Structures and pesticidal activities of derivatives of dinitrophenols. XI. —Effects of substitution of dinitrophenols with C 3 to C 13 α‐branched alkyl groups and of esterification on the eradication of cucumber mildew

The eradication of cucumber mildew caused by Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll. with 2‐(C 4 to C 13 α‐branched alkyl)‐4,6‐dinitrophenols and 4‐(C 4 to C 13 α‐branched alkyl)‐2,6‐dinitrophenols was examined. 2‐(C 8 to C 13 α‐Branched alkyl)‐4,6‐dinitrophenols were highly active, but O ‐methylation produced compounds with no activity. 4‐(C 7 to C 10 and several C 11 to C 13 α‐branched alkyl)‐2,6‐dinitro‐phenols gave a significant degree of eradication. 2‐(C 6 to C 13 α‐Branched alkyl)‐4,6‐dinitrophenols were significantly more active than their 4‐alkyl‐2,6‐dinitrophenol analogues. Esterification of C 4 to C 7 α‐branched alkyl dinitrophenols to methyl‐ or ethyl‐ carbonates or crotonates gave compounds with enhanced activity. Generally, the methyl‐ or ethyl‐ carbonates or 2‐C 8 ‐alkyl‐4,6‐dinitrophenols were as active as the parent phenols, but the higher alkyl carbonates or crotonates had lower activity. Esterification of 2‐(C 9 to C 13 α‐branched alkyl)‐4,6‐dinitrophenols to ethyl carbonates and crotonates gave compounds with reduced activity.