CH624946A5 - Process for the preparation of N-substituted oxazolidines - Google Patents

Description

The invention relates to the preparation of oxazolidines of the formula I.

wherein

I)

R Ci-CjQ-haloalkyl, C ^ Cm-alkyl or lower alkyl-thio;

Rj and R2 independently of one another are hydrogen, Ci-C12-alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; and

R3, R4, R5 and R0 independently of one another are hydrogen, lower alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; or in what

II)

R haloalkyl or chloroalkenyl;

Rj is hydrogen, lower alkyl, phenyl, naphthyl or mono- or dichloro, nitro, methyl, methoxy or hydroxy substituted phenyl;

R2 is hydrogen or lower alkyl;

R3 is hydrogen, lower alkyl, hydroxymethyl, N-methyl-carbamoyloxymethyl or dichloroacetoxymethyl;

R4 is hydrogen or lower alkyl;

R5 is hydrogen, lower alkyl or phenyl; and

R0 is hydrogen, where at least one of the symbols Rt and R5 is phenyl, correspondingly substituted phenyl or naphthyl,

mean.

For the above-mentioned compounds in group I) the terms “alkyl” and “haloalkyl” mean members of these groups which have 1 to 10 or 12 carbon atoms in a straight or branched chain. “Haloalkyl” should preferably be understood to mean groups substituted by chlorine or bromine, which are advantageously mono-, di-, tri-, tetra- and / or per-substituted. Examples of alkyl groups or the alkyl moieties of haloalkyl groups are: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, 1,1-dimethylbutyl, amyl, isoamyl, 2,4 , 4-trimethylpentyl, n-hexyl, isohexyl, n-heptyl, n-octyl, isooctyl, nonyl, decyl and dimethylheptyl. “Lower alkyl”, “lower alkylthio”, “lower alkoxyalkyl” and “hydroxy lower alkyl” are preferably groups with 1 to 6, in particular 1 to 4, carbon atoms; Examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl and hexyl; Methyl-thio, ethylthio, n-propylthio, n-butylthio and the like; Methoxymethyl, ethoxyethyl, hydroxymethyl, hydroxy-n-propyl and the like. For the sake of simplicity, these compounds are referred to below as “aliphatic-substituted oxazolidines”, which also include compounds which carry hydrogen as substituents, such as, for example, compound 1.

In the case of the compounds of group II), the following applies to the various groups of substituents: If R is haloalkyl, those members of this group which have 1 to 6 carbon atoms in a straight or branched chain and in which halogen is chlorine or bromine are particularly preferred. These groups can be mono-, di-, tri- or tetra-halogen-substituted. Examples of the alkyl part include: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, 1,1-dimethylbutyl, amyl, isoamyl, n-hexyl and isohexyl. If R is chloroalkenyl, it should preferably be understood to mean those members of this group which have 2 to 4 carbon atoms and at least one olefinic double bond and which are mono-, di-, tri- or tetra-substituted by chlorine, such as trichlorovinyl.

If Rt, R2, R3, R4 and R5 are lower alkyl, then groups with 1 to 4 carbon atoms in a straight or branched chain are preferred; Examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl and the like. For the sake of simplicity

5

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the compounds of formula b) hereinafter referred to as "aromatically substituted oxazolidines". Of the aromatically substituted oxazolidines, compounds are preferred in which R [and R2, which may be the same or different, both represent lower alkyl and R5 is phenyl.

It has been shown that compounds of this type have an activity which makes them suitable for use as antidotes in herbicides. Some of these compounds can be used as herbicides. Such compounds are described in various publications, e.g. in Belgian Patent Nos. 782 120, 806 038 and 806 040 and in DT-OS 2 341 810. Aro-5 matically substituted oxazolidines are also described in US Patent Application No. 627,986 by Eugene G. Teach, filed on 3. November 1975.

Representative examples of compounds of the type mentioned at the outset are listed in Table I.

TABLE I

Connection no.

