MXPA97003951A - Procedure for the preparation of halogenodifluoroacetatos de alqu - Google Patents

Abstract

The invention relates to a process for the preparation of alkyl halogenodifluoroacetates, this process consists in reacting a 1,1-difluoroethetrahaloethane with an alcohol in the presence of oxygen and a chemical radical initiator

Description

PROCEDURE FOR THE PREPARATION OF RENTED HFLLOGENODIFLUOROFLUTE DESCRIPTIVE MEMORY The present invention relates to a process for the direct preparation of alkyl halogenodi luoroacetates by the reaction of 1, 1- < 1? Fl uorotetrah loetanos with an alcohol. The halogenodi luoroacetatos of alkyl are intermediates in the synthesis of pharmaceutical and plant protection products. Many methods for obtaining these alkyl halogenodifluoroacetates have been described. Typically, these methods use the reaction of an alcohol with a halogenodifluoroacetic acid or preferably with the corresponding fluorides and chlorides. These halogenodi luoroacetyl halides (fluoride or chloride) can be obtained according to a variety of techniques. The patent of E.U.A. No. 5,259,938 describes a process for the preparation of halohalogenodifluoroacetyl chloride IKCF2) nC0Cl, wherein M = F or Cl and n goes from 10, by photochemical oxidation and in the presence of chlorine, of compounds of formula IKCF2) nCH? Cly with x = 1 or 2, as long as x + y = 3.

