truxillic acid
{{Chembox
| Name = Truxillic acid
| ImageFile = Truxillic acid.svg
| ImageSize = 150px
| ImageAlt =
| IUPACName = 7,8′-Cyclo-8,7′-neolignane-9,9′-dioic acid
| SystematicName = 2,4-Diphenylcyclobutane-1,3-dicarboxylic acid
| OtherNames =
|Section1={{Chembox Identifiers
| CASNo = 4462-95-7
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 821BB4R21V
| PubChem = 78213
| ChemSpiderID = 70589
| SMILES = OC(C1C(C2=CC=CC=C2)C(C(O)=O)C1C3=CC=CC=C3)=O}}
|Section2={{Chembox Properties
| C=18 | H=16 | O=4
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|Section3={{Chembox Hazards
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Truxillic acids are any of several crystalline stereoisomeric cyclic dicarboxylic acids with the formula (C6H5C2H2(CO2H)2. They are colorless solids. These compounds are obtained by the [2 + 2] photocycloadditions of cinnamic acid where the two trans alkenes react head-to-tail. The isolated stereoisomers are called truxillic acids.{{cite journal|author1=Cohen, M. D. |author2=Schmidt, G. M. J. |author3=Sonntag, F. I. |title= Topochemistry. II. The photochemistry of trans-cinnamic acids|journal=J. Chem. Soc.|year=1964|pages=2000–2013|doi=10.1039/jr9640002000}} The preparation of truxillic acids provided an early example of organic photochemistry.{{cite journal |doi=10.1002/anie.198911931|title=The Beginnings of Organic Photochemistry|year=1989|last1=Roth|first1=Heinz D.|journal=Angewandte Chemie International Edition in English|volume=28|issue=9|pages=1193–1207}}
Occurrence and reactions
These compounds are found in a variety of plants, for example in coca.{{cite journal|year=1888|volume=21|doi=10.1002/cber.188802102223|pages=3372–3376|url=https://zenodo.org/record/1425537 |title=Ueber Cinnamylcocaïn |last1=Liebermann |first1=C. |journal=Berichte der Deutschen Chemischen Gesellschaft |issue=2 }}{{cite journal|last=Krauze-Baranowska|first=Miroslawa|title=Truxillic and truxinic acids-occurrence in plant kingdom|journal=Acta Poliniae Pharmaceutica-Drug Research|year=2002|volume=59|issue=5|pages=403–410|pmid=12602803 }} Incarvillateine, an alkaloid from the plant Incarvillea sinensis, is a derivative of α-truxillic acid.
Upon heating, truxillic acids undergo cracking to give cinnamic acid.{{cite journal|author=Hein, Sara M.|title=An Exploration of a Photochemical Pericyclic Reaction Using NMR Data|journal=Journal of Chemical Education|year=2006|volume=83|issue=6 |pages=940–942|doi=10.1021/ed083p940|bibcode=2006JChEd..83..940H }}
Isomers
Truxillic acid can exist in five stereoisomers.{{cite journal|year=1924|volume=57|pages=15–23|doi=10.1002/cber.19240570105 |title=Zur Stereoisomerie der Truxillsäuren und über die Auffindung der letzten Säure dieser Gruppe (VIII.) |last1=Stoermer |first1=R. |last2=Bachér |first2=F. |journal=Berichte der Deutschen Chemischen Gesellschaft (A and B Series) }}{{cite book|last=Agarwai|first=O. P.|title=Organic Chemistry Reactions and Reagents|year=2011|publisher=Krishna Prakashan Media|isbn=978-8187224655}}
File:Truxillic and truxinic acid stereo.svg
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|+ align="center" style="background:DarkSlateBlue; color:white"|Truxillic acid isomers ! width="140 px" style="background:Lavender; color:Black"|Isomer ! width="80 px" style="background:Lavender; color:Black"|a ! width="80 px" style="background:Lavender; color:Black"|b ! width="80 px" style="background:Lavender; color:Black"|c ! width="80 px" style="background:Lavender; color:Black"|d ! width="80 px" style="background:Lavender; color:Black"|e ! width="80 px" style="background:Lavender; color:Black"|f | ||||||
| α-truxillic acid (cocaic acid{{cite web|url=http://www.chemspider.com/Chemical-Structure.10218892.html|publisher=ChemSpider|title=ChemSpider ID 10218892|access-date=15 October 2016}}) | COOH | H | H | C6H5 | H | COOH |
| γ-truxillic acid | COOH | H | H | C6H5 | COOH | H |
| ε-truxillic acid | H | COOH | C6H5 | H | H | COOH |
| peri-truxillic acid | COOH | H | C6H5 | H | COOH | H |
| epi-truxillic acid | COOH | H | C6H5 | H | H | COOH |
Below are the five stereoisomers of truxillic acid, called alpha, gamma, epsilon, peri, and epi. These are shown both in a 2D skeletal diagram with stereocenters indicated and a 3D rendering of the structural geometry of the isomers themselves.
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See also
- Truxinic acids are isomers of the truxillic acids with phenyl groups on adjacent methyne centers.