METHOD FOR PREPARING THIONOCARBAMATE AND CO-PRODUCING 2-MERCAPTOETHANOL OR O-ALKYLTHIOETHYL XANTHATE

Abstract

The invention belongs to the field of mineral flotation collector materials, and particularly discloses a method for preparing thionocarbamate. In the preparation process, xanthate and 2-haloethanol are esterified to obtain O-alkyl-S-hydroxyethyl xanthate, and then O-alkyl-S-hydroxyethyl xanthate and fatty amine are reacted to obtain a mixture of thionocarbamate and 2-mercaptoethanol. The mixture of thionocarbamate and 2-mercaptoethanol is washed with alkali, and the oil phase and water phase are separated. The oil phase and water phase are thionocarbamate and 2-hydroxyethylthiolate, respectively, and 2-mercaptoethanol is obtained by washing with an acid. 2-alkylthioethanol is obtained by reacting 2-hydroxyethanethiolate with alkyl halide, and then with carbon disulfide and alkali to prepare O-alkylthioethyl xanthate. Thionocarbamate, 2-mercaptoethanol and O-alkylthioethyl xanthate prepared by this method possess high yield and high purity. The process is green and environmentally friendly, and is beneficial to the industrialization of co-production.

Claims

1. A method for preparing a thionocarbamate, comprising the following steps: step 1): esterification reaction of a xanthate having a structure shown in formula I with 2-haloethanol to obtain an O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate having a structure shown in formula II; step 2): aminolysis reaction of the O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate with a fatty amine shown in formula III to obtain a mixture of a thionocarbamate shown in formula IV and 2-mercaptoethanol; step 3): washing the mixture of the thionocarbamate and the 2-mercaptoethanol with an alkali to separate the thionocarbamate as an oil phase from a 2-hydroxyethyl thiolate as an aqueous phase; ##STR00008## wherein, in formula I to formula IV, R.sup.1 is C.sub.1 to C.sub.16 alkyl, C.sub.1 to C.sub.16 aryl, or alkylthioethyl shown in formula V: R.sup.2 is C.sub.1 to C.sub.8 alkyl; and M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+;
R.sup.3SCH.sub.2CH.sub.2Formula V wherein, in formula V, R.sup.3 is C.sub.1 to C.sub.16 alkyl or aryl.

2. The method according to claim 1, wherein the 2-haloethanol is 2-chloroethanol or 2-bromoethanol; a molar ratio of the xanthate to the 2-haloethanol is 1.0:(0.9-1.2); a solvent for the esterification reaction is water used at an amount of 0-50 ml per 1 mol of the xanthate; the esterification reaction is conducted at a temperature of 20-100 C. for a reaction time of 1-8 h; and the 2-haloethanol is reacted with the xanthate at 20-30 C. for 1-2 h before the water is added to the esterification reaction at 20-100 C.

3. The method according to claim 1, wherein the aminolysis reaction in step 2) is conducted at a temperature of 30-100 C. for reaction time of 1-6 h; and the fatty amine is added at an amount of 0.9-1.2 times a molar weight of the O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate.

4. The method according to claim 1, wherein in step 3), the mixture of the thionocarbamate and the 2-mercaptoethanol is washed 1-5 times with the alkali having a concentration of 0.1-5 mol/L.

5. A method for preparing a thionocarbamate and co-producing 2-mercaptoethanol, comprising: washing the 2-hydroxyethyl thiolate obtained in step 3) in the method according to claim 1, with an acid, to obtain the 2-mercaptoethanol.

6. A method for preparing a thionocarbamate and co-producing O-alkylthioethyl xanthate, comprising: a thioalkylation reaction of the 2-hydroxyethyl thiolate obtained in step 3) in the method according to claim 1 with an alkyl halide having a structure shown in formula VI, to obtain a 2-alkylthioethanol having a structure shown in formula VII, and the 2-alkylthioethanol is reacted with carbon disulfide and an alkali to obtain the O-alkylthioethyl xanthate as shown in formula VIII; ##STR00009## wherein R.sup.1 is C.sub.1 to C.sub.8 alkyl and aryl, or alkylthioethyl as shown in formula V; X is Cl, Br or I; and M is a cation of the alkali, wherein the cation of the alkali is Na.sup.+ or K.sup.+; or NH.sub.4.sup.+.

7. The method according to claim 6, wherein the thioalkylation reaction is conducted at a temperature of 5-50 C. for a reaction time of 0.5-3 h, and the alkyl halide is added at an amount of 0.8-1.3 times a molar weight of the 2-hydroxyethyl thiolate.