In Journal of Organic Che istry, 33 (2) pp. 816-9, (1968) describes a process for obtaining access to brodifluoroacetyl chloride, the following steps including this procedure: THF b blot CF2 = CF2 + NaOCH3 > CF2 = C (F) (0CH3) > > CF2 B rCF B rOCH3 CF2BrCFBrOCH3 + 2CI O3H > CF2BrC (0) CI The final yield of CF2BrC (0) Cl relative to tetraf luoroethylene C2F4 is less than 30%. The difluorohaloace + ilo fluorides can also be obtained from C2F4. In particular, bromodifluoroacetyl fluoride can be obtained according to the following steps described in the Japanese patent application published under No. JP 82 40434: CF2BrC 2Br (obtained according to CF2) + SO3 (or H? O3F) gives an intermediate containing the group BrCF2CF2? S02-. This intermediate is heated with H2SO4 or KF / sulfolane and leads to fluoride fluorifluoroacetyl CF2BrC (0) F. However, the most frequently cited methods are to carry out a sulfuric hydrolysis, in the presence of mercuric salts, of 1, 1-difluorotetrahaloethanes such as CF2BrCFClBr, CF2CICCI3. In this way, D. Morel a F. Da ans (Tetrahedron, 33 (12) pp. 1445-7) mention that the 1,2-dibro oclorot i luoroethane obtained by the brightening of cío rot p luoroeti le, is hidroli in a medium oil in the presence of HgO according to the reaction: oil CF2BrCFClBr > CF2BrC (0) F HgO With 30-40% oil, the amount of HgO used to activate the reaction is approximately 1% by weight in relation to CF2BrCFClBr. If the concentration of oil is greater than 60%, mercury oxide can be dispensed with. DE 1,020,970 describes the preparation of 0F2C1C (0) C1 according to an analogous method, which consists in treating CF2ClCClBr2 with an oil in the presence of HgS0 «at a temperature in the region of 50 ° C, according to the reaction: HgS04 CF2ClCClBr2 + oil (65) % S03) > S02 + CF2C1C (0) C1 50-60 ° C CF2C1C (0) C1 can be purified by catalytic chlorination in the gas phase and then separated by fractional distillation. It should also be noted that olefin oxides such as tetra-luoroethylene oxide or F2C-CCI2 / 0 can be used as starting materials. Patent EP 380,129 describes the preparation of CF2BrC (0) F according to the reaction: activated carbon F2C -CF2 + Et3SlBr > CF-2BrC (0) F \ / -196 ° C 0 Finally, it is pointed out that Chang-Ming Hu et al. (Journal of Fluorine Chernistry, 49 (1990) pp. 275-280) have described an almost general method, which converts a haloethane to the corresponding acid by reacting stoichiometric quantities of poly fluoroperhaloalkane and a redox couple consisting of ammonium persulfate and sodium formate. In this way, 1, 1-difluorote elo oe is not converted to chlorodifluoroacetic acid according to the reaction: CF2CICCI3 + (NH1) 2 S20ß + HC0ßNa, 2H20 CF2C1C00H (66.5% yield - 100% conversion). The reaction is carried out at 30 ° C in DMF medium with air bubbled through it. Once the reaction is complete, the medium is poured into water and the highly acid solution is extracted with ether. The ether extract is neutralized with aqueous NaHC 3 solution. The aqueous phase is evaporated to dryness and the residue (CF.sub.2? LC? 2 a) is raised in concentrated H2SO4 and subsequently distilled. All these methods have many disadvantages. These normally use corrosive reaction media (oil-H2SO4"concentrated"), environmentally hazardous catalysts (mercury salts) or others may make use of reactions that are prone to release corrosive gases such as HF. This implies, on the one hand, specific and expensive items of equipment (metallic coating of PVDF or PTFE), and, on the other hand, complex treatments of the effluents if it is desired to protect the environment. Furthermore, it should be noted that it is difficult to have access to certain starting materials or they are dangerous to handle, requiring very specific equipment items. The process which forms the subject matter of the present invention makes it possible to directly obtain, in a simple manner and in high yields, starting with readily accessible reagents, the alkyl halogenodi luoroacetates of formula in which X represents a fluorine, chlorine, bromine or iodine atom, R represents a linear or branched aliphatic hydrocarbon radical having a carbon number on the scale of 1 to 10, and preferably on a scale of 1 to 8, this process is further characterized because it consists of: 1 / placing a 1.1 -difluorotetrahaloethane of the formula: CF2XCY2Z (II) in which X has the same meaning as in the formula (I), Y and Z, which may be identical or different, represent a bromine, chlorine or iodine atom, in contact with alcohol ROH (III), R having the same meaning of formula (I), according to a molar ratio ROH / CF2 XCY2Z of not more than 30 and preferably between 5 and 20, in the presence of oxygen and a lower molar quantity p of at least one free radical chemical initiator; 2 / heating the reaction medium obtained in step 1 / to a temperature at least equal to 40 ° C and preferably between 60 ° C and 80 ° C; 3 / introduce continuously or by successive additions, although at the same time maintaining the temperature of step 2 / and always in the presence of oxygen, a molar quantity greater than at least one free radical chemical initiator for which the molar ratio? + q / CF2XCY2Z is between 0.01 and 0.2 and preferably between 0.05 and 0.1; 4 / cooling the reaction medium to room temperature and subsequently extracting a crude product by distillation of said reaction medium, subsequently subjecting said crude product to distillation in the presence of an aliphatic, cycloaliphatic or aromatic solvent; 5 / recover the alkyl halogenodifluoroacetate (I). According to the present invention, it is understood that the term crude product refers to a mixture consisting of water, excess ROH, the alkyl halogenodifluoroacetate (I), the unconverted 1,1-di luorotetrahaloethane (II) and several by-products. This crude product represents at least 60% and preferably 70% by weight of the reaction medium. By way of illustration of the 1,1-difl? Orotetrahaloetanes (II) which can be used according to the present invention, mention may be made of the compounds of the formula: CF2BrCCl2Br, CF2CICCI2I, CF2BrCCl2l, CF3CBr3.

