CS195273B2 - Method of producing monohalogene acylhalogenides by halogenation of ketenes - Google Patents

Abstract

In the preparation of alpha -mono-haloacyl halides by halogenating ketenes in the liquid phase, the formation of di- and trihaloacyl halides is inhibited or prevented and the formation of corresponding other acyl halides is limited to a minimum, when the solvent used is a sulphone of the formula (I) or a phosphoric triester of the formula (II). In the formulae, R and R<1> denote optionally substituted alkyl radicals having 1-8 C, cycloalkyl radicals having 5-6 C, optionally substituted phenyl radicals or, together, an alkylene radical having 3-8 C, R<2> denotes an optionally substituted alkyl radical or an optionally substituted phenyl radical, or two R<2> together denote an alkylene radical having 2-4 C. Monohaloacetyl halides obtained can be used for the preparation of herbicidal alpha -haloacetanilides by carrying out an appropriate monohaloacetylation. <IMAGE>

Description

The invention relates to a process for the production of monohaloacyl halides by halogenation of the ketene liquid phase, in particular by halogenation of ketones in the presence of a solvent or reaction medium which slows or prevents the formation of polyhalogenacyl halides and minimizes acyl halide formation. The term "halogenating agent" as used herein includes chlorine, bromine, iodine and halogen halides - such as iodo monochloride, iodo monobromide, - bromo monochloride and the like. '

Halogenation of the ketone in the liquid phase is well known, but previously known methods of carrying out this method result in the formation of monohaloacetyl halides contaminated by a considerable amount of dihalogenacetyl halides and by-halogenated by-products. These earlier methods use solvents such as chlorinated benzenes, nitrobenzene, carbon tetrachloride, chloroacetyl chloride, acetyl chloride, 1,2-dichloroethane, acetonitrile, benzonitrile, nitromethane and various other solvents. Each of these solvents usually has a certain drawback, that is, all lead to the formation of considerable amounts of the dihaloacetyl halide, - together with the desired product, the monohaloacetyl halide. Undesirable trihaloacetyl halides are also formed in some of these solvents. Dihalogenderivatives have - none - commercial utilization and their separation from monohalogenderivatives is expensive and time consuming. For example, dichloroacetyl chloride has a boiling point of approximately 107 degrees Celsius while. . monochloroacetyl chloride - has a boiling point of about 105 ° C. This proximity to the boiling points of these two compounds makes their separation extremely difficult and also assumes the inclusion of an - expensive and uneconomic - stage in the halogenation process when using the previously known solvents.

The monohaloacylh-allogenides produced by the process of this invention are valuable intermediates in the production of herbicidal alpha-haloacetanilides and other products. Conversely, the respective di- and trihaloacyl halides have no commercial significance. In other words, they are more present as diluents that reduce the efficacy of commercially valuable monohaloacyl halides. The importance of the problem stems from the fact that all commercially available chloroacetyl chloride is contaminated with considerable amounts of dichloroacetyl chloride and in some cases the dichloroacetyl chloride content is up to six percent.

These drawbacks are largely eliminated in the process of the invention. The essence of the invention is that halogenation occurs

The ketones are carried out with chlorine or bromine in the presence of a solvent which is a sulfone of the formula I

O

R — S — R ¹

II o (i), wherein R and R ¹ are each alkyl of 1 to 8 carbon atoms, optionally substituted with halogen or phenyl, cycloalkyl of 5 to 6 carbon atoms, phenyl, optionally substituted with 1 to 3 halogen atoms, trhalomethyl, or cyano, nitro, C 1-5 alkyl or C 1-5 alkoxy, or R ¹ and R ¹ together form an alkylene of the empirical formula C _n H _2n in which n is an integer of 3 to 10 and the number of carbon atoms is 3 to 8 in a continuous chain;

O '

II

R2-O-P-O-R ²

IR ² (P), wherein R ² is C 1-6 alkoxy-C 1-6 alkyl, C _1-5 alkyl optionally substituted with halogen or phenyl, phenyl optionally substituted with 1 to 3 halogen atoms, trihalomethyl, cyano, nitro groups, C 1-5 alkyls or C _1-5 alkoxy, or two R ² taken together form the alkylene of the empirical CnHan formula wherein n is an integer of 2 to 8 and the number of carbon atoms is 2 to 4 in a continuous chain.

