Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1998-05-05
1999-11-09
Siegel, Alan
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
570259, 570261, C07C 1700, C07C 1900
Patent
active
059818158
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the direct preparation of .alpha.,.omega.-bromochloroalkanes from cyclic ethers.
Haloalkanes, and more particularly .alpha.,.omega.-bromochloroalkanes, are widely used as starting reactants for the preparation of pharmaceutical, pesticidal and detergent products.
Many methods have been described for producing these .alpha.,.omega.-bromochloroalkanes.
They most often involve the reaction of halogens (bromine or chlorine) or of their derivatives, such as PBr.sub.3 or SBr.sub.6, with an .alpha.,.omega.-chlorohydroxyalkane or alternatively the reaction of halogens (bromine or chlorine) or of their derivatives, such as SOCl.sub.2, with a haloalkane or an .omega.-haloalkanoic acid.
British Patent 788,349 describes a process for the preparation of 1-bromo-4-chlorobutane which consists in treating, in a first stage, THF with dry hydrochloric acid in the presence of traces of ZnCl.sub.2 at a temperature which reaches approximately 100.degree. C. and then, in a second stage, in treating the 4-chloro-1-butanol obtained above with red phosphorus and then with dry bromine at a temperature of between 0.degree. C. and -10.degree. C. The 1-bromo-4-chlorobutane is obtained with a yield of approximately 62% with respect to the TEF used.
U.S. Pat. No. 2,839,574 mentions a process for the preparation of 1-bromo-4-chlorobutane which avoids the use of red phosphorus and of bromine or of SBr.sub.6. This process consists in treating predistilled 4-chloro-1-butanol with dry gaseous hydrobromic acid in the presence of a solvent at boiling point which forms an azeotrope with the water formed according to the reaction:
In the Japanese patent application published under No. JP 5791930, the 1-bromo-4-chlorobutane was obtained with a yield of approximately 90% by treating freshly distilled 4-chloro-1-butanol with SBr.sub.6 formed from sulphur and bromine, according to the reaction scheme: SO.sub.4 +2H.sub.2 O
In the case where SBr.sub.6 is reacted with an unpurified 4-chloro-1-butanol, arising in particular from a mixture of tetrahydrofuran and hydrochloric acid, the 1-bromo-4-chlorobutane yield is approximately 70%.
D. C. Sayles and Ed. F. Degering (Journal of American Chemistry Society, 71, page 3162, 1949) describe a method for the preparation of 1-bromo-4-chlorobutane by treating n-bromobutane with sulphuryl chloride (SO.sub.2 Cl.sub.2) in the presence of benzoyl peroxide, at reflux of the reactants. The 1-bromo-4-chlorobutane yield is 35%.
Smushkevich, Yu. I et al. apply the Borodin-Hunsdiecker reaction to .omega.-chloroalkanoic acids (Tr. Mosk. Khim. Technol. Inst. No. 61, pp 47-48, 1969).
They thus obtain .alpha.,.omega.-bromochloroalkanes by treating .omega.-chloroalkanoic acids with HgO and bromine in CCl.sub.4 medium according to the reaction scheme: +HBr
All these methods have many disadvantages. They use starting compounds which are often impure, requiring purification operations, and reactants which are expensive and difficult to handle (P+bromine, S+bromine).
The .alpha.,.omega.-bromochloroalkane yields are low and the products obtained contain impurities, the removal of which results in difficult and expensive separation operations.
A process has now been found for the direct preparation of .alpha.,.omega.-bromochloroalkanes of formula of formula ##STR1## in which n has the same meaning as in the formula (I), characterized in that:
a) the said cyclic ether (II) is brought into contact with gaseous hydrobromic acid and then
b) the phase obtained above in a) is brought into contact with thionyl chloride (SOCl.sub.2) and a compound containing an N-alkylated or N-dialkylated carboxylic acid amide group.
Mention may be made, as an example of a cyclic ether (II) which can be used according to the present invention, of 1,3-propylene oxide (oxetane), tetrahydrofuran, tetrahydropyran, 1,6-hexamethylene oxide (oxepane) or 1,7-heptamethylene oxide (oxocane).
The process of the present invention applies very particularly to the preparation of 1-bromo-4-chlorobutane from tetrahydrofuran.
REFERENCES:
patent: 2218018 (1940-10-01), Cass
patent: 2852532 (1958-09-01), Hamel
patent: 3406212 (1968-10-01), Christie et al.
Drivon Gilles
Ruppin Christophe
Elf Atochem S.A.
Siegel Alan
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