8. The method according to claim 6, wherein to obtain the O-alkylthioethyl xanthate, the 2-alkylthioethanol is reacted with the carbon disulfide and the alkali at a temperature of 10-40 C. for a reaction time of 1-6 h, and a molar ratio of 1.0:(1.0-5.0):(0.9-1.2) of the 2-alkylthioethanol to the carbon disulfide to the alkali.

9. An O-alkylthioethyl xanthate collector, wherein an O-alkylthioethyl xanthate has a structure shown in formula VIII and the O-alkylthioethyl xanthate is prepared in the method according to claim 6.

10. A method of using the O-alkylthioethyl xanthate collector according to claim 9, wherein the O-alkylthioethyl xanthate collector is used in flotation separation of nonferrous metal sulfide ores.

11. The method according to claim 5, wherein the 2-haloethanol is 2-chloroethanol or 2-bromoethanol; a molar ratio of the xanthate to the 2-haloethanol is 1.0:(0.9-1.2); a solvent for the esterification reaction is water used at an amount of 0-50 ml per 1 mol of the xanthate; the esterification reaction is conducted at a temperature of 20-100 C. for a reaction time of 1-8 h; and the 2-haloethanol is reacted with the xanthate at 20-30 C. for 1-2 h before the water is added to the esterification reaction at 20-100 C.

12. The method according to claim 5, wherein the aminolysis reaction in step 2 is conducted at a temperature of 30-100 C. for a reaction time of 1-6 h; and the fatty amine is added at an amount of 0.9-1.2 times a molar weight of the O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate.

13. The method according to claim 5, wherein in step 3), the mixture of the thionocarbamate and the 2-mercaptoethanol is washed 1-5 times with the alkali having a concentration of 0.1-5 mol/L.

14. The method according to claim 6, wherein the 2-haloethanol is 2-chloroethanol or 2-bromoethanol; a molar ratio of the xanthate to the 2-haloethanol is 1.0:(0.9-1.2); a solvent for the esterification reaction is water used at an amount of 0-50 ml per 1 mol of the xanthate; the esterification reaction is conducted at a temperature of 20-100 C. for a reaction time of 1-8 h; and the 2-haloethanol is reacted with the xanthate at 20-30 C. for 1-2 h before the water is added to the esterification reaction at 20-100 C.

15. The method according to claim 6, wherein the aminolysis reaction in step 2 is conducted at a temperature of 30-100 C. for a reaction time of 1-6 h; and the fatty amine is added at an amount of 0.9-1.2 times a molar weight of the O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate.

16. The method according to claim 6, wherein in step 3), the mixture of the thionocarbamate and the 2-mercaptoethanol is washed 1-5 times with the alkali having a concentration of 0.1-5 mol/L.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] FIG. 1 is a .sup.1H Nuclear Magnetic Resonance Spectrogram of O-isopropyl-S-hydroxyethyl xanthate;

[0059] FIG. 2 is a .sup.1H Nuclear Magnetic Resonance Spectrogram of O-isobutyl-S-hydroxyethyl xanthate;

[0060] FIG. 3 is a .sup.1H Nuclear Magnetic Resonance Spectrogram of hydroxyethyl benzyl sulfide;

[0061] FIG. 4 is a .sup.1H Nuclear Magnetic Resonance Spectrogram of O-benzylthio ethyl xanthate;

[0062] FIG. 5 is a hydrogen-spectrogram of O-isopropyl-N-ethylthiocarbamate;

[0063] FIG. 6 is an infrared spectrogram of O-isopropyl-S-hydroxyethyl xanthate;

[0064] FIG. 7 is an infrared spectrogram of O-isobutyl-S-hydroxyethyl xanthate;

[0065] FIG. 8 is an infrared spectrogram of O-benzylthioethyl xanthate;

[0066] FIG. 9 is an infrared spectrogram of O-isopropyl-N-ethylthiocarbamate;

[0067] FIG. 10 is a gas chromatography-mass spectrometry spectrogram of hydroxyethyl benzyl sulfide; and

[0068] FIG. 11 is a process flow diagram of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0069] The present invention is further illustrated by, but not limited to, the following examples. All parts and percentages in the examples refer to mass, unless otherwise specified.

