Disclosed are optical brightening agents, such agents being 2-(2')-benzimidazoyl-furans substituted in the 5-position of the furan ring by a 1-aryl-pyrazolyl-3, -4 or -5 radical, by a pyrazolyl-1 radical or by a 2-aryl-v-triazolyl-4 radical, such compounds being in free base, acid addition or quaternary ammonium salt form.
展开▼
