WO1989011470A1 - Dihalogeno-3,3 fluoro-2 propenols-1, preparation method and utilization for the synthesis of fluoro-2 acrylic and dihalogeno-3,3 fluoro-2 acrylic acids and their derivatives - Google Patents

Abstract

The invention relates to dihalogeno-3,3 fluoro-2 propenol-1 having the formula X?1X?2C=CF-CH2?OH (I), wherein X?1 and X?2, which may be identical or different, represent a fluorine, a chlorine or a bromine atom providing that X?1 and X?2 do not represent both a chlorine atom. These compounds may be prepared by reaction of an alcohol having the formula HCH?1X?2-CFX?3-CH2?OH (II), X?1 and X?2 have the meaning given hereabove and X?3 is a fluorine, chlorine or bromine atom, similar to or different from X?1 and/or X?2, with an organolithian compound. They may be used to prepare halides of the fluoro-2 acrylic acid and of the dihalogeno-3,3 fluoro-2 acrylic acids or their esters.

Description

 DIHALOGENO-3,3 FLUORO-2 PROPENOLS-1, PROCESS FOR THEIR PREPARATION AND THEIR USE FOR SYNTHESIS OF ACID FLUORO-2 ACRYLIC AND DIHALOGENO-3,3 FLUORO-2 ACRYLIC AND DERIVATIVES THEREOF

The present invention relates to new alcohols which are the 3,3-dihalo-2-fluoro-1-propenols-1 which can be used as precursors of 2-fluoro-acrylic acid or of a halide of this acid for the preparation of fluoro -2 acrylates.

Fluoro-2 acrylates are of great industrial interest because their polymers or copolymers are used in the composition of many materials such as paints, varnishes, dental resins and special windshields.

The fluoro-2 acrylates can be obtained by conventional methods from fluoro-2-acrylic acid or a halide of 2-fluoro acrylic acid. there is also known a method for preparing fluoro-acrylates which uses 2-fluoro acrolein as a precursor compound.

Fluoro-2 acrolein can be prepared by condensation of dichlorofluoromethane with n-butylvinyl ether, as described by H. MOLINES et al. in "Synthesis" (1985) pages 754 to 756.

A halide of 2-fluoro acrylic acid, for example the fluoride of 2-fluoro acrylic acid, can be prepared from tetrafluoro-2,2,3,3-oxetane by ring opening, as described in European patent EP-A-0 136 668.

The methods described in this European patent have the drawback of being relatively difficult to implement since they require a certain number of steps to arrive at the halides of 2-fluoro acrylic acid. The present invention specifically relates to new 3,3-dihalo-fluoro-2-propenols-1 which make it possible to prepare the halides of 2-fluoro acrylic acid of a much simpler way.

Among the 3,3-dihalo-fluoro-2 propenols-1, only 3.3-dichloro-fluoro-2 propenol-1 is known, which was prepared by hydrolysis of CCl ₂ = CFCH ₂ Br as described in Chemical Abstracts, vol. 47, No. 22, November 1953, No. 12213 h. However, this compound is not intended for the synthesis of 2-fluoro acrylates.

Russian patent 375,298 reports the use of difluoro-3,3 fluoro-2 propénol-1 for the preparation of 0- (2,3,3-trifluoroalkyl) 0-alkyl methyl phosphonates but gives no indication on the mode of preparation and characteristics of this compound; therefore, it does not constitute sufficient disclosure of this compound.

According to the invention, the 3,3-dihalo-fluoro-2-propenols-1 correspond to the formula:

X ¹ X ² C = CF-CH ₂ OH (I)

in which X ¹ and X ² which may be identical or different, represent a fluorine, chlorine or bromine atom provided that X ¹ and X do not both have a chlorine atom.

The compounds described above, as well as 3,3-dichloro-2-fluoro-propenol-1, can be used in particular for the preparation of 2-fluoro-acrylic acid halides which can be converted into 2-fluoro-acrylic acid or its derivatives.

In this case, when the compound of formula (I) is intended for the preparation of acid fluoride, at least one of X ¹ and X ² represents fluorine and the other can represent chlorine or bromine.

