Organic Tin Compounds Research Articles

Detection of Organic Tin Compound in Starch

Detection of Organic Tin Compound in Starch

Studies on Organic Tin Compound Poisoning

Studies on Organic Tin Compound Poisoning

The Properties and Manipulation of Mercaptan Base and Silicone Base Impression Materials

The presently available rubber impression materials can be classified as mercaptan base and silicone base materials, according to their composition. The sub-classes of each type can be designated as “heavy type,” “regular type” and “syringe type” according to their viscosity after mixing and their general specialized uses. “Thiokol Polysulfide Rubber,” a polyfunctional mercaptan, is the chief constituent of the mercaptan base materials. A polymerization to a synthetic rubber is effected by means of lead peroxide and sulfur as accelerators. Both the base and the accelerator are supplied in paste form containing plasticizers and fillers. One of the products of the reaction is water. The principal ingredient of the silicone rubber impression materials is thought to be polydimethyl siloxane, which is formed into a paste with a carefully compounded filler. The accelerator (an organic tin compound) is usually supplied as a liquid. Hydrogen and other gases may be evolved during polymerization and may cause pitting of the stone model unless eliminated by a hydrogen acceptor or by the use of a more complex dimethyl siloxane. Volatiles of some nature are always evolved during the vulcanization reactions. It has been shown that the working time of various products varies between 3 and 9 minutes, and the setting time varies between 6 and 13 minutes; the silicone base materials generally set faster than the mercaptan base materials. An increase in temperature accelerates the setting time, particularly in the case of the mercaptan base impression materials. The setting time of the silicone base materials can be controlled by the amount of accelerator employed, but the relation is not in direct proportion. The control of the setting time of the mercaptan base materials can be effected by the mixing temperature, or by the addition of a drop of water for acceleration or a small amount of fatty acid for retardation. The better rubber impression materials may possess elastic properties equal or superior to those of the hydrocolloid impression materials. In general, the strength of these materials is comparatively high. All of the rubber impression materials shrink after setting; the present silicone base materials tend to shrink more than the mercaptan base materials. Although the materials cannot be considered to be dimensionally stable, in some instances the change may be within the allowed tolerance of error. In all instances they are superior in this respect to the hydrocolloid impression materials. Rubber impressions can be electroplated successfully with silver. In general, the electroplated die may not be quite as accurate as a stone die constructed within 30 minutes after the removal of the impression from the mouth. Techniques were suggested for the proper procedures based upon the research findings. The importance of a uniform mix of the base and accelerator was emphasized, as well as the necessity for complete retention of the material in the tray during withdrawal from the parts impressed. The rubber impression pastes are virtually universal impression materials for any dental procedure. The silicone materials at present generally set too rapidly and exhibit poor dimensional stability in comparison to the mercaptan base materials. On the other hand, the silicone materials present the advantages over the mercaptan materials of cleanliness in handling, less tendency to stain, less sensitivity to temperature change, and less toxicity when in continuous contact with the tissues. Once these important disadvantages are eliminated, it is predicted that the silicone base impression materials will supplant the mercaptan base materials.

The Toxicity of Some Organic Tin Compounds

[in Japanese]

Effect of the method of making modifying additions on the properties of oxide catalysts

1. A study was made of the catalytic and adsorptive properties of magnesium oxide samples containing additions of stennic oxide introduced in quantities of 0.01–6.4% by various methods: by application to prepared magnesium oxide via organic and inorganic tin compounds, and by coprecipitation. 2. It was shown that the introduction of stannic oxide into magnesium oxide by impregnation with tetraphenyl tin or stannic chloride results in a modification of the action of the magnesium oxide catalyst in the decomposition of hydrogen peroxide.The main effect is already brought about by the very smallest additions of stannic oxide. As the temperature of the catalytic process is lowered from 90' to. 5% the modification curves change is form, becoming flattened out. 3. The dependence on stannic oxide content of the activity of catalysts prepared by the coprecipitation of magnesium and tin salts is expressed by a curve having a minimum and a maximum. Minimum catalytic activity corresponds to a stannic oxide content of 0.02% and maximum activity to a stannic oxide content of 1%. 4. It was shown that the introduction of stannic oxide into magnesium oxide by impregnation with tetraphenyl we showed previously-results in a marked change in the adsorptive properties of the catalyst. When stannic oxide is introduced into prepared magnesium oxide. the adsorptivity and specific surface of the sample Increases with increase in additive content. When stannic oxide is introduced into magnesium oxide by coptecipitation, the adsorptivity and specific surface of the products are almost unaffected by increase in additive content 5. On the basis of a comparison of the catalytic and adsorptive properties of the catalysts studied, we have advanced the hypothesis that the ways in which additions of stannic oxide are incorporated into magnesium oxide are of two different types and that the manner in which the additions act depends on the method by which they are introduced into the catalyst.

A new series of organic compounds of tin: The stannonic acids and some of their derivatives

A new series of organic compounds of tin: The stannonic acids and some of their derivatives