Promoting agent potassium hydroxide

If tin and sulfur are heated, a vigorous reaction takes place with the formation of tin sulfides. At 100—400°C, hydrogen sulfide reacts with tin, forming stannous sulfide however, at ordinary temperatures no reaction occurs. Stannous sulfide also forms from the reaction of tin with an aqueous solution of sulfur dioxide. Molten tin reacts with phosphoms, forming a phosphide. Aqueous solutions of the hydroxides and carbonates of sodium and potassium, especially when warm, attack tin. Stannates are produced by the action of strong sodium hydroxide and potassium hydroxide solutions on tin. Oxidizing agents, eg, sodium or potassium nitrate or nitrite, are used to prevent the formation of stannites and to promote the reactions. 

The proton abstracting agent must be sufficiently strong to promote the formation of the -yne bond so the hydroxides of the alkali metals lithium, sodium and potassium are of first choice. It reacts effectively at a molar ratio to the phenolic compound in the range between 12 1 and 30 1 a molar ratio of between 17 1 and 23 1 appears to be most advantageous. 

Tetanus toxoid and tetanus toxoid adsorbed (adsorbed onto aluminum hydroxide, phosphate, or potassium sulfate to increase antigenicity) are sterile suspensions of the toxoid derived from C. tetani. Both toxoids are used to promote active immunity against tetanus however, tetanus toxoid adsorbed is the preferred agent because it elicits a greater immune response and is associated with fewer adverse reactions. 

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