When the compound of formula (I) is intended for the preparation of the acid chloride. at least one of X ¹ and X ² represents chlorine and neither of the two X ¹ and X ² represents fluorine.

When the compound of formula (I) is intended for the preparation of acid bromide, X ¹ and X ² represent bromine. The di ha logeno-3.3 f luoro-2 propeno ls-1 corresponding to the formula:

X ¹ X ² C = C F-CH ₂ OH (I)

in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom, can be easily prepared from the corresponding halogenated saturated alcohols. In this case we treat an alcohol of formula:

HCX ¹ X ² -CFX ³ -CH ₂ OH (II)

in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained is separated from the reaction medium. This reaction is generally carried out at a temperature of 0 to 40 ° C, in an anhydrous organic solvent such as ether. The organolithium compound can in particular be methyllithium.

This process is analogous to that described by C. WAKSELMAN et al. in J. Org. Chem., 1977, 42, pages 565 and 566, but surprisingly it leads to a different result.

In this article, the reaction of a halogen compound

RCF ₂ -CF ₂ H with an organolithic compound R ' ₂ NLi leads to the production of the compound R-CF = CF-NR' ₂ . However, in the invention, by treating the alcohol of formula (II) at room temperature with an organolithium compound R ¹ Li, the alcohol of formula (I) is obtained instead of forming the compound R ¹ -CX ¹ = CF-CH ₂ OH. Indeed, this compound is only formed in small proportion and the reaction essentially leads to the compound of formula (I) sought, which is a surprising result. The alcohols of formula (II) used as starting material for this reaction are commercial compounds or compounds which are easy to prepare by conventional methods, for example by radical condensation of methanol on halogenated olefins, as described by JD La Zerte in JACS (1955), vol.77, p.910.

Can be prepared in particular tetraf luoropropanol according to R.M. Joyce US 2,559,628 (1951).

The alcohols of formula (I) of the invention can be converted into halides of 2-fluoro acrylic acid in a single step.

The subject of the invention is also a process for preparing a halide of 2-fluoro acrylic acid of formula:

CH ₂ = CF-COX (III)

in which X is a fluorine, chlorine or bromine atom, characterized in that an acid 3,3-2-fluoro-1-propenol-dihalogen of formula:

X ¹ X ² C = CF-CH ₂ OH (I)

in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom, to obtain by allylic transposition the 2-fluoro acrylic acid halide of formula

(III). This reaction corresponds to the following reaction scheme:

Cette réaction est effectuée en milieu acide tel que l'acide sulfurique, en solution dans un solvant organique par exemple dans du chlorure de méthylène ou du tétrachloroéthane. Dans ce dernier cas, après réaction, on distille généralement l'halogénure d'acide directement du milieu réactionnel sous un léger vide et on le piège dans un bain froid.

This reaction is carried out in an acid medium such as sulfuric acid, in solution in an organic solvent, for example in methylene chloride or tetrachloroethane. In the latter case, after reaction, the acid halide is generally distilled directly from the reaction medium under a slight vacuum and it is trapped in a cold bath.

To obtain the desired acid halide, it is necessary to start from a derivative of formula (I) in which X ¹ and X ² are chosen for this purpose.

Thus, if one wants to obtain the acid fluoride at least one of X ¹ and X ² is fluorine. If we want to obtain an acid chloride, X ¹ is chlorine and X ² is chlorine or bromine. When we want to obtain acid bromide, X ¹ and X ² are bromine.

Indeed, it is the heavier halogen which is preferentially eliminated.

The acid halides of formula (III) can be used for the preparation of 2-fluoro acrylic acid or its derivatives, in particular esters.

Also, the subject of the invention is also a process for preparing 2-fluoro acrylic acid or its esters of formula:

H ₂ C = CF-COOR (IV)

in which R ² represents a hydrogen atom, an alkyl radical of 1 to 10 carbon atoms or an aryl radical, which comprises the following steps: a) - preparing a 3,3-dihalo-2-fluoro-propenol-1 of formula :

X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² which may be identical or different, represent a fluorine, chlorine or bromine atom, by treatment of an alcohol of formula:

HC X ¹ X ² -CFX ³ -CH ₂ OH (II)

in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separation of the reaction medium from the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained, b) - to be treated in an acid medium, the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained to obtain by allylic transposition a halide of 2-fluoro acrylic acid of formula CH ₂ = CF-COX (III) in which X is a fluorine, chlorine or bromine atom, and c) - to hydrolyze or esterify the acid halide of formula (III) by reaction with a compound of formula R ² -OH in which R ² has the given meaning above.

