Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
  • C07C303/26—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of esters of sulfonic acids
  • C07C303/28—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of esters of sulfonic acids by reaction of hydroxy compounds with sulfonic acids or derivatives thereof
• • 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
  • C07C21/18—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C19/00—Acyclic saturated compounds containing halogen atoms
  • C07C19/08—Acyclic saturated compounds containing halogen atoms containing fluorine
  • C07C19/14—Acyclic saturated compounds containing halogen atoms containing fluorine and bromine
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
  • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
  • C07C29/143—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of ketones
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
  • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
  • C07C29/147—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof

Definitions

• the present invention relates to a novel process for the preparation of 4-bromo-l,l-difluorobut-l-ene.
• the present invention also relates to a novel process for the preparation of 2,4-dibromo- 1,1,1 -trifluorobutane.
• 4-bromo-l,l-difluorobut- l-ene is a useful compound in many fields of activity such as agrochemicals and fluoro polymers, both as an end product and particularly as an intermediate.
• 1,1,2-difluorobut-l-ene in an inert solvent optionally in the presence of a free radical generator, to give l,4-dibromo-l,l,2-trifluorobutane.
• This compound is then treated with a debromofluorinating agent to give 4-bromo- 1,1 -difluorobut- 1 -ene.
• the present invention relates to an improved process for preparing
• 4-bromo- 1,1 -difluorobut- 1 -ene and therefore also to an improved process for preparing end products which have 4-bromo- 1,1 -difluorobut- 1 -ene as an intermediate.
• Advantages of the process of the present invention include avoidance of the use of hazardous reagents, such as HF and LiAlHF.
• a process for the preparation of 4-bromo- 1,1 -difluorobut- 1 -ene comprising the step of reacting 2,4-dibromo- 1,1,1 -trifluorobutane with a defluorobrominating agent in a liquid reaction mass and recovering the desired product therefrom.
• the liquid reaction mass is preferably water; a water miscible, polar, non-reducible liquid, such as methanol and DMF; or a combination thereof.
• Preferred defluorobrominating agents include zinc, magnesium and aluminium. Zinc is especially preferred.
• the scope of the invention is not limited to the use of metals as defluorobrominating agents and other techniques such as electrochemical defluorochlorination processes may be used and are within the scope of the present invention.
• the reaction is preferably carried out using at least a stoichiometric amount of the defluorobrominating agent. More preferably about 1.2 to about 1.5 moles of defluorobrominating agent are used per mole of 2.4-dibromo-l,l,l,-trifluorobut-l-ene.
• less than stoichiometric amounts of the defluorobrominating agent can be used.
• the reaction is preferably carried out at a pressure of about 1 atmosphere up to a temperature of about 100°C.
• an initiator is used to start the reaction.
• Suitable initiators include iodine, concentrated HCl or even any residual metal from a preceding reaction.
• a process for the preparation of 4-bromo- 1,1 -difluorobut- 1 -ene comprising the steps of (a) reacting a l,l,l-trifluorobutane-2,4-suIphonate, wherein the sulphonate is a leaving group, with a source of bromide to produce 2, 4-dibromo- 1,1,1 -trifluorobutane; and
• the sulfonate is preferably a tosylate or mesylate.
• the reaction is preferably carried out at a temperature of at least about 100°C, more preferably from about 130°C to about 250°C, even more preferably, from about 130°C to about 200°C, at a pressure of about 1 atmosphere.
• the reaction is preferably carried out in a polar aprotic solvent such as tetrahydrofuran, dimethylformamide, N-methylpyrrolidone, formamide, sulpholine and ketones.
• a polar aprotic solvent such as tetrahydrofuran, dimethylformamide, N-methylpyrrolidone, formamide, sulpholine and ketones.
• the bromide source is preferably a neutral source of bromide, which is soluble in the solvent in which the step is preferably carried out, such as an alkali metal bromide, e.g. lithium bromide, sodium bromide or potassium bromide, calcium bromide, a quaternary ammonium bromide, and a quaternary pyrimidine bromide.
• an alkali metal bromide e.g. lithium bromide, sodium bromide or potassium bromide
• calcium bromide e.g. lithium bromide, sodium bromide or potassium bromide
• a quaternary ammonium bromide e.g. quaternary pyrimidine bromide
• a process for the preparation of 4-bromo- 1,1 -difluorobut- 1 -ene comprising the steps of