R

Ri

Ra

Ra

R4

Rs

Rs

Aliphatic substituted oxazolidines

1

CHC12

H

H

H

H

H

H

2nd

CHCla ch3

CH3

H

H

H

H

3rd

CHC12

ch3

ch3

H

H

ch3

H

4th

CHCla ch3

ch3

H

H

n-C3HT

H

5

CH2CI

ch3

ch3

H

H

H

H

6

CBr3

ch3

ch3

H

H

H

H

7

CH2Br ch3

ch3

ch3

ch3

H

H

8th

CHCl2

ch3

ch3

c2h5

H

H

H

9

CCla ch3

H

H

H

ch3

H

10th

CC13

c2h5

H

C2H5

H

H

H

II

chci2

ch3

ch3

ch3

ch3

H

H

12th

chci2

ch3

t-C4Hn

H

H

H

H

13

chci2

H

H

ch3

ch3

H

H

14

CBra

H

H

c2h5

H

H

H

15

chci2

ch3

Ì-C3H7

H

H

H

H

16

CBr3

ch3

c2h5

H

H

H

H

17th

CBr3

c2h5

H

H

H

H

H

18th

CH3CHBr ch3

ch3

H

H

ch3

H

19th

CH ^ CMBr c2h3

H

H

H

ch3

H

20th

CH2Br ch3

ch3

C2H5

H

H

H

21st

CH2Br ch3

H

H

H

H

H

22

CH3 (CHBr) 4

ch3

ch3

H

H

H

H

23

C! CH2CH2

ch3

ch3

H

H

H

H

24th

CH2BrCHBr ch3

t-C, H ,,

H

H

H

H

5

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TABLE I (continued)

Connection no.

R

Ri

Ra

Rs

R4

Rs r6

25th

CHBr2

c2h5

H

H

H

H

H

26

(CH3) 2CBr c2h5

H

H

H

ch3

H

27th

CC13

ch3

H

H

H

H

H

28

CH2BrC (CH3) Br ch3

H

H

H

ch3

H

29

CH2BrCH2

ch3

ch3

H

H

H

H

30th

CI (CH2) 3

ch3

ch3

H

H

H

H

31

ch3chcich2

ch3

ch3

H

H

H

H

32

C2H5CHBr ch3

ch3

H

H

ch3

H

33

C3H7CHBr ch3

ch3

H

H

H

H

34

CH2C1CH2CH2

ch3

ch3

H

H

ch3

H

35

CH2Br (CH2) 4

ch3

ch3

H

h ch3

H

36

c2H6s h

H

c2h5

H

H

H

37

c2h5s ch3

H

H

H

ch3

H

38

c3h7s ch3

ch3

C2H5

H

H

H

39

i-C3H7S

ch3

ch3

c2h5

H

H

H

40

CH3S

ch3

H

c2h5

H

H

H

41

n-C4Hr, S

ch3

H

c2h5

H

H

H

42

cchi3

ch3

ch3

H

H

H

H

43

chci2

CaH7

H

H

H

H

H

44

chci2

ch8och2

H

H

H

H

H

45

ch2ci ch3

ch3

H

H

n-C3H7

H

46

chci2

ch3

ch3

ch3

CH2OH

H

H

47

ch2ci n-CgHn

H

ch3

ch3

H

H

48

ch2ci

2,6-dimethyl-heptyl

H

ch3

ch3

H

H

49

ch2ci n-C3H7

ch3

ch3

ch3

H

H

50

ch2ci c2h5

C2Hr,

ch3

ch3

H

H

51

ch2ci n-C3H7

n-C3H7

ch3

ch3

H

H

Aromatically substituted oxazolidines

52

chci2

m-NO2-C0H4

h ch3

ch3

H

H

53

cci3

CeH5

H

H

H

H

H

54

CHBrCH3

CuHg

H

H

H

H

H

55

CC12-CH3

ccH,

H

H

H

H

H

56

CHBr2

c6h.,

H

H

H

H

H

57

CC1 = CC12

CcH3

H

H

H

H

H

58

CH2C1

m-ClCcH4

H

H

H

H

H

59

CH2Br m-CIC0H4

H

H

H

H

H

60

CHC12

cch5

H

C2H5

H

H

H

61

chci2

c2h5

H

H

H

cuh5

H

624946

6

TABLE I (continued).

Connection no.

R

Rl

Rs

Rs

R4

Rs

re

62

cc13

CA.

H

H

h approx

H

63

chc12

ch3

ch3

H

H

CA.

