Organotin Compounds Robert Ono 4 December 2012. Organotin Uses Protodehalogenation Cross-Coupling...
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Transcript of Organotin Compounds Robert Ono 4 December 2012. Organotin Uses Protodehalogenation Cross-Coupling...
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Organotin Compounds
Robert Ono4 December 2012
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Organotin Uses
Sn
R
R
R
H
Br
Sn
R
R
R
Br
H
AIBN
Sn
R
R
R
Cl
1) n-BuLi
2) Ar-Br Ar-SnR3
Ar-SnR3 + Ar2-Xcat.
Ar-Ar2
• Protodehalogenation
• Cross-Coupling (Stille)
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Trialkyltin Chlorides
Size of R
Reactivitydecrease increase
Toxicity
Example:SnMe3Cl vs. SnBu3Cl
LD50 12.6 mg/kg 129 mg/kg (NaCN LD50: 4.8 mg/kg)
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Toxicity• Ingestion, inhalation, or skin exposure • Skin, eye irritation• Neurotoxin
– Accumulates in parts of the brain– Dizzyness, vertigo, memory loss, aggressiveness…
• Reproductive toxicity in lab animals• Not really carcinogenic• Also,
Sn
n-Bu
n-Bu
n-Bu
H H2O Sn
n-Bu
n-Bu
n-Bu
OH H2
Sn
n-Bu
n-Bu
n-Bu
Cl H2O Sn
n-Bu
n-Bu
n-Bu
OH HCl
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Handling
• Proper PPE – Protect eyes, hands, skin
• Chlorides – avoid contact with moisture• Hydrides – handle under inert gas atmosphere• Disposal:
– Wash contaminated equipment with organic solvent, into container, tag for pickup
– Same for small spills (larger spills, call EHS)
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How to get rid of R3Sn-X byproducts from your reactions
Sn
R
R
R
Cl
1) n-BuLi
2) Ar-Br Ar-SnR3 ( + SnR3-Br or Cl)
• Vigorously stir crude reaction mixture (in organic solvent) with 1M NaOH for 1h
• Separate organic phase, filter through silica
• R3Sn-X is converted to polar R3Sn-OH, which does not elute on silica gel
Tetrahedron Lett. 1998 , 39 , 2123.