Production and Key Properties
Glycine was discovered in 1820, by Henri Braconnot who boiled gelatin with sulfuric acid.
Glycine is manufactured industrially by treating chloroacetic acid with ammonia:
- ClCH2COOH + 2 NH3 → H2NCH2COOH + NH4Cl
About 15 million kg are produced annually in this way.
In the USA (by GEO Specialty Chemicals, Inc.) and in Japan (by Shoadenko), glycine is produced via the Strecker amino acid synthesis.
There are two producers of glycine in the United States: Chattem Chemicals, Inc., a subsidiary of Mumbai-based Sun Pharmaceutical, and GEO Specialty Chemicals, Inc., which purchased the glycine and naphthalene sulfonate production facilities of Hampshire Chemical Corp, a subsidiary of Dow Chemical.
Chattem's manufacturing process ("MCA" process) occurs in batches and results in a finished product with some residual chloride but no sulfate, while GEO’s manufacturing process is considered a semi-batch process and results in a finished product with some residual sulfate but no chloride.
Its pKA values are 2.35 and 9.78, so above pH 9.78, most of the glycine exists as the anionic amine, H2NCH2CO2-. Below pH 2.35, its solutions contain mostly the cationic carboxylic acid H3N+CH2CO2H. Its isoelectric point (pI) is 6.06.
Glycine exists in zwitterionic form in solution. In this form, the partial charges on different atoms as determined using Gasteiger charge method are given as follows: N (+0.2358), H (attached to N) (+0.1964), alpha-C (+0.001853), H (attached to alpha-C) (+0.08799), carbonyl C (+0.085) and carbonyl O (-0.5445).
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