Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C327/00—Thiocarboxylic acids
  • C07C327/02—Monothiocarboxylic acids
  • C07C327/04—Monothiocarboxylic acids having carbon atoms of thiocarboxyl groups bound to hydrogen atoms or to acyclic carbon atoms
  • C07C327/06—Monothiocarboxylic acids having carbon atoms of thiocarboxyl groups bound to hydrogen atoms or to acyclic carbon atoms to hydrogen atoms or to carbon atoms of an acyclic saturated carbon skeleton

Definitions

• the invention relates to a process for the preparation of thioacetic acid and its salts.
• Thioacetic acid and its salts are important industrial starting materials and are used, for example, for the production of D-acetylthioisobutyric acid or pharmaceutical active ingredients such as captopril (ACE inhibitor against high blood pressure, JP-A-09-295963) and for the synthesis of biotin (DE-A-2807200) , Potassium thioacetate is used, for example, in the production of testosterone derivatives (DE-A-19860917).
• Known processes for the synthesis of thioacetic acid are based, for example, on acetic anhydride, which is reacted with hydrogen sulfide (OA-A-2110) or metal hydrogen sulfide (US-A-2568020) to give the desired product.
• OA-A-2110 hydrogen sulfide
• US-A-2568020 metal hydrogen sulfide
• Another method is based on ketene, which with hydrogen sulfide in the gas phase and in the presence of a solid, aluminum-containing catalyst, at 10 to 204.4 ° C (50 to 400 ° F), preferably at 65.6 to 176.7 ° C (150 to 350 ° F) is converted to thioacetic acid or diacetyl sulfide (US-A-2639293).
• a common process for the preparation of alkali metal thiocarboxylates is based on thiocarboxylic acids, which are converted into the corresponding salts, for example by means of alkali metal hydrides (Kato, S. et al., Z Naturforsch. 1983, 38B (12), 1585-1590).
• the object of the present invention was therefore to provide a simple process for the direct production of thioacetic acid and its salts, which can also be operated in a "one-pot process", works inexpensively, uses easily accessible starting materials and provides little waste and by-products.
• this object is achieved by the method according to claim 1. It has been found that in the presence of a nitrogen base, ketene is directly substance or a dissolved alkali metal bisulfide can be implemented. Depending on requirements, the thioacetic acid or subsequent addition of ammonia, an alkali metal or alkaline earth metal, aluminum or titanium base, the corresponding salt thereof can be obtained directly in good yield and high purity by subsequent distillation. The formation of the thioacetic acid with subsequent salt formation can be particularly preferred as
• M " + is ammonium or an alkali metal, alkaline earth metal, aluminum or titanium cation selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, barium, aluminum and titanium, and wherein n is the number of positive charges of the Is cation, ketene is reacted in the presence of a nitrogen base with hydrogen sulfide or a dissolved alkahmetal hydrogen sulfide and, if appropriate, subsequently the thioacetic acid obtained is reacted with ammonia or an alkali metal, alkaline earth metal, aluminum or titanium base to give the corresponding salt.
• Alkali metal hydrogen sulfides are to be understood here and below in particular as the hydrogen sulfides of lithium, sodium and potassium.
• Alkali metal or alkaline earth metal, aluminum or titanium bases include here and below in particular hydroxides, carbonates, hydrogen carbonates, alcoholates, phenolates, Carboxylates, oxides, hydrides, sulfonates, phosphates, sulfides, sulfmates, oxalates, hexafluorophosphates and tetrafluoroborates of lithium, sodium, potassium, magnesium, calcium, barium, aluminum and titanium are to be understood.
• Alcoholates and phenolates of alkali metals, alkaline earth metals, aluminum and titanium are to be understood here and below in particular the compounds of the formula R * O _ • ⁇ M " + , where R 1 is a C 1-4 alkyl or phenyl radical and M" + Alkali metal cation, preferably Li + , Na + or K + , an alkaline earth metal cation, preferably Mg 2+ , Ca 2+ or Ba, an aluminum cation or a titanium cation, and where n is the number of positive charges of the cation.
• Carboxylates of alkali metals, alkaline earth metals, aluminum and titanium are to be understood here and below in particular to mean compounds of the formula R 2 COO ⁇ • - -M " + , where R is an optionally partially or completely halogenated C 6 alkyl or phenyl radical and M "* an alkali metal cation, preferably Li + , Na + or K +
