5-(4-Hydroxyphenyl) hydantoin (p-HPH), an important intermediate in production of D-2-(4- hydroxyphenyI) glycine, was synthesized by employing new amidoalkylation reaction of phenol with glyoxylic acid and urea under acidic conditions, accompanied by formation of the isomer, ie. 5-(2-hydroxyphenyl) hydantoin (o-HPH). The ratio of p-HPH was found to be mainly influenced by the reaction method (the manner of charging raw materials) and ...