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.

Glycine 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

Glycine oxalate

Glycine oxalate

Glycine oxalate

Glycine oxalate

Glycine oxalate

Glycine oxalate

Glycine oxalate

Glycine oxalate

Birefringence

Glycine oxalate crystals display strong birefringence:

Glycine oxalate

Glycine oxalate

Glycine oxalate