MXPA00001452A - Approachto the conversion of 2-(methylthio)-5-(trifluoromethyl)-1,3,4-thiadiazole (tda) to 2-(methylsulfonyl)-5-(trifluoromethyl)-1,3,4-thiadiazole (tda sulfone) - Google Patents
Approachto the conversion of 2-(methylthio)-5-(trifluoromethyl)-1,3,4-thiadiazole (tda) to 2-(methylsulfonyl)-5-(trifluoromethyl)-1,3,4-thiadiazole (tda sulfone)Info
- Publication number
- MXPA00001452A MXPA00001452A MXPA/A/2000/001452A MXPA00001452A MXPA00001452A MX PA00001452 A MXPA00001452 A MX PA00001452A MX PA00001452 A MXPA00001452 A MX PA00001452A MX PA00001452 A MXPA00001452 A MX PA00001452A
- Authority
- MX
- Mexico
- Prior art keywords
- thiadiazole
- trifluoromethyl
- methylthio
- tda
- acetic acid
- Prior art date
Links
- ULROOIOMHZXHRY-UHFFFAOYSA-N 2-methylsulfanyl-5-(trifluoromethyl)-1,3,4-thiadiazole Chemical compound CSC1=NN=C(C(F)(F)F)S1 ULROOIOMHZXHRY-UHFFFAOYSA-N 0.000 title claims abstract description 21
- SQLPTSMJAQPVKR-UHFFFAOYSA-N 2-methylsulfonyl-5-(trifluoromethyl)-1,3,4-thiadiazole Chemical compound CS(=O)(=O)C1=NN=C(C(F)(F)F)S1 SQLPTSMJAQPVKR-UHFFFAOYSA-N 0.000 title claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 title claims description 8
- 150000003457 sulfones Chemical class 0.000 title description 19
- MHAJPDPJQMAIIY-UHFFFAOYSA-N hydrogen peroxide Chemical group OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 35
- QTBSBXVTEAMEQO-UHFFFAOYSA-N acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229960000583 Acetic Acid Drugs 0.000 claims abstract description 25
- 239000012362 glacial acetic acid Substances 0.000 claims abstract description 21
- KGBXLFKZBHKPEV-UHFFFAOYSA-N Boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000004327 boric acid Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 18
- 230000003647 oxidation Effects 0.000 claims abstract description 15
- 239000007800 oxidant agent Substances 0.000 claims abstract description 11
- -1 thiadiazole sulfones Chemical class 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N toluene Substances CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 21
- 239000002904 solvent Substances 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000007795 chemical reaction product Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 230000001590 oxidative Effects 0.000 claims description 5
- 125000002816 methylsulfanyl group Chemical group [H]C([H])([H])S[*] 0.000 claims description 4
- 125000003944 tolyl group Chemical group 0.000 claims description 3
- 125000002023 trifluoromethyl group Chemical group FC(F)(F)* 0.000 claims description 3
- 239000000010 aprotic solvent Substances 0.000 claims description 2
- 125000003118 aryl group Chemical group 0.000 claims description 2
- 238000010533 azeotropic distillation Methods 0.000 claims description 2
- 238000002955 isolation Methods 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 abstract description 6
- 230000003197 catalytic Effects 0.000 abstract description 4
- 239000011541 reaction mixture Substances 0.000 description 13
- DTQVDTLACAAQTR-UHFFFAOYSA-N trifluoroacetic acid Chemical compound OC(=O)C(F)(F)F DTQVDTLACAAQTR-UHFFFAOYSA-N 0.000 description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N methylene dichloride Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 4
- 238000007792 addition Methods 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- VZJVWSHVAAUDKD-UHFFFAOYSA-N Potassium permanganate Chemical compound [K+].[O-][Mn](=O)(=O)=O VZJVWSHVAAUDKD-UHFFFAOYSA-N 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000005712 crystallization Effects 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000002194 synthesizing Effects 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- IUVACELPFXBLHY-UHFFFAOYSA-N 2,5-bis(methylsulfanyl)-1,3,4-thiadiazole Chemical compound CSC1=NN=C(SC)S1 IUVACELPFXBLHY-UHFFFAOYSA-N 0.000 description 1
