(1,1'-Biphenyl)-4-butanoic acid, 2',4'-difluoro-gamma-oxo- 2',4'-Difluoro-gamma-oxo-(1,1'-biphenyl)-4-butanoic acid 39241-03-7 Lactonol of (Z)-4-(2',4'-difluorobiphenyl-4-yl)-3-methyl-4-oxobut-2-enoic acid