CAS 4251-21-2 appears in our catalog under these names: p–Phenylenedipropionicacid, 1,4-Phenylenedipropionic acid 97%, p-Phenylenedipropionicacid, 97%, 97%, p-Phenylenedipropionicacid, 96.43%, 3,3'-(1,4-Phenylene)dipropanoic acid, 95%. Offered by: GLPBio, Ambeed, Chemat, MedChemExpress, Fluorochem. Available pack sizes: 1g, 250mg, 5g, 100mg, 10g, 100 mg, 250 mg, 1 g.