Nadic anhydride
{{Use mdy dates|date=January 2023}}
{{Chembox
|Name = Nadic anhydride
|ImageFile1 = Nadic anhydride.png
|ImageSize1 = 150px
|ImageName1 = Structural formula
|ImageFileL2 = Endo nadic anhydride vdw.png
|ImageSizeL2 = 150px
|ImageCaptionL2 = endo
|ImageFileR2 = Exo nadic anhydride vdw.png
|ImageSizeR2 = 150px
|ImageCaptionR2 = exo
|SystematicName = 24-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione
|OtherNames = 5-Norbornene-2,3-dicarboxylic anhydride
Nadic acid anhydride
Himic anhydride (exo)
Carbic anhydride (endo)
|Section1={{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 12668
|InChI = 1S/C9H8O3/c10-8-6-4-1-2-5(3-4)7(6)9(11)12-8/h1-2,4-7H,3H2
|InChIKey = KNDQHSIWLOJIGP-UHFFFAOYSA-N
|PubChem = 13223
|EINECS = 212-557-9
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C9H8O3/c10-8-6-4-1-2-5(3-4)7(6)9(11)12-8/h1-2,4-7H,3H2
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = KNDQHSIWLOJIGP-UHFFFAOYSA-N
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 826-62-0
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo1 = 2746-19-2
| CASNo1_Comment = (exo)
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo2 = 129-64-6
| CASNo2_Comment = (endo)
|SMILES = C1C2C=CC1C3C2C(=O)OC3=O
}}
|Section2={{Chembox Properties
|C=9|H=8|O=3
|Appearance = white solid
}}
}}
Nadic anhydride, also known as 5-norbornene-2,3-dicarboxylic anhydride, is an organic acid anhydride derivative of norbornene.
Stereochemistry
Nadic anhydride exhibits endo-exo isomerism. In the exo isomer, the acid anhydride group points in the same direction towards the bridging carbon of the norbornene, while in the endo isomer the acid anhydride group points in the opposite direction. These isomers are respectively named cis-5-norbornene-exo-2,3-dicarboxylic anhydride (also known as himic anhydride) and cis-5-norbornene-endo-2,3-dicarboxylic anhydride (also known as carbic anhydride).{{Cite PubChem|cid=75977|title=cis-5-Norbornene-exo-2,3-dicarboxylic anhydride|access-date=January 19, 2023}}{{Cite PubChem|cid= 126963424|title=cis-5-Norbornene-endo-2,3-dicarboxylic anhydride|access-date=January 19, 2023}} Commercially available nadic anhydride is mainly the endo isomer, as this is the isomer predominantly made in the Diels-Alder reaction in its synthesis.
| class="wikitable" style="margin:1em auto; text-align:center;" | 160px |
| 160px | 160px |
| endo | exo |
Preparation
In the patent for the Diels-Alder reaction, nadic anhydride was given as an example of the reaction, made by the addition of maleic anhydride to cyclopentadiene, which gives mostly the endo isomer.{{cite patent |country=United States |number=US1944731A |title=Organic compound having hydrogenated ring systems and process of preparing it |pubdate=January 23, 1934 |gdate= |fdate= |pridate= |invent1=Otto Diels |invent2=Kurt Alder |url=https://worldwide.espacenet.com/patent/search/family/007750680/publication/US1944731A?q=US1944731}} The endo isomer can be converted into the exo isomer by irradiation with UV light.{{cite journal |last1=Pandey |first1=Bipin |last2=Athawale |first2=Asawar A. |last3=Reddy |first3=Ravinder S. |last4=Dalvi |first4=Pravinder S. |last5=Kumar |first5=Pradeep |date=1991 |title=A Remarkably Efficient Photochemical Methodology for Endo to Exo IsomerizatLon of Dials–Alder Cycloadducts |journal=Chemistry Letters |volume=20 |issue=7 |pages=1173–1176 |doi=10.1246/cl.1991.1173}}
Uses
Due to the reactivity of the norbornene moiety in the thiol-ene reaction, nadic anhydride is used in the synthesis of monomers for cross-linked polymer networks based on thiol-ene linkages.{{cite journal |last1=Hoyle |first1=Charles E. |last2=Bowman |first2=Christopher N. |title=Thiol–Ene Click Chemistry |journal=Angewandte Chemie International Edition |year=2010 |volume=49 |issue=9 |doi=10.1002/anie.200903924 |pages=1540–1573}}