CAS 1919045-01-4 appears in our catalog under these names: Azido–PEG4–hydrazide–Boc, Azido-PEG4-hydrazide-Boc 97%, tert-Butyl 18-azido-4-oxo-7,10,13,16-tetraoxa-2,3-diazaoctadecanoate, 97%, 97%, Azido-PEG4-hydrazide-Boc, 97.0%, Azido-PEG4-hydrazide-Boc, 97%. Offered by: GLPBio, Ambeed, Chemat, MedChemExpress, Fluorochem. Available pack sizes: 100mg, 250mg, 1g, 50 mg, 100 mg, 250 mg, 5g.