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Experiment 7, page 2

This work arose from the observation by Professor Bill Griffith of this department that tertiary amines, and bicyclic tertiary amines in particular, accelerate the rate of osmium tetroxide dihydroxylation of olefins by co-ordination to the metal.⁶The ligand systems shown above are the result of many years of experimentation by the Sharpless group and others. Note that, since natural alkaloids are only available in one enantiomeric form, the ligands which give rise to opposite enantiomers in the dihydroxylation are not derived from two different alkaloids. The ligands are thus not enantiomers of each other, but are termed 'pseudoenantiomeric' by Sharpless. In this experiment, you will be using the commercial AD-mix - a powder containing an osmium source (K₂OsO₂(OH)₄), the chiral ligand ([DHQ]₂PHAL for AD-mix a, [DHQD]₂PHAL for AD- mix b), a co-oxidant for regeneration of osmium (VIII) (K₃Fe(CN)₆and a pH buffer (K₂CO₃) - to perform the dihydroxylation of one of several olefins.

HAZARD DATA - READ THIS BEFORE GOING ANY FURTHER!!!!

AD-MIX aor b
AD-MIXES contain approx. the following chemicals per 4.2g loading (as used here):
Potassium osmate: 4.4mg
(DHQ)₂PHAL or (DHQD)₂PHAL: 23mg
Potassium ferricyanide: 2.94g
Potassium carbonate: 1.24g

POTASSIUM OSMATE:
TOXIC
SEVERE IRRITANT TO EYES AND RESPIRATORY SYSTEM

Violet solid, m.pt. decomposes. Soluble in water, with slow decomposition. OES0.002 mg/m³(Os)

Toxic effects:Toxic by ingestion, or in contact with skin/eyes.Severe irritant to eyes and respiratory
system. If ingested can cause abdominal pain and vomiting, and irritation of the
respiratory system with coughing. Eye contact results in severe pain, blurred vision and
possible blindness.
Hazardous reactions:Incompatible with strong oxidising materials.
Fire hazards:Gives off toxic fumes in fire.
Spillage & disposal:Absorb onto inert material and package in containers for disposal.

POTASSIUM FERRICYANIDE (POTASSIUM HEXACYANOFERRATE(III) ):
HARMFUL BY INGESTION

Ruby red crystals or orange powder; m.p. n/a. Very soluble in water. OEL not assigned

Toxic effects:Harmful by ingestion. Irritating to skin eyes.
Hazardous reactions:No known hazards, although solutions should NOT be treated with acid to avoid
generation of hydrogen cyanide.
Fire hazards:MAY EVOLVE TOXIC FUMES IN FIRE. Flash point 76ºC, ignition temp. not
available; extinguish fire with dry powder.
Spillage & disposal:Mop up with plenty of water and run to waste, diluting with copious water. For larger
spillages, transfer to container for disposal.