Example 1: Preparation of O-isopropyl-S-hydroxyethyl xanthate

[0070] 8.13 parts of 2-chloroethanol with the purity of 99% are added into a reactor, 18.9 parts of sodium isopropyl xanthate with the purity of 83.54% are added in batches while stirring is conducted, then 15 parts of distilled water are added, the temperature is increased until the temperature in the reactor reaches 60 C., the mixture is cooled to the room temperature after a constant-temperature reaction is conducted for 5 h, liquid separation is conducted to obtain an oil phase O-isopropyl-S-hydroxyethyl xanthate, and analysis shows that the yield of the O-isopropyl-S-hydroxyethyl xanthate is 88.3%. The product is characterized after being purified by column chromatography, .sup.1H NMR of the O-isopropyl-S-hydroxyethyl xanthate is shown in FIG. 1, and an infrared spectrogram is shown in FIG. 6.

Example 2: Preparation of O-isobutyl-S-hydroxyethyl xanthate

[0071] 8.13 parts of 2-chloroethanol with the purity of 99% are added into a reactor, 19.32 parts of sodium isobutyl xanthate with the purity of 89.0% are added in batches while stirring is conducted, then 15 parts of distilled water are added, the temperature is increased until the temperature in the reactor reaches 50 C., the mixture is cooled to the room temperature after a constant-temperature reaction is conducted for 7 h, liquid separation is conducted to obtain an oil phase O-isobutyl-S-hydroxyethyl xanthate, and analysis shows that the yield of the O-isobutyl-S-hydroxyethyl xanthate is 78.2%. The product is characterized after being purified by column chromatography, H NMR of the O-isobutyl-S-hydroxyethyl xanthate is shown in FIG. 2, and an infrared spectrogram is shown in FIG. 7.

Example 3: Preparation of O-isopropyl-N-ethylthiocarbamate and 2-mercaptoethanol

[0072] The oil phase obtained in example 1 is transferred into a reactor, 7 parts of ethylamine aqueous solution (the content is 65-70%) are added into a constant-pressure dropping funnel at the temperature of 20 C. or below, the temperature is raised to be 70 C., reaction lasts for 1 hour, the product is cooled to room temperature, reaction liquid is washed with 50 parts of a sodium hydroxide solution with the concentration of 8.3%, and liquid separation is carried out to obtain an oil phase which is O-isopropyl-N-ethylthiocarbamate with the purity of 96.7%, the yield based on the O-isopropyl-S-hydroxyethyl xanthate is 85.7%, the aqueous phase is sodium 2-hydroxyethyl thiolate, the purity is 28.097%, the yield based on the O-isopropyl-S-hydroxyethyl xanthate is 98.1%, 50 parts of a hydrochloric acid solution with the concentration of 10.95% are added into the aqueous phase, and acidifying is carried out at normal temperature for 2 h to obtain a 2-mercaptoethanol product with the yield of 92.34%. The product is characterized after being purified by column chromatography, .sup.1H NMR of the O-isopropyl-N-ethylthiocarbamate is shown in FIG. 5, and an infrared spectrogram is shown in FIG. 9.

Example 4: Preparation of O-isobutyl-N-ethylthiocarbamate and 2-mercaptoethanol

[0073] The oil phase obtained in example 2 is transferred into a reactor, 7 parts of ethylamine aqueous solution (the content is 65-70%) are added into a constant-pressure dropping funnel at the temperature of 20 C. or below, the temperature is raised to 70 C., the reaction lasts for 1 hour, the reaction product is cooled to room temperature, reaction liquid is washed with 50 parts of sodium hydroxide solution with the concentration of 8.3%, liquid separation is carried out to obtain an oil phase which is O-isobutyl-N-ethylthiocarbamate with the purity of 95.3%, the yield based on O-isobutyl-S-hydroxyethyl xanthate is 82.7%, the aqueous phase is sodium hydroxyethyl thiolate with the purity of 27.97%, and the yield based on O-isopropyl-S-hydroxyethyl xanthate is 97.9%. 50 parts of hydrochloric acid solution with the concentration of 10.95% are added into the aqueous phase, and acidifying is carried out at normal temperature for 2 h to obtain the 2-mercaptoethanol product with the yield of 90.34%.

Example 5: Preparation of Hydroxyethyl Benzyl Sulfide

[0074] 12.78 parts of benzyl chloride are added into 50 mL of aqueous solution containing 10.0 parts of sodium 2-hydroxyethyl thiolate, and the mixture reacts for 1 h at 10 C. to obtain an oil phase which is the hydroxyethyl benzyl sulfide with the purity of 89.97% and the yield of 96.5% based on the sodium 2-hydroxyethyl thiolate. The product is characterized after extraction, water washing and then purification, and .sup.1H NMR of the hydroxyethyl benzyl sulfide is shown in FIG. 3, and a gas chromatography-mass spectrometry spectrogram is shown in FIG. 10.

