Decalin: Difference between revisions

| verifiedrevid = 443563099

| Name = Decalin

| ImageFile = Decahydronaphthalene.png

| ImageSize = 250px

| ImageName = Decalin

| IUPACName = Decahydronaphthalene

| OtherNames = decalin<br />bicyclo[4.4.0]decane

| Section1 = {{Chembox Identifiers

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| CASNo_Ref = {{cascite|correct|CAS}}

| Section2 = {{Chembox Properties

| C=10|H=18

| MolarMass = 138.25 g/mol

| Appearance = Clear, colorless liquid

| Density = 0.896 g/cm³

| Refractive index = 1.481

| Solubility = Insoluble

| MeltingPt = racemate: −40 °C (−40 °F)<br />trans: −31 °C (−23 °F)<br />cis: −43 °C (−45 °F)

| BoilingPt = trans: 187 °C (369 °F)<br />cis: 196 °C (384 °F)

| Section7 = {{Chembox Hazards

| ExternalMSDS = [http://hazard.com/msds/mf/baker/baker/files/d0064.htm Decalin MSDS]

| FlashPt = 57 °C

| Autoignition = 250 °C

| }}

| Section8 = {{Chembox Related

| OtherCpds = [[Naphthalene]]; [[Tetralin]]

'''Decalin''' ('''decahydronaphthalene''', also known as '''bicyclo[4.4.0]decane''')<ref>{{cite web| url = http://dictionary.reference.com/browse/decahydronaphthalene| title = Dictionary.com}}</ref>, a [[bicyclic]] [[organic compound]], is an industrial [[solvent]]. A colorless liquid with an aromatic odor, it is used as a solvent for many [[resin]]s or fuel additive.<ref>{{cite web| url = http://www.decalinchemicals.com/fueladditive.html| title =Fuel Additive Product}}</ref> It is the saturated analog of [[naphthalene]] and can be prepared from it by [[hydrogenation]] in a fused state in the presence of a [[catalyst]]. Decahydronaphthalene easily forms [[explosive]]<ref>{{cite web| url = http://idea.library.drexel.edu/bitstream/1860/16/11/agosta_thesis.pdf| title =PDF – Surrogate JP-8 Aviation Fuel Study – Alessandro Agosta Thesis Drexel University}}</ref> [[organic peroxide]]s upon storage in the presence of air.<ref>{{cite web| url = http://www.inchem.org/documents/icsc/icsc/eics1548.htm| title =Inchem.org Data}}</ref><ref>{{cite web| url = http://hazard.com/msds/mf/baker/baker/files/d0064.htm| title =MSDS Sheet – JT Baker}}</ref>

Decahydronaphthalene occurs in [[Cis-trans isomerism|cis]] and [[trans isomer|trans]] [[Geometric isomerism|forms]]. The trans form is energetically more stable because of fewer [[steric interaction]]s. ''Cis''-decalin is a chiral molecule without chiral center; it has a two-fold rotational symmetry axis going through the center of 1-6 bond but no reflective symmetry. However, the [[Chirality (chemistry)|chirality]] is canceled through a chair flipping process that turns the molecule into its mirror image.

<gallery>

Image:Cis-trans isomerism of decahydronaphthalene.png|<center>'''1:''' ''trans'' (left) and ''cis'' (right) isomers</center>

Image:Cis-decalin-3D-balls.png|'''2:''' <center>[[ball-and-stick model]] of ''cis''-decalin</center>

Image:Trans-decalin-3D-balls.png|'''3:''' <center>''trans''-decalin</center>

</gallery><ref>{{cite web| url = http://www.isfuel.com/27.html| title =ISFuel.com Animation}}</ref>

=== Trans decaline ===

<gallery>

Image:Cyclohexane-chair-colour-coded-3D-balls.png|<center>'''4:''' Half a decalin molecule: cyclohexane in ''chair'' conformation. Axial positions are shown in red, while those in equatorial positions are in blue.

Image:Androstanediol.png|<center>'''5:''' Androstanediol, a biomolecule with three ''trans'' fused six membered rings (and an also ''trans'' fused five membered one)

As can be seen on the model of [[cyclohexane]], the trans configuration comes with a price: the only possible way to join the two six membered rings in ''trans'' relation will mean the second ring needs to start out of two equatorial bonds of the first ring. A six membered ring does not offer space enough to start out on an axial position (say up), and reach for the axial position of the carbon atom next door, which then will be on the down side of the molecule.

A second price to be paid is the effective freezing of the rings in a fixed conformation. In [[biology]] this fixation is widely used in the [[steroid]] skeleton to construct [[molecule]]s that play a key role in the signaling between far separated cells.

* [[Dilin]]

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