Carbaryl insecticide conjugation onto chitosan via iodochitosan and chitosan carbonyl imidazolide precursors

Chitosan conjugated with 1-naphthyl methylcarbamate or carbaryl (CBR), were prepared by two molecular designs, i.e. without spacer via iodochitosan to obtain chitosan-carbaryl (Type 1, CHI-CBR), and with spacer by using N,N ' -carbonyldiimidazole (CDI) to obtain chitosan acetate-carbonyl imidazolide -carbaryl (Type 2, CA-CDI-CBR). The chitosan precursors of Types 1 and 2 we re accomplished for 50-60% substitution as confirmed by FT-IR, NMR, and ele mental analysis. The conjugation of carbaryl onto iodochitosan (Type I) was achieved via alkylation of N-substituted amide using NaH as a catalyst. Th e coupling reaction of carbaryl onto chitosan acetate was succeeded by carb onyl imidazolide which proceeded by nucleophilic substitution. The introduc tion of carbaryl was identified from the ester peak at 1707 cm(-1) by FT-IR curve fitting technique. (C) 2001 Elsevier Science Ltd. All rights reserve d.