All these compounds are obtained in a known manner and do not form the material of the present invention. A departure from the scope of the invention would not be considered if step 1 / were carried out in the presence of water. This amount in water can vary within a wide range and can be up to 50% of the total mass of the reagents. By way of illustration of ROH of alcohol that can be used according to the present invention, mention may be made of methanol, ethanol, isopropanol, propanol, n-butanol or 2-ethylhexanol. By way of illustration of a free radical chemical initiator that can be used according to the present invention, mention may be made of hydrogen peroxide, organic peroxides such as benzoyl peroxide, lauroyl peroxide, acetylcyclohexane sulfonyl peroxide, isobutyryl peroxide , dichloroacetyl peroxide, trichloroacetyl peroxide; organic hydroperoxides such as tert-butyl hydroperoxide, ter-amyl hydroperoxide, eumeno hydroperoxide, para-rnentane hydroperoxide; peroxydicarbonates such as ethyl peroxydicarbonate, ethylexyl peroxydicarbonate, isopropyl peroxydicarbonate, but isobutyl idicarbonate, cetyl peroxydicarbonate, cyclohexyl peroxydicarbonate, myristyl peroxydicarbonate, tert-butylcyclohexyl peroxydicarbonate; ter-butyl perneodecanoate, which is a perneodecanate; tert-butyl lacetate permeate; tei-butyl perexyacetate; azo compounds such as 2,2'-azob? s (2,4-d? met? lvalero-rutp lo), 1, 1-azob? (cyclohexanecarbomtplo), azobisi isobutyronitrile) and 2,2'-azob? s (2-met? lbutyl? tplo.) Among these chemical initiators it is preferred to use azo compounds such as azobis (isobutyrronic acid). mentioned co or filBM or 2,2 '-azob? s (2-met? lb? t? ron? rilo) mentioned as AMBN. It is very particularly preferred to use AMBN. According to the present invention, identical or different free radical chemical initiators can be used in steps 1 / and 2 /, but preferably an identical initiator will be used. In accordance with the present invention, it is understood that the term "lower molar amount p" of a free radical initiator refers to a molar amount that is not greater than 40% and preferably between 10% and 20% of the molar amount total p + q used in steps 1 / and 3 / of the procedure. As a solvent that can form an azeotrope with ROH and / or water, any non-alcoholic solvent can be used which should not be reactive towards reactants (II) and (III) or have an influence on the products formed (I). It must also be totally inert under the operating conditions of the distillation. By way of illustration of such solvents that can be used in accordance with the present invention, mention may be made of linear paraffins such as hexane and heptane, cycloparates such as cyclohexane and cycloheptane, and aromatics such as toluene, benzene, energetic and xylenes. . According to the present invention, a weight amount of solvent of between 50% and 200%, and preferably an amount of between 60 and 100% relative to the crude product that will be used will be used. According to a variant of the procedure it is possible to proceed by adding, in step 1 /, a solvent that is identical or different to that used in step 4 / .. In this variant, the extraction operation is replaced by the distillation of the crude product that comes from the reaction medium. In accordance with the present invention, the duration of step 3 / may vary within a wide range. This is at least equal to 1 hour and preferably between 6 hours and 24 hours. In accordance with the present invention, the reaction is carried out in the presence of oxygen or air, or alternatively oxygen enriched air, or again alternatively in an inert gas such as nitrogen or argon enriched with oxygen. According to the present invention, the process will be carried out with a molar amount of oxygen at least equal to 1 mole per mole of the (II) used. The process is generally carried out at atmospheric pressure (105 Pa), but would not constitute a departure from the scope of the invention if a different pressure were used. The invention applies in particular to the preparation of ethyl brodifluoroacetate, ethyl chlorodi-fluoroacetate and ethyl trifluoromethate. In general, the products of formula (I) are prepared in any device that allows a good dispersion of the oxygen in the reaction medium. The procedure will be carried out more particularly in a vertical (glass) cylindrical reactor equipped with a cover in which a heat exchange fluid or a coolant can be circulated, equipped with an upward condenser connected with a hydraulic protection, a submerged tube, a point to measure the temperature and a point of introduction, and the base of which consiete a porous plate through which oxygen diffuses into the reactor. The porosity of the plate at the base of said reactor is such that it allows a good diffusion of oxygen into the reaction medium. Said reactor may optionally be equipped with an agitator or alternatively a loop recirculator. The products of formula (I) are advantageously prepared according to the following procedure. He 1,1-difluorotetrahaloethane (II), the alcohol ROH (III), a p amount of free radical chemical initiator and optionally water, they are introduced into a reactor as described above and under an oxygen stream (said oxygen reaching the base of said reactor and crossing the porous plate at the base of the reactor). The reactor medium is heated but still remains under a stream of oxygen. The quantity q of free radical chemical initiator is subsequently introduced continuously or by successive additions. Once the addition is complete, the reaction medium is cooled and then a first distillation is carried out, which allows a crude product as defined above to be extracted from the reaction medium. Next, this crude product is subjected to distillation in the presence of a solvent capable of forming one or more azeotropes (binary and / or ternary azeotropes) with water and / or alcohol.

