Of organotins

Triorganotins. Triorganotins and diorganotins constitute by fat the most important classes of organotins. 

Hexaorganoditins with short-chain ahphatic groups are colorless Hquids, distillable under vacuum, soluble in organic solvents other than the lower alcohols, and insoluble in water. They are generally unstable in ak, undergoing ready oxidation to a mixture of organotin compounds. Hexaarylditins are usually crystalline soHds and are much more stable towards oxidation. 

The current OSHA TLV standard for exposure to all organotin compounds is 0.1 mg of organotin compounds (as tin)/m air averaged over an 8-h work shift (192). NIOSH has recommended a permissible exposure limit of 0.1 mg/m of tin averaged over a work shift of up to 10 h/d, 40 h/wk Reference 193 should be consulted for more detailed information. Additional information on the health effects of organotin compounds is given in Reference 48. 

Commercially available tin compounds having aimual production or gross sales of >2.3 metric tons or 5,000.00 are Hsted in References 194 and 195. Principal U.S. producers of inorganic tin compounds include M T Chemicals, Inc., Vulcan Materials Company, and Allied Corporation. M T Chemicals, Inc., is the largest U.S. producer of organotin compounds, followed by Carstab Corporation, Witco Chemical Corporation, and Cardinal Chemical Company minor producers are Interstab, Synthetic Products Company, Tenneco Chemicals Company, and Ferro Chemical Company... 

In 1975, the estimated world aimual production of tin chemicals represented the consumption of 12,000—14,000 t of tin metal or 5% of total tin consumption (196). In 1978, ca 20,000 t/yr was consumed worldwide, with equal amounts represented by inorganic tin and organotin compounds (197). It is estabhshed that worldwide production of organotins rose from ca 50 t in 1950 to a possible 30,000—35,000 t in 1980. 

R. C. PoUer, The Chemistry of Organotin Compounds, Academic Press, New York, 1970. 

In more recent years, molded flexible foam products are becoming more popular. The bulk of the molded flexible urethane foam is employed in the transportation industry, where it is highly suitable for the manufacture of seat cushions, back cushions, and bucket-seat padding. TDI prepolymers were used in flexible foam mol ding ia conjunction with polyether polyols. The introduction of organotin catalysts and efficient siHcone surfactants faciHtates one-shot foam mol ding, which is the most economical production method. 

Fig. 1 Chromatogram of organotin compounds. Dibutyltin dilaurate (1), dibutyltin dichloride (2), dioctyltin oxide (3), tributyltin oxide (4), tributyltin chloride (5), tetrabutyltin (6).

Promotes and fosters the dissemination of scientific and technical information on the environmental effects of organotin compounds. 

Another major use of organotin compounds is as curing agents for the room temperature vulcanization of silicones the 3 most commonly used compounds are Bu2SnX2, where X is acetate, 2-ethylhexanoate or laurate. The same compounds are also used to catalyse the addition of alcohols to isocyanates to produce polyurethanes. 

Intramolecular Pd(0)-catalyzed Stille reaction of organotin reagents with electrophiles leading to C—C a-bond formation in synthesis of heterocycles, particularly, macrocyclic lactones 99JCS(P1)1235. 

Coupling reaction of organotin compounds with carbon electrophiles... 

Gielen, M. Chirality, Static and Dynamic Stereochemistry of Organotin Compounds. 104, 57-105... 

Rzaev, Z. M. O. Coordination Effects in Formation and Cross-Linking Reactions of Organotin Macromolecules. 104, 107-136(1982). 

Polymerization using the Stille coupling, the cross-coupling of aryl-alkenyl halides with organotins in the presence of palladium catalysts (Scheme 9.10),13 appeared in 1989 (Scheme 9.11).14 The low nucleophilicity of organotins makes it possible to use functionalized monomers for the polymerization.15... 

Physicochemical and Biological Methods for Study of Organotin(IV) Compounds... 

The rapid rise in the industrial (catalyst in PVC and foam production), agricultural (fungicides and acaricides), and biological applications (wood, stone, and glass preservatives) of organotin(IV) compounds during the last few decades has led to their accumulation in the environment and, consequently, in biological systems. 

II. PHYSICOCHEMICAL AND BIOLOGICAL METHODS FOR STUDY OF ORGANOTIN(IV) COMPOUNDS... 

Some structural data obtained by these methods are also discussed in the following sections. The XANES spectra of organotin(lV) are usually not so informative. The advantages and disadvantages of EXAFS as a structural probe are discussed... 

It is possible to observe effects of organotin(lV) compounds exposure such as inhibition of cleavage of fertilized eggs, interference with the formation of the mitotic spindle, damages affecting chromosome structure, and electron-dense precipitate formation in organelles. 

---