The compounds of formula (I) of the invention can also be used for the preparation of 3,3-dihalo-2-fluoro-acrylic acids of formula:

X ¹ X ² C = CF-COOH (V)

in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom.

In this case, the following steps are carried out: halogenating a 3,3-dihalo-fluoro-2 propenol-1 of formula (I) with a halogen X ⁴ to form a tetrahalo-fluoro-2 propanol of formula:

X ⁴ X ¹ X ² C-CFX ⁴ -CH ₂ OH (VI)

oxidize the tetrahalo-fluoro-2-propanol of formula (VI) thus obtained to convert it into tetrahalo-fluoro-2-propanoic acid of formula:

X ⁴ X ¹ X ² CC FX ⁴ - COOH (VII)

converting the tetrahalo-fluoro-2-propanoic acid of formula (VII) thus obtained into dihalo-3,3-fluoro-2 acrylic acid of formula (V) by reaction with a reducing metal. In this process. the halogen X ⁴ used to form the tet raha logeno fluoro-2 propanol is chosen so as to be more easily eliminated than the halogens X ¹ and X ² of the compound of formula (I).

When X ¹ and X ² are fluorine, X ⁴ can be chlorine, bromine or iodine.

When one of X ¹ and X ² is chlorine, X ⁴ can be chlorine, bromine or iodine.

When one of X ¹ and X ² is bromine, X ⁴ can be bromine or iodine.

The following oxidation reaction can be carried out using specific oxidation reagents for allyl alcohols, such as MnO ₂ , CrO ₃ - pyridine, CrO ₃ -H ₂ SO ₄ . One can also use potassium permanganate in acetic acid.

For the last step of converting the acid of formula (VII) into the acid of formula (V), the reaction is carried out with a reducing metal such as zinc. This process is very interesting because the acids of formula (V) are monomers which can lead to polymers having interesting optical properties, which do not have any notable absorption in the near infrared, which makes them usable for the production of fibers. optics, as described by B. BOUTEVIN et al. in J. Fluorine Chem., 1987, 37, 150 and 151 - 169.

The polymers of the compounds of formula (V) or their esters can also find interesting uses as resistant functional membranes.

The acid esters of formula (V) correspond to the formula:

X ¹ X ² C = CF-COOR ³ (VIII)

in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom and R ³ is an alkyl or aryl radical. They can be prepared by an analogous process comprising the following successive steps: a) - preparing a 3,3-dihalo-fluoro-2-propenol-1 of formula:

X ¹ X ² C = CF-CH 0H (I)

in which X ¹ and X ² have the meaning given above, by treatment of an alcohol of formula:

HC X ¹ X ² -CFX ³ -CH ₂ OH (II)

in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ L i in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separation of the reaction medium from 3,3-dihalo-2-fluoro-propenol-1 of formula (I) thus obtained, b) - halogenating the 3,3-dihalo-fluoro-2 propenol-1 of formula (I) thus obtained by a halogen X ⁴ ₂ to form a tet raha logeno fluoro-2 propanol of formula:

X ⁴ X ¹ X ² C-CFX ⁴ -CH ₂ OH (VI)

c) - oxidize the tetralo-fluoro-2-propanol of formula

(VI) thus obtained to convert it into tetralo-fluoro-2-propanoic acid of formula:

X ⁴ X ¹ X ² C-CFX ⁴ -COOH (VII)

d) - esterifying the tetrahalo-fluoro-2-propanoic acid of formula (VII) thus obtained with an alcohol or a phenol of formula R ³ OH in which R ³ has the meaning given above to form the ester of formula:

X ¹ X ² X ⁴ C-CFX ⁴ -COOR ³ (IX)

in which X ¹ , X ² , X ⁴ and R ³ have the meaning given above, and e) - convert the ester of formula (IX) thus obtained into ester of 3,3-dihalo-2-fluoro-acrylic acid of formula (VIII) by reaction with a reducing metal.

