Synthesis and herbicidal activity of 4, 8-DHT and its derivates

Abstract

The chemosynthesis and potential as green herbicides of 4,8-dihydroxy-1-tetralone (4, 8-DHT) and its derivates were emphatically addressed in this study. Firstly, the synthesis of 4, 8-DHT from commercially available material 1, 5-dihydroxynaphthalene was carried out through a novel route of five reaction steps. Then, its five derivates including 4-benzoyl-8-hydroxy-1-tetralone, 4-(3-hydroxypropoxy)- 8-hydroxy-1- tetralone, 4-(2,3-dihydroxypropoxy)-8-hydroxy-1-tetralone, 4-hydroxy-8-(3-hydroxy propoxy) −1-tetralone and 4-hydroxy-8-(2,3-dihydroxypropoxy)-1- tetralone were prepared by modifying alcoholic and phenolic hydroxyl in C-4 and C-8 position of 4,8-DHT molecular structure. After that, these synthesized compounds were examined for their toxicity against six kinds of weeds (Lolium perenne, Phalaris arundinacea, Elymus dahuricus, Cichorium intybus, Sorghum sudanense, and Trifolium repens) in vitro. In general, high concentration could generally inhibit while low concentration might promote the growth of weeds. Among these compounds, 4-(3-hydroxypropoxy)-8 −hydroxy-1-tetralone and 4-hydroxy-8- (3-hydroxypropoxy) −1-tetralone showed significant phytotoxic activities against the six tested weeds, while 4-hydroxy-8-(2,3-dihydroxypropoxy) −1-tetralone was less toxic. For all the six tested weeds, E. dahuricus appeared the most sensitive to the treatments of 4, 8-DHT compounds. Hence, it has been suggested that variables including compound type and concentration as well as weed species should be seriously considered in order to develop and utilize the group of 4, 8-DHT compounds as herbicide in future.