H

64

ch2ci ch3

ch3

H

H

CcH,

H

65

CHBrCH2Br p-CH3-CeH4

H

H

H

h h

66

cc12ch p-CH3-CeH4

H

H

H

H

H

67

chci2

m-CHaO-C6H4

H

H

H

H

H

68

cci2ch3

m-CH, 30-CoH4

1

H

H

H

H

H

69

ch2ci

H

H

H

H

H

70

cc12ch3

© à

H

H

H

H

H

71

chci2

cch5

H

H

H

ch3

H

72

ch2ci c6h5

H

ch3

ch3

ch3

H

73

chci2

approx

H

ch3

ch3

ch3

H

74

cc13

qa

H

ch3

ch3

ch3

H

75

ch2c1

3,5-Cl2-C0H3

H

H

h h

H

76

chci2

3,5-Cl2-C0H3

H

H

h h

H

77

cci2ch3

3,5-Cl2-CeH3

H

H

H

H

H

78

ch2ci

H

H

h h

approx

H

79

CH2-CH2Br

H

H

H

H

c6h5

H

80

chc12

m-OH-C0H4

H

H

H

H

H

81

chci2

c6h5

H

ch3

ch3

H

H

82

cc13

ch3

cha ch3

H

CA.

H

83

CHBrCH2Br ch3

ch3

ch3

h c "h5

H

84

chc12

o-C1-C6H4

H

h h

H

H

85

ch2ci p-ci-cbh4

H

h h

H

H

86

chci2

p-Cl-C6H4

H

H

h h

H

87

cc1 = cc12

p-ci-ca

H

H

H

H

H

88

chc12

ch3

ch3

ch2oh h

approx

H

O

II

89

chci2

ch3

ch3

II

ch2ocnhch3

H

approx

H

O

II

90

chci2

ch3

ch3

II

ch2occhcl2

h approx

H

Of the alkyl-substituted oxazolidines, compounds with a suitable aldehyde or ketone in a fertilizer are preferred, in which R1 and R2 are, independently of one another, solvents such as benzene and subsequent removal of the

Hydrogen, lower alkyl, lower alkoxyalkyl or hydroxy- 65 water produced in the condensation. A sol lower alkyl mean. The process is, for example, in the publication of

According to the prior art, Oxazoli-Bergmann et al., JACS 75 (1953) page 358 have been described.

dines in general by condensation of alkanolami- To give the N-substituted oxazolidines of the initially

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As mentioned, the condensation product was treated with an acid chloride in the presence of a hydrogen chloride acceptor such as triethylamine. This reaction was carried out under anhydrous conditions after the water formed in the condensation of the alkanolamine with the carbonyl compound was removed. Such methods are described, for example, in the Belgian patents mentioned above and in US Pat. No. 3,707,541.

Substituted oxazolidines produced in this way were often contaminated by by-products, which generally resulted from the reaction of the acid chloride with by-products or from intermediates formed during the condensation step. Removal of such by-products has often proven difficult, due to their quantity or chemical behavior, or both. In the manufacture of substituted oxazolidines in small amounts, e.g. for laboratory or experimental purposes, the product could be obtained in an essentially pure state with sufficient cleaning. However, such cleaning steps often result in a considerable loss of material, which is particularly disruptive when the compounds are present in large quantities, e.g. for commercial use. In addition, the elimination or reduction of such cleaning steps is also an advantage from a commercial point of view, since this saves equipment and / or operating costs by eliminating the costs for equipment and / or solvents.

The object of the invention is to provide an improved process for the preparation of N-substituted oxazolidines, in particular those of appropriate purity. Furthermore, it is an object of the invention to provide a process for the preparation of N-substituted oxazolidines in which fewer cleaning steps are required compared to older processes.

It is also an object of the invention to provide a process for the preparation of N-substituted oxazolidines in which the formation of undesirable by-products can be reduced to a minimum.

The invention therefore relates to a process for the preparation of compounds of the formula I.

wherein the symbols R, Rj, R2, R, a, R4, R5 and R0 have the meaning given above, which is characterized in that an oxazolidine of the formula II

HN

with a compound of formula III

O

II

R — C — X (III)

where X is halogen, preferably chlorine, in the presence of water and a hydrogen halide acceptor.

