Editing Paraldehyde (section)

{{Distinguish|Paraformaldehyde}}

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464197327
| Name = Paraldehyde
| ImageFile1 = Paraldehyde structure.svg
| ImageSize1 = 115
| ImageAlt1 = Skeletal formula
| IUPACName = 2,4,6-Trimethyl-1,3,5-trioxane
| SystematicName = 2,4,6-Trimethyl-1,3,5-trioxane
| OtherNames =

| Section1 = {{Chembox Identifiers
| Abbreviations =
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = S6M3YBG8QA
| InChI = 1/C6H12O3/c1-4-7-5(2)9-6(3)8-4/h4-6H,1-3H3
| InChIKey = SQYNKIJPMDEDEG-UHFFFAOYAO
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI =1S/C6H12O3/c1-4-7-5(2)9-6(3)8-4/h4-6H,1-3H3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = SQYNKIJPMDEDEG-UHFFFAOYSA-N
| CASNo = 123-63-7
| CASNo_Ref = {{cascite|correct|CAS}}
| EINECS = 204-639-8
| PubChem = 31264
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 21106173
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1410743
| SMILES = CC1OC(C)OC(C)O1
| RTECS = 
| MeSHName = Paraldehyde
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 27909
| KEGG_Ref = {{keggcite|changed|kegg}}
| KEGG = D00705
  }}

| Section2 = {{Chembox Properties
| C=6 | H=12 | O=3
| Appearance = Colourless liquid
| Odour = Sweet
| Density = 0.996 g/cm<sup>3</sup>
| MeltingPtC = 12
| MeltingPt_ref = 
| BoilingPtC = 124
| BoilingPt_ref = <ref name = Sigma>{{Sigma-Aldrich|id=76260|name=Paraldehyde|access-date=16/1/2020}}</ref>
| Solubility = soluble 10% vv at 25 Deg.
| SolubleOther =
| Solvent =
| LogP =
| VaporPressure = 13 hPa at 20 °C<ref name = Sigma />
| HenryConstant =
| AtmosphericOHRateConstant =
| pKa =
| pKb =
| MagSus = −86.2·10<sup>−6</sup> cm<sup>3</sup>/mol
  }}

| Section6 = {{Chembox Pharmacology
| ATCCode_prefix = N05
| ATCCode_suffix = CC05
| Bioavail =
| Metabolism =
| HalfLife =
| ProteinBound =
| Excretion =
| Legal_status =
| Legal_US_comment =
| Legal_AU =
| Legal_CA =
  }}

| Section7 = {{Chembox Hazards
| ExternalSDS = <ref name = Sigma />
| GHSPictograms = {{GHS02}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|226}}
| PPhrases = {{P-phrases|210|233|303+361+353|370+378|403+235|501}}
| MainHazards = Flammable
| NFPA-H =
| NFPA-F =
| NFPA-R =
| NFPA-S =
| AutoignitionPt =
| ExploLimits = Upper limit: 17 %(V)<BR />Lower limit: 1.3 %(V)
| FlashPt = 24°C - closed cup
| LD50 = Oral - Rat - 1,530 mg/kg<BR /> Dermal - Rabbit - 14,015 mg/kg
| LC50 =
| PEL =
  }}
}}

'''Paraldehyde''' is the cyclic [[trimer (chemistry)|trimer]] of [[acetaldehyde]] molecules.<ref>{{cite journal|last1=Wankhede|first1=N N|last2=Wankhede|first2=D S|last3=Lande|first3=M K|last4=Arbad|first4=B R|title=Densities and ultrasonic velocities of binary mixtures of 2,4,6-trimethyl-1,3,5-trioxane + ''n''-alcohols at 298.15, 303.15 and 308.15 K|journal=Indian Journal of Chemical Technology|date=March 2006|volume=13|issue=2|pages=149–155|url=http://nopr.niscair.res.in/bitstream/123456789/7015/1/IJCT%2013%282%29%20149-155.pdf}}</ref> Formally, it is a derivative of [[1,3,5-trioxane]], with a [[methyl group]] substituted for a [[hydrogen]] atom at each carbon. The corresponding tetramer is [[metaldehyde]]. A colourless liquid, it is sparingly soluble in [[properties of water|water]] and highly soluble in [[ethanol]]. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of [[acetic acid]]. It attacks most plastics and rubbers and should be kept in glass bottles.

Paraldehyde was first observed in 1835 by the German chemist [[Justus Liebig]]; its empirical formula was determined in 1838 by Liebig's student [[Hermann von Fehling|Hermann Fehling]].<ref>Liebig, Justus (1835) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457901;view=1up;seq=523 "Ueber die Producte der Oxydation des Alkohols"] (On the products of the oxidation of ethanol), ''Annalen der Chemie'', '''14''' :  133–167; see especially p. 141.</ref><ref>Fehling, H. (1838) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457908;view=1up;seq=331 "Ueber zwei dem Aldehyd isomere Verbindungen"] (On two compounds that are isomeric to acetaldehyde), ''Annalen der Chemie'', '''27''' :  319–322; see pp. 321–322.</ref> The German chemist Valentin Hermann Weidenbusch (1821–1893), another of Liebig's students, synthesized paraldehyde in 1848 by treating acetaldehyde with acid (either sulfuric or nitric acid) and cooling to 0°C. He found it quite remarkable that when paraldehyde was ''heated'' with a trace of the same acid, the reaction went the other way, recreating acetaldehyde.<ref>Weidenbusch, H. (1848) [https://babel.hathitrust.org/cgi/pt?id=chi.47401598;view=1up;seq=584 "Ueber einige Producte der Einwirkung von Alkalien und Säuren auf den Aldehyd"] (On some products of the reaction of alkalies and acids with acetaldehyde), ''Annalen der Chemie'', '''66''' :  152-165; see pp. 155–158.</ref><ref>Paraldehyde was first synthesized by Weidenbusch in 1848:
*  (Editorial staff)  (April 15, 1885) "The action of paraldehyde,"  ''The Therapeutic Gazette'', '''9''' :  247-250; [https://books.google.com/books?id=bzWgAAAAMAAJ&pg=PA247 see p. 247.]
*  See also:  Henry Watts, Matthew Moncrieff Pattison Muir, and Henry Forster Morley, ''Watts' Dictionary of Chemistry'', rev'd, vol. 1 (London, England:  Longmans, Green, and Co., 1905), [https://books.google.com/books?id=dNznAAAAMAAJ&pg=PA106 p. 106.]

For biographical information about Valentin Hermann Weidenbusch, see: 
*   Neill Busse, ''Der Meister und seine Schüler: Das Netzwerk Justus Liebigs und seiner Studenten'' [The Master and His Disciples:  The network of Justus Liebig and his students] (Hildesheim, Germany:  Georg Olms Verlag, 2015); for Weidenbusch's dates, [https://books.google.com/books?id=PY9KCwAAQBAJ&pg=PA274 see p. 274.] 
*  See also:  Joseph S. Fruton (March 1988) "The Liebig research group: A reappraisal," ''Proceedings of the American Philosophical Society'', '''132''' (1) :  1–66;  see p. 59.
*  See also:  [http://www.rambow.de/download/DBE-Buchstabe-W.pdf ''Deutsche Biographische Enzyklopädie''] {{Webarchive|url=https://web.archive.org/web/20140811213150/http://www.rambow.de/download/DBE-Buchstabe-W.pdf |date=2014-08-11 }} (German Biographical Encyclopedia), p. 1154.</ref>

Paraldehyde has uses in industry and medicine.