Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D333/00—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom
  • C07D333/02—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings
  • C07D333/04—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom
  • C07D333/06—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to the ring carbon atoms
  • C07D333/08—Hydrogen atoms or radicals containing only hydrogen and carbon atoms

Definitions

• the invention relates to a process for the preparation of 3- substituted thiophenes in which the substituent consists of a C 4 -C 18 alkyl group.
• 3-substituted thiophene is more difficult than the preparation of 2-substituted thiophene
• 3-substituted thiophene is a desirable intermediate or final product in various applications, for example as an herbicide or a fungicide.
• Certain 3 -substituted thiophenes can also be used as monomers in the preparation of, for example, electrically conductive polymers.
• 3-substituted thiophene can in principle be prepared in two different ways: by using as the initial material a thiophene or a thiophene provided with a modifiable 3 -substituent, or by using as the initial material an acyclic compound.
• Substituted thiophenes can, of course, also be prepared by other methods, but in that case the products are usually 2-substituted.
• 3-Bromothiophene can be prepared, for example according to EP publication 299 586, catalytically from 2,5-dibromothiophene and thiophene.
• 3-Bromothio- phene is one of the most important intermediates from which a wide variety of 3-substituted thiophenes are obtained, for example by means of Grignard reactions, by lithiation, or by oxidation.
• 3-bromothiophene as the initial material in a production process is, however, hampered by the undesirable bromides formed as byproducts and by the difficult reaction conditions, such as an unsuitable temperature and an inert atmosphere.
• the preparation of 3-substituted thiophenes by using an acyclic compound as the initial material has been studied extensively. These processes often have the disadvantage that they produce large amounts of 2-substituted thiophenes as byproducts.
• Some examples of these processes are the use of various mercaptans or thioethers as the initial material (Butler, A.R., Henry, J.B., J. Chem. Soc, B, 1970, or Campaigne, E., Monroe, P.A., J. Am.
• 3-substituted thiophene can also be prepared from other compounds which contain either double bonds or other functional groups (Veal, K.T., Grinter, T.J., EP 38121, or Duus, F., Tetrahedron, 32 (1976), 2817).
• the object the present invention is to provide a maximally selective process for the preparation of a 3-substituted C 4 - C 18 -alkylthiophene, the yield and the degree of purity being maximally high.
• the said objectives have now been achieved by process which is characterized in that the preparation is carried out by allowing an alkali metal salt of a C 4 -C 18 -alkylsuccinic acid to react with a compound of sulfur and phosphorus in an organic solvent at a temperature of 100-180 °C, the resulting product being 3-(C 4 -C 18 -alkyl) thiophene.
• the alkyl substituents are different from those in the present invention, in addition to which the reaction has been carried out within a temperature range of 225-300 °C, preferably at 250 °C, i.e. at a temperature substantially higher than in the present invention.
• the preparation of 3-substituted thiophene is carried out preferably by reacting first a C 4 -C 18 -alkylsuccinic acid anhydride with an alkali metal hydroxide to give the alkali metal salt of C 4 -C 18 -alkylsuccinic acid, and by reacting thereafter the said salt with a compound of sulfur and phosphorus so that the final product obtained will be a 3-(C 4 -C 18 -alkyl) thiophene.
• the initial material in the preparation of 3-substituted thiophene may be maleic acid anhydride, the process consisting of the following steps:
• the present process differs substantially from that disclosed in US publication 2,658,903, in which the preparation of 3- methylthiophene is started with the hydrogenation of the di- sodium salt of itaconic acid.
• the compound of sulfur and phosphorus used in the process according to the invention is preferably tetraphosphorus decasulfide, P 4 S 10 .
• a high yield has been achieved with a mixture of tetraphosphorus decasulfide and red phosphorus, the molar ratio of the components in the mixture being 1:4-1:6, suitably 1:5.3.
• the molar ratio of the active compound of sulfur and phosphorus to the alkali salt of alkylsuccinic acid is suitabl 0.5:1-2:1, most preferably approx. 0.5:1.
• organic solvent aliphatic or aromatic hydrocarbons or their mixtures, e.g. xylene, halogenated hydrocarbons, e.g. chloro- or dichlorobenzene, ethers, e.g. 2-ethoxyethyl ether, of mixtures of these.
• halogenated hydrocarbons e.g. chloro- or dichlorobenzene
• ethers e.g. 2-ethoxyethyl ether
• the reaction temperature is preferably within the range 130-180 °C.
• the reaction time may vary between 1 and 20 hours.
• the reaction may occur in a normal atmosphere or under slight overpressure in an argon or nitrogen blanket.
• the solid precipitate is first removed, for example, by filtration or centrifugation. Thereafter the solvent is removed by distillation, and ultimately the 3-(C 4 -C 18 -alkyl) thiophene obtained as the product is recovered by vacuum distillation. A washing or neutralization of the organic phase before the vacuum distillation is not necessary in the process of the invention.
• the octenylsuccinic acid anhydride was dissolved in ethyl acetate and was hydrogenated using a palladium/carbon catalyst (5% by weight of the initial material). The catalyst was filtered out, and the solvent was evaporated. The obtained yield of octylsuccinic acid was 24g (95% of the theoretical amount).
• Example 3 The procedure was as in Example 3, but dodecylsuccinic acid anhydride was used, which had been prepared by substantially the same procedure as used in Examples 1 and 2, and a
• octylsuccinic acid was 168.3g, which was 91% of the theoretical amount.
• the reaction mixture was treated by removing the inorganic precipitate by filtration.
• the precipitate was washed upon a filter with 600ml of MTBE, which was used in four 150ml
• the crude product was thereafter subjected to fractional distillation at a pressure of approx. 1.5mbar using the same fractional distillation column.
• the product obtained was 77.5g of 3-octylthiophene having a purity of 94.4%, which corresponded to a yield of 71.1% as calculated from the theoretical yield.
• Example 10-12 and 14-16 were the dipotassium salt and in Examples 13 and 17 the disodium salt of octylsuccinic acid (HASA).
• HASA octylsuccinic acid
• the solvent used was o-dichlorobenzene (o-DCB), 2-ethoxyethyl ether, or products LI 200 and SOLVESSO 100.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 1991
  • 1991-12-09 FI FI915785A patent/FI93110C/fi not_active IP Right Cessation
• 1992
  • 1992-12-08 EP EP92924743A patent/EP0642505A1/en not_active Withdrawn
  • 1992-12-08 US US08/244,379 patent/US5512685A/en not_active Expired - Fee Related
  • 1992-12-08 WO PCT/FI1992/000333 patent/WO1993012106A1/en not_active Application Discontinuation

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