US1868192A - Method of making dithiophosphates and compositions containing same - Google Patents

Description

July 19, 1932, G. H. BUCHANAN METHOD OF MAKING DITHIOPHOSPHATES AND' COMPOSITIONS CONTAINING SAME Filed Feb. 18, 1930 SODA ASH MIXER TRAY DRYER KETTLE BLOW CASE STORAGE PDT ALCOHOL MILL WAZDJ FINES STORAGE )6 TO VENT REFLUX CONDENSER Q V R O m A ALCOHOL STORAGE FROM AClD' BLOW CASE JACKETED I GLASS LINED REACTION KETTLE INVENTOR Gug H. Buchanan 8 ATTORNEY F5 preferably using an excess of Patented July 19, 1932 UNITED STATES PATENT OFFICE GUY H- ZBUCHANAN, 01 WESTFIELD, NEW JERSEY, ASBIGNOR TO AMERICAN CYANAMID COMPANY, OF NEW XOBK,

N. Y., A CORPORATION OF MAINE Imon OF MAKING DI'IHIOPHOSPHA'IES AND COMPOSITION CONTAINING SAME Application filed February 18, 1980. Serial No. 429,270.

The present invention relates to the manufacture of alkali metal salts of dithiophosphoric acids and more particularly the salts of the or anicdithiophosphoric acids.

5 There as been described previously the manufacture of various or anic dithiophosphoric acids and the salts t ereof, which are used for various purposes, such as flotation reagents and the like. In the preparation of the salts of these acids, the usual method, of course, is to neutralize the acid in solution with an alkaline material also in solution, with subsequent evaporation of the water to obtain a solid product. Aside from the costly drying operation, the product so prepared is dithcult to dry completely in view of the oily impurities usually contained in the commercial acid. Dr ing the solution also results in loss of pro not by decomposition and the color of the final product is affected.

It'is one of the objects of the present invention to prepare. the alkali metal salts of the organic dithiolphosphoric acids in an economicaland simp e manner, obtaining a dry, white product which is comparatively free from lumps. Such lumps as may be present are broken up easily with the hands. Another object is to obtain salts and mixtures which are stable and which .are substantially non-deliquescent.

These and other objects are attained by neutralizing the dithiophos horic acid with a dry alkahnecompound an alkali metal, the-alkali metal compoun In the accompanying drawing constituting a part hereo Fig. 1 illustrates diagrammatically substantially the entire process and apparatus;

Fig. 2 is a more detailed diagrammatic view of a portion of the apparatus; and

Fig. 3 1s a detailed diagrammatic view of another portion of the apparatus.

The production of the dithiophosphoric acidis carried out in reaction kettle 1 which is preferably a glass-lined, jacketed kettle rovided with a stirrer or tator 2, driven 5 suitable means 21. Using a kettle of a at 100 gallon capacity, there is placed in ly been crushed to a maximum size of about The manhole cover (not shown) is clamped down and 206 lbs. of ethyl alcohol from storage container 4 is slowly run into the kettlel. The cooling water in thekettle jacket must be so regulated that after all the alcohol is in, the final temperature of the mix is about 40 C. The stirrer 2 is rotated during the course of the addition. The kettle and contents are allowed to stand (from a source not shown) about and cool overnight. The next morning the mixture is heated to 90 C., and the temperature kept there for 2% hours with agitation, after which period, the mix is cooled down to room temperature. The crude acid soprepared is condueted,to storage pot 5. If desired, a ortion of the acid may be left in the kettle or further preparation of acid. As shown in somewhat more detail in Fig. 2, the kettle is provided with a suitable reflux condenser 6 to prevent loss of alcohol orother materials during the reaction. The rocedure just described results in the pro uction of about 400 lbs. of crude (86%) diethyl dithiophosphorie acid having a specific gravity of about 1.19.

Torepare the sodium salt of the acid, a

suitab e mixer 7 is charged with .200lbs. "of

soda ash 'from storage bin 8. This soda ash should be asdryas possible andfree from lumps. Acid from the storage pot 5 is drawn into aluminum blowcase 9 and blown thence to feed pot 10. Thence it is run into the mixer 7 by gravity through a suitable aluminum or similar tube (not shown). Ordinarily the first 100 lbs. of acid is added at the full capacity of the feed mechanism. Stirrers 11 in mixer 7 are operated throughout the addi tions of the acid. The second 100 lbs. of acid the mixture becomes dark in color or tends to become sticky during addition-0t the acid, the

- are added more slowly and, in the event that sis a substantially dry This mawhite powder. terial is preferably placed in a tray drier 12 and dried overnight at about 150 F. The dried product is screened in screening device 13 to remove the lumps which are ground in a mill 14, the fines from 13 to 14 being sent to storage bin 15. The final product has an iodine number. between 29.5 and-30.5 and is well adapted for use as a flotation reagent. It has a white color and does not form objectionable lumps.

