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4-Phenylethynylphthalic anhydride (PEPA)

CAS Number 119389-05-8

Chemistry Building Blocks, Heterocyclic Building Blocks, Materials, Monomers


Product Code B2151-LT-10g
Price $138 ex. VAT

A phthalic anhydride intermediate

For the synthesis of polyimides as end-capping reagent in application of gas separation membranes and high-performance polymers


Specifications | MSDS | Literature and Reviews


4-Phenylethynylphthalic anhydride (PEPA), CAS number 119389-05-8, a phthalic anhydride derivative, has a phenylethynyl substituent at 4-position. 4-Phenylethynylphthalic anhydride is commonly used as an end-capping reagent for polyimides synthesis and modification, such as TriA-X polyimides. The diphenylacetylene end-capping moiety undergoes thermally induced radical curing process for crosslinked polyimides. The crosslink further improves the thermal stability of the polyimides (5% decomposition temperature Td5 = 591.3 °C). Diphenylacetylene also reacts with tetraphenylcyclopentadienone forming a fully conjugated hexaphenylbenzene under Diels-Alder reaction.

PEPA can also be introduced as an imide pedant onto a polymer backbone that has free amines. The modified polymer membranes show improved gas permeability in application of gas separation.

General Information


CAS Number 119389-05-8
Chemical Formula C16H8O3
Full Name 4-Phenylethynylphthalic anhydride
Molecular Weight 248.23 g/mol
Synonyms 5-(Phenylethynyl)isobenzofuran-1,3-dione, 5-(Phenylethynyl)-2-benzofuran-1,3-dione
Classification / Family Anhydride building block, Separation membranes, High-performance polymers

Chemical Structure


4-Phenylethynylphthalic anhydride (PEPA) chemical structure, CAS 119389-05-8
4-Phenylethynylphthalic anhydride (PEPA) chemical structure, CAS 119389-05-8

Product Details


Purity >99%
Melting Point Tm = 152 °C
Appearance Pale yellow to yellow powder/crystal

MSDS Documentation


4-Phenylethynylphthalic anhydride (PEPA)4-Phenylethynylphthalic anhydride (PEPA) MSDS Sheet

Literature and Reviews


  1. Diels–Alder cycloaddition polymerization of highly aromatic polyimides and their multiblock copolymers, D. Cristurean et al., Polym. Chem., 12, 3160(2021); DOI: 10.1039/d1py00314c.
  2. Improved melt processabilities of thermosetting polyimide matrix resins for high temperature carbon fiber composite applications, H.-Y. Zhang et al., Polymers, 14, 965(2022); DOI: 10.3390/polym14050965.
  3. Liquid crystalline thermosetting (LCT) composites based triboelectric nanogenerator with intrinsic flame retardancy, M. Qadeer et al., Adv. Mater. Technol., 7(10), 2200002(2022); DOI: 10.1002/admt.202200002.
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