- WETWJCDKMRHUPV-UHFFFAOYSA-N Acetyl chloride Chemical compound CC(Cl)=O WETWJCDKMRHUPV-UHFFFAOYSA-N 0.000 description 1
- MQJKPEGWNLWLTK-UHFFFAOYSA-N Di(p-aminophenyl)sulphone Chemical compound C1=CC(N)=CC=C1S(=O)(=O)C1=CC=C(N)C=C1 MQJKPEGWNLWLTK-UHFFFAOYSA-N 0.000 description 1
- VLAPMBHFAWRUQP-UHFFFAOYSA-L Molybdic acid Chemical compound O[Mo](O)(=O)=O VLAPMBHFAWRUQP-UHFFFAOYSA-L 0.000 description 1
- 102000014961 Protein Precursors Human genes 0.000 description 1
- 108010078762 Protein Precursors Proteins 0.000 description 1
- CMPGARWFYBADJI-UHFFFAOYSA-L Tungstic acid Chemical compound O[W](O)(=O)=O CMPGARWFYBADJI-UHFFFAOYSA-L 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating Effects 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 125000004390 alkyl sulfonyl group Chemical group 0.000 description 1
- 230000000843 anti-fungal Effects 0.000 description 1
- 239000003849 aromatic solvent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 125000002534 ethynyl group Chemical class [H]C#C* 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000002363 herbicidal Effects 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- AUHZEENZYGFFBQ-UHFFFAOYSA-N mesitylene Substances CC1=CC(C)=CC(C)=C1 AUHZEENZYGFFBQ-UHFFFAOYSA-N 0.000 description 1
- 125000001827 mesitylenyl group Chemical group [H]C1=C(C(*)=C(C([H])=C1C([H])([H])[H])C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- 125000004170 methylsulfonyl group Chemical group [H]C([H])([H])S(*)(=O)=O 0.000 description 1
- 150000002751 molybdenum Chemical class 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N o-xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 150000004291 polyenes Polymers 0.000 description 1
- OZAIFHULBGXAKX-UHFFFAOYSA-N precursor Substances N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- BUUPQKDIAURBJP-UHFFFAOYSA-M sulfinate Chemical class [O-]S=O BUUPQKDIAURBJP-UHFFFAOYSA-M 0.000 description 1
- 150000003455 sulfinic acids Chemical class 0.000 description 1
- 150000003461 sulfonyl halides Chemical class 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 150000003657 tungsten Chemical class 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Abstract
The present invention provides a process for making thiadiazole sulfones. In particular, the present process is used to make 2-(methyl-sulfonyl)-5-(trifluoromethyl)-1,3,4-thiadiazole using catalytic oxidation in the presence of a suitable oxidizing agent. A preferred oxidizing agent is hydrogen peroxide. The catalyst system used for the oxidation reaction is a mixture of boric acid and glacial acetic acid. The molar ratio of glacial acetic acid to 2-(methylthio)-5-(trifluoromethyl)-1,3,4-thiadiazole is from about 0.1:1 to about 0.5:1.
Description
A NEW APPROXIMATION TO THE CONVERSION OF 2- (METHYLTHY) -5- (TRIFLUOROMETHYL) -1, 3, 4-TIADIAZOL (TDA) IN 2- (METILSULFONIL) -5- (TRIFLUOROMETHYL) -1,3, 4-TIADIAZOL ( TDA SULFONA)
TECHNICAL FIELD OF THE INVENTION
The field of the present invention is the synthesis of thiadiazole sulfones. More specifically, the present invention relates to an improved process for converting 2- (methylthio) -5- (trifluoromethyl) -1,4,4-thiadiazole (TDA) to 2- (methylsulfonyl) -5- (trifluoromethyl) -1, 3, 4-thiadiazole (TDA sulfone) by means of catalytic oxidation.
