Organotin column chromatography

Monohalides afforded by reduction with tin hydrides are potentially difficult to isolate and purify by distillation. The problem is circumvented by isolating the product by column chromatography and by adding potassium fluoride which results in precipitation of the organotin fluoride, e.g. isolation of 11. ... 

A-(Morpholin-4-yl)-l-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-l//-pyra-zole-3-carboxamide (61). To a magnetically stirred solution of organotin compound 66 (290 mg, 0.40 mmol) in carbon tetrachloride (15 mL) was added dropwise a 0.02 M solution of iodine in carbon tetrachloride (25 mL, 0.50 mmol) at room temperature. After TLC showed that the reaction was completed, carbon tetrachloride was removed under reduced pressure. The residue was purified by flash column chromatography on silica gel (petroleum ether ethyl acetate 50 50) to afford the desired product 61 as a white solid (215 mg, 97% yield) MP 265-268°C (dec.). 

Tributyltin hydride-mediated hydrodebromination of bromoarenes is selectively carried out. However, removal of the tin residue should be carefully carried out. The 10% w/w anhydrous potassium carbonate-silica repeatedly reduces organotin impurity levels below 15 ppm in this system (Table 3-12). In addition, organotin reagents such as tributyltin hydride, allyl stannanes, vinyl stannanes, arylstannanes, and distannanes can be purified by the K2CO3 and silica column chromatography. On the contraiy, halostannanes and sulfonated stannanes are trapped through this process (Table 3-13). 

Ion chromatography using a weak cation-exchange column with direct conductivity detection was applied in the determination of aqueous tributyltin ions, with short elution times LOD 0.01 ppm, without preconcentration or derivatization. No organotin remains adsorbed on the column94. 

Oudsema, J.W. and Poole, C.F. (1992) On-line supercritical fluid extraction and chromatography of organotins with packed microbore columns and formic acid modified carbon dioxide. Fresenius J. Anal. Chem., 344, 426-434. 

Jiang, G. B., M. Ceulemans, and F.C. Adams. 1996. Optimization study for the speciation analysis of organotin and organogermanium compounds by on-column capillary gas chromatography with flame photometric detection using quartz surface-induced luminescence. J. Chromatogr. A 727 119-129. 

Takahasi [754] converted tributyltin and triphenyltin compounds in seawater to the corresponding organotin hydrides prior to determination by packed column gas chromatography with electron capture detection. 

Gas-liquid chromatography affords another technique by which the purity of the organotin hydrides may be ascertained. Tri-n-butyltin hydride, for example, may be chromatographed in a Pyrex column packed with Gas-Chrom Z solid support containing a 5% dispersion of silicone oil. 

SPME capillary gas chromatography (SPME-GC) can be used for the extraction of organometal compounds after these have been derivatized to a sufficiently volatile form (see also organotin speciation). A silica fiber coated with polydimethylsiloxane (PDMS) is brought into the (headspace) of the sample. After exposure, the fiber is inserted into the GC injection port and the compounds are thermally desorbed for subsequent analysis. This method has higher sensitivity compared to the injection of solvent on a capillary column (usually 1 fil) but requires the use of standard addition as a calibration method. After GC separation, analysis can be performed by furnace atomization plasma emission spectrometry (FARES)." ... 

Total tin present as chloride or chloro complexes in urine can be analyzed by reversed phase high-pressure liquid chromatography (HPLC) and detected by ETAAS [98]. Tri-, di-, and monobutyltin can be extracted with ethyl acetate from the homogenized tissues acidified with HCl. Organotin compounds are separated on a silica gel column and then eluted with various solvent mixtures. The confirmation of each tin compound in the different fractions is carried out by flameless AAS and by chromatography. The detection limit is 1.5 ng of tin for each of the tin compounds [99]. 

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