Then, the residue of this distillation is subjected to purification to recover the alkyl halogenodifluoroacetate (I). This purification usually consists in carrying out distillation under reduced pressure. The unconverted reagents, in particular such as the alcohol ROH and the solvent can be recycled. The products are analyzed by gas chromatography and identified by means of nuclear magnetic resonance. The process forming the subject matter of the present invention makes it possible to obtain alkyl halogenodifluoroacetates (I) directly, under mild operating conditions, by simple reaction between a 1,1-d? Fluorotethalohateethane and? N alcohol, with a high conversion of the 1,1-difluorotetrahaloethane in ester. In addition, the effluents consist of products that can be optionally recycled, in particular such as solven e. The following examples illustrate the invention.

EXAMPLE 1 An air stream is introduced at a flow rate of 8 1 / ha through a disperser into a 430 ml tubular reactor equipped with a cover in which a heat exchange fluid circulates, a gas disperser in its base (concreted glass), a gas inlet in the lower part of said reactor, a condenser connected to a cooled collector, a dropping funnel, a temperature probe and a supply pipe, after which it is successively introduced. following: -74.03 g (ie 0.253 mol) of CF2BrCl2Br, -174.5 g (ie 3.789 mmol) of ethanol, which corresponds to a molar ratio of ethanol / CF2 BrCCl Br equal to approximately 15, and -486 mg of 2.2 'azob? e (2-meti Ib? ti roni rilo), mentioned later in the present as AMBN, as free-radical chemical initiator. The mixture is heated to 70 ° C by means of an oil circulating in the cover. The air flow rate of 8 i / h and the temperature of 70 ° C are maintained for 12 hours, during which time 486 g of AMBN are added every 2 hours, that is, 5 x 486 - 2.430 g of AMRN (0.0126) mol). This corresponds to a molar ratio of? Nc? Ador / CF2 BrCCl2 Br equal to: 0. 0025 - 0.0126 - 0.0596 0.253 The progress of the reaction is monitored by determining the conversion of CF2BrCCl2Br by gas chromatographic analysis (GC) of samples taken from the reaction medium. The results are reported below: Reaction time Conversion of CF2BrCCl2 r (or ra s) (%) 1 24 5 65 12 91 The reaction medium is cooled to room temperature. 236.4 g of a mixture are obtained, which is subjected to distillation in an adiabatic column of 20"Oldershaw" plates equipped with a time controller. The temperature at the base of the column is brought to 88 ° C, the column is allowed to equilibrate and a crude product is removed from the head of the column with a reflux of 9/1, to a temperature of 77.5 ° C. After 8 hours 50 minutes of distillation, it is stopped. 165.5 g of crude product are obtained (about 70% by weight of the reaction mixture subjected to the distillation), which consists of ethanol (40% by weight), brornodi fluoroacetate of ethyl (19.57% by weight), water, etc. This crude product is subjected to a second distillation in the presence of 100 g of cyclohexane to remove water and ethanol. The same previous column is used. The head of the column is equipped with a time controller and a Florentine flask to recycle the organic phase (cyclohexane). The temperature at the base of the column is brought to 90 ° C and let the column equilibrate. The ternary azeotrope of ag? A / ethanol / cyclohexane is distilled at the head of the column at a temperature of 62.1 ° C, after which the binary azeotrope of ethanol / cyclohexane is distilled at 64.9 ° C with a reflux of 9 / 1. The cyclohexane is distilled in excess. The ethyl bromodi luoroacetate (EBDFA) obtained at the base of the column, with a purity of about 95%, is subjected to an additional distillation under reduced pressure. 34 g of ethyl bromodi fluoroacetate are obtained by distilling at 57 ° C / 58 ° C at a pressure of 133.32 Pa (100 m Hg).

