trans-2,5-Difluorocinnamic acid(2E)-3-(2,5-Difluorophenyl)acrylic acidtrans-2,5-Difluorocinnamic acid 97%trans-3-(2,5-Difluorophenyl)prop-2-enoic acid反式-2,5-二氟肉桂酸trans-2,5-Difluorocinnamic acid3-(2,5-difluorophenyl)prop-2-enoic acid2,5-二氟苯乙烯酸2,5-Difluorocinnamic acid