Preferably the substituted alkyl group has the formula —C _x H _{2 x y} + i R ³ y, wherein R ³ is halogen, phenyl or substituted phenyl, x is an integer from 1 to 8 and у is an integer from 1 to 8 and у is an integer It is more preferred that in the case where R ³ is phenyl, у is equal to 1, and in the case where x is 1 and у is 3, R ^{3 is} halogen.

Preferably, the substituted phenyl group has the formula "Ο-ζ _Λ" in which Z represents a halogen atom, a trihalomethyl, a cyano group, a nitro group, a lower alkyl or a lower alkoxy group and m is an integer of 1 to 3; Preferred Z substituents are halogen, nitro, lower alkyl, trifluoromethyl and lower alkoxy.

Preferred alkoxy groups are those having a straight or branched aliphatic chain and having a total of 2 to 8 carbon atoms. A preferred alkyl is a straight or branched chain of 1 to 8 carbon atoms.

As used herein, the terms "lower alkyl" and "lower alkoxy" refer to groups in which the aliphatic chain is straight or branched and has 1 to 5 carbon atoms.

The term "halogen" means fluorine, chlorine, bromine and iodine.

The process of the present invention includes halogenation of ketenes, i.e., Ng = S = O, as well as substituted ketenes such as methyl ketene, dimethyl ketene, ethyl ketene, diethyl ketene, phenyl ketene, diphenyl ketene and the like.

In the process of the invention, the ketenes and the halogenating agent are introduced into a solvent environment where they react to form monohaloacyl halides which are separated from the reaction medium by conventional means such as distillation, preferably under reduced pressure. The march is feasible either as smooth or in batches. The process conditions under which the reaction is carried out are not critical, but it is recommended to keep them within the specified limits to maximize the yield of monohaloacyl halides. Essentially, it is only necessary for the reaction mass to be liquid under the reaction conditions. However, for practical reasons, the reaction is usually carried out in a temperature range of - 50 to 150 ° C, preferably 0 to 150 degrees C, at a pressure of 6.7 to 200 kPa. In most cases, however, it is preferable to proceed in a continuous manner at a temperature of 0 to 110 degrees C and a pressure of about 13 to 100 kPa. In a batchwise process, a pressure of 6.5 to 100 kPa is preferred at said temperature. The reaction of the halogenating agent and the ketenes proceeds mainly to the pure monohaloacyl halides regardless of the molar ratio. reactants. However, the advantages of the process of the invention are more useful if the molar ratio of halogenating agent to ketenes is maintained between about 0.81: 1 to 2.0: 1 and optimal results are obtained at molar ratios of halogenating agent to ketenes between about 1: 1 and The presence of a solvent according to the invention in the reaction mass substantially reduces the formation of undesired acyl halides and, in particular, reduces the formation of longhalacyl halides and other polyhalogenated by-products.

In the process of the invention, the solvent may replace substantially all or a small part of the reaction medium. The advantages of the process of the invention are definitely greater when the solvent ratio is high, but considerable advantages are obtained even when the solvent is present in relatively small doses. Unwanted poles of halogenated acyl halides are formed only in small amounts, although the reaction mass contains a low solvent ratio, and are substantially eliminated at higher ratios. Solvent weight ratio k

195ЙЗ of the total amount of solvent and product, that is, the weight ratio of solvent, can range from about 0.05: 1 to 0.99 to 1. During the normal course of the reaction, if batchwise, the weight ratio of the salt decreases with the resulting product, which is mixed with the solvent to form a reaction mass. If the weight ratio of the solvent drops, the temperature of the reaction mass can be reduced below the melting point of the sulfone, but still keeping the reaction vessel in a liquid state. In the practice of the process in a continuous manner, the weight ratio of the solvent may be kept constant or varied within the desired limits. Correcting the weight ratio of the solvent allows flexibility in selecting the reaction temperature within the desired range even when using high melting point sulfones.

The invention is illustrated by the following detailed description of specific examples thereof. In the examples and throughout the description, all ratios are expressed in weight ratios unless otherwise indicated.

