Tin II

Data available for the solubility of tin(II) oxide have been reviewed by Gamsjager et al. (2012). They selected heat capacity and entropy data on the basis of the study of Kostryukov et al. (1978) and concluded that the best enthalpy of formation value was 

From the selected entropy and enthalpy, the following Gibbs energy value was derived  

This latter value can be used, together with the Gibbs energy for Sn given by Gamsjager et al. (2012) and water in Chapter 5, to determine the solubility constant of SnO(s) at zero ionic strength and 25 C  

This value is in reasonable agreement with the constant determined by Mes-mer and Irani (1966) (log = 1.756) but somewhat less negative than that derived from earlier studies (log = 2.0) (Garrett and Heiks, 1941 Gorman 

Ionic Strength Dependence Pettine, Millero and Macchi (1981) studied the hydrolysis of tin(II) in a range of media, including in NaNOj from 0.10 to 1.0 moll . Gamsjager et al. (2012) utilised the data for the stability constant of SnOH from the study, together with the standard specific ion interaction theory, to determine the stability constant for the species at zero ionic strength. The constant so obtained, and its associated ion interaction coefficient, are 

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Concentrated nitric acid, however, is an oxidising agent and tin reacts to give hydrated tin(IV) oxide in a partly precipitated, partly colloidal form, together with a small amount of tin(II) nitrate, Sn(N03)2 ... 

If a solution of a tin(II) salt is treated with a small amount of an alkali, tin(II) hydroxide is precipitated, the reaction being represented by the equation ... 

The precipitate obtained is in fact colloidal and has no definite composition. Careful drying of the precipitate gives the anhydrous oxide, SnO, which may also be prepared by heating tin(II) ethane-dioate (oxalate) ... 

Tin(II) oxide is a dark-coloured powder which oxidises spontaneously in air with the evolution of heat to give tin(IV) oxide, SnO, ... 

It is amphoteric it gives tin(II) salts with dilute acids and hydroxo stannates(II) with alkalis, for example ... 

Stannate(II) ions are powerful reducing agents. Since, for tin, the stability of oxidation state -b4 is greater than that of oxidation state -b2, tin(II) always has reducing properties, but these are greater in alkaline conditions than in acid (an example of the effect of pH on the redox potential, p. 101). 

This chloride is prepared by dissolving tin in concentrated hydrochloric acid on cooling, the solution deposits crystals of hydrated tin(II) chloride. SnClj. 2H2O ("tin salt ). The anhydrous chloride is prepared by heating tin in a current of hydrogen chloride ... 

A solution of tin(II) chloride is a reducing agent. Hence it reduces ... 

Tin(II) chloride is slowly oxidised in air. but keeping a piece of tin metal in the solution prevents this. 

In presence of hydrochloric acid, tin(II) in aqueous solution (1) is precipitated by hydrogen sulphide as brown SnS, and (2) will reduce mercury(II) chloride first to mercury(I) chloride (white precipitate) and then to metallic mercury. 

Sulphites react with molecular oxygen (or air) to give sulphates, a reaction catalysed by certain ions (for example Fe, Cu, arsenate(III) ion, AsO ) and inhibited by, for example, phenol, glycerol and tin(II) ions, Sn ... 

Calcium carbide Moisture, selenium, silver nitrate, sodium peroxide, tin(II) chloride, potassium hydroxide plus chlorine, HCl gas, magnesium... 

Nitrates Aluminum, BP, cyanides, esters, phosphorus, tin(II) chloride, sodium hypophos-phite, thiocyanates... 

The other important direct alkylation processes involve reaction of electron-rich olefinic compounds with either tin metal or stannous chloride (tin(II) chloride) in the presence of stoichiometric amounts of hydrogen chloride (22). Butyl acrylate (R = C Hg) was used commercially in this process to prepare the estertin or P-carboalkoxyethyltin chlorides as iHustrated in the foUowing. 

Condensation catalysts include both acids and bases, as well as organic compounds of metals. Both tin(II) and tin(IV) complexes with carboxyhc acids ate extremely useful. It has been suggested that the tin catalyst is converted to its active form by partial hydrolysis followed by reaction with the hydrolyzable silane to yield a tin—sdanolate species (eqs. 22 and 23) (193,194). 

Tin, having valence of +2 and +4, forms staimous (tin(II)) compounds and stannic (tin(IV)) compounds. Tin compounds include inorganic tin(II) and tin(IV) compounds complex stannites, MSnX., and staimates, M2SnX, and coordination complexes, organic tin salts where the tin is not bonded through carbon, and organotin compounds, which contain one-to-four carbon atoms bonded direcdy to tin. 

Solutions of anhydrous stannous chloride are strongly reducing and thus are widely used as reducing agents. Dilute aqueous solutions tend to hydrolyze and oxidize in air, but addition of dilute hydrochloric acid prevents this hydrolysis concentrated solutions resist both hydrolysis and oxidation. Neutralization of tin(II) chloride solutions with caustic causes the precipitation of stannous oxide or its metastable hydrate. Excess addition of caustic causes the formation of stannites. Numerous complex salts of stannous chloride, known as chlorostannites, have been reported (3). They are generally prepared by the evaporation of a solution containing the complexing salts. 

Stannous Oxide. Stannous oxide, SnO ((tin(II) oxide), mol wt 134.70, sp gr 6.5) is a stable, blue-black, crystalline product that decomposes at above 385°C. It is insoluble in water or methanol, but is readily soluble in acids and concentrated alkaHes. It is generally prepared from the precipitation of a stannous oxide hydrate from a solution of stannous chloride with alkaH. Treatment at controUed pH in water near the boiling point converts the hydrate to the oxide. Stannous oxide reacts readily with organic acids and mineral acids, which accounts and for its primary use as an intermediate in the manufacture of other tin compounds. Minor uses of stannous oxide are in the preparation of gold—tin and copper—tin mby glass. 

Pyrazolediazonium salts (448) couple with activated aromatic molecules, like naphthols (79KGS805), and can be reduced to hydrazines (452) with tin(II) chloride (74MI40406). 

Aminoisoxazoles are obtained by reduction of 4-nitroisoxazoles with amalgamated aluminum, tin(II) chloride and hydrochloric acid, or zinc dust and acetic acid (62HC(17)1, p. 73). 

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