MXPA98000426A - Procedure for the preparation of alpha, omega-bromocloroalca - Google Patents

Abstract

The present invention relates to a process for the direct preparation of alpha-omega-bromochloroalkane of the formula: Br (CH 2) nCl in which n represents an integer ranging from 3 to 8, of a cyclic ether of the formula (II) : in which n has the same meaning as in formula (I), further characterized by: a) cyclic stethoscope (II) is added, optionally with an amount of water added equal to much to 20 parts by weight per 100 parts in cyclic (II) weight, in contact with gaseous hydrochloric acid and then b) the previous phase obtained in a) in contact with hydrogen bromide gas

Description

PROCEDURE PRRfl Lñ PREPARATION OF ALPHA, OMEGA- BROnOCLQROflLCflNOS DESCRIPTIVE MEMORY The present invention relates to a process for the direct preparation of alpha, omega-brornochloroalkanes to couple + Lr of cyclic ethers. The Jogenoal canos, and more particularly the al fa, omega-brornocloroa. It is widely used as starting materials for the preparation of pharmaceuticals, pesticides and detergents. It has been described many methods to produce these alf, ornega-brornocloroalcanos. It very often involves the reaction of halogens (bromine or chlorine) or their derivatives, such as PBr3 or r- > Br & , with an alpha, ornega-chlorohydroxalkane or alternatively the reaction of halides (bromine or chlorine) or their derivatives, such as OCI2, with a halogenoalkane or an ornega-halogenated acetic acid. British Patent 788,349 describes a process for the preparation of l-brorno-4-chlorobutane which consists of treating in a first stage, THF with dry hydrochloric acid in the presence of ZnCl 2 indications at a temperature reaching approximately 100 ° C and then , in a second stage, in the treatment of 4-cyclo-1-butanol obtain Ldo previously with red phosphorus and then with dry bromine at a temperature of between 0 ° C and -10 ° C. rj obtains 1-brorno-4-chlorobutane with yield of approximately 52% with respect to the THF used. The Patent of E.U.fi. No. 2,839,574 mentions a process for the preparation of 1-bromine-4-chloro-utane which avoids the use of phosphorus or bromine or of SBrβ - This procedure consists in treating 4-chloro-1-butanol predestined with dry gornohydrous acid in presence of a solvent at the boiling point that forms an azeotrope with the water fopnada according to the reaction: C1 (CH2 0H + HBr Br (CH2UCl + H2O.