He did

169 parts (QUANTITY OF SOLVENT) of 1,4-tetramethylenesulfone (SOLVENT) is placed in a suitable reaction vessel equipped with a gas outlet, a temperature logger and two gas distributors below the sulfone level. The ketene (ΚΈΤΕΝ) and chlorine (HALOGEN) are given constant and substantially equimolar ratios to the reaction vessel at a pressure of 9.2 kPa (PRESSURE) and to the reaction medium maintained at a temperature of about 28 to 30 degrees C (TEMPERATURE). the chlorine is in sufficient excess to detect weak traces of chlorine in the exhaust system. After about 45 minutes, the reaction temperature in the reactor was reduced to ca. M.p. 14-16 ° C. After about 3 hours and 15 minutes, the addition of the reactants was stopped. At the completion of the reaction, the ratio of solvent to total solvent and product is about 0.52. The reaction mixture consists essentially of sulfone, chloroacetyl chloride (HALOGENACYL CHLORIDE) and cetyl chloride. The reaction mixture contains slightly less than 2% dichloroacetyl chloride (DIHALOGENACYLHALOGENID) and other polychlorinated by-products. Analysis of the fractionated reaction mixture reveals that 169 g of solvent is present. This overall solvent return indicates that the chlorination of the sulfone or other side reactions that result in loss of solvent does not occur during the reaction. After distillation to obtain pure chloroacetyl chloride, the molar percentage yield of chloroacetyl chloride is found to be 93% along with about 5% acetyl chloride. Although not stirred in this example, the mixing is left to the discretion and can be used as needed, depending on the shape of the reactor and the choice of reactants, i.e., ketene and halogenating agent. If the halogenating agent is bromine, it is convenient to stir the reaction mixture, but good results are also obtained without stirring.

Following the procedure of Example 1, but under the conditions and materials selected as set forth in Table I, the products were obtained. The names of each row of Table I are enclosed in parentheses in the example description '1, where appropriate;

In Examples 3-5, the yields of haloacyl halides are large, i.e., about 90 percent, and the amount of dihaloacyl halide is minimal, resulting in a purity of haloacyl halide greater than 95%. In Example 2, the yield of iodoacetyl chloride is about 80 to 90 percent. The diiodoacetyl chloride is exceptionally unstable and therefore cannot be detected in the reaction mass according to Example 2.

Since some of the sulfones of the present invention are solids having a melting point at or above the desired reaction temperature, in such cases, when operating in batches, it is necessary to initiate a halogenation process at a temperature sufficient to maintain the reaction mass in the batch. liquid state. Once the reaction is initiated, the presence of the monohaloacyl halide allows the reactor temperature to be reduced to the desired value. This is illustrated in Examples i through

3. In a continuous process, the presence of the monohaloacyl halide in the reaction mixture ensures its fluidity even at operating temperatures which may be below the melting point of the sulfone.

Ί

195 273

Table I

EXAMPLE no. 2 '3. 4 · /./б· SOLVENT 1,4-´tetramethy- 1,5-penta- 1,4-tetramethyl- 1,4-tetra- 1. . . lensulfon methylenesulfone lensulfon méth.yleηsulfon pressure kPa 13 40 atmospheric atmospheric temperature ° C 5—10 ¹ ) 202), 30 • 50 keten keten keten methylketene halogen jodmonochlorld chlorine chlorine chlorine amount of solvent, parts 200 100 ALIGN! 150 32 amount of halogen, parts 179 85 148 22nd amount of ketene, parts 42 48 100 ALIGN! 36 .alpha.-chlorophenyl halacyl halide iodoacetyl chloride chloracetylchloride a-chlorpropicr- nylchlorid dihalogenacyl halide dichloroacetyl chloride α, α-dichloropropionyl chloride α, α-dichlorophenylacetyl chloride

X] An initial temperature of up to 25 ° C is lowered to this temperature within a short time after the reaction has begun. .

2) The initial temperature of about 100 ° C is reduced to this temperature within a short time after the start of the reaction.

The 1,4-tetramethylenesulfone used in Example 1 as solvent may be replaced by 1,6-hexamethylenesulfone, di-n-propylsulfone, di-tert-butylsulfone, methylethylsulfon, phenylisopropyisulfone, cyclohexylisobutylsulfone, octylisopropylsulfone, dibenzylsulfone and dibenzylsulfone. thereby obtaining similar results, if necessary adjusting the starting temperature to maintain the reaction mass in a liquid state.

