- Water Solubility. Place 0.05 mL or 25 mg of compound in a small test tube, and add 0.75 mL
of water in small portions. Shake test tube vigorously after the addition of each portion of solvent. If water
soluble, go on to step 2; otherwise proceed to step 3.
- Ether Solubility. Place 0.05 mL or 25 mg of compound in a small test tube, and add 0.75 mL
of diethyl ether in small portions. Shake test tube vigorously after the addition of each portion of solvent.
If the compound is both water and ether soluble, the acid-base properties of the compound should be determined
with litmus.
- litmus turns red - water soluble acidic compound (class Sa)
- litmus turns blue - water soluble basic compound (class Sb)
- litmus neutral - water soluble general compound (class Sg)
If the compound is not ether soluble it is a salt, amino acid, or contains many hydrophilic functionalities
(class S)
- 5% NaOH Solubility. Place 0.05 mL or 25 mg of compound in a small test tube, and add 0.75 mL
of NaOH solution in small portions. Shake test tube vigorously after the addition of each portion of solvent. If
NaOH soluble, go on to step 4; otherwise proceed to step 5.
- 5% NaHCO3 Solubility. Place 0.05 mL or 25 mg of compound in a small test tube,
and add 0.75 mL of NaHCO3 solution in small portions. Shake test tube vigorously after the addition of
each portion of solvent. If NaHCO3 soluble, then it is a strong organic acid
(class As). If not NaHCO3 soluble, then it is a weak
organic acid (class Aw).
- 5% HCl Solubility. Place 0.05 mL or 25 mg of compound in a small test tube,
and add 0.75 mL of HCl solution in small portions. Shake test tube vigorously after the addition of
each portion of solvent. If HCl soluble, then it is an organic base
(class B). If not HCl soluble and (from elemental analysis) is found to contain
nitrogen or sulfur, then it is a miscellaneous neutral compound
(class Nm). If not HCl soluble, then go on to step 6.
- 96% H2SO4 Solubility. Place 0.6 mL of H2SO4 in a
small test tube, and add 0.05 mL or 25 mg of compound. Shake test tube vigorously. If H2SO4
soluble, then it is a neutral compound (class N). If not H2SO4
soluble, then it is an inert compound (class I).