BACKGROUND OF THE INVENTION
The sulfones have the general structure RR'S02. The sulfones can be produced from a variety of precursors. For example, sulfones can be prepared by (a) oxidation of sulfides, (b) rearrangement of sulfinate esters, (c) addition of sulfonyl halides to alkenes and acetylenes, (d) addition of sulfinic acids to polarized bonds and (e) addition of S02 to polyenes (see, for example, Durst, T., in Comprehensive Organic Chemistry: Chapter 11.6, Barton and Ollis, Eds., Pergamon Press, Oxford, 1979). A particular class of sulfones, 2- (alkylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazoles, are intermediates used in the production of herbicides. A particular sulfone within this class, 2- (methylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazole, has been described as having antifungal activity (see US Patent 3,562,284). According to U.S. Pat. 3,562,284, 2- (sulfonyl-substituted) -5- (trifluoromethyl) -1,3,4-thiadiazoles can be prepared by oxidation of a corresponding 2- (substituted tio) -5- (trifluoromethyl) -1,3 , 4-thiadiazole in the presence of an oxidizing agent, such as potassium permanganate, hydrogen peroxide or peroxytrifluoroacetic acid. The oxidation takes place in an acidic aqueous medium, which includes acetic acid and methylene chloride, as a solvent. Methylene chloride is an undesirable solvent from the point of view of industrial hygiene and handling. Handling is difficult due to its low boiling point (high vapor pressure). In addition, it contaminates the aqueous streams. The sulfone product is isolated using crystallization. There is talk of a sulfone yield, based on the starting sulphide, of about 65%. In this known process, the use of acetic acid in the presence of water introduces an excess of water into the reaction and requires purification of the sulfone using expensive crystallization processes, with the result of low yields. Thus, there continues to be a need in the art for a practical method that is inexpensive to prepare thiadiazole sulfones in high yield.
COMPENDIUM OF THE INVENTION
The present invention provides a process for preparing 2- (methylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazole, consisting of oxidizing 2- (methylthio) -5- (trifluoromethyl) -1, 3, 4 -thiadiazole in a reaction mixture containing boric acid and glacial acetic acid, to form a reaction product containing the sulfone. In one embodiment of this invention, hydrogen peroxide is a preferred oxidizing agent. According to this embodiment, 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole reacts with hydrogen peroxide in the presence of boric acid and glacial acetic acid. The hydrogen peroxide used in the reaction mixture is preferably an aqueous solution containing from about 30 weight percent to about 50 weight percent hydrogen peroxide. The hydrogen peroxide is present in a molar excess relative to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadia-zol. Preferably, the molar ratio of hydrogen peroxide to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 2.0: 1 to about 3.0: 1. Even more preferably, the molar ratio is from about 2.05: 1 to about 2, 5: 1. The boric acid is present in an amount of about 0.1 moles to about 0.5 moles of boric acid per mole of 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole. Preferably, the mole ratio of boric acid to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 0.2: 1 to about 0.3: 1. Glacial acetic acid is present in an amount of about 0.1 moles to about 0.5 moles of acetic acid per mole of 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole. In a preferred embodiment, the molar ratio of glacial acetic acid to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 0.2: 1 to about 0.3: 1. The oxidation typically takes place at a temperature of about 60 ° C to about 110 ° C and, preferably, at a temperature of about 70 ° C to about 100 ° C. The method of the present invention may include additional steps. Sulfuric acid can be added to the reaction mixture to acidify the mixture. In addition, water can be removed from the reaction product. The removal of water is preferably performed azeotropically. Still further, an embodiment of this invention may include the step of isolating the 2- (methylsulfonyl) -5- (trifluoromethyl) -1,4,4-thiadiazole product. After completion of the reaction, an aqueous phase and an organic phase are formed. The aqueous phase does not contain solids, only a solution of boric acid and acetic acid in water. The 2- (methylsulfonyl) -5- (trifluoromethyl) -1,4,4-thiadiazole is contained in the organic phase of the reaction mixture. In Patent Application No. 08 / 989,568, a process for preparing 2- (methylsulfo-nyl) -5- (trifluoromethyl) -1,3,4-thiadiazole by oxidizing 2- (methylthio) -5- ( trifluoromethyl) -1,4,4-thiadiazole in a reaction mixture containing an activated molybdenum or tungsten catalyst. The molybdenum or activated tungsten catalyst of the invention is molybdic acid or tungstic acid, respectively. The reaction of the process is carried out in the absence of glacial acetic acid. In Patent Application No. 08 / 989,594, a process for preparing 2- (methylsulfo-nyl) -5- (trifluoromethyl) -1,4,4-thiadiazole by oxidizing 2- (methylthio) -5- ( trifluoromethyl) -1,3,4-thiadiazole in the presence of a catalyst consisting of glacial acetic acid. In Patent Application No. (MD-98-10), a process for preparing 2- (methylsulfo-nyl) -5- (trifluoromethyl) -1,3,4-thiadiazole, consisting of oxidizing 2- (methylthio), is described. ) -5- (trifluoromethyl) -1,4,4-thiadiazole in a reaction mixture containing glacial acetic acid and a catalytic amount of a tungsten catalyst to form a reaction product containing the TDA sulfone.