Example 6

149 parts (QUANTITY OF SOLVENT) of triethyl phosphate (SOLVENT) are placed in a suitable reaction vessel equipped with a gas evacuation device, a temperature logger, and two gas distributors below the solvent level. pressure of 9 kPa (PRESSURE) and to the reaction medium maintained at about 14 to 16 ° C (TEMPERATURE) introduces ketene (KETEN) and chlorine (HALOGENATING REAGENT) by separate distributors at constant and v essentially, in equimolar ratios with a sufficient excess of chlorine to be detectable weak in the exhaust system. traces of chlorine. After about 3 hours, the addition of the reactants is complete. After completion of the reaction, the ratio of solvent to total amount of solvent and product is 0.5. The reaction mixture contains mainly solvent, chloroacetyl chloride (HALOGENACYL CHLORIDE) and acetyl chloride. The reaction mixture contains only traces, i.e. less than 0.1%, of dichloroacetyl chloride. (DIHALOGENACYLHALOGENIDE) and other polychlorinated by-products. After distillation to separate pure chloroacetyl chloride, the molar percentage yield of chloroacetyl chloride is 97% along with about 3% acetyl chloride. Analysis of the solvent fraction showed that about 146 grams of solvent was present. This · high recovery value of the solvent indicates that there was a negligible chlorination or other side reaction requiring a solvent during the reaction, resulting in a loss of · solvent. .

Although the reaction mass is not mixed in this example, the mixing is left free and can be used if necessary depending on the shape of the reactor and the size of the reactants, i.e. ketene and halogenating agent. If the halogenating agent is bromine, it is advisable to mix the reaction mass, but good results are obtained with 1 mixing.

In the procedure of Example 6, however, under the conditions and materials selected as set forth in Table II, the products are obtained. The names of each row in Table II are given in brackets in the example description. 6 at appropriate locations. t

In the examples · 8. Up to 10, the yield of the haloacyl halide is high, that is about 90 percent, and the amount of the dihaloacyl halide is minimal, so that the haloacyl halide is obtained in a purity greater than 95 percent. In Example 7, the yield of iodoacetyl chloride is 80-90 percent. The diiodoacetyl chloride is very unstable and is therefore not found in the reaction mass of Example 7.

Table II

EXAMPLE no. 7 8 9 10

---- · ._________________________________________________________________________________________; ____________________: ____________________________________

SOLVENT Triethylphosphate Tris (2-chloroethyl) phosphate Triethylphosphate Triethylphosphate pressure kPa 13 13 ¹ atmospheric atmospheric temperature ° C 5—10 20 May 30 50 keten keten keten methylketene phenylketene halogenating agent iodmonochlorid chlorine chlorine chlorine amount of solvent, · parts 200 100 ALIGN! 150 32 amount of · halogen, · parts 179 85 148 22nd amount of ketene, parts 42 48 100 ALIGN! 36 halacyl halide iodoacetyl chloride chloroacetyl chloride α-chloropropionyl chloride α-chlorophenylacetyl chloride dihalogenacyl halide dichloroacetyl chloride and, propionyl chloride α, α-dichlorophenylacetyl chloride

Triethylphosphate. as the solvent in Example 6, trimethylphosphate, triphenylphosphate, tri-2-methoxyethylphosphate, diethylpropylphosphate, tris-2-phenylethylphosphate, tri-para-tolylphosphate, and ethylethylene phosphate can be substituted for similar results.

Example 11

158 parts of tri-n-butyl phosphate are added to a reactor equipped with a distributor and a thermometer. Chlorine and ketene are introduced into the reactor at 50 psi and maintaining a temperature of about 20 ° C for about 3 hours. The chlorine fed to the reactor during this time should be in a slight excess relative to the ketene. Analysis of the product gives the following results:

Yield of chloroacetyl chloride,% 89.7

Purity,% 99.4

- Yield of acetyl chloride,% · 9.8

Yield of dichloroacetyl chloride,% 0.4

Regenerated solvent, g153.2

To demonstrate the benefits of solvents. used in the process of the present invention, the procedures of Examples 1, 6 and 11 are essentially repeated using other solvents within the reaction pressure range. The yields thus obtained, together with the results of typical examples of the invention, are summarized in Table III. The recovered solvent is the amount of solvent present in the analysis after completion of the reaction.