The purity determined by GC is 98.5%. The molar yield of the obtained ethyl bromodi f uoroacetate (purity: 98.5%) is 68% relative to the CF2BrCCl2Br used. Ethyl bromodi fluoroacetate was identified by nuclear magnetic resonance (NMR) of proton HH), carbon 13 (13C) and fluorine 19 (* 9F) in a Brücker AC300 rn? Ltinuclear type machine (frequencies for 1H = 300.13 MHz, for 13Q = 75.47 MHz and for? * F = 282.4 MHz). Identification of NMR of a b c d CF2CICOCH2CH3 NMR spectrum of 13C (solvent = CDCl3) gives = 108.8 ppm db = 159.5 ppm dc = 64.5 ppm dd = 13.5 ppm NMR spectrum of? * F (solvent = CDCI3 / external parameter: trifl? oroacetic acid) d (CF2Br) = -16.8 ppm coupling constant JC-F = 314 Hz coupling constant JC-F = 31 Hz NMR spectrum * H (solvent = CDCI3 / internal parameter: tetramethylsilane) d (CH2) = 4.4? pprn d (CH3) = 1.40 ppm EXAMPLE 2 The procedis carried out in the same apparatus as in example 1. A stream of air is injected at a flow rate of 8 1 / ha through the dispenser, after which the following are introduced successively: -38g (ie 0.130 mol) of CF BrCCl2Br, -87.2 g of 1,893 mol) of ethanol, which corresponds to a molar ratio of ethanol / CF2 rCCl2Br equal to 14.56, and 242.5 mg (i.e. 0.0013 mol) of AMBN. The mixtis heated to 70 ° C by means of an oil circulating in the cover. The air flow velocity of 8 1 / h and the temperatd 70 ° C are maintained for 12 hours, during which time 15.15 g of an ethanol solution of AMBN are injected continuously at a rate of 1,262 g / h. ** This solution consists of 1,248 g (i.e. 0.0065 mol) of AMBN, 9.7 g of ethanol and 4.2 g (i.e. 0.143 mol) of CF2BrCCL2Br. This corresponds to a molar ratio of initiator / CF2BrCCl2Br equal to: 0.0013 + 0.0065 0.130 + 0.014 = 0.0542 As in Example 1, the progress of the reaction is monitored by determining the conversion of CF2BrCCl2Br by GC analysis of samples taken from the medium. reaction. The results are reported below: Reaction time Conversion of CF2BrCCl2Br (hours) (%) 1 18 5 45 12 72 The reaction medium is cooled to room temperat 131.5 g of a mixtare obtained, which is treated according to the distillation conditions of example 1. The crude product obtained after the first distillation (93 g) is subjected to a second distillation in the presence of 60 g of cyclohexane. The ethyl bromodifluoroacetate obtained after distillation under reduced presshas an identical purity to that obtained in example 1. 14.25 g of ethyl bromodi luoroacetate are obtained, which corresponds to a molar yield of 54% relative to CF2B CCl B total used.