DETAILED DESCRIPTION OF THE INVENTION The present invention provides a process for producing thiadiazole sulfones. The present process is used to prepare 2- (methylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazole (TDA sulfone) from 2- (methylthio) -5- (trifluoromethyl) -1, 3, 4 -thiadiazole (TDA). The TDA sulfone is prepared using catalytic oxidation of the TDA in the presence of a suitable oxidizing agent. The catalyst used for the oxidation reaction is a combination of boric acid and glacial acetic acid. The process of the invention includes the step of oxidation of 2- (methylthio) -5- (trifluoromethyl) -1,3-thiadiazole (TDA) in a reaction mixture containing boric acid and glacial acetic acid to form a product of reaction that contains the TDA sulfone. The oxidation of TDA takes place in the presence of a suitable oxidizing agent. Examples of such oxidation agents are well known in the art (see, for example, Durst, T., in Comprehensive Organic Chemistry: Chapter 11.6, Barton and Ollis, Eds., Pergamon Press, Oxford (1979). Preferred is hydrogen peroxide (H202) According to this embodiment, the TDA reacts with hydrogen peroxide in the presence of boric acid and glacial acetic acid The hydrogen peroxide used in the reaction mixture is preferably an aqueous solution containing about 30 weight percent to about 50 weight percent hydrogen peroxide The molar ratio of H2O2 to TDA is from about 2.0: 1 to about 3.0: 1 and, preferably, about 2.05 : 1 to about 2.5: 1 Oxidation conditions are well known in the art Typically, oxidation is carried out at a temperature of about 60 ° C to about 110 ° C and, preferably, at a temperature from about 70 ° C to about 100 ° C. The TDA used in the present procedure can be obtained from any source. Preferably, the TDA is prepared by a process that provides TDA in an aprotic aromatic solvent, such as toluene. Especially preferred means for preparing TDA can be found in US Patent Applications. Titrated "A Process for Making 2- (Methylthio) -5- (Trifluoromethyl) -1, 3, 4-Thiadiazole Using Methyldithiocarbazinate and Trifluoroacetic Acid" (Serial No. 08 / 989,152, filed 12/12/97) , "A Process for Making 2- (Methylthio) -5- (Trifluoromethyl) -1, 3, 4-Thiadiazole Using Methyldithiocarbazinate with Tri-Fluoroacetic Acid with Selective Removal of 2,5-Bis (Methylthio) -1, 3, 4 -Thiadiazole "(Serial No. 08 / 989,563, filed 12/12/97) and" A Process for Preparing 2- (Methylthio) -5- (Trifluoromethyl) -1, 3, 4-Thiadiazole Using Methyldithiocarbazinate and a Molar Excess of Trifluoroacetic Acid with Recovery of Trifluoroacetic Acid "(Serial No. 08 / 989,485, filed 12/12/98). The descriptions of the three applications are all here incorporated by way of reference. The oxidation of TDA occurs in the presence of a solvent. Preferably, the solvent is an aromatic aprotic solvent. Said solvents are well known in the art. Examples, and also preferred, of said solvents are toluene, xylene, eumeno and mesitylene. Toluene is especially preferred. The amount of solvent used can vary over a wide range, as will be readily determined by one skilled in the art. The precise amount of solvent will de-pend on the particular solvent used. When the solvent is toluene, it is present in an amount of about 0.5 moles to about 3.5 moles of toluene per mole of TDA. Preferably, the toluene is present in an amount of about 1.0 mole to about 2.0 mole per mole of TDA and, more preferably, in an amount of about 1.0 mole to about 1.5 mole of toluene per mole of TDA The TDA is oxidized in the reaction mixture containing boric acid and glacial acetic acid to form a reaction product containing TDA sulfone. The sources of TDA, the use of a solvent, the oxidation conditions and the choice of suitable oxidizing agents are the same as those indicated above. The oxidizing agent (e.g., hydrogen peroxide) used in the reaction mixture is preferably present in a molar excess relative to the TDA. Preferably, the molar ratio of oxidizing agent to TDA is from about 2.0: 1 to about 3.0: 1. Even more preferably, the ratio is from about 2.05: 1 to about 2.5: 1. Boric acid and glacial acetic acid are added directly to the reaction mixture. The boric acid is present in an amount of about 0.1 moles to about 0.5 moles of boric acid per mole of TDA. Preferably, the molar ratio of boric acid to TDA is from about 0.2: 1 to about 0.3: 1. Glacial acetic acid is present in an amount of about 0.1 