Table III

Solvent Chloracetyl-  chloride výtě-ís- Acetyl chloride Dlchloracetyl- Regenerated solvent,% Reaction pressure kPa yield% chloride yield% žek % tota o / o Example 1 93 97 5 1.9. 100 ALIGN! 9.2 Example 6 97 99.9 3 0.1 98.4 9.0 Example 11 89.7 99.4 9.8 0.4 97 9.6 Ethyl acetate 88 97.8 11 1.5 84 9.6 Ethyl acetate 92 96 5 3 78 atmospheric Tetrachloride 42 69 43 15 Dec 75 atmospheric carbon dioxide 1,2-Dichlor- 35 53 41 24 90. atmospheric ethylene Methyl acetate 91 94 4 4 88 atmospheric Acetonltril 46 83 47 7 66 ' . atmospheric Nitromethane 48 74 39 13 75 atmospheric n-Butyl acetate 82 95 15 Dec 3 84 atmospheric n-Hexyl acetate 81 99 15 Dec 4 83 atmospheric Benzonitrile 87 94 9 4 92 atmospheric-

5

When comparing the same procedure using other solvents, it is clear that the solvents used in the process of the present invention strongly suppress the formation of polychloroacetyl chlorides and reduce the formation of acetyl chloride. The separation of pure chloroacetyl chloride from acetyl chloride and solvent by distillation by distillation is not a problem since the boiling points of these compounds are considerably different.

The improvement achieved by the use of the sulfones of the invention is also apparent from the almost complete recovery of the solvent for recycling purposes. This achieves considerably improved economics, progress. It is also apparent from the high percentage of solvent recovery that the useful effect of these solvents is

7 'must be attributed to the nature of the chemical structure of the solvent.

Good results in the process according to the invention are obtained in a similar manner with the other solvents according to the invention and with the other halogenating agents mentioned above. The bromine can be introduced into the system as a liquid, combined with the solvent in solution, or in a gaseous state below the surface of the reaction mass. In most cases, it is preferred to carry out the bromination with the method of the invention using a solution of bromine in a solvent. If iodmonochloride is used as the halogenating agent, it can be added to the reactor dissolved in the solvent so that the resulting solution is added to the reaction system.

OBJECT OF INVENTION

Claims (7)

A process for the production of monohaloacyl halides by ketene halogenation, characterized in that the ketene halogenation is carried out with chlorine or bromine in the presence of a solvent which is a sulfone of the formula I O 'II R-S-Rl II o (i) wherein R and R 1 are each alkyl of 1 to 8 carbon atoms, optionally substituted with halogen or phenyl, cycloalkyl of 5 to 6 carbon atoms, phenyl, optionally substituted with 1 to 3 halogen atoms, trihalomethyl, cyano, nitro, C 1-6 alkyl or C _1-5 alkoxy, or R ¹ and R ¹ together form an alkylene of the empirical formula C n H 2n, wherein n is an integer of 3 to 10 and the number of carbon atoms is 3 to 8 in a continuous chain, or tertiary phosphoric ester of formula II O II R2-O-P-O-R2 I o AND R 2 (II) wherein R 2 is C 1-6 alkoxy-C 1-6 alkyl, C 1-5 alkyl optionally substituted with halogen or i, phenyl, phenyl optionally substituted with 1 to 3 halogen atoms, trihalomethyl, cyano, nitro, C 1-5 alkyl or C _1-5 alkooyls, or two R 2 together form an alkylene of the empirical formula C ₁₁ H 2n, wherein n is an integer of 2 to 8 and the number of carbon atoms is 2 to 4 in a continuous chain. . 2. The method 'according to claim 1, characterized in that the reaction is carried out in the presence of a sulphone of general formula I wherein R and R ¹ are, individually' n-propyl, isobutyl or isopropyl. 3. The process of claim 1 wherein the reaction is carried out in the presence of a sulfone of formula I wherein R is methyl and R1 is ethyl. 4. The process of claim 1 wherein the reaction is carried out in the presence of a sulfone of formula I wherein R is phenyl and R1 is isopropyl. 5. The process of claim 1 wherein the sulfone is 1,6-halo-methylene sulfone. 6. The method of claim 1 wherein said reaction is carried out in the presence of a tertiary · phosphorous ester of formula II wherein one R 2 is C alkyl and the other two substituents R ² together are alkylene _& C3 '. 7. The process of claim 1 wherein the reaction is carried out in the presence of tri-n-butyl phosphate.