In the invention, the aryl radicals which can be used for R ² and R ³ are for example the phenyl, biphenyl, naphthyl, anthracenyl unsubstituted or substituted by one or more substituents such as halogen atoms, alkyl and ether radicals.

The compounds of formula (I) of the invention are therefore very advantageous compounds because they allow access, under mild conditions and by methods comprising few steps, to the 2-fluoro acrylates used for the preparation of polymers and copolymers with significant industrial interest. The following examples are of course given without implied limitation to illustrate the invention.

EXAMPLE 1 Preparation of trifluoroallyl alcohol

CF ₂ = CF-CH ₂ OH (compound No. 1) The method of the invention is used to prepare a compound of formula (I) with X ¹ = X ² = F.

20g (151 mmol) of tet raf luoropropanol are introduced into a three-necked flask provided with a nitrogen inlet, a dropping funnel, a condenser and a calcium chloride guard, cooled to 0 ° C. HCF ₂ CF ₂ CH ₂ OH and 20 ml of ether. With stirring, 320 mmol of CH ₃ Li are poured in dropwise. After five hours at room temperature, the mixture is cooled to 0 ° C. and acidified with an excess of concentrated chlorofluoric acid (approximately 18 ml). It is drained on celite, the ethereal phase is separated, washed with sodium bicarbonate and dried over magnesium sulfate. After removal of the ether, distilled under a slight vacuum (100 Torr) 13 kPa. 17 g of a mixture boiling at 60 ° C. under 13 kPa are thus collected. This mixture contains 74% of compound No. 1, 16% of CH ₃ CF = CF-CH ₂ OH and 10% of the starting tetrafluoropropanol. By rectification, 12.5 g (112 mmol) of compound No. 1 having a boiling point of 98 ° C are obtained; the yield is 74%. Nuclear magnetic resonance analysis gives the following results: 1 H NMR CDCl ₃ / TMS: δ ppm: 4.4 (dxdxd, CH ₂ O, J _HF = 2.3 and

22 Hz).

1 ⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -104.5 (dxdxt,

CF =, ³ J _FF = 32, ² J _FF = 84, ⁴ J _HF = 2 Hz) - 121 (dxdxt,

CF =, ³ J _FF = 120, ⁴ J _HF = 3 Hz), - 179 (dxdxd, CF =, ³ J _HF :

22 Hz).

Elementary analysis C ₃ H ₃ F ₃ O. M = 112

C (%) H (%) - calculated 32, 1 7 2, 7

- found 32, 34 2, 75

EXAMPLE 2 Preparation of 3-chloro-2,3-difluoro-allylic alcohol, CFCl = CF-CH ₂ OH (compound No. 2).

The procedure is as in Example 1 by introducing 137 mmol of CH ₃ Li into a solution of 10 g (68.4 mmol) of alcohol HCFCICF ₂ CH ₂ OH in 10 ml of anhydrous ether. After five hours, the medium is neutralized with concentrated hydrochloric acid (approximately 17 ml) after adding 50 ml of salt water. The organic phase is decanted, washed and dried over magnesium sulfate. When the ether is removed, the reaction product is distilled under a partial vacuum Eb: 90-95 ° C (17 kPa, 125 Torr).

7.86 g of product are thus collected. This product contains 74% of compound 2 which is separated either by rectification or by vapor phase chromatography. The yield is 73%. It is a mixture of the E and Z isomers in an E / Z ratio equal to 45/55, which boils at 116 ° C. Isomer E

RMN CDCl ₃ / TMS ppm 4.4 (dxt CH ₂ , ³ J _HF = 22 Hz,

⁴ J _HF = 2 Hz)

¹⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -104 (dxt, CFCl, ³ J _FF = 14 Hz) - 141 (dxt, CFCH ₂ , ³ J _FF = 14 Hz).

Isomer Z

¹ H NMR CDCl ₃ / TMS: δ ppm: 4.4 (dxt, CH ₂ , ³ J _HF = 22 Hz, ⁴ J _HF = 5 Hz)

¹⁹ F NMR CDCl ₃ / CFCl: ɸ ppm: -122 (dxt, CFCl, ³ J _FF = 138 Hz) - 152 (dxt, CFCH ₂ , ³ J _HF = 22 Hz).

