产品详情(用途,包装等)
Acid blue is also known as Patent Blue V, and is a dark bluish synthetic triphenylmethane dye used as a food coloring. As a food additive, it has E number E131. It is a sodium or calcium salt of [4-(α-(4-diethylaminophenyl)-5-hydroxy- 2,4-disulfophenylmethylidene)-2,5-cyclohexadien-1-ylidene] diethylammonium hydroxide inner salt. The color of the dye is pH-dependent. In aqueous solution, its color will vary from a deep blue in alkaline or weakly acidic medium to a yellow–orange in stronger acidic conditions. It is useful as a pH indicator for the range 0.8–3.0. The structure is also redox-sensitive, changing from a reduced yellow form to an oxidized red form in solution. The reduction potential of around 0.77 volts is similar to that of other triphenylmethane dyes. It is usable as a reversible redox indicator in some analytical methods.
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