Example 6: Preparation of O-benzylthio ethyl xanthate

[0075] 18.67 parts of hydroxyethyl benzyl sulfide with the purity of 89.97% is transferred into a three-necked flask, 27.7 parts of carbon disulfide with the purity of 99% and 4.17 parts of sodium hydroxide with the purity of 96% are added into the three-necked flask, the reaction temperature is controlled at 25 C., and the reaction time is controlled to be 3 hours to obtain the O-benzylthio ethyl xanthate with the purity of 94.3% and the yield of 99.1% based on the hydroxyethyl benzyl sulfide. .sup.1H NMR of the O-benzylthio ethyl xanthate after petroleum ether/acetone purification of the product is completed is shown in FIG. 4, and an infrared spectrogram is shown in FIG. 8.

[0076] .sup.1H Nuclear Magnetic Resonance Spectrograms of parts of the foregoing prepared target products are shown in Table 1.

TABLE-US-00001 TABLE 1 Analysis of 1H Nuclear Magnetic Resonance Spectrogram Compound H-NMR/ O-isopropyl-S- : 1.33(6H, CH.sub.3); 1.70(1H, OH); hydroxyethyl 3.28(2H, CH.sub.2); 3.82(2H, CH.sub.2); xanthate (CDCl.sub.3) 5.70(1H, CH). O-isobutyl-S- : 0.95(6H, CH.sub.3); 2.09(1H, CH); hydroxyethyl xanthate 3.22(2H, CH.sub.2); 3.62(2H, CH.sub.2); (deuterated DMSO) 4 36(2H, CH.sub.2); 5.08(1H, OH). Hydroxyethyl benzyl : 2.46(2H, CH.sub.2); 3.50(2H, CH.sub.2); sulfide (deuterated 3.74(2H, CH.sub.2); 4.78(1H, OH); DMSO) 7.31(5H, C.sub.6H.sub.5). O-benzylthio ethyl : 2.62(2H, CH.sub.2); 3.82(2H, CH.sub.2); xanthate (deuterated 4.37(2H, CH.sub.2); 7.32(5H, C.sub.6H.sub.5). DMSO) O-isopropyl-N- : 1.23(6H, CH.sub.3); 1.30(3H, CH.sub.3); ethylcarbamate 3.47(2H, CH.sub.2); 3.76(1H, NH); (CDCl.sub.3) 5.46(1H, CH)

[0077] Infrared analysis of parts of the foregoing prepared target products is shown in Table 2.

TABLE-US-00002 TABLE 2 Infrared analysis of target products Compound Peak shift and possible attribution O-isopropyl-S- 3363 cm.sup.1 is OH stretching vibration; hydroxyethyl 2985 cm.sup.1 and 2872 cm.sup.1 are CH.sub.3 stretching xanthate vibration; 2928 cm.sup.1 is CH.sub.2 stretching vibration; 1234 cm.sup.1 is COC stretching vibration; 1042 cm.sup.1 is CS stretching vibration; and 934 cm.sup.1 is CS stretching vibration. O-isobutyl-S- 3360 cm.sup.1 is OH stretching vibration; hydroxyethyl 2963 cm.sup.1 and 2875 cm.sup.1 are CH.sub.3 stretching xanthate vibration; 2934 cm.sup.1 is CH.sub.2 stretching vibration; 1221 cm.sup.1 is COC stretching vibration; 1061 cm.sup.1 is CS stretching vibration; and 929 cm.sup.1 is CS stretching vibration. O-benzylthio 3063 cm.sup.1 and 3032 cm.sup.1 are stretching ethyl xanthate vibration of CCH on a benzene ring; 2947 cm.sup.3 is CH.sub.2 stretching vibration; 1493 cm.sup.1 and 1452 cm.sup.1 are benzezne ring skeleton stretching vibration; 1229 cm.sup.1 is COC stretching vibration; 1073 cm.sup.1 is CS stretching vibration; 939 cm.sup.1 is CS stretching vibration; and 764 cm.sup.1, 702 cm.sup.1 and 642 cm.sup.1 are benzene ring bending vibration. O-isopropyl-N- 3265 cm.sup.1 is NH stretching vibration; ethylthiocarbamate 2982 cm.sup.1 and 2877 cm.sup.1 are CH.sub.3 stretching vibration; 2928 cm.sup.1 is CH.sub.2 stretching vibration; 1530 cm.sup.1 is CN stretching vibration; 1220 cm.sup.1 is COC stretching vibration; 1053 cm.sup.1 is CS stretching vibration; and 908 cm.sup.3 is CS stretching vibration.