• Alkaline earth metal cation preferably Mg 2+ , Ca 2+ or Ba 2+ , an aluminum cation or a titanium cation, and wherein n is the number of positive charges of the cation.
• nitrogen bases are to be understood in particular as meaning nitrogen-containing compounds which have a pK a of> 7, such as, for example, primary, secondary and tertiary alkylamines such as, for example, di-tert-butylamine, trimethylamine and triethylamine, primary, secondary and tertiary arylamines, cyclic amines such as piperidine, pyrrolidine or morpholine, aromatic nitrogen heterocycles such as pyridine or substituted pyridines such as 4-dimethylaminopyridine, ammonia, guanidines, bicyclic nitrogen compounds such as 1,4-diazabicyclo [2.2.2] octane
• primary, secondary and tertiary alkylamines such as, for example, di-tert-butylamine, trimethylamine and triethylamine
• primary, secondary and tertiary arylamines cyclic amines such as piperidine, pyrrolidine or morpholine
• DBU 5-diazabicyclo [4.3.0] non-5-ene
• DBU 1,8-diazabicyclo [5.4.0] undecene
• basic nitrogen-containing ion exchanger for example, under the name of Lewatit ® , Duolite ® and Dowex ® are available.
• the task of the nitrogen base is to activate the H 2 S.
• M n + is selected from the group consisting of Li + , Na + , K + , Mg 2+ , Ca 2+ and Ba 2+ .
• the reaction of ketene with hydrogen sulfide or a dissolved alkali metal hydrogen sulfide is carried out in a polar solvent.
• a C 1 - alcohol, water, diethyl ether, tetrahydrofuran, dichloromethane, pyridine, methyl pyridine or dimethyl formamide is used as the polar solvent.
• a C 1 alcohol or water is used as the polar solvent.
• 1-butanol is used as the polar solvent for the production of potassium or sodium thioacetate, in which potassium and sodium thioacetate crystallize particularly well.
• ketene in a special process variant, can be reacted in aqueous solution with an alkali metal hydrogen sulfide solution, optionally with the addition of gaseous hydrogen sulfide.
• hydrogen sulfide and ketene or alkali metal hydrogen sulfide and ketene are advantageously used in a molar ratio between 0.5: 1 and 2: 1.
• a molar hydrogen sulfide: ketene ratio or alkali metal hydrogen sulfide: ketene ratio between 0.8: 1 and 1.3: 1 is used.
• a molar hydrogen sulfide: ketene ratio or alkali metal hydrogen sulfide: ketene ratio of 1: 1 is used.
• a molar ketene: nitrogen base ratio between 1: 0.001 and 1: 0.5 is used in the process according to the invention.
• a molar ketene: nitrogen base ratio between 1: 0.001 and 1: 0.1 is used in the process according to the invention.
• the reaction of ketene with hydrogen sulfide is carried out at temperatures between +60 and -40 ° C, particularly preferably between +10 and -20 ° C.
• Alkali metal, alkaline earth metal, aluminum or titanium bases can be used in the process according to the invention for the formation of the salts of thioacetic acid.
• Preferred alkali metal or alkaline earth metal, aluminum or titanium bases are hydroxides, carbonates, bicarbonates, alcoholates, phenates, carboxylates, oxides, hydrides, sulfonates, phosphates, sulfides, sulfinates, oxalates, hexafluorophosphates or tetrafluoroborates of lithium, sodium , Potassium, magnesium, calcium, barium, aluminum or titanium are used.
• the metal thioacetate obtained can optionally be separated from the corresponding acid of the metal base used by filtration, and depending on the solubility the metal thioacetate or the corresponding acid can be dissolved.
• a hydroxide, alcoholate, phenolate or carboxylate of lithium, sodium or potassium is used for salt formation.
• the alkali metal, alkaline earth metal, aluminum or titanium base can be added as a solid or as an aqueous solution and / or suspension.
• the reaction with the alkali metal or alkaline earth metal, aluminum or titanium base can be carried out at temperatures from -20 to +100 ° C, particularly preferably at temperatures from -10 to +10 ° C.
• the salt formation can be carried out as a “one-pot process” without prior isolation of the thioacetic acid.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
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• 2004
  • 2004-03-02 US US10/546,651 patent/US20080161597A1/en not_active Abandoned
  • 2004-03-02 CN CNB2004800057432A patent/CN1314668C/zh not_active Expired - Fee Related
  • 2004-03-02 JP JP2006504506A patent/JP2006519242A/ja not_active Withdrawn
  • 2004-03-02 CA CA002517703A patent/CA2517703A1/en not_active Abandoned
  • 2004-03-02 EA EA200501361A patent/EA008941B1/ru unknown
  • 2004-03-02 EP EP04716226A patent/EP1601645A1/de not_active Withdrawn
  • 2004-03-02 WO PCT/EP2004/002089 patent/WO2004078706A1/de not_active Ceased

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