Glycine oxalate

Formula: (NH₃CH₂COOH)₂C₂O₄

Oxalic acid H₂C₂O₄ is among the strongest inorganic acids, and can easily form salts with many weak bases such as amino-acid glycine. When one mole of oxalic acid is crystallized together with 2 moles of glycine, transparent sticks of glycine oxalate grows.

Different names: diglycine oxalate, glycinium oxalate.

Properties

• Crystal shape: sticks with rectangular cross-section and slant ends
• Color: colorless
• Stability on air: stable
• Optical properties: displays strong birefringence (see photos below)

Preparation

Prepare solution containing glycine and oxalic acid in 2:1 molar ratio, then crystallize it. The equation is:

2NH₂CH₂COOH + H₂C₂O₄ = (NH₃CH₂COOH)₂C₂O₄

Growing

As always, I used slow evaporation method. Solubility, according to my own measurements, is around 31g/100ml, but it might be a bit off.

Safety

Oxalic acid is moderately toxic and corrosive.

More photos

Birefringence

Glycine oxalate crystals display strong birefringence:

Links

• Imgur gallery