The yield is approximately 70%. In the Japanese Patent application published with the No. 3P 5791930, L-bromo- -chlorobutane was obtained in a yield of about 90% by treating freshly distilled 4-chloro-l-butanol with Brß formed from sulfur and bromine, according to the reaction scheme: SBr6 + 6 CKCH2 OH 6Br (Cg2) - «Cl + H2 SO4 + 2H20 In the case where SBrβ is reacted with a Unpurified 4-chloro-l-butanol, which originates in particular from a mixture of tet rehydrofuran and hydrochloric acid, the yield of l-brorno-4-chlorbutane is approximately 70%. D.C. Sayles and Ed. F. Degepng (Journal of the American Chernistry Society, 71, page 1162, 1949) describe a method for the preparation of l-brorno-4-c-Lorobutane by treating n-bromobutane with sulfur chloride (SO2CI2) in the presence of peroxide of benzoyl, to reflux of the reactants. The yield of L-brorno-4-chlorobutane is 35%. Srnush evich, Yu. T and others apply the reaction of Borodin-Hunsdiec er to the ornealol-alkanoic acids (Tr. Mosl-Kh, Technol.Inst. No. 61, pp. 47-48, 1969). Be thus obtained, ornega-brornocloroalcanos t-ratando ornega-chloroalcanoicos acids with HgO and bromine in the middle of CCI4 according to the reaction scheme: Cl (CH2) nC00H + Br? Cl (CH2) nBr + CO2 • - HBr It should also be reported that Hahn, Roger C. (Dournal of Organic Chernistry, 53 (6), pp. 1331-3, 1988) describes a method for the preparation of alpha, omega-brornochloroal canos by a halogen exchange reaction. In this way, 1 -bronium ~ 6- ~ chlorhexane is obtained by heating a mixture of n-brornobutane and 1,6-d-chlorohexane in the presence of tet rabutilarnonio bromide according to the reaction scheme: Br (CH2) 3CH3-Cl (CH2) 6Cl Br (CH2) -6Cl •• C] (0H2) 3CH3 All these methods have many disadvantages. They use starting compounds that are often impure, requiring 5 purification operations and reagents that are costly and difficult to handle (P - * bromine, S + bromine). The yields of al fa, omega-brornoalcano are low and the products obtained contain impurities, the removal of which results in difficult and costly separation operations. 10 A procedure has now been discovered for the di ectation of alpha, ornega ~ brornochloroalkane from La forrnuLa Br (CH2) nCl (I) L5 in which n represents an integer that varies from 3 to 8, from a MCIIC ether of the formula (II) 20 wherein n has the same meaning as in the formulas (I) characterized in that: a) said cyclic ether (II) is put, optionally with a quantity of water added and equal to the most to 20 parts by weight per 100 parts by weight of the cyclic ether (II) in contact with the gaseous hydrochloric acid and then b) the previous phase obtained in a) is contacted with gaseous brornhídpco acid. According to the present invention, the amount of water added to the cyclic ether (II) is between 1 part and 15 parts by weight per 100 parts by weight of cyclic ter (TI) used and preferably an amount of and 10 parts by weight . It would not be deviating from the scope of the invention if step a) were carried out without the addition of water. Mention can be made, as an example of a cyclic ether of the formula (TI) that can be used according to the present invention, of the oxide of 1,3-α-pyrolylene (oxetane) tet rahydro furan, tetrahydropyran, I, 6-Hexarnetium Oxide (Oxepane) or 1,7-Heptanetnetium Oxide (Oxocan). The process of the present invention is applicable in particular to the preparation of l-brorno-4-chlorobutane to form tetrahydrofuran. According to the present invention, it is not necessary to isolate and / or purify the alpha, ornega-clorohi droxial cano (ITT) obtained in a) by hydrochlorination of the cyclic ether (II) according to the reaction scheme: + HCl gas H0 (CH2) nCl A (II) (III) Stage b) is carried out by directly reacting the previous phase- obtained in a) containing the intermediate compound (III) with gaseous brornhidpco acid to give as a result the al fa, ornega-bromochloroal cano (I) according to the reaction scheme: H0 (CH2) nCl + HBr Br gas (CH? InCl + H20 B (III) (I) One of the advantages of the invention is clearly evident here; it is not necessary to isolate and purify the intermediate compound to fa, omega-chlorh? drox? alkane (III) obtained in a) before reacting it with gaseous brornhydric acid (step b)). Steps a) and b) of the process according to the invention are carried out at a temperature ranging from room temperature (approximately 20 ° C) to approximately 100 ° 0 and preferably at a temperature varying from 40 ° C to 70 ° C. According to the present invention, the temperatures can be identical or different in the two stages but it is preferable to operate at a single temperature. According to the present invention, step a) is carried out with a molar ratio of HCl gas / cyclic ether of between 1 and 3 and probably between 1.10 and 2 and step b) is carried out with a molar ratio HBr gaseous / cyclic ether of between 1 and 2 and preferably between L.20 and L.60 »The duration of the reaction for each of Steps a) and b) may vary within wide limits but is generally between 2 and 30 hours and preferably between 10 and 25 hours. The reaction can be carried out at atmospheric pH. According to the present invention, gaseous hydrochloric acid is introduced into the cyclic ether, to which water has been optionally added, and then, after completing the introduction, the reaction is continued by directly introducing hydrobromic acid gas to the reaction mixture obtained above. . After the introduction of the HBr is complete, the water formed is removed by sedimenting the reaction mixture and then puri? Ed in alpha, orne-1-methyl bromide, particularly by distillation under reduced pressure. The preparation of alpha, ornega-brOrnochloroalkane according to the process of the invention has the advantage that it is carried out in two successive reaction steps in the same equipment without any purification or separation of the intermediate alpha, ornega-clorh drox? alkane The process of the invention also has the advantage that its solvent is carried out in the absence of a catalyst. The yields of alpha, ornega-bromochloroalkane are high and the products obtained can be easily purified. In certain cases, its purity is such that it makes it possible to use them as they are found. The following examples illustrate the invention.

E3EMPL0 1 Step a 325 g (4.5 moles) of tetrahydrofuran and 16.2 g of water (5% by weight) are introduced, under an inert atmosphere, into a liter glass reactor, equipped with mechanical stirrer (anchor), temperature probe and tube for gas injection, and crowned by a condenser cooled with gil col / water (temperature approximately -20 ° 0). The entire assembly is heated to 55 ° C and then, for 14 hours, 255 g (7 moles) of HCl gas is injected at a decreasing flow rate ranging from 1.5 mmol / h to 0.15 mol / h, while maintaining the temperature of the reaction mixture at 60 ° C. After completing the introduction of HCl, the crude reaction mixture (593 g) contains 2.7% water 14% HCl, 76.5% 4-chloro-l-butanol, 3% 1.4, d? chlorobutane and 1.5% of THF resLdual. In this manner, the THF conversion is greater than 97% of the crude molar yield of 4-chloro-l-butanol is about 93% with respect to the THF used.

