Succinimidyl carbonate hydrolysis

The neutral alkali metal salts of benzohydroxamic acids have been found to undergo an unprecedented rearrangement to A(,A( -diarylureas. 2 side reaction, producing /9-alanine derivatives by way of a Lossen rearrangement, has been observed to accompany the hydrolysis of alkyl succinimidyl carbonates in basic aqueous buffers (see Scheme 97). The development of a modified Lossen rearrangement, whereby... 

To remove excess CDI and reaction by-products, Beauchamp et al. (1983) dialyzed against water at 4°C. However, the imidazole carbamate groups on mPEG formed during the activation process are subject to hydrolysis in aqueous environments. A better method may be to precipitate the activated mPEG with diethyl ether as in the protocol described for succinimidyl carbonate activation (Section 1.2). 

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