According to a further process according to the invention for the preparation of the N-substituted aliphatic oxazolidines of the formula I, the procedure is that a) an alkanolamine of the formula IV Ria Rs

I I

H2N — C — C — OH (IV)

R4 R "

with a carbonyl compound of formula V

O

II

Ri — C — R2 (V)

condensed;

b) keeps the water formed during the condensation in contact with the oxazolidine obtained; and c) the oxazolidine formed in the presence of water and a hydrogen halide acceptor with a compound of the formula III

O

II

R — C — X (III)

implements.

According to a further process according to the invention, the procedure is as follows: a) an alkanolamine of the formula IV Ra R »

I I

H2N — C — C — OH (IV)

I I

R4 Rß

with a carbonyl compound of formula V

O

II

Ri — C — R2 (V)

implements;

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b) the water formed in the condensation in step a) is removed; and c) the oxazolidine obtained from stage b) with a compound of the formula III

O

II

R — C — X (III)

in the presence of water and a hydrogen halide acceptor.

This variant of the process according to the invention is used in the production of aromatically substituted oxazolidines and can also be used for the production of the aliphatic substituted oxazolidines.

It is known that when an alkanolamine is condensed with an aldehyde or ketone, an oxazolidine is obtained as the reaction product. However, it is generally believed that the oxazolidine is in a tautomeric equilibrium with a Schiff base. For example, the reaction of ethanolamine with acetone in the presence of a solvent such as benzene gives a mixture of 2,2-dimethyloxazolidine and a Schiff base of the formula VI

ch3

CH2OH-CH2N = Cd (VI)

ch3

plus water. Longer chain alkanolamines, in which the hydroxyl group is attached to the carbon atom adjacent to the amino group, react in a similar manner and give oxazolidines with different ring substituents. In general, both the desired oxazolidine and the undesirable Schiff base are present in the reaction mixture. In the prior art processes, the water is removed from the reaction mixture by stripping or distillation, after which the remaining products are reacted with an acid chloride in an anhydrous system to form an N-substituted oxazolidine and hydrogen chloride.

However, the Schiff base reacts with the acid chloride, producing undesirable by-products of various types, which are believed to be primarily esters. These must be separated from the desired N-substituted oxazolidine if it is to be used commercially or otherwise. In many cases, good separation is difficult to achieve; in other cases it can be achieved, but requires different levels of cleaning.

It has now been found that when the reaction of the oxazolidine with the acid chloride is carried out in the presence of water, in contrast to the practice which belongs to the prior art, the purity of the substituted oxazolidine obtained is substantially greater and thus allows a purification process which requires fewer steps comprises than the previously known methods. In addition, the yield of the desired oxazolidine can be increased.

In general, the reaction of the oxazolidine with the acid chloride is carried out in the presence of water and a hydrogen sulfide acceptor such as sodium hydroxide. The concentration of the hydrogen halide acceptor is generally 5 to 50%.

In one embodiment of the process according to the invention, the water formed in the condensation of the alkanolamine with the aldehyde or ketone is retained in the reaction system and the entire reaction mixture, which includes the oxazolidine and water, with the

Acid chloride reacted in the presence of a hydrogen halide acceptor.

In another embodiment, the water is separated from the condensation products, but is subsequently reintroduced into the system in the form of an aqueous solution of a hydrogen halide acceptor such as sodium hydroxide.

In another embodiment of the method according to the invention, an aqueous alkali which contains 5 to 50% sodium hydroxide is added to the system before the acid chloride is added. The strong base serves as a hydrogen halide acceptor in the subsequent reaction stage; however, it is believed that it also causes a decrease in water vapor pressure across the reaction system, and thus more favored the formation of oxazolidine from the diol intermediate than the formation of Schiff's base. If the concentration of sodium hydroxide exceeds 20%, sodium chloride will precipitate out of the system, requiring dilution of the reaction mixture prior to purification or removal of the sodium chloride by filtration or similar measures.

