]] compound dissolves in the solvent. After many cycles the desired compound is concentrated in the distillation flask. The advantage of this system is that instead of many portions of warm solvent being passed through the sample, just one batch of solvent is recycled.

After extraction the solvent is removed, typically by means of a [[rotary evaporator]], yielding the extracted compound. The non-soluble portion of the extracted solid remains in the thimble, and is usually discarded.
Like Soxhlet extractor, the Kumagawa extractor has a specific design where the thimble holder/chamber is directly suspended inside the solvent flask (having a vertical large opening) above the boiling solvent. The thimble is surrounded by hot solvent vapour and maintained at a higher temperature compared to the Soxhlet extractor, thus allowing better extraction for compounds with higher melting points such as [[bitumen]]. The removable holder/chamber is fitted with a small siphon side arm and, in the same way as for Soxhlet, a vertical [[Condenser (laboratory)|condenser]] ensures that the solvent drips back down into the chamber which is automatically emptied at every cycle.

==History==
[[William B. Jensen]] notes that the earliest example of a continuous extractor is archaeological evidence for a [[Mesopotamian]] hot-water extractor for organic matter dating from approximately 3500 BC.<ref name=jensen>{{cite journal |title=The Origin of the Soxhlet Extractor |first=William B. |last=Jensen |volume=84 |issue=12 |date=December 2007 |journal=[[Journal of Chemical Education]] |pages=1913–1914 |doi=10.1021/ed084p1913 |bibcode=2007JChEd..84.1913J |author1-link=William B. Jensen}}</ref> The same mechanism is present in the [[Pythagorean cup]]. Before Soxhlet, the French chemist [[Anselme Payen]] also pioneered with continuous extraction in the 1830s.

A Soxhlet apparatus has been proposed as an effective technique for washing [[Standard (metrology)|mass standards]].<ref>{{cite journal |title=Stability of reference masses V: UV/ozone treatment of gold and platinum surfaces |first1=Peter |last1=Cumpson |first2=Naoko |last2=Sano |date=February 2013 |journal=[[Metrologia]] |volume=50 |issue=1 |pages=27–36 |doi=10.1088/0026-1394/50/1/27 |quote=The apparatus we propose for the solvent pre-wash is the Soxhlet apparatus, which has been used very successfully before for washing stainless-steel standard-mass surfaces. This apparatus has its main application in chemistry for dissolving weakly soluble species from solid matrices.|bibcode=2013Metro..50...27C }}</ref>

== Gallery ==
<gallery widths="250" heights="250">
File:Soxhlet mechanism.gif|alt=|Animation of Soxhlet extractor at work
File:Soxhlet Extractor.jpg|Fruit extraction in progress. The sample is placed directly in the extraction chamber, no thimble used.
File:Soxhlet siphoning.webm|The siphoning part of a Soxhlet extraction.
</gallery>

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20100527170151/http://www.campbell.edu/faculty/jung/soxhlet.ppt The Soxhlet Extractor explained]
* [http://www.rsc.org/chemistryworld/Issues/2007/September/ClassicKitSoxhletExtractor.asp Royal Society of Chemistry: Classic Kit: Soxhlet extractor]
* [https://www.science.org/content/blog-post/new-tricks-glassware Soxhlet apparatus used as a replenishing source of solvent in chromatography]
* [https://www.youtube.com/watch?v=YGZddY3R1pU Extracting the Spicy Chemical in Black Pepper] video demonstrating the use of a Soxhlet extractor to extract [[piperine]] from black pepper.
* [https://insilscientific.com/cellulose.html thimbles used for Soxhlet extraction]

{{Laboratory equipment}}
{{Distillation}}

{{DEFAULTSORT:Soxhlet Extractor}}
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