Editing Glycine (section)

==Chemical reactions==
Its acid–base properties are most important. In aqueous solution, glycine is [[amphoteric]]: below pH = 2.4, it converts to the ammonium cation called glycinium. Above about pH 9.6, it converts to glycinate.
:[[File:Glycine-protonation-states-2D-skeletal.png|540x540px|class=skin-invert-image]]

Glycine functions as a [[bidentate ligand]] for many metal ions, forming [[amino acid complex]]es.<ref>{{cite journal |last1=Tomiyasu |first1=Hiroshi. |last2=Gordon |first2=Gilbert. |title=Ring closure in the reaction of metal chelates. Formation of the bidentate oxovanadium(IV)-glycine complex |journal=Inorganic Chemistry |date=April 1976 |volume=15 |issue=4 |pages=870–874 |doi=10.1021/ic50158a027 }}</ref> A typical complex is Cu(glycinate)<sub>2</sub>, i.e. Cu(H<sub>2</sub>NCH<sub>2</sub>CO<sub>2</sub>)<sub>2</sub>, which exists both in cis and trans isomers.<ref>{{cite journal | vauthors = Lutz OM, Messner CB, Hofer TS, Glätzle M, Huck CW, Bonn GK, Rode BM | title = Combined Ab Initio Computational and Infrared Spectroscopic Study of the cis- and trans-Bis(glycinato)copper(II) Complexes in Aqueous Environment | journal = The Journal of Physical Chemistry Letters | volume = 4 | issue = 9 | pages = 1502–1506 | date = May 2013 | pmid = 26282305 | doi = 10.1021/jz400288c }}</ref><ref>{{Cite journal | vauthors = D'Angelo P, Bottari E, Festa MR, Nolting HF, Pavel NV  |date= April 1998 |title=X-ray Absorption Study of Copper(II)−Glycinate Complexes in Aqueous Solution |journal=The Journal of Physical Chemistry B |volume=102 |issue=17 |pages=3114–3122 |doi=10.1021/jp973476m }}</ref>

With acid chlorides, glycine converts to the amidocarboxylic acid, such as [[hippuric acid]]<ref>{{Cite journal | vauthors = Ingersoll AW, Babcock SH |year=1932 |title=Hippuric Acid |journal=Org. Synth. |volume=12 |page=40 |doi=10.15227/orgsyn.012.0040}}</ref> and [[acetylglycine]].<ref>{{Cite journal | vauthors = Herbst RM, Shemin D |year=1939 |title=Acetylglycine |journal=Org. Synth. |volume=19 |page=4 |doi=10.15227/orgsyn.019.0004}}</ref> With [[nitrous acid]], one obtains [[glycolic acid]] ([[van Slyke determination]]). With [[methyl iodide]], the amine becomes [[Quaternary compound|quaternized]] to give [[trimethylglycine]], a natural product:
:{{chem|H|3|N|+|CH|2|COO|-}} + 3 CH<sub>3</sub>I  →  {{chem|(CH|3|)|3|N|+|CH|2|COO|-}}  +  3 HI

Glycine condenses with itself to give peptides, beginning with the formation of [[glycylglycine]]:<ref>{{cite journal | vauthors = Van Dornshuld E, Vergenz RA, Tschumper GS | title = Peptide bond formation via glycine condensation in the gas phase | journal = The Journal of Physical Chemistry B | volume = 118 | issue = 29 | pages = 8583–8590 | date = July 2014 | pmid = 24992687 | doi = 10.1021/jp504924c }}</ref>
:2 {{chem|H|3|N|+|CH|2|COO|-}}  →  {{chem|H|3|N|+|CH|2|CONHCH|2|COO|-}}  +  H<sub>2</sub>O
Pyrolysis of glycine or glycylglycine gives [[2,5-diketopiperazine]], the cyclic diamide.<ref>{{Cite journal | vauthors = Leng L, Yang L, Zu H, Yang J, Ai Z, Zhang W, Peng H, Zhan H, Li H, Zhong Q | date = November 2023 |title=Insights into glycine pyrolysis mechanisms: Integrated experimental and molecular dynamics/DFT simulation studies |journal=Fuel |volume=351 |pages=128949 |doi=10.1016/j.fuel.2023.128949 | bibcode = 2023Fuel..35128949L }}</ref>

Glycine forms [[ester]]s with [[Alcohol (chemistry)|alcohols]]. They are often isolated as their [[hydrochloride]], such as [[glycine methyl ester hydrochloride]]. Otherwise, the free ester tends to convert to [[diketopiperazine]].

As a bifunctional molecule, glycine reacts with many reagents. These can be classified into N-centered and carboxylate-center reactions.