摘要:
Disclosed is a method for extracting an amino acid ester from a hydrous solution which comprises adding thereto a water-insoluble organic solvent and then an amount of a base effective to liberate only a portion of the amino acid ester in free base form, and transferring the thus liberated amino acid ester in the free base form into the organic layer, and repeating the neutralization-extraction steps until all of the amino acid ester has been extracted.
摘要:
Provided are a color-developing agent comprising a multivalent metal salt of a salicylic acid derivative and a sulfonated phenol and/or a metal salt thereof and having excellent initial and ultimate color-developing capacities and improved waterproofness; and a color-developing sheet making use of the color-developing agent.