prov:value
| - R is an alkylene di-radical having from 2 to 8 carbon atoms, R1 is hydrogen, alkyl, aryl, aralkyl or alkaryl, preferably hydrogen or lower alkyl having up to 7 and, more preferably, up to 4 carbon atoms, such as, for example, methyl, ethyl or propyl; aryl having up to 10 carbon atoms, and also aralkyl or alkaryl having up to 14 carbon atoms; and R2 is hydrogen or lower alkyl having up to 7 and, mo
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