Patented Apr. 23, 1940 2,197.964 UNITED STATES PATENT OFFICE 2,197,964 METHOD FOR THE PRODUCTION OF AN ?t ALKAL META, SAT OF A MONO-ALKY, TRTHIOCARBONATE William T. Bishop, Wilmington, Del, assignor to Hercules Powder Company, Wilmington, Del, a corporation of Delaware No Drawing. Application July 10, 1937, Seria No. 153,061 Claims. (CI. 260-455) This invention relates to an improved method will desirably be anhydrous. The reaction will for the production of an alkali metal salt of a preferably be carried out in the absence of any mono-alkyl trithiocarbonate, and more particu added water either in the reagents or otherwise. larly to a method for the direct production of a The product obtained from such operation will 5 Solid alkali salt of a mono-alkyl trithiocarbonate contain only the water released by the reaction. 5. containing not more than two molecules of water When using an alkali metal hydroxide as a re per molecule of the trithiocarbonate. actant the product will contain one mol of water It is the object of this invention to provide per mol of trithiocarbonate, and when using an a method by which an alkyl trithiocarbonate alkali metal monoxide it will contain one-half 10 Suitable, for example, for use as a flotation re mol of Water per mol of trithiocarbonate. 10 agent can be produced with inexpensive materials I have found, however, that I can obtain a and without cumbersome purification procedure. solid product which requires no further treat The product of this method is an alkali metal ment, provided the total water contained in the Salt of a mono-alkyl trithiocarbonate containing product does not exceed about two mols per mol 15 not in excess of two moles of water to each mole of the trithiocarbonate. When using an alkali 15 of the trithiocarbonate. Surprisingly enough, I metal hydroxide, then, I may addin the reagents have found that this limited quantity of water or otherwise, water not in excess of about one. does not detrimentally effect the stability of the mol per mole of trithiocarbonate, and when using product, or in any way decrease its usefulness, an alkali metal monoxide I may add water not 20 for example, as a flotation reagent. in excess of about one and one-half mols per mol. 20 The method in accordance with this invention of trithiocarbonate. 3a. comprises reacting an alkyl mercaptain with an In carrying out the method in accordance with alkali metal hydroxide, or an alkali metal mon this invention, I prefer to use substantially mo Oxide, and with carbon disulfide to produce an lecular proportions of the reactants. In any case 25 alkali metal mono-alkyl trithiocarbonate. The it is desirable to carry the reaction to completion 25 product of this reaction is a solid and requires so that a minimum of free alkali metal hydrox no purification procedure whatever before use, ide remains in the final product, since its pres for instance, as a flotation reagent. ence tends to cause the product to be unstable. In this method an alkyl mercaptain may be Substances non-reactive under the conditions of 30 first reacted with a solid alkali metal hydroxide, reaction, such as, for example, organic sulfides, 39 or a Solid alkali metal monoxide to produce an hydrocarbons, etc., do not interfere with the alkali metal mercaptide, and then with carbon reaction and do not harm the product for use as . disulfide to produce an alkali metal mono-alkyl a flotation reagent, provided they are not pres trithiocarbonate. Alternately, the alkali metal ent in excessive quantities. 35 hydroxide or alkali metal monoxide and the car The temperature at which I carry out the re- 35 bon disulfide may be added simultaneously to the action in accordance with this invention may be alkyl mercaptan, and again the carbon disul within the range of about 0° C. to an upper limit fide may be added to the alkyl mercaptain, and Set by the reflux temperature of the volatile in the Solid alkali metal hydroxide or solid alkali gredients of the reaction mixture, and preferably O metal monoxide then added. Thus, it will be within the range of about 0° C. to about 40°C. 40 appreciated that the order in which the ingre The time of reaction will be that required for dients are added is not critical, the reaction to go to completion. The end of In carrying out the reaction in accordance the reaction can be readily determined by the with my invention it is unnecessary to utilize re uniformity of the product and by the heat evo As action medium, such as water or the like to ob lution of the reaction mixture. When the mix- 45 tain a complete and rapid reaction. Surpris ture ceases to evolve heat and is uniform in ap ingly, I obtain a complete and rapid reaction pearance, the reaction is complete. The actual without the addition of water, and can