• the sulfonate is the tosylate or mesylate obtained by reaction with the appropriate sulphonyl chloride.
• the reaction is preferably carried out in the presence of a solvent.
• the solvent is preferably a polar aprotic solvent such as those mentioned above.
• the reaction is preferably carried out below the boiling point of the selected solvent at about 1 atmosphere.
• the reaction is carried out in the presence of a base, preferably an organic base such as a tertiary amine.
• a base preferably an organic base such as a tertiary amine.
• the base aids in the formation of the alkoxy species.
• Step (a) may be carried out along the lines of the method described in J. Fluorine
• the borohydride is preferably sodium borohydride and the reaction is preferably carried out in a polar aprotic solvent such as those mentioned above.
• the solvent should not be reducible by the borohydride.
• the present invention also relates to a process for the preparation of 2,4-dibromo- 1, 1 , 1 -trifluorobutane.
• Misani et al in J. Am. Chem. Soc, (1956), 78, 2801-2804 describes a failed attempt to prepare 2,4-dibromo- 1,1,1 -trifluorobutane by reacting l,l,l-trifluorobutane-2,4-diol with phosphorus tribromide.
• the 2,4-dibromo- 1,1,1 -trifluorobutane was eventually prepared via ethyl ⁇ -bromo- ⁇ , ⁇ , ⁇ -trifluorobutyrate and l,l,l-trifluoro-2-bromo-4-butanol.
• Vasil'eva et al, Izv. Akad. Nauk. SSSR, SerKhim, 1989 (11) 2558-62 report that 2,4-dibromo-l,l,l- trifluorobutane was obtained in mixture with other products by the reaction of dibromomethane with 3,3,3-trifluoroprop-l-ene. However these processes utilise hazardous or volatile reactants.
• This Example illustrates the preparation of 1,1,1 -trifluorobutane- 2,4-diol.
• nmr CF 3 CH (Mult. 4.2ppm); OHCH 2 (Mult. 1.85ppm); CH 2 (Mult. 3.9ppm) [note: in CDCI3 the OH protons were not clearly discernable] l ⁇ F nmr: CF3 (Sing. -81 ppm).
• GLC showed the reaction mass to be a mixture of the desired product (60%), monohydroxy tosylate (10%) and 2-chloro-4-tosylate (10%).
• the reaction mass was mixed with 300ml diethyl ether and filtered. The filter cake was washed with tetrahydrofuran. The filtrate was evaporated under reduced pressure to give 86g of a viscous amber coloured oil. 76g of the oil was dissolved in dichloromethane and washed with water. The mixture was dried to give 43g of the crude product.
• GLC MS showed the major peak to be l,l,l-trifluorobutane-2,4-bis-p-toulene sulphonate of MWt 452.
• This Example illustrates the preparation of 2,4-dibromo- 1,1,1 -trifluorobutane.
• Lithium bromide was charged into 120ml n-methylpyrrolidone and heated to 100°C producing a solution, this was cooled to 70°C and 40ml absolute ethanol added. The mixture was then reheated to 218°C whilst distilling out 40ml ethanol plus traces of water. The mixture was allowed to cool to 80°C and 30ml cyclohexane added. The mixture was again heated to 218°C whilst collecting the distillate.
• the mixture was allowed to cool and the previously prepared crude l,l,l-trifluorobutane-2,4-bis-p-tosylate was added over 30 minutes, washed in with the aid of 2 x 20ml n-methylpyrrolidine. GLC analysis of the mixture after 1 hour at room temperature showed that all of the bis-tosylate had been converted to the 4-bromo-2-tosylate. The mixture was then heated to 90°C for approximately 2 hours and then allowed to cool to room temperature overnight. GLC analysis showed that conversion to the product was not complete. The mixture was heated to 130°C for 5 hours and at the end of this period the reaction was deemed complete. The reaction mass was allowed to cool to room temperature and drowned into water.
• the aqueous phase was extracted with 3 x 100ml of 30/40 petrol ether.
• the organic extracts were washed once with water, dried over sodium sulphate and the bulk of the petrol ether removed by flash distillation at atmospheric pressure up to a head temperature of 40°C.
• the residue was distilled under reduced pressure using a water pump and the fraction up to 50°C collected.

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• 1995
  • 1995-09-06 GB GBGB9518111.1A patent/GB9518111D0/en active Pending
• 1996
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  • 1996-08-23 IL IL12346096A patent/IL123460A0/xx unknown
  • 1996-08-23 JP JP9510925A patent/JPH11512110A/ja active Pending
  • 1996-08-23 EP EP96928560A patent/EP0850211A1/de not_active Withdrawn
  • 1996-08-23 CN CN96197873A patent/CN1200717A/zh active Pending
  • 1996-08-23 KR KR1019980701663A patent/KR19990044419A/ko not_active Application Discontinuation
  • 1996-08-23 AU AU68288/96A patent/AU6828896A/en not_active Abandoned
  • 1996-08-23 WO PCT/GB1996/002072 patent/WO1997009292A1/en not_active Application Discontinuation
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