Tetra-n-butyl tin

Let us use some of the methods applied to the germanium compounds to assess a few values from Table 3. A plot of the three gaseous enthalpies of formation for tetraethyl, tetra-n-propyl and tetra-n-butyl tin species versus the number of carbon atoms in the compound (equation 1) shows that probably at least one of them is inaccurate. In the liquid phase there is an additional enthalpy of formation, that for tetra-w-hexyl tin. A plot of the liquid enthalpies of formation versus total carbon number shows that the enthalpy of formation for tetraethyl tin is an outlier and the remaining three points define a fairly good straight line15 (r2 = 0.99953, a = -21.77 0.80, = 47.78 12.39). If... 

Bimetallic catalysts can be obtained by surface organometallic chemistry on metals. These catalysts are prepared by the controlled reaction under hydrogen between tetra n-butyl tin and silica supported rhodium particles. For a given amount of tin fixed, these solids exhibit increasing activities and selectivities for the conversion of acetophenone to phenylethanol. 

Surprisingly, if the surface of silica supports a platinum particle covered with hydrogen, the reaction of tetra-n-butyl tin leads aheady at room temperature to the platinum particle reported in the following equation, on which SnRs groups are grafted and the sihca support is untouched [62]. No reaction occurs on the support in such conditions. 

The reaction is usually performed at low temperature, typically 20-50 °C, in order to avoid a reaction of the tin complex with the hydroxy groups of the support, as shown by solid-state C CP-MAS NMR. Indeed, it has been shown that tetra-n butyl tin or tributyl tin hydride reacts, above ca. 150 °C with the hydroxy groups of silica, siUca-alumina or alumina with formation of a surface grafted =M-0-Sn(n- 4119)3 fragment and evolution of butane or hydrogen [61, 109-111] (Scheme 18.5). 

M[pz(A4)] A = S2ML2. The octakis(.V-R)porphyra/,ines reported by Schramm and Hoffman (2), M[pz(S-R)8 (M = Ni, Cu), (60), can be converted to the octathiolate M[pz(S )g] (Scheme 11) via reductive cleavage of the sulfur-carbon bond when R = benzyl (Bn), and this tetra-bis(dithiolate) can then be peripherally capped with metal-ligand systems to yield peripherally tetrametalated star porphyrazines. The benzyl dinitrile 57 can be macrocyclized around magnesium butoxide to form [Mg[pz(S-Bn)8] (58) (35-40%), which can then be demetalated with trifluoroacetic acid to form 59 (90%), which is subsequently remetalated with nickel or copper acetate to form 60a (95%) and 60b (70%) (Scheme 11) (3, 23, 24). Deprotection of 60a or 60b with sodium in ammonia yields the Ni or Cu tetra-enedithiolates, 61a or 61b to which addition of di-ferf-butyl or n-butyl tin dinitrate produces the peripherally metalated star porphyrazines 62a (37%), 62b (80%), and 62c (41%). 

Surface Organometallic Chemistry on Metals Selective hydrogenation of citral on silica supported Rhodium modified by tetra-n-butyl Germanium, Tin and Lead. 

Tetra-n-butyltin is oxidised by chromium trioxide (1 1 molar ratio) to yield tri-n-butyltin acetate and compounds derived from the n-butyl group cleaved from the tin atom (mainly n-butyraldehyde and butyric acid)29. In the initial stages of the oxidation, the reaction follows the simple rate expressions v = k2 [Bu Sn] [Cr03]. Values of the second-order rate coefficient for the oxidation of a number of tetraalkyitins by Cr03 in solvent acetic acid at 20 °C were reported29 to be as follows... 

SYNS TETRA-n-BUTYLCIN (CZECH) TETR. BUTYL-TIN... 

Mono-n-butyltin tris(j-octylmercaptoacetate) combines improved early color with shortened longterm stability. This is due to its intermediate Lewis acid character between that of diisooctyl bis(t-octylmercaptoacetate) and tin tetra(i-octylmercaptoacetate). The decreased effectiveness of tri-n-butyltin i -octylmercaptoacetate may be ascribed to the increased reluctance to coordination by the tin atom, due to presence of the third alkyl (n-butyl) group. Additionally, the use of trialkyltin derivatives in PVC stabilization has been avoided because of their toxicity. 

With trifluoroacetic acid at 80° C di-n-butylbis(pentafluoroethyl)tin yielded only about 7% of its butyl groups as butane. Under similar conditions a sample of tetra- -butyltin gave butane in nearly 50% yield 29). It is evident that (n-C4H9)2Sn(C2Fs)2 is more similar to ( -C4H9)2SnCl2 than to (n-C4H9)4Sn. 

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