百菌清，又名2,4,5,6-四氯-1,3-苯二腈，是一种有机化合物，主要用作广谱抗生素。

百菌清可由间苯二腈的直接氯化得到，或者通过四氯间苯二甲酰胺利用三氯氧磷脱氢得到

Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) is an organic compound mainly used as a broad spectrum, nonsystemic fungicide, with other uses as a wood protectant, pesticide, acaricide, and to control mold, mildew, bacteria, algae. Chlorothalonil-containing products are sold under the names Bravo, Echo, and Daconil. It was first registered for use in the US in 1966. In 1997, the most recent year for which data are available, it was the third most used fungicide in the US, behind only sulfur and copper, with some 12 million pounds used in agriculture alone that year. Including nonagricultural uses, the EPA estimates, on average, almost 15 million pounds were used annually from 1990-1996.