View source for Stilbene

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! {{chembox header}} | Stilbene
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| align="center" colspan="2" |
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! {{chembox header}} | General
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| [[IUPAC nomenclature|Systematic name]]
| trans-1,2-diphenylethylene<br />
(E)-1,2-diphenylethene
|-
| Other Names
| (E)-stilbene
|-
| 
| trans-stilbene
|-
| [[Chemical formula|Molecular formula]]
| C<sub>14</sub>H<sub>12</sub>
|-
| 
| C<sub>6</sub>H<sub>5</sub>CH=CHC<sub>6</sub>H<sub>5</sub>
|-
| [[SMILES]]
| c1(/C=C/c2ccccc2)ccccc1
|-
| [[Molar mass]]
| 180.24928 g/mol
|-
| Appearance
| Solid
|-
| Color
| white - slightly beige
|-
| [[CAS registry number|CAS number]]
| 103-30-0
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! {{chembox header}} | Properties
|-
| [[Soluble|Solubility]] in [[Water (molecule)|water]]
| practically insoluble
|-
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| [[Melting point]]
| 122°C - 125°C
|-
| [[Boiling point]]
| 305°C - 307°C
|-
| Flash Point
| >112°C
|-
! {{chembox header}} | Hazards
|-
| [[Material safety data sheet|MSDS]]
| [https://fscimage.fishersci.com/msds/97108.htm External MSDS]
|-
|-
| {{chembox header}} | <small>Except where noted otherwise, data are given for<br> materials in their [[standard state|standard state (at 25°C, 100 kPa)]]<br/>[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>
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{{SI}}


==Overview==
{{dablink|For the class of [[antioxidant]] compounds that share the same chemical skeleton see [[stilbenoid]]s.}}

Officially known as '''trans-1,2-diphenylethylene''', aka, stilbene, or more specifically, '''([[Geometric isomerism#E/Z notation|E]])-stilbene''', is the [[alkene]], [[ethene]] with two [[phenyl]] groups on either [[carbon]] of the parent chain. The name was derived from the [[Greek language|Greek]] word ''stilbos'', which means shining. It should also be noted, there is also a (Z)-stilbene which is sterically hindered and less stable because of it. Also notice that (Z)-stilbene has a melting point of 5°C to 6°C, while the melting point of (E)-stilbene is in the 125°C area, this illustrates the significant differences between the two. Because (E)-stilbene is so much more common than (Z)-stilbene, this page will focus only on (E)-stilbene.

Its risk and safety phrases are:
*{{R22}} — harmful if swallowed
*{{R37}} — irritating to [[respiratory system]]
*{{R38}} — irritating to skin
*{{R62}} — possible risk of impaired [[fertility]]
*{{S22}} — do not breathe dust
*{{S26}}A — in case of contact with eyes, rinse immediately with water and seek medical advice
*{{S36}} — wear suitable protective clothing
*{{S37}} — wear suitable gloves
*{{S45}} — in case of accident or if you feel unwell seek medical advice immediately, and show the label if possible

==Uses of Stilbene==
Stilbene is used in manufacture of [[dye]]s and [[optical brightener]]s, and also as a [[phosphor]] and a [[scintillator]].

Stilbene is one of the [[gain medium]]s used in [[dye laser]]s.

Many stilbene derivates ([[stilbenoid]]s) are present naturally in plants. An example is [[resveratrol]] and its cousin, [[pterostilbene]].

==Stilbene Reactions==
===Halogenation of Stilbene===
Simple [[hydrocarbons]] are relatively unreactive. In order to form more complex [[molecule]]s, it is generally necessary to introduce more reactive [[functional groups]]. [[Alkenes]] ([[olefins]]) containing the [[carbon]]-carbon double bond may be [[halogenation|halogenated]] to form [[alkyl]] [[halides]], which are more capable of undergoing further [[chemical reactions]]. 

