Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1996-01-11
1996-12-17
O'Sullivan, Peter
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
548561, 549 74, 549426, C07C21300
Patent
active
055855202
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP94/02239, filed 8 Jul. 1994.
The present invention relates to an improved process for preparing O-substituted hydroxylammonium salts of the general formula I -alkyl and R.sup.1 is phenyl, thienyl, furanyl or pyrrolyl which, if desired, are substituted or a radical --CR.sup.2 .dbd.CR.sup.3 R.sup.4, R.sup.2, R.sup.3 and R.sup.4 independently of one another being hydrogen, halogen or C.sub.1 -C.sub.4 -alkyl, ##STR2## with water and a mineral acid H--L with continuous removal of the acetone formed in this process.
O-Substituted hydroxylamines can be prepared, inter alia, by acidic hydrolysis of O-substituted acetone oxime ethers at boiling point. For example, DE-A 36 31 071 thus discloses a process for hydrolyzing acetone oxime ethers of the compound II type with hydrochloric acid, which is carried out in a continuously operated reaction column. For this purpose, however, an expensive special apparatus is necessary.
Substantially more economical processes are those, however, which can be carried out in standard apparatuses:
For example, Behrend et al. (Liebigs Ann. Chem. 257 (1890), 203), prepared benzyloxyamine hydrochloride in 50% yield.
Borek et al. (J. Am. Chem. Soc. 58 (1936), 2020) synthesized carboxymethylenoxyamine hydrochloride in 50% yield.
Holland et al. (J. Chem. Soc. 1948, 182) obtained diethylaminoethylenoxyamine according to this method, but they do not indicate any yield.
Brossi et al. (Heterocycles 20 (1983), 839) obtained 3'-(2,4,5-trichlorophenoxy)propyloxyamine hydrochloride by hydrolysis of the corresponding acetone oxime ether in ethanolic hydrochloric acid. The yield, however, was only 47%.
A disadvantage of these known processes, however, is the unsatisfactory purity of the products. The interfering by-products result mainly from the partial decomposition of the desired hydroxylamine derivatives under the reaction conditions required (for this also see Zech and Metzget in Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry), Vol. 10/1, 4th Edition 1971, p. 1186). Apart from the additional purification step, the processes are also not very viable industrially because of the low yield of the product of value.
The earlier German Application DE-A 42 33 333 describes a process for the synthesis of O-alkylhydroxylammonium salts containing short-chain alkyl radicals. The hydrolysis of the acetone oxime ether is carried out here using concentrated hydrochloric acid in a two-phase system using nonpolar solvents such as xylene, toluene and cyclohexane. This process is suitable, however, only for the synthesis of relatively polar O-alkylhydroxylammonium salts. It is not suitable for the synthesis of the less polar compounds II, which would dissolve in the solvent. The reaction times in this case are very long due to phase transition.
Org. Synth., Coll. Vol. 3, p. 172 discloses the hydrolysis of acetone oxime O-(methoxycarbonylmethylene) ether with aqueous hydrochloric acid with simultaneous removal of the by-product acetone by distillation. Hydrolysis is carried out at 100.degree. C. The yields are 66-72%. This method, however, is also not suitable for the synthesis of the compounds I, as the O--allyl-- and O-benzyl-substituted hydroxylammonium salts I are not stable at above 50.degree. C. As a result of cleavage of the N--O bond, ammonium chloride would be formed as a by-product, which would only have to be separated off again in a subsequent purification step. At above 100.degree. C., the decomposition of the compounds II can even take place explosively. A high yield of I can in any case not be achieved according to this process.
It was therefore the object of the present invention to provide an improved process with which the O-substituted hydroxylammonium salts I can be prepared in good yield and with very high purity.
Accordingly the present process has been found, which comprises carrying out the hydrolysis batchwise at 0.degree.-50.degree. C. and under a pressure of 10-500 mbar.
The reaction is particularly advantageously carried out
REFERENCES:
patent: 5382685 (1995-01-01), Klein et al.
Liebigs Am. Chem., vol. 257, pp. 203-247, Mar. 1890.
J. Am. Chem. Soc., vol. 58, pp. 2020-21, 1936.
J. of Chem. Soc., pp. 182-186, 1948.
Heterocycles, vol. 20, pp. 839-843, 1983.
Houben-Weyl, Methoden der Org. Chem., vol. 10/4, 4th Ed., 1968, pp. 265-273.
Chem. Abst., vol. 109, 1988, Abs. No. 8922s (Abstract of CS-A 243 595).
Houben-Weyl, Methoden der Org. Chem., vol. 10/1, 4th Ed., 1971, p. 1186.
Org. Synth. Coll., vol. 3, p. 172.
Buschmann Ernst
G otz Norbert
Harreus Albrecht
Keil Michael
Klein Ulrich
BASF - Aktiengesellschaft
O'Sullivan Peter
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