Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
  • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
  • C07C21/19—Halogenated dienes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/35—Preparation of halogenated hydrocarbons by reactions not affecting the number of carbon or of halogen atoms in the reaction
  • C07C17/358—Preparation of halogenated hydrocarbons by reactions not affecting the number of carbon or of halogen atoms in the reaction by isomerisation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/361—Preparation of halogenated hydrocarbons by reactions involving a decrease in the number of carbon atoms
  • C07C17/363—Preparation of halogenated hydrocarbons by reactions involving a decrease in the number of carbon atoms by elimination of carboxyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/38—Separation; Purification; Stabilisation; Use of additives
  • C07C17/395—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to a chemical modification of at least one compound

Definitions

• the present invention relates to a new process for the preparation of 1, 1-dichloro-4-methyl-1, 3-pentadiene of 97-99 % purity of formula I.
• diene (further on 1,3-diene) is an important intermediate for the preparation of 2,2-dimethyl- 3-(2,2-dichlorovinyl)-cyclopropane carbonic acid which is the acid component of several insecticide piretroids.
• the present invention relates to a process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene of 97-99 % purity from the mixture of trichloro-methyl-pentenol isomers of formula II and III of optional ratio by acetylating the compounds with acetic anhydride, reduction with zinc dust, thereafter by isomerization with sulphonic acid, characterized, by the following steps: on acetylation and subsequent reduction of the trichloro-methyl-pentenol the diene of formula IV present in the raw product or distilled mixture is transformed into the isomer of formula I by isomerization with methane sulphonic acid and/or p-toluene sulphonic acid, at 40-130oC, whereafter the contaminations present mainly consisting, of trichloro pentene isomers are reacted with alkali hydroxides in the presence of water and alkanol.
• One of the fundaments of our invention is the recognition that the 1,4 ⁇ 1,3 isomerization can be carried out with a shorter reaction time by a complete transformation using a 1 - 3 % methane sulphonic acid, catalyst instead of p-toluene sulphonic acid.
• the bitumenization is significantly lower and less byproduct of 3.85 relative retention time is formed.
• the yield can be increased to 70 %, but a 1,3-diene of more than 90 % purity can only be obtained by fractional distillation.
• the product After isolation by way of extraction the product can be distilled, with a purity of 98 - 99.5 % without adapting a column.
• the single contaminating substance is signalized by the peak of a relative retention time 1.23, but, this quantity is no more than 0.5 %.
• thermodinamically the 1,3-diene is the most stable molecule among the isomers of similar structure and the trihalo pentenes formed. With the acidic and the subsequent alkaline isomerization the totally shiftee balance is reached so that the troublesome contaminations are not merely removed, - which is the case in all of the known processes but these contaminations are transformed into the end product.
• the reaction mixture obtained by reductive elimination was subjected, to fractional distillation and every fraction was separately isomerized with acid and alkali. We found that up to the fraction of 105 - 125 °C/l2 - 20 mercury mm from all fractions only 1,3-diene of the formula I was formed.
• composition of the advantageously applied Claisen alkali in the alkaline isomerization according to thepresent invention is: 35 g of potassium hydroxide dissolved, in 25 ml of water and 100 ml of methanol.
• the reagent is applied in a molecular rate of 0.2 - 3 calculated, on the compounds II and III respectively.
• Working up of the obtained reaction mixture comprises removal of the alkali in its salt form, removal of the solvent and simple distillation of the product.
• the forerun contains the contaminations (eventually water).
• To the 144 g (0,924 moles) of the main fraction 3 weight % (4.32 g, 3.2 ml) of a 99 % purity methane sulpho nic acid are added and at 90-95oC the mixture is stirred for 30 minutes, whereafter the obtained dark coloured solution is admixed, at 20oC while stirring with 150 ml of a "Claisen-alkali" solution, while the temperature is increasing to 50 - 60oC.
• the solution becomes emulsified and oily. For 60 minutes the reaction mixture is re fluxed while stirring.
• the solution obtained is admixed with 600 ml of water and the precipitating organic phase is separated, the aqueous phase is extracted with dichloromethane and the unified organic phases are dried, filtered, and washed with 20 ml of dichloromethane and the solvent is removed.
• the residue is distilled as follows: forerun : at 15 mm up to 60 °C : 3-10 g; main fraction : at 15 mm up to 65-58 °C: 132-143 g
• the main fraction contains, the 1,1-dichloro-4-methyl-1,3-pentadiene in a purity of 98-99 %.
• the product is of 98-99 % purity.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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Publications (1)

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ID=10963683

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Citations (1)

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• 1981
  • 1981-11-10 HU HU335081A patent/HU188157B/hu unknown
• 1982
  • 1982-11-10 DE DE19823249169 patent/DE3249169T1/de not_active Withdrawn
  • 1982-11-10 GB GB08317785A patent/GB2122996B/en not_active Expired
  • 1982-11-10 JP JP50339082A patent/JPS58501910A/ja active Pending
  • 1982-11-10 WO PCT/HU1982/000059 patent/WO1983001616A1/en active Application Filing

Patent Citations (1)

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