IR (CDCl ₃ ): 3300 cm ^-1 CH ₂ OH, 1710 cm CF = CFCl.

Elementary analysis C ₃ H ₃ ClF ₂ O (M = 128.5)

C (%) H (%)

- calculated 28.04 2.35 - found 28.18 2.48

EXAMPLE 3 Preparation of 2-fluoro-acryloyl fluoride CH ₂ = CF-COF, (compound n ° 3)

10 ml of concentrated sulfuric acid and a magnetic bar are introduced into a distillation apparatus provided with a tared receiver and cooled to -70 ° C. While stirring, drop this dropwise 2.5g (22.5 mmol) of trifluoroallyl alcohol

(compound n ° 1). The reaction is exothermic. At the end of the addition, draw under a slight vacuum (27kPa, 200

Torr). 1.15 g (12.5 mmol) of 2-fluoroy acryloyl fluoride are collected in the receptor. The yield is

55%.

Analysis by 1 H NMR CDCl ₃ NMR / TMS: δ ppm: 5.6 (CH =);

6 (dxd, CH =, ² J _HH = 4 Hz)

1 ⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm:

14 (d, CF = 0, ³ J _FF = 18 Hz) - 117 (2dxd, CF = ³ J _HF = 12 and

46 Hz).

EXAMPLE 4 Preparation of 2-fluoroy acryloyl CH ₂ = CF-COF (compound No. 3) The same procedure is followed as in Example 3, but starting with compound No. 2. In this case, 4.5 g (35 mmol) of compound No. 2 and 10 ml of concentrated sulfuric acid are used. 2.7 g (29 mmol) of compound No. 3 are collected. The yield is 82%. Note the absence of a compound of formula:

CH ₂ = CF-COCI. EXAMPLE 5 Preparation of 2-fluoro phenyl acrylate

CH ₂ = CF-COOC ₆ H ₅ (compound n ° 4)

The distillate obtained in Example 3 is diluted in 10 ml of CH ₂ Cl ₂ . 1.2 g (12.7 mmol) of phenol are added thereto and the mixture is left overnight at room temperature.

Wash with sodium bicarbonate, water and dry over magnesium sulfate. After removal of the solvent, 1.6 g (10 mmol) of compound No. 4 are obtained. The yield is 78%. Purify by chromatography aphia on a silica column with CH ₂ Cl ₂ . Compound # 4 tops the list. 0.9g (5.4 mmol) of pure compound 4 is obtained.

Analysis by 1 H NMR CDCl ₃ NMR / TMS: δ ppm: 5.37 (dxd, CH =, ³ J _HF = 14,

² J _HH = 4 Hz) 5.8 (dxd, CH =, ³ J _HF = 45Hz); 7.3 (n, C ₆ H ₅ ). ¹⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -117 (dxd, CF).

IR (CCl ₄ ): 1745 cm ^-1 (COOR); 1660 cm ^-1 (CH ₂ = CF).

Elementary analysis: C ₉ H ₇ FO ₂ (M = 160)

C (%) H (%)

- calculated 65.08 4.24

- found 64.94 4.31

EXAMPLE 6 Preparation of 2-fluoro ethyl acrylate,

CH ₂ = CF-COOC ₂ H ₅ (compound n ° 5)

The same procedure is followed as in Example 5, replacing the phenol with ethanol. This gives compound No. 5 of boiling point: 101 ° C. The yield is 70%.

1 H NMR analysis CDCl ₃ NMR / TMS: δ ppm: 1.3 (t, CH ₃ , ³ J _HF = 7 Hz);

4.3 (q, CH ₂ ); 5.25 (dxd, CH =, ³ J _HF = 14Hz, ² J _HH = 3 Hz);

5.67 (dxd, CH =, ³ J _HF = 45 Hz).

¹⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -97 (dxd, CF =).

IR (CCl ₄ ): 1745 cm ^-1 (COOR); 1660 cm ^-1 (CH ₂ = CF).