EXAMPLE 3 The process is carried out in the same apparatus as in example 1 and in accordance with identical operating conditions, except that 95% ethanol is used. Amount of reagents used: -37.12 g (i.e. 0.127 mol) of CF2BrCCl2Br, -93.21 g of 95% alcohol, which corresponds to 88. 55 g of 100% ethanol, that is, 1922 rnol and 4.66 g of water, -242.5 rng (i.e. 0.0013 mol) of AMBN. The air flow rate is 8 1 / h, the temperatis 70 ° C and the reaction time is 12 hours, during which 242.5 mg of AMBN are added every 12 hours. This corresponds to a molar ratio of initiator / CF2BrCCl2Br equal to: 0.0013 + 5 x 0.0013 0.127 = 0.0614 The progress of the reaction is monitored by terminating the conversion of CF2BrCCl2Br as in the previous examples. The results are reported below: Reaction time Conversion of CF2BrCCl2Br (hours) (%) 1 35 3 48 5 65 7 79 9 87 12 99 The reaction medium is cooled to room temperat 119 g of a mixtare obtained, which is treated according to the distillation conditions of example 1. The crude product obtained after the first distillation (about 85 g) is subjected to a second distillation in the presence of 70 g of cyclohexane . After distillation under reduced press 15.2 g of ethyl bromodi fluoroacet to a purity equal to about 98% are obtained, which corresponds to a molar yield of 59% relative to the CF2BrCCl2Br used.

EXAMPLE 4 The procedure is carried out in the same apparatus as in example 1. A stream of air is injected at a flow rate of 8 1 / ha through the disperser and the following is introduced successively: -37.21 g (ie 0.127 mol) of CF2BrCCl2Br, -114.08 g i.e. 1.90 mol) of isopropanol, which corresponds to a molar ratio of? Sopropane) / CF2 BrCCl2 Br of 14.96; and -244.6 gd.e. 0.00127 mol) of AMBN. The mixture is heated to 70 ° C by means of an oil circulating in the cover. The air flow velocity of 8 1 / h and the temperature of 70 ° C are maintained for 7 hours, during which time 242.6 mg of AMBN are added every 10 hours, ie 3 x 242.6 = 727.8 mg of AMBN (0.00379 mmol). ). This corresponds to a molar ratio of? N? C? Ador / CF2 BrCCl2 Br equal to: 0.00127 * 0.00379 0.127 = 0.0398 As in example 1, the progress of the reaction is determined by determining the conversion of CF2BrCCl2Br by GC analysis of samples taken from the reaction medium. The results are reported below: Reaction time Conversion of CF2BrCCl2Br (hours) (%) 1 48 3 70 5 90 7 98 2.1 The reaction medium is cooled to room temperature. 142.3 g of a mixture are obtained, which is treated according to the distillation conditions of example 1. The crude product obtained after the first distillation (99.6 g) is subjected to a second distillation in the presence of 70 g of toluene . The isopropyl bromodi luoroacetate obtained after distillation under reduced pressure has a purity of more than 99%. 19.7 g of isopropyl bromodifluoroacetate were obtained, which corresponds to a molar yield of 71% relative to the CF2BrCCl2Br used.

EXAMPLE 5 The procedure is carried out in the same apparatus as in example 1. A stream of air is injected at a flow rate of 16 1 / ha through the disperser, after which the following is introduced successively: - 35.31 g ( ie 0.12 mol) of CF2BrCCl2l, 82.84 g (ie 1.8 rnol) of ethanol, which corre- sponds to a molar ratio of ethanol / CF2BrCCl2 I of 15; and - 0.1157 mg (i.e. 0.0006 mol) of AMBN. The mixture is heated to 71 ° C.