To obtain a higher ade product, it is sometimes advisable to a (1 about 60% of the acid to the soda ash in mixer 7 and after a thorough mixing to remove the resulting product to drier 12 .or a similar drier where it is maintained at a temperature of about 115 F. for about twenty hours. The dried material is then returned to the mixer and the additional so 40% acid is added slowly with stirring. The alternate mixing and d 'ng operations may be multiplied to any desired de ee. The resulting product is a white or bu -colored powder containing a very small percentage 0 gers. The material so prepared may be again sent to drier 12 and put through the succeeding steps in the process as previously described. In this method somewhat better elds are obtained and the product has a igher purity as well as other desirable characteristics.

While the preparation of sodium di-ethyl dithiophosphoric acid has been described in detail, other alcohols or alcoholic bodies may be utilized in reparing the corresponding organic dithiop osphoric acid by reaction with phosphorus entasulphide. Thus we may prepare the i-methy di-lSOlilO yl, di-normal but 1, di-secon ary but i-amyl, diphenyl, '-eresyl,etc., dithiop osphoric acids. As a neutralizing agent we may use any of the alkaline compounds of the alkali metals suchas potassium, sodium, or ammonium carbonates hydrates, etc. The alkaline material is pre erably used in excess and may bepresent to the extent of 200% in excess of that necessary to neutralizethe acid. The mixture of alkali metal salt of the dithiophosphoric acid with an excess of the alkaline material is particularly valuable for use as a flotation re- L agent. This is partly due ;to its hysical nature which permits storage, handling anduse with facility and lack f decomposition.

lumps which can easily be broken with the fin- Also, in actual flotation, the presence of exv cess alkali assists materially the chemical action of the flotation agent. 1

Any suitable apparatus may be used in carrymg out the various steps of the process since the elements described may be varied at will, the examples being given only for puroses of illustration.

Suitable changes in details of o eration and materials used may be made wit out departing from the spirit and scope of the invention, except as stated in the appended claims.

What I claim is 1. The process of preparing alkali metal salts of organic dithiophosphoric acids which I comprises intimately mixin an organic ditlll: ophosphoric acid with a so 'd alkaline alkali metal compound by adding a portion of the acid to the compound, drying the mixture, and adding the remainder of the acid.

2. The process of preparing sodium salts of di-alkyl dithiophos horic acids which comprises intimately mixing the acid with solid sodium carbonate in excess of the amount required for a complete neutralization of the acid. J

3. The

process of preparing sodium salts of di-alkyl dithiophosphoric acids which comthe acid with solid proportion of not of that required for prises intimately mixing sodium carbonate in the more than 200% in excess complete neutralization of the acid.

4. The process of preparing a sodium salt of di-ethyl dithiophosphoric acid which com: prises intimately mixing 100 parts by weight of di-ethyl dithiophosphoric acid with 100 parts b weight of solid sodium carbonate, the aci being added in several portions with a drying step between additions. p 5. Acomposition comprisin analkali metal salt of an or anic dithio osphoricacid and a' substanti quantity 0? an alkaline alkali metal compo d.

6. A composition comprisinglan alkali metal salt of di-ethyl dithiophosp oric acid d a substantial quantity of an alkaline alkali metal compound.

7. A composition comprising a sodium salt of an organic dithiophosphoric acid and a substantial quantity of an alkaline sodium compound.

8. A compfisition comprising a sodium salt of di-ethyl stantial quantity of so um carbonate.

9. A composition comprising a sodium ethyl dithiophosphate and sodium carbonate, the latter forming mixture.

of alkali metal salts of or phoric acids suitable as otation reagents which comprises intimatel mlxin an organic dithiophosphoric acid with a so id-alkaline alkali metal compound.

11. The process of preparing compositions 10. The process of preparin com 'tions an le dithiophosthiophosghoric acid and a sub-- the major portion of the to the sodium carbonate of sodium salts of di-alkyl dithiophosphoric acids suitable as flotation reagents which com rises intimately mixing the acid with solid sodium carbonate.

12. The processof preparin compositions of a sodium salts of di-ethyl di 'ophosphoric acid suitable as flotation reagents which comprises intimatel mixing di-ethyl dithiophosphoric acid wit solid sodium carbonate.

In testimony whereof, I have hereunto subscribed my name this 11 day of February,

GUY H. BUCHANAN.

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