Elementary analysis: C ₅ H ₇ FO ₂ (M = 118) C (%) H (%)

- calculated 50.89 5.97

- found 50.25 5.82

EXAMPLE 7 Preparation of 2,3-dibromo-2,3,3-trifluoro-propanol, BrCF ₂ -CFBr-CH ₂ OH (compound n ° 6). 7 ml ( ₂₁ g, 134 mmol) of bromine are introduced into a solution of 15 g (134 mmol) of compound No. 1 in 150 ml of CH ₂ Cl ₂ . The mixture is heated at reflux for 1 hour and left to stir overnight. Wash twice with water, dry over magnesium sulfate and evaporate the solvent. 27g of crude product are obtained. After rectification, 23 g (84.5 mmol) of compound n ° 6 Eb 80 ° (2.7 kPa, 20 Torr) are obtained. The yield is 62%.

Analysis by 1 H NMR CDCl ₃ NMR / TMS δ p pm 4.25 (d, CH ₂ O, ³ J _HF = 16 Hz).

1 ⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -55.4 (dxd, CF ₂ Br,

³ J _FF = 18 and ² J _FF = 184 Hz); -55.6 (dxd, CF ₂ Br,

³ J _FF = 18 Hz); -124 (dxd, CFBr).

IR (CCl ₄ ): 3600 cm ^-1 . Elementary analysis: C ₃ H ₃ Br ₂ F ₃ O (M = 272)

C (%) H (%)

- calculated 13, 24 1.11

- found 13.46 1.02

Br (%) F (%)

- calculated 58.82 20.95 - found 58.21 20.81

EXAMPLE 8 Preparation of 2,3-dibromo-2,3-trifluoro-2,3,3 propanoic acid, BrCF ₂ CFBrCOOH (compound No. 7) Is introduced in portions and with stirring,

20.5 g (129 mmol) of KMnO ₄ in a solution of 22.9 g (84 mmol) of compound No. 6 in 80 ml of acetic acid. We stirred for 24 hours and ended with heating to 60 ° C for one hour. Alternatively, 40 ml of 37.5% sodium bisulfite and 170 ml of 20% sulfuric acid are added in portions to the medium. A clear, colorless solution is obtained. 15 g of salt are introduced before extracting 3 times with CH ₂ Cl ₂ . The organic phase is washed, dried over magnesium sulfate and distilled to remove the solvents and acetic acid. The heavy products are then distilled under a water pump vacuum. Compound No. 7 is collected in the fraction boiling under 20 Torr (2.7 kPa) at 120 ° C., which gives 12 g (42 mmol) of compound No. 7, ie a yield of 51%. Analysis by NMR 1 ⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -55 (dxd, CF ₂ Br, ² J _FF = 184, ³ J _FF = 16 Hz); -58 (dxd, CF ₂ Br, ³ J _FF = 18 Hz);

-124 (dxd, CFBr).

EXAMPLE 9 Preparation of 2,3-dibromo-2,3-trifluoro-2,3,3 methyl propanoate, CF ₂ Br-CFBrCOOCH ₃ (compound n ° 8)

A solution containing 5 g (17.4 mmol) of compound No. 7, 15 ml of absolute methanol and 2 ml of concentrated sulfuric acid is brought to reflux for 5 h. The mixture is allowed to cool, poured into 100 ml of salted water and extracted with ether. The ethereal phase is washed with sodium bicarbonate, with water, and dried. The rectification gives 4.0 g (13.3 mmol) of compound n ° 8 boiling under 15 Torr, 2 kPa at 70 ° C. The yield is 76%.

Analysis by 1 H NMR CDCl ₃ NMR / TMS: δ ppm: 4.1 (s, CH ₃ ).

¹⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -53 (dxd, CF ₂ Br, ² J _FF = 192 Hz, ³ J _FF = 17 Hz) -57 (dxd, CF ₂ Br, ³ J _FF = 17 Hz) -

-123 (t, CFBr).

EXAMPLE 10 Preparation of methyl trifluoroacrylate CF ₂ = CF-COOCH ₃ (compound n ° 9)

7 ml of anhydrous ether, 1.3 g (20 mmol) of powdered Zn and a pinch of hydroquinone are introduced into a distillation column equipped with a receiver cooled to -70 ° C. A solution of 4.3 g (14.3 mmol) of compound No. 8 is dropped on this mixture with stirring in 4 ml of anhydrous ether. The reaction is exothermic.