An example of [[halogenation]] is the [[bromination]] of (E)-stilbene. [[Bromine]] is somewhat of a special case due in no small part, to its relatively enormous size compared to [[carbon]]. Since elemental [[bromine]] (Br<sub>2</sub>) is [[Volatility (chemistry)|volatile]] and highly [[corrosive]], pyridinium tribromide is commonly used to generate Br<sub>2</sub> ''[[in situ]]''. 

===Green halogenation===
To [[green chemistry|green]] this reaction, the pyridinium tribromide ''[[in situ]]'' generation of [[bromine|Br<sub>2</sub>]] is replaced with [[hydrobromic acid|hydrobromic]] [[acid]], which is [[oxidizer|oxidized]] by [[hydrogen peroxide]](H<sub>2</sub>O<sub>2</sub>).

:2HBr + H<sub>2</sub>O<sub>2</sub> → Br<sub>2</sub> + 2H<sub>2</sub>O

In either case the [[halogenation]] of stilbene is as follows; as seen in the first reaction, the Br-Br bond attracts the attention of the π-bonding [[electrons]] (π-bonds being e<sup>-</sup> dense and Br being very electronegative), this leads to a weakening and eventual break (heat, plays a crucial role in driving the break forward) of the [[pi bond|π-bond]]. Once the [[pi bond|π-bond]] has been broken, its [[electrons]] are transferred to Br<sub>2</sub>, causing the Br-Br bond to be severed when the bonding [[electrons]] are transferred to the other [[bromine]]. At this stage there is the positively charged intermediate and the loose bromine ion (Br<sup>-</sup>), coming from the opposite direction as the Br<sub>2</sub>, the Br<sup>-</sup> loosens one of the C-Br Bonds, leaving the final brominated product.

It doesn't matter which stilbene is used for this reaction, (E)-stilbene and (Z)-stilbene will both produce 1,2-dibromo-1,2-diphenylethane. However, bromination of the (Z) isomer results in a racemic mixture of dl stilbene dibromide, while the bromination of an (E) [[isomer]] results in a majority meso-stilbene dibromide along with minor amounts of the dl [[enantiomers]]. The minor dl product in the bromination of (E)-stilbene is a result of resonance in the bromonium bridge intermediate, where a positive charge is located on one of the two bridge carbons, thus allowing for a syn-addition of a bromine anion.

===Photochemical reaction===
{{Main|Diarylethene}}
trans-stilbene [[trans-cis isomerization|isomerizes]] to cis-stilbene under the influence of light. The reverse path can be induced by heat or light.

==More Information==
===Spectra===
* [http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_frame_disp.cgi?spectrum_type=ir&sdbsno=1844 IR Spectra]
* [http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_frame_disp.cgi?spectrum_type=cnmr&sdbsno=1844 Mass Spectra]
* [http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_frame_disp.cgi?spectrum_type=hnmr&sdbsno=1844 HNMR Spectra]
* [http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_frame_disp.cgi?spectrum_type=cnmr&sdbsno=1844 CNMR Spectra]

==References==
* [http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi Spectral Database for Organic Compounds, SDBS]
* [http://newsearchch.chemexper.com/cheminfo/servlet/org.dbcreator.MainServlet?searchTemplate=rn.value=%3D%3F&action=PowerSearch&format=ccd&options=brandqtyoffer&target=entry&searchValue=103-30-0 (E)-Stilbene on ChemExper]
*
* ''Green Organic Chemistry'', Strategies, tools, and Laboratory Experiments. Kenneth M, Doxsee & James E. Hutchison.
* ''Organic  Chemistry'', Eighth Edition. T.W. Graham Solomonds & Craig B. Fryhle.

==External links==
* [http://www.ch.ic.ac.uk/vchemlib/course/mo_theory/main.html Introduction to Molecular Orbital Theory]

[[Category:Aromatic hydrocarbons]]
[[Category:Luminescence]]
[[Category:Phosphors and scintillators]]
[[Category:Laser gain media]]