Step b After cooling to 50 ° C, 567 g (7 moles) of gaseous HBr is directly infected to the reaction mixture a) obtained previously by stirring it for 20 hours with a decreasing flow rate varying from 0.75 mmol / ha 0.15 rnol / h. During the introduction of HBr, the dissolved HCl above is degassed from the reaction mixture. The progress of the reaction is monitored by a gas phase chromatographic (CFG) analysis. After completing the introduction of the HBr after cooling to room temperature and stopping the stirring, the reaction mixture settles. 280 g of a yellowish aqueous phase are obtained which contains 58% HBr and 728 g of a colorless organic phase, the organic phase containing 91% of 1-bromo-4-chlorobutane, 2.8% of 1, -d? Chlorobutane, 5.8% of 1, 1-dibromobutane and 0.1% residual 4-chloro-1-butanoL result in a crude molar yield of l-bromo-4-chlorobutane of 92.5% with respect to 4-chloro-l-butanol and 86% with respect to the THF used. The l-brorno-4-chlorobutane is then purified by distillation under reduced pressure (30 rnrn Hg) with an adiabatic column containing 20 theoretical plates. After extracting an upper reaction containing the residual 4-chloro-l-butanol, 1,4-d-chlorobutane, distills 584 g with l-brorno-4-chlorobutane with a purity, determined by CFG, of 99.3% , that is to say, with a distillation yield of 97.5%. The result is a slow molar yield of distilled 1-romo-chlorobutane of the order of 75% with respect to the THF used (P.F.30 mi »Hg = 83.5 ° C).

EXAMPLE 2 Step a 325 g of terahydrofuran and 16.2 g of water are introduced to the same equipment as for Example L. The whole assembly is heated to 50 ° C, stirring, and then 365 g of HCl gas is injected for 25 hours at a time. flow rate from 1.5 mmol / h to 0.35 mol / h, while maintaining the temperature of the reaction mixture at 50 ° C. 586.5 g of a crude reaction mixture, a reaction mixture containing 2.8% of water, 12.5% of HCl, 78.5% of 4-chloro-butanol, 2% of 1,4-dichlorobutane, are then obtained. and the L.7% residual THF. The result is a conversion of the THF of the order of 97% and a molar-crude yield of 4-chloro-l-butanol of 94% with respect to the starting THF.

Step b 6.9 moles of HBr gas are then injected directly into this reaction mixture at 50 ° C for 18 h 30 at a flow rate of 0.7 mmol / h to 0.15 mmol / h. After settling and separation, 273 g of an aqueous acid phase and 747 g of an organic phase are obtained, the organic phase comprising 2.2% of 1,4-d-chlorobutane, 5.5% of 1.4 -dibrornobutane and 92. 1% l-brorno-4-chlorobutane. The result is a crude molar yield of L-brorno-4-c Lorobutane of 94.5% with respect to k -chloroley-butanol and of 89% with respect to THF used.

EXAMPLE 3 The preparation is carried out in the same equipment and in accordance with the same conditions as in Example 1, except that step a) s n addition of water is carried out. After completing the introduction of gaseous HC1, the conversion of the THF is 85% and the crude molar yield of 4-chloro-l-butanol is about 82%.

EXAMPLE 4 (Comparative Example) 108 g of tetrahydrofuran (1.5 mol) are introduced and 444 g (4.5 g) of an aqueous solution of 37% HCl at the same time as in Example 1. After heating, stirring, at 65 ~ 70 ° C for 5 hours, the conversion of THF to 4 ~ chloro-L -butanol is 78%. After heating for 6 additional hours, the conversion of THF to 4-cLoro-1-buranol remains below 82%.

Under the conditions of this Example, the second stage of synthesis of l-bromo-4-chlorobu + ano requires first a separation step of the aqueous phase and then a purification step of the crude intermediate 4-chloro-L-butanol, In order to avoid 'excessive formation of 1, 4-d? rornohutano of the residual THF.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - Procedure for the direct preparation of or ~ w-brornocloroalcano of the formula Br (CH2) nCl (I) in which n represents an integer that ranges from 3 to 8, of an ether-cyclic of the formula wherein n has the same meaning as in formula (I), further characterized by: a) said ether-cyclic (II), optionally with an amount of water added equal to a lot to 20 parts by weight per 100 parts by weight of the cyclic ether (II), in contact with gaseous hydrochloric acid and then b) the previous phase obtained in a) is placed in contact with bromidic acid gas.

2. Method according to claim 1, further characterized in that the cyclic ether (II) is tetrahydrofuran.

3. Method according to claim 1, further characterized in that the amount of water added to the cyclic ether (TI) is between 1 part and 15 parts by weight per 100 parts by weight of the ether-cyclic. (II) used.

4. Method according to claim 3, further characterized in that the amount of water added to the ether '(II) is between 5 and 10 parts by weight per 100 parts by weight of the cyclic ether (II) used.

5. Method according to one of claims 1 to 4, further characterized in that, in step a) the molar ratio HCl gas / cyclic ether is between 1 and 3 and because, in step b), the molar ratio The gaseous HBr / cyclic ether is between 1 and 2.

6. Process according to claim 5, further characterized in that the gas / gas HC1 / cyclic ether ratio is between 1.10 and? and because the molar ratio HBr gaseous / ether cyclic is between 1.20 and 1.60.

7. Method according to one of claims 1 and 6, further characterized in that steps a) and b) are carried out at a temperature ranging from room temperature to approximately 100 ° C.

8. Method according to claim 7, further characterized in that steps a) and b) are carried out at a temperature ranging from 40 ° C to 70 ° C.