The mixture is stirred for one hour, then drawn under a slight vacuum (20.2 kPa, 150 Torr) to distill until dry.

The distillate is rectified in the presence of hydroqui none.

1.7 g (12 mmol) of compound No. 9 are obtained, Eb: 80-85 °. The yield is 83%.

Analysis by 1 H NMR CDCl ₃ NMR / TMS: δ ppm: 4.1 (s, CH ₃ ).

¹⁹ F NMR CDCl ₃ / CFCl ₃ : ɸ ppm: -86 (dxd, CF =,

² J _FF = 28 Hz, ³ J _FF = 36 Hz); -98 (dxd, CF =, ³ J _HF = 120 Hz);

-184 (dxd, CF =).

EXAMPLE 11 Preparation of trifluoroacrylic acid,

CF ₂ = CF-COOH (compound # 10).

7 ml of anhydrous ether, 1.5 g (23 mmol) of zinc powder and a pinch of hydroqui none are introduced into a distillation column fitted with an agitator and a receiver cooled to -70 ° C. Was dropped dropwise, with stirring, in this mixture a solution of 6.5 g (22.7 mmol) of compound No. 7 in 4 ml of anhydrous ether. The reaction is exothermic. The mixture is stirred for one hour and then the water pump is drawn under vacuum to dry distillate. The distillate is rectified in presence of hydroqui none, which gives 2.4 g (19 mmol) of compound 10. Eb: around 80 ° C under 15 Torr. The yield is 85%.

Analysis by NMR 1 ⁹ F NMR CDCl ₃ / CFCl ₃ ɸ ppm: -88 (dxd, CF =, ² J _FF = 30Hz, ³ J _FF = 36 Hz); -97 (dxd, CF =, ³ J _FF = 120 Hz);

-182.5 (dxd, CF =).