Another advantage of the process according to the invention is that it is not necessary to use relatively expensive hydrogen chloride acceptors such as triethylamine, since the reaction of the oxazolidine with the acid chloride is carried out in aqueous solution, although such hydrogen halide acceptors can of course also be used in this process. In general, however, less expensive substances, e.g. a weak sodium hydroxide solution, or another Aikalimetallhydr-oxide such as potassium hydroxide (in aqueous solution) is used. The most common hydrogen chloride acceptors are miscible with water or soluble in water under the reaction conditions; however, water-immiscible hydrogen chloride acceptors such as dimethylaniline can also be used. If, as already mentioned, an aqueous alkali is added to the reaction mixture before the acid chloride is added, this alkali also serves as a hydrogen chloride acceptor.

The reaction is preferably carried out at low temperatures, e.g. at -5 ° C to + 5 ° C. However, the reaction can also take place at somewhat higher temperatures, e.g. at temperatures up to 25 ° C, although at these temperatures the yield of the desired product is somewhat lower. Any lower alkanolamine which has 2 to 6 carbon atoms can be used as the alkanolamine, provided that the hydroxyl group and the amino group are bonded to adjacent carbon atoms. Any suitable aldehyde or ketone of the formula RjCORa, in which Rx and R2 have the meaning given above, can be used as the carbonyl compound.

The following examples serve to explain the method according to the invention.

Preparation of 2,2-dimethyl-3-dichloroacetyloxazolidine (Compound 2 in the Table)

Example 1 (prior art)

5.1 g of 2,2-dimethyloxazolidine dissolved in 50 ml of benzene was treated with 5.5 g of triethylamine and 7.4 g of dichloroacetyl chloride was added dropwise with stirring and cooling in an ice bath. The mixture was poured into water, the benzene solution separated, dried over anhydrous magnesium sulfate and the solvent

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evaporated under vacuum. The product was a waxy solid which had a melting point of 113 ° to 115 ° C. after recrystallization from diethyl ether.

Example 2

122 ml (122 g) of ethanolamine, 150 ml of acetone and 600 ml of benzene were placed in a 2 liter reaction vessel. The mixture was heated to reflux temperature, water was removed, the reaction mixture was allowed to cool and 200 ml of 37% NaOH and 175 ml of water were added. The mixture was kept at about 5 ° C while 100 ml of di-chloroacetyl chloride was added. The mixture was left to stand for 1 hour, then another 93 ml of dichloroacetyl chloride was introduced. The pH of the mixture dropped below 13 and 25 ml of 20% NaOH was added to bring the pH to 13.8. The reaction mixture was neutralized with concentrated hydrochloric acid, benzene evaporated and the product filtered and dried. 282 g (66.7% of theory) of a solid with a melting point of 117.5 ° to 119.5 ° C. were obtained.

Example 3

122 ml (122 g) of ethanolamine, 150 ml (116 g) of acetone and 600 ml of benzene were placed in a 2 liter reaction vessel. The reaction was carried out at a temperature of about 33 to 34 ° C. The reaction mixture was stirred for 1 hour, 200 ml of 33% NaOH were added, the temperature was lowered to about 5 ° C. using an acetone-ice bath and the mixture was stirred for a further 3 hours.

110 ml (168.5 g) of dichloroacetyl chloride were added over a period of one hour, then 25 ml of 83% NaOH and a second portion of 110 ml of dichloroacetyl chloride (slowly). The reaction mixture was neutralized with concentrated hydrochloric acid. In order to dissolve the sodium chloride formed, 190 ml of water were added, benzene was evaporated off, the product was filtered and dried. 347 g (82% of theory) of product with a melting point of 117.5 to 119 ° C. were obtained.

Preparation of 2,2,5-trimethyl-3-dichloroacetyloxazolidine (Compound 3 in the Table)

Example 4 (prior art)

18 ml of a benzene solution containing 4.6 g of 2,2,5-trimethyloxazolidine was added to 25 ml of benzene and 4.5 g of triethylamine. 5.9 g of dichloroacetyl chloride was added dropwise with stirring and cooling in an ice bath. After the reaction was completed, the mixture was poured into water and the benzene layer was separated, dried over anhydrous magnesium sulfate, and the benzene was evaporated under vacuum. The yield was 7.7 g of an oil, nD30 = 1.4950.

