CAS 168640-82-2 appears in our catalog under these names: Azide–PEG4–Tos, 11-Azido-3,6,9-trioxaundecanyl p-toluenesulfonate, 98%, 98%, Azide-PEG4-Tos, 99.59%, Azido-PEG4-tosylate, 98%. Offered by: GLPBio, Chemat, MedChemExpress, Fluorochem. Available pack sizes: 100mg, 250mg, 1g, 5g, 10g, 25g, 1 g, 500 mg.