Dibutyltin carboxylate

Mercaptides are unchallenged as the ligand of choice for the other entities bonded to the tin, but carboxylates can also be used. Whereas a variety of mercaptans are used, the thioglycolic acid derivatives remain the largest single mercaptan. Dibutyltin bis(isooctyl thioglycolate) [25168-24-5] and butyltin tris(isooctyl thioglycolate) [25852-70A] are two common examples. These materials are produced by the reaction of the appropriate alkyl tin chloride or oxide, and the mercaptan. 

Dibutyltin and dioctyltin diacetate, dilaurate, and di-(2-ethylhexanoate) are used as catalysts for the curing of room-temperature-vulcanized (RTV) sihcone elastomers to produce flexible siUcone mbbers used as sealing compounds, insulators, and in a wide variety of other appHcations. Diorganotin carboxylates also catalyze the curing of thermosetting siHcone resins, which are widely used in paper-release coatings. 

Other Octoate Uses. Metal octoates are also used as driers in printing inks. Another appHcation of octoates includes the use of the aluminum salt to gel paint. Stannous, dibutyltin, and bismuth carboxylates find appHcation as catalysts in polyurethane foam appHcations in order to obtain a reaction efficiency suitable for industrial production. In polyurethane foam manufacture the relative rate of polymeriza tion and gas foaming reactions must be controlled so that the setting of the polymer coincides with the maximum expansion of the foam. 

The most common catalyst used in urethane adhesives is a tin(lV) salt, dibutyltin dilaurate. Tin(IV) salts are known to catalyze degradation reactions at high temperatures [30J. Tin(II) salts, such as stannous octoate, are excellent urethane catalysts but can hydrolyze easily in the presence of water and deactivate. More recently, bismuth carboxylates, such as bismuth neodecanoate, have been found to be active urethane catalysts with good selectivity toward the hydroxyl/isocyanate reaction, as opposed to catalyzing the water/isocyanate reaction, which, in turn, could cause foaming in an adhesive bond line [31]. 

In solution, the 170 NMR spectra of tributyltin acetate and dibutyltin diacetate show a single signal in a variety of solvents over the range 200-300 K. This is interpreted to imply the existence, in solution, of a cyclic monomer in which the carboxylate groups ate anisobidentate, and are undergoing rapid intramolecular exchange 34.350... 

Catalysts Catalysts are widely used for PU manufacture. Sometimes a combination of two or three catalysts is required to obtain the desired balance of reaction rates between compounds of differing active hydrogen activity. Metal compounds, especially organotin compounds, are much more efficient catalysts than tertiary amines for the -OH/NCO reaction. In addition to more commonly used dibutyltin(IV) dilaurate, dibutyltin(IV) diacetate, dialkyltin(IV) oxide or salts of divalent fin with a variety of carboxylic acids such as stannous octoate, hexoate and naphthenate etc. are available for this purpose. Combination of tin catalysts with tertiary amines has been reported to lead to a synergistic increase in catalytic activity. 

Chemical Properties. Trimethylpentanediol, with a primary and a secondary hydroxyl group, enters into reactions characteristic of other glycols. It reacts readily with various carboxylic acids and diacids to form esters, diesters, and polyesters (40). Some organometallic catalysts have proven satisfactory for these reactions, the most versatile being dibutyltin oxide. Several weak bases such as triethanolamine, potassium acetate, lithium acetate, and borax are effective as stabilizers for the glycol during synthesis (41). 

Potassium nitrosodisulfonate, 258 other methods Bis(tributyltin) oxide, 41 /-Butyl hydroperoxide-Dichlorotris-(triphenylphosphine)rutheni-um(II), 54 Dibutyltin oxide, 95 Hydrogen hexachloroplatinate(IV)-Copper(II) chloride, 145 4-Methoxy-2,2,6,6-tetramethy 1-1 -oxopiperidinium chloride, 183 of alcohols to carboxylic acids Cetyltrimethylammonium permanganate, 69... 

From oxidative cleavage of 1,2-diols and 1,2-amino alcohols Dibutyltin oxide, 95 By reaction of alkyl halides with sulfur-stabilized carbanions Methylthiomethyl p-tolyl sulfone, 192 From reduction of carboxylic acids Vilsmeier reagent, 341 From terminal alkenes by addition reactions... 

Most thermal stabilizers for poly (vinyl chloride) are metal salts of carboxylic acids or mercaptans. The commonly used metals are cadmium, barium, zinc, lead, calcium, and dibutyltin. Originally it was assumed the metal salts act as scavengers for hydrogen chloride. However, Frye and Horst (7, 8) found evidence for the introduction of ester groups in the polymer from metal carboxylate stabilizers, which led them to postulate that thermal stabilizers function by substituting the unstable chlorine atoms with the ligands of the stabilizer to yield derivatives which are more thermally stable than the original chloride. 

The two different functionalities (mercaptide and carboxylate) of dibutyltin / -mercaptopropionate react at different rates with the allylic chloride) stabilization of dibutyltin salts of maleic acid or monoesters... 

In dimethyltin diformate, however, the two carbonyl groups bridge intermolecularly, to form infinite sheets similar to those in dimethyltin difluoride or dimethyltin di(fluorosulfonate).29 If the linearly polymeric diorganotin carboxylates are dissolved in chloroform, the 119Sn NMR chemical shift moves downfield by 50 to 100 ppm, and is then almost independent of concentration, showing that the compounds are monomeric in solution.23-30 Dibutyltin glutarate is a linear polymer as shown in 13-9.31... 

Figure 4.4.14 Dibutyltin di(carboranecarboxylate), dicarboranetin (2,6-pyridine dicarboxyl ate) and di-carboranetin di(5-oxopyrrolidine-2-carboxylate)...

Another class of organotin heat stabilizers is the sulphur-free estertins or organotin carboxylates like dibutyltin maleate. Estertins work especially well in out-door applications like transparent and translucent double-walled panels for greenhouses, sidings, and window profiles. 

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