Example 7: Flotation of Chalcopyrite by O-isopropyl-S-hydroxyethyl xanthate

[0078] When the concentration of O-isopropyl-S-hydroxyethyl xanthate is 14 mg/L, the pH value of ore pulp is 6.5, the amount of a foaming agent (MIBC) is 15 mg/L and the rotating speed is 1992 r/min, chalcopyrite with the granularity of minus 0.076 mm to plus 0.038 mm is floated for 5 minutes, and the flotation recovery of the chalcopyrite is 97.94%.

Example 8: Flotation of Pyrite by O-isopropyl-S-hydroxyethyl xanthate

[0079] When the concentration of the O-isopropyl-S-hydroxyethyl xanthate is 14 mg/L, the amount of a foaming agent (MIBC) is 15 mg/L and the rotating speed is 1992 r/min, pyrite with the granularity of minus 0.076 mm to plus 0.038 mm is floated for 5 minutes, the flotation recovery of the pyrite is 45.2% when the pH value of ore pulp is 2.0, and the flotation recovery of the pyrite is 15.3% when the pH value of the ore pulp is 6.5.

Example 9: Flotation of Chalcopyrite by O-benzylthio ethyl xanthate

[0080] When the concentration of O-benzylthio ethyl xanthate is 5.3 mg/L, the amount of a foaming agent (MIBC) is 15 mg/L and the rotating speed is 1992 r/min, chalcopyrite with the granularity of minus 0.076 mm to plus 0.038 mm is floated for 5 minutes, and when the pH of ore pulp is 8.0, the flotation recovery of the chalcopyrite is 97.2%.

Example 10: Flotation Experiment of Porphyry Copper-Molybdenum Ores

[0081] A certain copper sulfide ore sample in Shangri-La contains 0.53% of copper, and the main copper ore is chalcopyrite.

[0082] When the grinding fineness of minus 200 meshes accounts for 64.5%, the use amount of roughing lime is 600 g/t, and the pH value of ore pulp is about 8.0; after a process of one-time roughing and one-time scavenging, the flotation result of the copper by butyl xanthate and the O-isopropyl-S-hydroxyethyl xanthate is shown in table 3, and the flotation result shows that the O-isopropyl-S-hydroxyethyl xanthate can achieve a comparable copper recovery rate under the condition of less use amount compared with the butyl xanthate. If the butyl xanthate is used in combination with the O-isopropyl-S-hydroxyethyl xanthate without MIBC, the copper recovery rate is greatly improved compared to the two reagents used alone.

TABLE-US-00003 TABLE 3 Copper ore flotation experimental conditions and results Cu Cu Yield grade recovery Reagent conditions (g/t) Product (%) (%) rate (%) Roughing: butyl xanthate Rough 3.93 11.35 83.59 50, MIBC 12; Scavenging: concentrate butyl xanthate 15, MIBC 4 Middlings 2.54 1.35 6.43 Tailings 93.53 0.057 9.98 Raw ore 100 0.53 100.00 Roughing: O-isopropyl-S- Rough 7.74 5.95 83.37 hydroxyethyl xanthate 32, concentrate MIBC 12; Scavenging: O- Middlings 3.67 1.03 6.84 isopropyl-S-hydroxyethyl Tailings 85.59 0.061 9.79 xanthate 8. Raw ore 100 0.53 100.00 Roughing: O-isopropyl-S- Rough 7.24 6.29 88.96 hydroxyethyl xanthate 16, concentrate butyl xanthate 30; Middlings 1.33 1.00 2.62 Scavenging: butyl xanthate Tailings 91.43 0.047 8.42 15 Raw ore 100 0.53 100.00

[0083] In the present invention, xanthate and 2-haloethanol are taken as initial raw materials to obtain the high-purity thionocarbamate, and meanwhile, the flotation collectors of O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate and O-alkylthioethyl xanthate are co-produced. By comparison of flotation examples, it is found that O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate has a higher flotation effect, a comparable flotation recovery rate can be achieved with a lower use amount of O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate than conventional flotation for copper sulphide ores by the butyl xanthate, and the flotation recovery can be greatly increased when the butyl xanthate is used in combination with the O-alkyl/alkylthioethyl-S-hydroxyethyl xanthate. In the present invention, a plurality of products with high added values can be obtained by one process.