Sodium Hydroxide → Azido-PEG1-CH2CO2H

Participants

Reaction Steps

To a solution of ethyl 2-azidoethoxyacetate (6.56 g, 37.9 mmol) in MeOH (80 ml) was added 1 N aq. NaOH (80 ml) and the mixture was stirred at room temperature overnight (17 h). After removing the insoluble material, the methanol was evaporated in vacuo and this was saturated with sodium chloride and washed with ether (30 ml ×3). The aqueous layer acidified with 3 N HCl (30 ml) was extracted with ether (40 ml ×4). The ether extracts were washed with brine, dried (MgSO4) and evaporated to yield 4.25 g (29.3 mmol, 77.3%) of 2-azidoethoxyacetic acid as a colourless oil: 1Hmr (CDCl3) δ:3.3-4.0 (4H, m, --OCH2CH2N3), 4.22 (2H, s, --COCH2O--), 9.52 ppm (1H, s, --CO2H, exchanged with D2O); ir (neat) νmax : 2600-3300 (br, --CO2H) 2100 (azide) and 1740 cm-1C=O--CO2H). This material was used in the next step without further purification.

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