Synthesis of tetrasodium pentaerythrityl tetrakis (dithiocarbamate)
GOVERNMENT RIGHTS 
     The Government has rights in this invention pursuant to Contract Number H-2284R, awarded by the Department of Housing and Urban Development. 
    
    
     BACKGROUND OF THE INVENTION 
     TSPTD has been found to be a excellent lead precipitant for use in the detoxification of lead paint covered surfaces. The conventional method of manufacturing TSPTD from carbon disulfide sodium hydroxide and pentaerythrityl tetramine produces poor yields as a result of undesirable side reactions. According to this invention we have discovered a method for manufacturing TSPTD from carbon disulfide, sodium hydroxide and pentaerythrityl tetramine which produces yields in the order of 78% of theoretical. It is accordingly an object of this invention to provide a method of synthesis of TSPTD. These and other objects of the invention will be readily apparent from the following description of the invention. 
     DESCRIPTION OF THE INVENTION 
     The method of making TSPTD from pentaerythrityl tetramine, carbon disulfide sodium hydroxide proceeds according to the following reaction: ##STR1## Owing to yield reducing side reactions, simple mixing of the tetramine with four equivalents of carbon disulfide and sodium hydroxide does not produce a satisfactory yield. According to this invention it has been found that substantially greater yields can be obtained if the reaction is carried out in the presence of a slightly basic, water soluble, inert solvent such as pyridine in the presence of an excess of carbon disulfide with the sequential addition of sodium hydroxide. The following example illustrates this invention, however, it should be recognized that while the example relates specifically to sodium hydroxide and the preparation of the sodium salt it is usable in connection with any of the alkali metal salts. 
    
    
     EXAMPLE I 
     Preparation of Tetrasodium Pentaerythrityl Tetrakis (Dithiocarbamate) 
     16.1 grams (0.212 mols) of carbon disulfide and five milliliters of pyridine were placed in a 100 milliliter three-necked Morton flask equipped with a mechanical stirrer, reflux condenser and two addition funnels. Three drops of 1% phenolphthalein were added and the reaction flask was placed in an ice bath. The mixture was cooled to below about 5° C. and 3.5 grams (0.0265 mols) of distilled pentaerythrityl tetramine dissolved in 7 milliliters of pyridine were slowly added with vigorous stirring. A precipitate formed immediately. The reaction flask was removed from the ice bath and three molar aqueous sodium hydroxide was slowly added until the pink color appeared. After a reaction period of several minutes, the pink color disappeared; sodium hydroxide solution was again added with continuous vigorous stirring until the pink color reappeared. This process was repeated until a total 34.5 milliliters (0.106 mols) of sodium hydroxide solution was added. At this point the orange reaction mixture contained two liquid layers and no solid material. The reaction mixture was then evaporated to dryness on a vacuum rotary evaporator and the solid residue recrystalized from ethanol to give 14.0 grams of colorless crystals. The NMR of the recrystalized material indicated its composition to be ##STR2## The 14 grams thus corresponds to a yield of 78% of the theoretical. 
     While this invention has been described with respect to a specific embodiment thereof it should not be construed as being limited thereto. Modification can be made by workers skilled in the art without departing from the scope of the invention which is limited only by the following claims wherein: