Phenylglycine is the organic compound with the formula C₆H₅CHCO₂H. It is a non-proteinogenic alpha amino acid related to alanine, but with a phenyl group in place of the methyl group. It is a white solid. The compound exhibits some biological activity. As a small aromatic alpha amino acid, phenylglycine (C8H9NO2, molar mass 151.16 g mol-1) exists predominantly as a zwitterion near neutral pH, with typical carboxyl pKa ~2.2 and amino pKa ~9.1 and an isoelectric point around 5.6; it is moderately soluble in water and more soluble in polar organic solvents such as methanol and ethanol, and forms crystalline polymorphs. It is widely used as a chiral building block and synthetic intermediate in amino acid and peptide chemistry; common characterization techniques include 1H and 13C NMR, LC-MS, IR and HPLC for assay and purity, and chiral HPLC for enantiomeric composition.
Typical quality specifications for phenylglycine used in research and pharmaceutical synthesis list assay by validated HPLC at 98.0 percent or greater, water content by Karl Fischer not more than 0.5 percent, and heavy metals below 20 ppm; total impurities are commonly limited to 1.0 to 1.5 percent by area in chromatographic analysis with individual related compounds typically limited to 0.1 to 0.5 percent each. Related compounds and likely impurities include the opposite enantiomer D-phenylglycine (enantiomeric impurity commonly controlled to less than 1.0 percent, corresponding to enantiomeric excess greater than 98 percent), phenylalanine (≤0.5 percent), phenylacetic acid (≤0.2 percent), benzoic acid and benzaldehyde (each ≤0.1 percent), trace amounts of residual solvents (controlled to ICH Q3C limits), and unreacted benzyl-type starting materials (typically ≤0.1–0.5 percent); these levels are dependent on synthetic route and final use and should be confirmed by supplier certificate of analysis and independent testing where required.
Glycine is the simplest amino acid and is used as a metabolic building block in protein biosynthesis, a precursor in the synthesis of porphyrins, creatine and glutathione, a buffering agent and pH regulator in biochemistry, and as an additive in pharmaceuticals, food, and cell culture media.
Phenylglycine is commonly abbreviated as Phg in peptide and synthetic chemistry literature; you may also see PheGly in some contexts.
Another name for glycine is aminoacetic acid; its three-letter code is Gly and its one-letter code is G.
The name glycine derives from the Greek word glykys meaning sweet, because the compound was noted to have a sweet taste when first isolated; the systematic name is aminoacetic acid.