Example 5

150 g (162 ml) of isopropanolamine, density 0.961, were mixed with 150 ml (116 g) of acetone and 600 ml of benzene. Existing water was evaporated, the reaction mixture was cooled and 200 ml of 20% NaOH and 175 ml of water were mixed with the products. 202 ml (310 g) of 96% pure dichloroacetyl chloride were then added. The temperature was kept at 5 ° C. The reaction product was neutralized with concentrated hydrochloric acid, transferred to a separatory funnel and washed once with distilled water. Benzene was evaporated. 343 g of 2,2,5-trimethyl-3-dichloroacetyloxazolidine (76% of theory) were obtained, melting point 77 ° to 84 ° C.

Example 6

150 g (162 ml) of isopropanolamine, 150 ml (116 g) of acetone and 600 ml of benzene were placed in a 2 liter reaction vessel. The whole was heated to 40 ° C and stirred for 1 hour. Then 200 ml of 33% sodium hydroxide were added and the resulting mixture was stirred for a further two hours. The mixture was rapidly cooled to 5 ° C with an ice bath using acetone and 110 ml of dichloroacetyl chloride was added slowly over an hour. The mixture was left to stand for a further 1 1/2 hours, then a further 110 ml of dichloroacetyl chloride were added over a further hour together with a further 10 ml of 33% NaOH. The pH of the reaction product was 11.1. The reaction products were neutralized with hydrochloric acid until the pH was about 3. 185 ml of water were added to dissolve the sodium chloride formed. Benzene was evaporated under vacuum, the product was filtered, evaporated and dried without further crystallization. 346.2 g of product (77% of theory) with a melting point of 87 ° to 88 ° C. were obtained.

Preparation of 2,2-dimethyl-3-dichloroacetyl-5-oxazolidine (Compound 63 in the Table)

Example 7 (prior art)

100 g of l-phenyl-2-aminoethanol were dissolved in 250 ml of benzene and 45 g of acetone were added. The mixture was heated at reflux temperature for several hours while removing about 15 ml of water with a modified Dean-Stark apparatus. The mixture was cooled and 75 ml of triethylamine and then 108 g of dichloroacetyl chloride were added dropwise with stirring and cooling in a water bath at room temperature. The solution was allowed to stand over anhydrous magnesium sulfate and the solvent was evaporated under vacuum. After standing, the thick oil, weight 170 g, crystallized and was triturated with dry ether. It gave 132 g (63% of theory) of the desired compound, a white solid with a melting point of 99.5 to 100.5 ° C.

Example 8

1 liter of benzene, which contained 531.6 g of l-phenyl-2-aminoethanol and 250 g of acetone, was heated at the reflux temperature and water was removed in a modified Dean-Stark apparatus. When about 70 ml of water had been collected, the mixture was cooled to 5 ° C. in an isopropanol dry ice bath, 470 g of 50% NaOH solution and then 630 g of dichloroacetyl chloride in 500 ml of benzene added at such a rate that the temperature at Was held 1 ° to 3 ° C. After the addition was complete, the mixture was allowed to warm to room temperature and neutralized to pH 3 with concentrated hydrochloric acid. At this point a precipitate appeared which was filtered off and gave 458 g of solid with a melting point of 103 ° to 105 ° C. The benzene solution was washed with water, dried and the benzene evaporated. 374 g of a solid with a melting point of 81 ° to 91 ° C. were obtained. This was triturated with ether and gave a solid with a melting point of 102 ° to 103 ° C. This was combined with the first product, and a total of 778 g of product (70% of theory) was obtained.

As can be seen from the examples, using any embodiment of the present invention, a product of higher purity was obtained in the preparation of alkyl-substituted oxazolidines than in work 5

io

IS

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ten in an anhydrous system according to the known methods. In the preparation of 2,2-dimethyl-3-dichloroacetyloxazolidine, after removing the water from the system and reintroducing it in the form of an aqueous sodium hydroxide solution (as in Example 2), a much purer product was obtained than in Example 1 (prior art Technology). The product obtained according to the invention does not require recrystallization. If the water is retained in the system (Example 3), a product is obtained with a similarly improved purity and moreover in a higher yield.

Similar results can be seen from the comparison in the preparation of 2,2,5-trimethyl-3-dichloroacetyloxazolidine in Examples 4 to 6. Both methods according to the invention provide a crystalline product, while according to the known methods an oil, a much less pure product, is obtained. Retaining water 5 in the system (Example 6) provides a product that was the purest.