moles to about 0.5 moles of acetic acid per mole of TDA. In a preferred embodiment, the molar ratio of glacial acetic acid to TDA is from about 0.2: 1 to about 0.3: 1. In one embodiment of the present invention, sulfuric acid in an amount less than or equal to about 0.5 moles may be added to the reaction mixture to acidify the mixture. In addition, water can be removed from the reaction product. Still further, a method of this invention may include the isolation step of the formed sulfone. The removal of water is preferably performed azeotropically. The azeotropic removal of water is easily carried out in the presence of the solvent, particularly when the solvent is toluene. Since the azeotrope has a boiling point lower than that of water, heating the reaction product to the boiling point of the solvent effectively removes the water. Because the oxidation reaction occurs in the range of about 60 ° C to about 110 ° C, the water is removed during that reaction; no additional stage is required. The following Example illustrates a preferred embodiment of the present invention and is not limiting of the specification or the claims.
EXAMPLE Synthesis of TDA sulfone using boric acid and glacial acetic acid Approximately 1.5 moles of TDA in toluene, approximately 30 grams (0.49 moles) of boric acid and about 40 grams (0.67 moles) were charged to a reactor vessel. of glacial acetic acid. The reaction mixture was then heated to a temperature of about 80 ° C and 3.65 moles of 35% hydrogen peroxide were added over a period of time of about 4 hours. The resulting mixture was then heated for a period of about 4 hours and water was removed azeotropically. The percent yield and the average purity percentage of the TDA sulfone were approximately 95.0% and 99.2%, respectively. Although the invention has been described in detail in the foregoing for illustrative purposes, it is to be understood that said detail has only those purposes and that those skilled in the art can make variations therein without departing from the spirit and scope of the invention, except in what may be limited by the claims.
Claims (14)
1. A process for preparing 2- (methylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazole, consisting of oxidizing 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole in a mixture of reaction containing an oxidizing agent, boric acid and glacial acetic acid to form a reaction product, wherein the molar ratio of glacial acetic acid to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is about 0.1: 1 to about 0.5: 1.
2. The process of Claim 1, wherein the molar ratio of boric acid to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 0.1: 1 to about 0.5: 1.
3. The method of Claim 1, wherein the oxidizing agent is hydrogen peroxide.
4. The process of Claim 1, wherein 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is dissolved in an aromatic aprotic solvent.
5. The process of Claim 4, wherein the solvent is toluene.
6. The process of Claim 5, wherein the molar ratio of toluene to 2- (methylthio) -5- (trifluoromethyl) -1,3-thiadiazole is from about 0.5: 1 to about 3.5: 1.
7. The process of Claim 6, wherein the molar ratio of toluene to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 1: 1 to about 1,5: 1.
8. The method of Claim 1, wherein the oxidation occurs at a temperature of about 60 ° C to approximately 110 ° C.
9. The method of Claim 8, wherein the temperature is from about 70 ° C to about 100 ° C.
10. The method of Claim 3, wherein the molar ratio of hydrogen peroxide to 2- (methylthio) -5- (trifluoromethyl) -1,4,4-thiadiazole is from about 2.0: 1 to about 3.0: 1. .
11. The method of Claim 10, wherein the molar ratio of hydrogen peroxide to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 2.05: 1 to about 2.50: 1. .
12. The method of Claim 1, wherein the molar ratio of glacial acetic acid to 2- (methylthio) -5- (trifluoromethyl) -1,3,4-thiadiazole is from about 0.2: 1 to about 0.3: 1 .
13. The method of Claim 1, further including the azeotropic removal of water from the reaction product.
14. The method of Claim 1, further including the isolation of 2- (methylsulfonyl) -5- (trifluoromethyl) -1,3,4-thiadiazole formed.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09251571 | 1999-02-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| MXPA00001452A true MXPA00001452A (en) | 2002-06-05 |
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