Dark blue esterification liquid and preparation method thereof

The invention provides dark blue esterifying liquid and a preparation method thereof. The preparation method comprises the following steps: a pretreatment step: dissolving 2-amino-4-acetamino anisole in a solvent to obtain a pretreatment solution; a hydroxylation reaction step: carrying out a hydroxylation reaction on the pretreatment liquid and liquid ethylene oxide in a micro-channel reactor to obtain a hydroxylation liquid; a heat preservation reaction step: conveying the hydroxylation liquid from the micro-channel reactor into a reaction device for continuous heat preservation reaction to obtain a hydroxylation product; a dehydration step: carrying out vacuum dehydration on the hydroxylation product to obtain a dehydration product; esterification reaction: carrying out esterification reaction on the dehydration product and acetic anhydride to obtain dark blue esterification liquid. According to the preparation method, the gasification step of ethylene oxide is omitted, and a reaction device is simplified.