O It by Éew G. (2-Cal C) ATTORNEY Patented Sept
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Sept. 25, 1951 O, C. JONES 2,569,128 METHOD OF PRODUCING PHOSFHORUS SULFIDES Filed March 24, 1948 y Ns OA. C. JONES INVENTOR. 3HO It by éew G. (2-cal c) ATTORNEY Patented Sept. 25, 1951 2,569,128 UNITED STATES PATENT OFFICE 2,569,128 METHOD OF PRODUCING PHOSPHORUS SULFDES Otha C. Jones, Anniston, Ala., assignor to Mon Santo Chemical Company, St. Louis, Mo., a cor poration of Delaware Application March 24, 1948, Serial No. 16,785 10 Claims. (C. 23-206) 1. 2 The present invention relates to phosphorus unless these reactants are brought together at sulfides and to an improved method of produc Such a slow rate as to render the method corn ing Same. f mercially unattractive, the reaction is very dif One object of the invention is to . provide an ficult to control and the localized Superheating economically and commercially feasible method 5 which invariably occurs brings about the develop of producing phosphorus Sulfides. ment of side reactions and varying degrees of Another object is to provide a method of pro volatilization of phosphorus, Sulfur and phoS ducing phosphorus Sufides in which the reaction phorus Sulfides throughout the batch with the proceeds rapidly and smoothly to completion result that the yield and quality of the desired Without the formation of undesirable by-products. 10 product are seriously impaired. Finally, the Another object is to provide a method of pro above method is subject to the drawback of re ducing phosphorus Sulfides in which the phos quiring relatively large equipment for large phorus-sulfur reaction is so controlled that little, Volume production, of offering many opportunities if any, phosphorus, Sulfur or phosphorus Sulfides for product degradation by moisture and ad are lost by volatilization and hence high quality 15 ventitious contamination and of yielding a hard products are directly formed in substantially solid material which presents a laborious grind quantitative yields. ing problem. An additional object is to provide a method of As a means of overcoming the above difficulties, producing phosphorus sulfides which avoids the it has been proposed to carry out the reaction be formation of crude heterogeneous mixtures such 20 tween phosphorus and Sulfur in the presence of as are obtained by directly reacting phosphorus an inert organic Solvent Such as alpha-chlornaph with sulfur in the absence of a solvent, and at the thalene, benzene, xylene or tetralin. These Sol same time yields, without the use of extraneous vents, by reason of their bulk and capacity for ab Solvents, the high quality products of the Solvent Sorbing heat, prevent the reaction from becoming method. 25 violent and by dissolving the reactants and reac A further object is to provide a method of tion products, facilitate the completion of the re producing phosphorus sulfides on a commercial action and the formation of the desired products. Scale which does not require the use of large This method constitutes a decided advance in the equipment, and the handling and recovery of rela art, but it has the disadvantage of requiring the tively large volumes of solvent. 30 handling and disposal of relatively large volumes A still further object is to provide a method of Solvent, and also the use of large equipment whereby phosphorus sulfides can be produced in for large Scale production. In addition, the fore a continuous and highly efficient manner. going method yields products which are con Other objects and advantages will be apparent taminated with adhering solvent and consequent to those skilled in the art as the description 35 proceeds. ly for Some applications, it is essential to include Heretofore, phosphorus sulfides have been pro an additional procedural step in order to provide duced by directly reacting phosphorus with Sulfur a product of the desired purity. All of these dis in the proportions calculated to yield the desired advantages materially add to processing and product, but due to the highly exothermic nature 40 equipment costs and thereby render the solvent of the reaction, this method has presented a num method commercially unattractive. ber of disadvantages. I have developed a relatively simple, economi For example, white phosphorus and Sulfur do cally and commercially feasible method of manu not react With each other at temperatures below facturing phosphorus sulfides which presents about 175° C. to 200° C. and when a batch of 45 none of the difficulties or disadvantages enumer phosphorus is heated to this temperature and ated above. In accordance with this method, sulfur added, the resulting heat of reaction is SO phosphorus and Sulfur are introduced with agita intense that a portion of the phosphorus is vio tion into a molten batch of phosphorus sulfide and lently converted to the red form and in addition reacted in the