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4.2.3.3 Reaction of amino acids with formaldehyde
The carboxyl group of α -amino acids cannot be accurately titrated in water solution, because it reacts with the basic amino group to form zwitterions that are not decomposed completely at the end of alkaline indicators (phenolphthalein, thymolphtahalein). But when formaldehyde is added to the solution of an amino acid it binds to the amino group as dimethylol and the amino acid can be titrated and estimated as an acid using the above indicators. |
Last modified: Thursday, 10 November 2011, 10:30 AM