obtain time required will depend upon a number of vari a product which contains only the Water formed able factors such as quantities of reactants, effi 50 in the reaction, e. g., one mol of water per mol ciency of stirring, etc. and can only be accu- 50 of trithiocarbonate produced, when using a solid rately set interms of the appearance and the heat alkali metal hydroxide, and which is a solid. evolution of the mass, . In carrying out this method the solid alkali In carrying out the reaction in accordance with metal hydroxide Will desirably be used in the form this invention it is desirable to avoid oxidizing 55 of flakes or powder to Secure rapid reaction, and conditions, since the product is sensitive in this 55 2 2,197,964 respect, and hence I prefer to exclude any oxy itself during the formation of the mercaptain, ac gen from the reaction mixture. This may con Cording to the reaction: veniently be done by blanketing the reaction S mixture With a non-oxidizing gas, such as, for example, nitrogen, carbon disulfide, alkyl mer MOH--RSH--CS - MS-C-SR--HO captain, etc., or by carrying out the reaction un (In which M=an alkali metal and R=an alkyl der Vacuum in a closed System. group.) The alkyl mercaptain used in this method may In carrying Out this reaction the mixer Will be any pure alkyl mercaptain, such as, for ex desirably be closed and provided with a reflux 0. ample, methyl mercaptain, ethyl mercaptain, pro condenser to prevent loss of carbon disulfide 10 pyl mercaptain, isopropyl mercaptain, butyl iner and/or the alkyl mercaptain or influx of air dur captain, isobutyl mercaptain, various isomeric amy ing the reaction, and will desirably be flooded mercaptains, mixtures thereof, etc., or I may use With an inert gas, Such as, nitrogen, hydrogen or a crude mixture of the mercaptains, such as may other non-oxidizing gases to prevent oxidation 5 be obtained as a by-product in the refining of Or explosion. 15 petroleum. To further illustrate the method in accordance It will be appreciated that in this method, the With this invention I may cite the following ex alkyl mercaptain reacts at the mercaptain group amples: and not at the alkyl group. The alkyl group Eacomple I 20 20 does not act as a functional group and may be Twenty-five pounds of flaked sodium hydroxide purely hydrocarbon in character or may con Were placed in a Werner-Pfleiderer type mixer, tain hydrocarbon groupings as well as other having a capacity of 28 gallons, and equipped groupS, provided, however, that Such groups are With a Water-jacket, an inlet pipe and outlet lead substantially non-reactive under the conditions ing to the condenser, and a thermometer Well. 25 25 employed. In any case the mercaptain group will The mixer is flooded with nitrogen to remove the be connected directly to a carbon atom contained air present. A total of 45 pounds of a mercaptain in an alkyl hydrocarbon group. Thus, for ex mixture containing principally methyl, ethyl, ample, I may react an alkyl mercaptain, the al propyl and butyl mercaptains with some sulfide, kyl group of which contains somewhere in its With the following boiling range, were the fed 30 30 structure an ether linkage, and thereby obtain into the mixer: an alkali metal mono-alkyl trithiocarbonate which likewise contains an ether linkage within Initial boiling point-------------------- 30° C. its alkyl group. It will be appreciated that where 0-------------------------------- 33 I use the term “alkyl herein, I do not limit 20-------------------------------- 35 35 myself to a group. Which is entirely hydrocarbon 30-------------------------------- 37 in character, but use the term to include all 40-------------------------------- 39 groups of the type indicated, including those 50-------------------------------- 42 which are not purely aliphatic hydrocarbon in 60-------------------------------- 45 70-------------------------------- 48 character. () 4) The alkali metal hydroxide which I may use 80-------------------------------- 54: maybe, for example, sodium hydroxide, potassium 90-------------------------------- 64 hydroxide, caesium hydroxide, etc. The alkali Final boiling point.--------- - - - - - - - - - - - - 163°C. metal oxide which I may use, may be, for exam The rate at which the mercaptain was added was ple, sodium monoxide, potassium monoxide, lith controlled So the temperature Was not allowed to ium monoxide, etc. exceed about 45-50° C., and required about 2% This reaction may be carried out in any Suit hours. After the addition of the mercaptain was able equipment in which the reaction mixture is complete the mixing Was continued until the re subjected to thorough agitation and preferably action was complete, as indicated by a drop in one in which it is subjected to thorough agita temperature.