Similarly, the preparation of an aromatically substituted oxazolidine after removal of the water from the system as an auxiliary and its re-introduction as a sodium hydroxide solution lead to a greater yield of pure product (Example 8) than in previous processes (Example 7).

v

Claims (3)

624946 * 1 2 with a compound of formula III O II R — C — X where X is halogen. 7. Process for the preparation of N-substituted oxa-55 zolidines of the formula I. (III) in which X is halogen, in the presence of water and a hydrogen halide acceptor. 1 C- 4. The method according to claim 1, characterized in that 2,2-dimethyl-3-dichloroacetyloxazolidine is prepared. 5. The method according to claim 1, characterized in that 2,2,5-trimethyl-3-dichloroacetyloxazolidine is prepared. 5 6. Process for the preparation of N-substituted oxazolidines of the formula I. (I) io 15 wherein I) R Cj-C10 haloalkyl, CrC10 alkyl or lower alkyl thio; Rj and R2 independently of one another hydrogen, C1-Ci2-alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; and R3, R4, Rs and R "independently of one another are hydrogen, lower alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; or in what II) R haloalkyl or chloroalkenyl; Rj is hydrogen, lower alkyl, phenyl, naphthyl or mono- or dichloro, nitro, methyl, methoxy or hydroxy substituted phenyl; R2 is hydrogen or lower alkyl; R3 is hydrogen, lower alkyl, hydroxymethyl, N-methyl-carbamoyloxymethyl or dichloroacetoxymethyl; R4 is hydrogen or lower alkyl; R5 is hydrogen, lower alkyl or phenyl; and R "is hydrogen, where at least one of the symbols Rj and R5 is phenyl, correspondingly substituted phenyl or naphthyl, mean, characterized in that an oxazolidine of the formula II (I) 20 where R is Cj-Qo-haloalkyl, Cj-C ^ alkyl or lower alkylthio; Rj and R2 independently of one another hydrogen, Q-C ^ alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; and 25 Rs, R4, R5 and R6 independently of one another are hydrogen, lower alkyl, lower alkoxyalkyl or hydroxy-lower alkyl, characterized in that a) an alkanolamine of the formula IV 30th 35 40 R «Rs I I H2N-C-C-OH I I R4 R " with a carbonyl compound of formula V O il Ri-C-R2 (IV) (V) condensed; b) keeps the water formed during the condensation in contact with the oxazolidine obtained; and 45 c) the oxazolidine obtained in the presence of water and a hydrogen halide acceptor with a compound of the formula III (II) 50 O II R — C — X (III) 2. The method according to claim 1, characterized in that one carries out the reaction at a temperature of - 5 ° C to + 5 ° C. 3. The method according to claim 1, characterized in that an alkali metal hydroxide is used as the hydrogen halide acceptor. 60 65 R- (i) 2nd PATENT CLAIMS 1. Process for the preparation of N-substituted oxazolidines of the formula I R- 0 3rd 624946 wherein I) R is Cj-C10 haloalkyl, Cj-Cm-alkyl or lower alkyl-thio; Rj and R2 independently of one another are hydrogen, C 1 -C 4 -alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; and Ra, R4, Rj and R0 independently of one another are hydrogen, lower alkyl, lower alkoxyalkyl or hydroxy-lower alkyl; or in what II) R haloalkyl or chloroalkenyl; Ri is hydrogen, lower alkyl, phenyl, naphthyl or mono- or dichloro, nitro, methyl, methoxy or hydroxy-substituted phenyl; R2 is hydrogen or lower alkyl; Ra is hydrogen, lower alkyl, hydroxymethyl, N-methyl-carbamoyloxymethyl or dichloroacetoxymethyl; R4 is hydrogen or lower alkyl; R5 is hydrogen, lower alkyl or phenyl; and Re is hydrogen, where at least one of the symbols Rt and R5 is phenyl, correspondingly substituted phenyl or naphthyl, mean, characterized in that a) an alkanolamine of the formula IV R, s Rs I I H2N — C — C — OH (IV) R4 Rg with a carbonyl compound of formula V O II Ri — c — R2 (V) condensed; b) the water formed in the condensation is removed from the product of a); and c) the oxazolidine obtained in step (b) in the presence of water and a hydrogen halide acceptor with a compound of the formula III O II R — C — X (III) where X is halogen.