MONOHALOGENOTRIFLUOROOXETANE AND ITS PREPARATION

Abstract: Novel monohalogenotrifluorooxetane of the formula: (wherein X is chlorine, bromine or iodine) which is prepared by reacting monohalogenotrifluoroethylene of the formula: CF₂=CFX (III) (wherein X is the same as defined above) with a compound having a -(CH₂O)- unit.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to novel monohalo­ genotrifluorooxetane and a method for preparing the same. Description of the Prior Arts 2,2,3,3-Tetrafluorooxetane is a known compound and can be prepared by reacting tetrafluoroethylene and paraform in anhydrous hydrogen fluoride (cf. J. Org. Chem., 28 , 492-­ 494(1963)). 2,2,3,3-Tetrafluorooxetane is polymerized to prepare a fluorine-containing polyether (cf. European Patent Publication No. 0148482 A2 and U.S. Patent Application Serial No. 684,345). 2,2,3,3-Tetrafluorooxetane and a diamine are reacted to prepare a fluorine-containing poly­ aminoamide (cf. European Patent Publication No. 0182132 A2 and U.S. Patent Application Serial No. 786,682). 2,2,3,3-­ Tetrafluorooxetane and a monoamine are reacted to prepare an amine amide (cf. European Patent Publication No. 0179443 A2 and U.S. Patent Application Serial No. 786,681). SUMMARY OF THE INVENTION The present invention provides novel monohalogeno­ trifluorooxetane of the formula wherein X is chlorine, bromine or iodine. The present invention also provide a method for preparing monohalogenotrifluorooxetane (I) or (II) which comprises reacting monohalogenotrifluoroethylene of the formula: CF₂=CFX (III) (wherein X is the same as defined above) with a compound having a -(CH₂O)- unit. DETAILED DESCRIPTION OF THE INVENTION Examples of the oxetane (I) or (II) according to the present invention are as follows: The oxetane (I) or (II) according to the present invention can be prepared by reacting monohalogenotrifluoro­ ethylene (III) with a compound having a -(CH₂O)- unit and easily decomposed to the unit (e.g. paraformaldehyde or trioxane). The reaction is preferably carried out in the presence of hydrogen fluoride. A molar ratio of monohalogenotrifluoroethylene (III) to the -(CH₂O)- unit is 0.5:1 to 10:1, preferably about 1:1. Hydrogen fluoride, which is preferably present, is used in an amount of 3 to 20, more preferably 5 to 10 moles per mole of the -(CH₂O)- unit. Usually a reaction temperature is from 20 to 100°C, preferably from 40 to 50°C. The reaction is carried out in a liquid phase. Reac­ tion time varies with other reaction conditions such as the reaction temperature and is usually from 10 to 20 hours. Oxetane (I) or (II) is separated from a reaction mixture by a conventional method such as distillation. Oxetane (I) or (II) is ring-opening polymerized to produce a linear polymer having substantially no side chain. In addition, oxetane (I) or (II) is more reactive than 2,2,3,3-tetrafluorooxetane and can be reacted with other compound to produce a compound having useful proper­ ties. For example, oxetane (I) or (II) is reacted with thiourea to produce a mixture of compounds of the formulas: wherein X is the same as defined above. In the reaction, a molar ratio of oxetane (I) or (II) to thiourea is preferably 1:1 to 1:5, more preferably 1:3. A reaction temperature is from 0 to 50°C, preferably from 0 to 10°C. Reaction time varies with other conditions such as the reaction tempera­ ture and is usually 1 to 2 hours. An ether such as ethylene glycol dimethyl ether is preferably used as a solvent. The compound (V) may be used as a microbicide. The compound (IV) is dehydrohalogenated to produce 5-fluorothiouracil. The dehydrohalogenation is usually carried out after isolating the compound (IV) from the reac­ tion mixture of oxetane (I) or (II) and thiourea, but the reaction mixture itself may be dehydrohalogenated. The dehydrohalogenation can be carried out by using, for exam­ ple, a base such as sodium alkoxide. A molar ratio of the compound (IV) to sodium alkoxide is preferably 1:1 to 1:2, more preferably 1:1. A reaction temperature is from 0 to 50°C, preferably 0 to 25°C. Reaction time varies with other conditions such as the reaction temperature and is usually 1 to 24 hours. An alcohol such methanol can be used as a solvent. According to Chemical Abstracts 61 , 5664h, 5-­ fluorothiouracil and Raney nickel are refluxed in 2 % aqueous ammonia solution for 2 to 4 hours to produce 5-­ fluorouracil having an anti-tumor activity. The present invention will be hereinafter explain­ ed further in detail by following examples. Example 1 In a 300 ml SUS-316 autoclave equipped with a stirrer, paraformaldehyde (20 g, 0.66 mol) was charged. A pressure in the autoclave was decreased and hydrogen fluo­ ride (produced by Daikin Industries Ltd.) (140 g) was added. Chlorotrifluoroethylene (CF₂=CFCℓ) was injected from a valve of the autoclave through a copper tube of 2/8 inch in diameter to pressurize the autoclave interior to 4.5 kg,/cm²G (at room temperature). Then the autoclave was heated to 45-54°C with stirring in an oil bath, the reaction was continued for 13 hours with injecting chlorotrifluoro­ ethylene to maintain said pressure. The reaction mixture was poured in ice water. A lower organic layer was separa­ ted and distilled under reduced pressure to give a mixture of 3-chloro-2,2,3-trifluorooxetane and 2-chloro-2,3,3-tri­ fluorooxetane (8.4 g). Boiling temperature: 22-24°C (120 mm/Hg). Gas chromatography analysis (DC 550 column of 3 m in length, heated from 50°C to 200°C at a rate of 10°C/min) revealed that the mixture contained 46 % by weight of 3-­ chloro-2,2,3-trifluorooxetane and 36 % by weight of 2-­ chloro-2,3,3-trifluorooxetane. Mass spectrometry 3-Chloro-2,2,3-trifluorooxetane: m/z = 146 (M⁺), 127 (M-19(F)), 116 (M-30(CH₂O)), 111 (M-35(Cℓ⁻)), 80 (CFCℓCH₂⁺). 2-Chloro-2,3,3-trifluorooxetane: m/z = 146 (M⁺), 127 (M-19(F)), 116 (M-30(CH₂O)), 111 (M-35(Cℓ⁻)), 64 (CF₂CH₂⁺). Example 2 In the same manner as in Example 1 but using bromotrifluoroethylene in place of chlorotrifluoroethylene, a reaction was carried out to produce a mixture of 72 % by weight of 3-bromo-2,2,3-trifluorooxetane and 28 % by weight of 2-bromo-2,3,3-trifluorooxetane. Boiling point: 44-46°C (120 mmHg). Mass spectrometry 3-Bromo-2,2,3-trifluorooxetane: m/z = 190 (M⁺), 172 (M-19(F)), 161 (M-30(CH₂O)), 112 (M-79(Br⁻)), 124 (CFBr-­ CH₂⁺). 2-Bromo-2,3,3-trifluorooxetane: m/z = 190 (M⁺), 172 (M-19(F)), 161 (M-30(CH₂O)), 112 (M-79(Br⁻)), 64 (CF₂­ CH₂⁺). Example 3 In a 50 ml eggplant type flask, ethylene glycol dimethyl ether (20 ml) and thiourea (3.4g, 45 mmol) were charged and stirred. A mixture of 3-chloro-2,2,3-trifluoro­ oxetane and 2-chloro-2,3,3-trifluorooxetane (2.2 g) (purity by gas chromatography: 46 % by weight of 3-chloro-isomer and 36 % by weight of 2-chloro-isomer) was dropwise added. After the completion of the addition, the reaction was con­ tinued at room temperature for 15 hours. Precipitates were recovered to give a white solid product (1.2 g). ¹H-NMR and ¹⁹F-NMR revealed that the product was a mixture of the fol­ lowing compounds: ¹H-NMR (DMSO-d₆): δ(ppm) = 3.8(-CF₂-C H ₂-NH-, t), 3.8-4.1(-CFCℓ-C H ₂-NH-), 8.8(-CO-N H -CS-N H -, br.). ¹⁹F-NMR (DMSO-d₆): δ(ppm) = 30.1(-CO-C F ₂-CH₂-, t), 36.1(-CO-C F Cℓ-CH₂, t). In a 50 ml eggplant type flask, methanol (20 ml) and the above produced crude product (0.85 g, 4.7 mmol) were charged. A 28 % by weight solution of sodium methoxide in 20 ml of methanol (sodium methoxide 4.7 mmol) (available from Wako Pure Chemical Industries Ltd.) was dropwise and slowly added with stirring at room temperature over 30 minu­ tes. After the completion of the addition, the reaction was continued for 15 hours. Precipitates were filtrated off and methanol was evaporated off from a filtrate to give a white solid (0.5 g). The solid was washed with ethylene glycol dimethyl ether (20 ml) to give a product (0.4 g). Mass spectrometry, ¹H-NMR and ¹⁹F-NMR revealed that the product was a mixture of the following compounds: Total yield of 5-fluorothiouracil: 50 %.

