Nadic anhydride

Nadic anhydride, also known as 5-norbornene-2,3-dicarboxylic anhydride, is an organic acid anhydride derivative of norbornene.

Nadic anhydride

Structural formula
endo exo
Names
Systematic IUPAC name 24-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione
Other names 5-Norbornene-2,3-dicarboxylic anhydride Nadic acid anhydride Himic anhydride (exo) Carbic anhydride (endo)
Identifiers
CAS Number	826-62-0 Y 2746-19-2 (exo) Y 129-64-6 (endo) Y
3D model (JSmol)	Interactive image
ChemSpider	12668 Y
ECHA InfoCard	100.011.416
EC Number	212-557-9
PubChem CID	13223
CompTox Dashboard (EPA)	DTXSID0047456
InChI InChI=1S/C9H8O3/c10-8-6-4-1-2-5(3-4)7(6)9(11)12-8/h1-2,4-7H,3H2 Y Key: KNDQHSIWLOJIGP-UHFFFAOYSA-N Y InChI=1S/C9H8O3/c10-8-6-4-1-2-5(3-4)7(6)9(11)12-8/h1-2,4-7H,3H2 Key: KNDQHSIWLOJIGP-UHFFFAOYSA-N
SMILES C1C2C=CC1C3C2C(=O)OC3=O
Properties
Chemical formula	C9H8O3
Molar mass	164.160 g·mol−1
Appearance	white solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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).^[1][2] Commercially available nadic anhydride is mainly the endo isomer, as this is the isomer predominantly made in the Diels-Alder reaction in its synthesis.^[3]

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.^[3] The endo isomer can be converted into the exo isomer by irradiation with UV light.^[4]

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.^[5]