? The air flow rate of 16 l / h and the temperature of 71 ° C are maintained for 2 hours, during which time 0.1157 g of AMBN is added every 30 minutes, that is, 3 x 0.115? = 0.3471 g of AMBN (0.0018 mol). This corresponds to a molar ratio of? N? C? Ador / CF2BrCCl2 I equal to: 0.0006 + 0.0018 0.1195 - 0.020 The conversion of F2 rCCl2l after 2 hours is from 81%. The reaction medium is cooled to room temperature. 117.1 g of a mixture are obtained, which is treated according to the distillation conditions of example 1. The crude product obtained after the first distillation (82 g) is subjected to a second distillation in the presence of 60 g. of cyclohexane. The style chlorodifluoroacetate obtained after distillation under reduced pressure has a purity of about 99% (determined by GC). The molar yield of the obtained ethyl chlorodifluoroacetate (purity: 99%) is 65% relative to the CF2BrCCl2l used. The ethyl chlorodi fluoroacetate was identified by NMR of isc, I »F and * H.

Identification of abe NMR CF2CICOCH2CH3 II O NMR spectra of 13C (solvent - CDCI3) gives = 116.9 pprn db = 159.2 pprn dc - 64.5 ppm dd = 13.7 ppm NMR spectrum of 19F (solvent = CDCI3 / pair external meter TFA) d (CF_2Cl) = -15.4 ppn JlC-F = 300 Hz J2C_F = 34.5 HZ NMR spectrum of IH (solvent = CDCI3 / internal parameter TMS) d (CH2) = 4.4 pprn d (CH3) = 1.4 ppm

Claims (9)

NOVELTY OF THE INVENTION CLAIMS

1. - A process for the preparation of alkyl halogenodifluoroacetates of formula: wherein X represents a fluorine, chlorine, bromine or iodine atom, R represents a linear or branched aliphatic hydrocarbon radical which has a carbon number on the scale of 1 to 10, further characterized because it comprises: / placing a 1, 1-difl? orotetrahaloethane of the formula: CF2XCY2Z (II) in which X has the same meaning as in the formula (I), Y and Z, which may be identical or different, represent a bromine atom , chlorine or iodine, in contact with? n ROH of alcohol (III), having R the same meaning as in formula (I), according to a molar ratio ROH / CF2 XCY2Z of not more than 30 and preferably between 5 and 20, in the presence of oxygen and a minor molar quantity p dβ, at least one free radical chemical initiator; 2 / heating the reaction medium obtained in step 1 / to a temperature at least equal to 40 ° C and preferably between 60 ° C and 80 ° C; 3 / introduce continuously or by successive additions, keeping the temperature of step 2 / and always in the presence of oxygen, a molar quantity greater than at least a free radical chemical initiator so that the molar ratio p + / CF2XCY2Z is between 0.01 and 0.2 and preferably between 0.05 and 0.1; 4 / cooling the reaction medium to room temperature and subsequently extracting a crude product by distillation of said reaction medium, subsequently subjecting said crude product to distillation in the presence of an aliphatic, cycloaliphatic or aromatic solvent; 5 / recover the alkyl halogenodi luoroacet (T).

2. A process according to claim 1, further characterized in that 1,1-difluorotetrahaloethane (II) is CF BrCCl2Br or CF2BrCCl2l.

3. A process according to claim 1, further characterized in that the alcohol ROH (III) is ethanol or isopropanol.

4. A process according to one of claims 1 to 3, further characterized in that the free radical chemical initiator is an azo compound.

5. A process according to claim 4, further characterized in that the azo compound is 2, 2'-azobis (2-methylbutyryltrifuge) 6.- A method according to claim 1, further characterized by the lower amount of nitrogen The free radical initiator is not greater than 40% and preferably between 10% and 20% of the total molar amount p + q used 7. A process according to claim 1, further characterized in that the solvent is cyclohexane or toluene 8. A process according to one of claims 7, further characterized in that it is carried out in the presence of ane 9. A method according to claim 1, further characterized in that it is carried out in the presence of of water.