Claims

CLAIMS 1. 3,3-dihalo-fluoro-2 propenol-1 corresponding to the formula: X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom provided that X ¹ and X ² do not both represent a chlorine atom. 2. 3,3-dihalo-2-fluoro-propenol-1 according to claim 1, characterized in that X ¹ is a fluorine atom and X ² is a chlorine or bromine atom. 3. Process for the preparation of a 3,3-dihalogen-fluoro-2-propenol-1 corresponding to the formula: X ¹ X ³ C = CF - CH ₂ OH (I) in which X ¹ and X ² , which may be identical or different, represent a fluorine, chlorine or bromine atom, characterized in that it consists in treating an alcohol of formula: HCX ¹ X ³ -CFX ³ -CH ₂ OH (II) in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and in separating the dihalo-3 from the reaction medium, 3 fluoro-2 propenol-1 of formula (I) thus obtained. 4. Method according to claim 3, characterized in that R ¹ is the methyl radical. 5. Process for the preparation of a halide of 2-fluoro acrylic acid of formula CH ₂ = CF-COX (III) in which X is a fluorine, chlorine or bromine atom, characterized in that one treats a 3,3-dihalo-fluoro-1-propenol-1 of formula X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² which may be identical or different, represent a fluorine, chlorine or bromine atom, in order to obtain by allylic transposition the 2-fluoro acrylic acid halide of formula (III). 6. Method according to claim 5, characterized in that X represents a fluorine atom and in that at least one of X ¹ and X ² is a fluorine atom. 7. A method according to any one of re ve nd i c a t i o n s 5 and 6, c a r a c t é r i s é e n c e q ue is prepared 3,3-dihalo-fluoro-1 propenol-1 of formula (I) by treating an alcohol of formula: HC X ¹ X ² -CFX ³ -CH ₂ OH (II) in which X ¹ and X ² have the meaning given in claim 5 and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separating from the reaction medium the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained. 8. Process for the preparation of fluoro-2 acid acrylic or its esters of formula: H ₂ C = CF-COOR ² (IV) in which R represents a hydrogen atom, an alkyl radical of 1 to 10 carbon atoms, or an aryl radical, characterized in that it comprises the following stages: a) - preparing a di ha logeno-3,3 fluoro -2 propenol-1 of formula: X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² which may be identical or different, represent a fluorine, chlorine or bromine atom, by treatment of an alcohol of formula: HCX ¹ X ² _-CFx ³ -CH ₂ OH (II) in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separation of the reaction medium from the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained, b) - to be treated in an acid medium, the 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained to obtain by allylic transposition a halide of 2-fluoro acrylic acid of formula CH ₂ = CF-COX (III) in which X is a fluorine, chlorine or bromine atom, and c) - to hydrolyze or esterify the acid halide of formula (III) by reaction with a compound of formula R ² -OH in which R ² has the meaning given above. 9. Process for the preparation of a 3,3-dihalo-2-fluoro acrylic acid of formula: X ¹ X ² C = CF-COOH (V) in which X ¹ and X ² which may be the same or different, represent a fluorine, chlorine or bromine atom, characterized in that it comprises the following successive steps: a) - prepare a 3,3-dihalo-fluorine- 2 propenol-1 of formula: X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² have the meaning given above, by treatment of an alcohol of formula: HC X ¹ X ² -CFX ³ -CH ₂ OH (II) in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine or bromine atom, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separation of the reaction medium from the 3,3-dihalo-2-fluoro-propenol-1 of formula (I) thus obtained, b) - halogenating the dihalo-3,3 fluoro-2 propénol-1 of formula (I) thus obtained by a halogen X ₂ ⁴ to form a tét raha logéno fluoro-2 propanol of formula: X ⁴ X ¹ X ² C-CFX ⁴ -CH ₂ OH (VI) c) - oxidizing the tetrahalo-fluoro-2-propanol of formula (VI) thus obtained to convert it into tetrahalo-fluoro-2-propanoic acid of formula: X ⁴ X ¹ X ² C-CFX ⁴ -COOH (VII) d) - converting the tet raha logeno-fluoro-2-propanoic acid of formula (VII) thus obtained into dihalo-3,3 fluoro-2 acrylic acid of formula (V) by reaction with a reducing metal. 10. Process for the preparation of an ester of 3,3-dihalo-fluoro-acrylic acid of formula: X ¹ X ² C = CF-COOR ³ (VIII) in which X ¹ and X ² which may be identical or different, represent a fluorine, chlorine or bromine atom, and R ³ is an alkyl or aryl radical, characterized in that it comprises the following successive stages: a) - prepare a 3,3-dihalo-fluoro-2-propenol-1 of formula: X ¹ X ² C = CF-CH ₂ OH (I) in which X ¹ and X ² have the meaning given above, by treatment of an alcohol of formula: HCX ¹ X ² -CFX ³ -CH ₂ OH (II) in which X ¹ and X ² have the meaning given above and X ³ is a fluorine, chlorine atom or bromine, identical or different from X ¹ and / or X ² , by an organometallic compound of formula R ¹ Li in which R ¹ is an alkyl radical, preferably from 1 to 4 carbon atoms, and by separation from the reaction medium 3,3-dihalo-fluoro-2-propenol-1 of formula (I) thus obtained, b) - halogenating di-halo-3,3 fluoro-2 propenol-1 of formula (I) thus obtained with a halogen X ₂ ⁴ for form a tetrahalo-fluoro-2-propanol of formula: X ⁴ X ¹ X ² C-CFX ⁴ -CH ₂ OH (VI) c) - oxidize the 2-fluoro-2-fluoro propanol tetraha of formula (VI) thus obtained to convert it into 2-fluoro-2-propanoic tetrahalo acid of formula: X ⁴ X ¹ X ² C-CFX ⁴ - C OO H (VII) d) - esterifying the tetrahalo-fluoro-2-propanoic acid of formula (VII) thus obtained with an alcohol or a phenol of formula R ³ OH in which R ³ has the meaning given above to form the ester of formula: X ¹ X ² X ⁴ C-CFX ⁴ - C OO R ³ (IX) in which X ¹ , X ² , X ⁴ and R ³ have the meaning given above, and e) - convert the ester of formula (IX) thus obtained into ester of 3,3-dihalo-2-fluoro-acrylic acid of formula (VIII) by reaction with a reducing metal.