Di-tert-butyl dicarbonate turns yellow.

An oxidation reaction occurs. Di-tert-butyl dicarbonate, as an organic compound, is prone to oxidation reaction under certain conditions, which leads to the discoloration of the product, showing yellow, brown or dark color. The main reason is that the double bond or carbonyl group in the compound is easily oxidized by oxidant, and the oxidation product is a substance with pigment, which leads to the discoloration of the solution. Di-tert-butyl dicarbonate is a commonly used reagent in organic synthesis, which is mainly used to protect amino groups in compounds such as amino acids and peptides.