Claims: 1. Monohalogenotrifluorooxetane of the formula: wherein X is chlorine, bromine or iodine. 2. Monohalogenotrifluorooxetane according to claim 1, which is 3-Chloro-2,2,3-trifluorooxetane. 3. Monohalogenotrifluorooxetane according to claim 1, which is 2-Chloro-2,3,3-trifluorooxetane. 4. Monohalogenotrifluorooxetane according to claim 1, which is 3-Bromo-2,2,3-trifluorooxetane. 5. Monohalogenotrifluorooxetane according to claim 1, which is 2-Bromo-2,3,3-trifluorooxetane. 6. Monohalogenotrifluorooxetane according to claim 1, which is 3-Iodo-2,2,3-trifluorooxetane. 7. Monohalogenotrifluorooxetane according to claim 1, which is 2-Iodo-2,3,3-trifluorooxetane. 8. A method for preparing monohalogenotrifluoro­ oxetane of the formula: (wherein X is chlorine, bromine or iodine) which comprises reacting monohalogenotrifluoroethylene of the formula: CF₂=CFX (III) (wherein X is the same as defined above) with a compound having a -(CH₂O)- unit. 9. The method according to claim 8, wherein the reaction is carried out in the presence of hydrogen fluo­ ride. 10. The method according to claim 8, wherein the compound having the -(CH₂O)- unit is paraformaldehyde. 11. The method according to claim 8, wherein mono­ halogenotrifluoroethylene (III) is used in an amount of 0.5 to 10 moles per mole of the -(CH₂O)- unit.

Inventors: KOHNO, SATORU URBANLAND AIKAWA NO. 403, OHSAKA, YOHNOSUKE
Applicants: DAIKIN INDUSTRIES, LIMITED
Application year: 1987
Main classification: C07D305
IPC codes: C08G65, C07D305