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. This occurred in about one hour tion and disintegrating action. Thus, for exam after the addition of the mercaptain. Forty seven and one-half pounds of carbon disulfide ple, a mixer of the Werner-Pfleiderer type was then slowly added to the mixture, the rate of equipped with blades for shredding action is Suit addition being adjusted so the temperature did able. not exceed 45-47 C. This addition required In carrying out the reaction in accordance With about three hours. The mixing was then con this invention flaked or powdered caustic may, tinued for another three hours, at the end of for example, be added to a mixer and then the which the reaction had gone to completion as alkyl mercaptain run in onto the caustic while it indicated by a drop of the temperature to is being agitated. Adequate cooling is provided 30-33°C. The product was found to be solid and 60 to avoid loss of the volatile reagents by evapora apparently dry, weighing 106/2 pounds. 50 tion and to avoid thermal decomposition of the Eacample II product. After the reaction has come to comple tion, as indicated by drop in the temperature, Twenty-five parts by Weight of a mixture of mercaptains described in Example I and 30.5 parts Ps-- 65 carbon disulfide is run into the mixture and the by weight of carbon disulfide were mixed together agitation continued. The carbon disulfide may in a reaction vessel provided With a reflux con also be added immediately after the addition of denser and provided for stirring the reaction mix the mercaptain, or they may be added simultane ture. Sixteen parts by weight of powdered so ously. dium hydroxide were added to the reaction mix 70 After the reaction has come to completion, the ture in small portions at short intervals. The product will be found suitable, for example, for mixture was agitated between each addition of use as a flotation reagent without furthel treat caustic, and a slight refluxing of the intercaptain ment of any kind, and will be found to contain and carbon disulfide took place. At the end of about one mol of water per mol of the trithiocar the reaction, the product after being cooled to 75 bonate. This water is produced in the reaction room temperature was a Solid, apparently dry 5 2,197,964 3 material. It was pulverized with a recovery of medium consisting of not more than one mol of 68 parts by Weight. The theoretical yield was water in excess of that formed by the reaction. 64.5 parts by Weight, so the product contained 3.5 2. A method for the production of an alkali parts by Weight of Water. metal salt of a mono-alkyl trithiocarbonate, Eacample III which comprises reacting substantially molecular proportions of an alkyl mercaptain, an alkali Ten parts by Weight of an aliphatic mercaptain metal hydroxide and carbon disulfide in the pres cut boiling within the range of about 70° C. to ence of a liquid reaction medium consisting of about 94 C. and consisting principally of butyl not more than one mol of Water in excess of that O mercaptain and 3.4 parts by Weight of Sodium formed by the reaction. monoxide Were thoroughly admixed together 3. A method for the production of an alkali 10 until all particles of the sodium monoxide were metal salt of a mono-alkyl trithiocarbonate, broken up and had disappeared. Ten parts by Which comprises reacting substantially molecular Weight of carbon disulfide. Were then added to the proportions of an alkyl mercaptain, an alkali 5 reaction mixture and the stirring continued. metal monoxide and carbon disulfide in the pres Reaction Was indicated by a rise in temperature ence of a liquid reaction medium consisting of not 5 and by the reaction maSS turning yellow. At the more than One mol of Water in excess of that end of the reaction, as indicated by a drop in the formed by the reaction. temperature, a thick pasty mass remained, which 4. A method for the production of an alkali 20 Set up to an apparently dry Solid on standing. metal Salt of a mono-alkyl trithiocarbonate, Fourteen parts by Weight of the trithiocarbonate which comprises reacting substantially molecular 20 Were recovered, Which consisted principally of a proportions of an alkyl mercaptain, a material mixture of Sodium butyl trithiocarbonate. from the group consisting of alkali metal hydrox 25 Eacample IV ides and alkali metal monoxides and carbon disulfide the only liquid medium present being 25 One grain. Of Sodium monoxide WaS placed in a the Water of reaction. test tube and to it. Were added 3.7 grams of a 5. A method for the production of an alkali mixture of amyl mercaptains. Three grams of metal Salt of a mono-alkyl trithiocarbonate, carbon disulfide Were then added. As the mix which comprises reacting substantially molecular 30 ture was stirred the mixture turned yellow, show ing that the trithiocarbonate Was being formed. proportions of an alkyl mercaptain, an alkali 30 Stirring Was continued until the mass became metal hydroxide and carbon disulfide, the only more viscous, and 3 to 4 drops of Water were liquid medium present being the Water of reac added to speed reaction to completion. After tion. 35 standing overnight, an apparently dry yellow solid 6. A method for the production of an alkali was obtained. This solid was a mixture of so metal salt of a mono-alkyl trithiocarbonate, dium amyl trithiocarbonates which contained a which comprises reacting substantially molecular small quantity of Water. proportions of an alkyl mercaptain, an alkali metal monoxide and carbon disulfide the only It will be understood that the details and liquid medium present being the Water of reac 40 examples hereinbefore set forth are illustrative tion. only, and that the invention as herein broadly 7. A method for the production of an alkali 40 described and claimed is in no Way limited there metal salt of a mono-alkyl trithiocarbonate, by. which comprises reacting substantially molecular What I claim and desire to protect by Letters proportions of an alkyl mercaptain, a material Patent is: from the group consisting of alkali metal hydrox 1. A method for the production of an alkali ides and alkali metal monoxides and carbon di 45 metal salt of a mono-alkyl trithiocarbonate, sulfide in the presence of a liquid reaction medium. which comprises reacting substantially molecular consisting of not more than one mol of water in proportions of an alkyl mercaptain, a material excess of that formed by the reaction, and under 50 from the group consisting of alkali metal hydrox sides and alkali metal monoxides and carbon substantially non-Oxidizing conditions. 50 disulfide in the presence of a liquid reaction WILLAM. T. BSHOP.