Glutamic acid

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Glutamic acid
L-Glutamic acid bottle and sample.jpg
L-Glutamic acid in solid form
Names
IUPAC name
2-Aminopentanedioic acid
Other names
2-Aminoglutaric acid
Properties
C5H9O4N
Molar mass 147.13 g/mol
Appearance White solid
Odor Odorless
Density 1.538 g/cm3 (20 °C)
Melting point 205 °C (401 °F; 478 K) (decomposes)
Boiling point Decomposes
0.75 g/100 ml (20 °C)
0.864 g/100 ml (25 °C)
2.18 g/100 ml (50 °C)
5.532 g/100 ml (75 °C)
14 g/100 ml (75 °C)[1]
Solubility Soluble in dil. HCl
Insoluble in glacial acetic acid, acetone, diethyl ether, ethanol, methanol, toluene
Solubility in ethanol 0.000448 g/100 ml
Vapor pressure ~1.10·10-5 mmHg (20 °C)
Acidity (pKa) 2.10, 4.07, 9.47
Hazards
Safety data sheet Sigma-Aldrich (D-Glutamic acid)
Sigma-Aldrich (L-Glutamic acid)
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
5.110 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Glutamic acid (symbol Glu) is an α-amino acid, widely encountered as monosodium glutamate (MSG), the key ingredient in the responsible for the savory flavor (umami) of certain foods, and used in glutamate flavorings in food industry.

Properties

Chemical

Partial neutralization with sodium hydroxide gives monosodium glutamate.

Physical

Glutamic acid is a colorless odorless solid compound, sparingly soluble in water and practically insoluble in organic solvents.

Glutamic acid can exist in two optical isomers, D(-) and L(+). The L form is the one most widely occurring in nature, but the D form occurs in some special contexts, such as the cell walls of the bacteria

Availability

Glutamic acid is sold by chemical suppliers, often as pure enantiomers, L and D. Can also be bought online.

L-Glutamic acid is more available in the form of monosodium glutamate, which is available as food flavoring. The free glutamic acid can be made by adding a strong acid, like hydrochloric acid to MSG.

Preparation and isolation

The addition of an acid, like hydrochloric acid to MSG will give the free acid.

Glutamic acid can be isolated from the product of aerobic fermentation of sugars and ammonia, using the bacterium Corynebacterium glutamicum. Recrystallization of the hydrochloric acid salt of glutamic acid will yield the pure compound. This route, while attractive, is not very economical for the home chemist.

Projects

  • Grow bacterial cultures
  • Make MSG

Handling

Safety

Glutamic acid has low toxicity. Excess consumption may cause headaches and unspecified neurological problems.

Storage

Glutamic acid should be kept in closed bottles, away from moisture and mold.

Disposal

No special disposal is required, as it's practically non-toxic. Discard it as you wish.

References

  1. https://www.sigmaaldrich.com/catalog/product/aldrich/128430

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