proportions calculated to yield the excessively large amounts of reactants and pro 50 desired product, the heat of reaction being ab duct are lost by volatilization. On the other hand, SOrbed by the molten batch and transferred there When the order of addition is reversed, that is, by to a suitable heat exchanging surface or mate when phosphorus is introduced into a batch of rial. The product of the reaction is withdrawn sulfur heated to a temperature within the above from the reaction zone, fiaked on chill rolls and range, a violent reaction also takes place with then converted into a powder by grinding in a substantially the same results. In either event, hammer mill or equivalent pulverizing device, 2,569,128 3 4 The composition of the molten reaction mediurn The above closely approximate the properties is varied with the phosphorus Sulfide to be pro of practically pure phosphorus penta Sulfide, duced, that is, if phosphorus pentaSulfide, phos." which are as follows: phorus sesquisulfide or phosphorus heptaSulfide is desired, then the reaction medium should have Substantially the same composition. Moreover, Per Cent E Per Cent S Melting Point if the final product is to be a mixture of phOS 'phorus sulfides of predetermined composition, the 27.93 72.7 286° C-290° C. same consideration applies to the composition of the reaction medium. O Eacample II The phosphorus and sulfur may be charged to the reaction medium at relatively rapid rates Phosphorus heptasulfide was introduced into with the assurance of obtaining a, quiet Uniform the above reactor and melted by heating to a reaction and a product Substantially free of un temperature of 315° C., whereupon the Stirrer desired impurities. In fact, the only limitation was set into motion and While purging With on the rate at which the above reactants may be carbon dioxide, 281 milliliters of Sulfur at 120 brought together under the foregoing conditions C. and 161 milliliters of phosphorus at about 60° is the efficiency with which the heat of reaction C. were slowly added and mixed in the molten is removed from the reaction medium. charge during a period of 1 hour. The resulting The phosphorus-Sulfur reaction may be carried 20 reaction proceeded Smoothly at a temperature of out batchwise, but is preferred to practica the from 312 C. to 315 C. and the molter phospho method in a continuous manner, in Which case rus heptasulfide thus produced was discharged the above materials are continuously reacted to continuously from the reactor into a receiver gether in the proportions required to produce the and allowed to cool in the presence of anhydrous desired phosphorus Sulfide, and the resulting 25 carbon dioxide. Upon Solidification, the product product is then renoved from the reaction Zone was finely divided by grinding and on analysis as rapidly as it is formed. When practiced in a was found to have the following properties Which batchWise or Semi-continuous manner, the phos indicated that it was Substantially pure phoS phorus and Sulfur may be charged to the reac phorus heptaSulfide. tion medium at different times or at a variable 30 rate provided the total amount of each reactant corresponds to that required to yield the desired Per Cent Per Cent S Melting Point product. 35.9 64.3 305-310 C. For a more complete understanding of the Theory 35.5 64.5 305-310 C. present improved method of making phosphorus 3 5 Sulfides, reference is made to the following Spe cific examples, it being understood that they Eacample III are illustrative and not in any sense linitative Phosphorus Sesquisulfide was added to the Of the invention. above reactor and converted to the molten State (ii by heating to a temperature of about 315° C. Eacample I Then, while operating the stirrer and purging the reactor with carbon dioxide, 112 milliliters The apparatus employed in this embodiment of Sulfur at about 120° C. and 42 milliliters of of the instant invention consisted essentially cf phOSphorus at about 60° C. Were introduced into Sulfur and phosphorus feeders, a reactor pro A. 5 the molten Sesquisulfide over a period of 1 hour, vided with a stirrer for agitating the charge, during which time the reaction temperature was inlets for introducing phosphorus and sulfur, maintained within the range of 313 C. to 318 means for purging the reactor with an inert C. The reaction proceeded very quietly and the gas and a take-off tube from the bottom thereof phosphorus Sesquisulfide thereby obtained was for discharging the molten product into a suitable ) discharged continuously from the reactor in the receiver. presence of anhydrous carbon dioxide and al The reactor was charged with phosphorus lowed to cool and Solidify in a receiver under pentasulfide and then heated to a temperature of the Same conditions. The product upon cooling 300 C. to convert the charge into the moltein to room temperature was a waxy yellow Solid condition.