IE63494B1 - Process for the synthesis of arylsulphonylakylamide - Google Patents

Abstract

Process for the synthesis of arylsulphonylalkylamides in which an arylsulphonyl halide is placed in contact with an excess of alkylamine and an aqueous solution of alkaline agent in excess in relation to the arylsulphonyl halide and then the water and excess amine are removed from the organic phase; the arylsulphonylalkylamide is then isolated. This process is particularly suited for N-n-butylbenzenesulphonamide which is obtained in a thermally stable quality and which can be advantageously employed as a plasticiser for polyamides.

Description

The present invention relates to a process for the synthesis of arylsulphonylalkylamide. Arylsulphonylalkylamides are used as plasticizers for polyamides, in particular for polyamides 11 and 12. It is important that these plasticizers, which are used at a high temperature (e.g. 200 - 250°C), should not be degraded by heat. That is to say that when being used, they must not be a source of formation of acid products, which may colour the plastic and additionally, may affect the mechanical properties of the polymers (e.g. by chain rupture). European Patent Application EP-A-7623 describes a process for the purification of arylsulphonylalkylamide by the action of an alkaline agent at 200°C to obtain a heat-stable product. A process has now been found which enables an arylsulphonylalkylamide to be synthesized that is heat-stable, and hence directly usable as a plasticizer in polyamides, without having to undergo a purification process such as that described in EP-A-7623.

The present invention thus provides a process for the synthesis of arylsulphonylalkylamide, by reacting an arylsulphonyl halide with an alkylamine, of formula (I) R. so2n /R1 'Ra (I) in which Rx represents a hydrogen atom or an alkyl group of 1 to 10 carbon atoms, R2 represents an alkyl group of 1 to 10 carbon atoms and R3 represents one or more identical or different substituents which are halogen, hydrogen and Cj — 5 alkyl comprising: a) mixing an arylsulphonyl halide with an excess of alkylamine and an aqueous solution of an alkaline agent, the quantity of alkaline agent being in excess relative to the arylsulphonyl halide involved; b) removing water and the alkylamine from the organic phase obtained in a); and, c) separating the arylsulphonylalkylamide from 15 the residue obtained in b).

Although R1 and R2 may be different, it is preferable that R1 and R2 are identical, and most preferable that R3 and R2 have not more than 3 carbon atoms. In addition, products of formula (I) in which Rx is hydrogen and R2 an alkyl of 2 to 6, preferably 4, carbon atoms are also of interest.

Preferred substituents for the benzene nucleus are fluorine, chlorine, bromine and methyl. The nucleus may have several of these substituents, for example methyl and one or more bromine atoms, or methyl and one or more chlorine atoms. Froducts of the formula I in which R3 is -4hydrogen, i.e. products with an unsubstituted benzene nucleus, in which Rx is hydrogen and R2 is alkyl of 2 to 6 carbon atoms are preferred.

Among these products N-(n-butyl) benzene5 sulphonamide of formula (II) is especially preferred.

A)-S°2N (II) CH2CH2CH2CH3 The initial arysulphonyl halide is of the formula (III) so2x *3 (III) IQ in which R3 has the same meaning as before and X represents halogen, preferably chlorine or bromine and most preferably chlorine. The initial alkylamine is of the formula (IV).

HN /R1 (IV) in which Rx and R2 have the same meaning as before.

The reaction between the arylsulphonyl halide and the alkylamine is essentially complete and in theory it requires one mole of halide for one mole of amine, one mole of HX being obtained which is converted with an alkaline agent.

It is preferred to use benzenesulphonyl chloride, that is to say the product in which R3 is hydrogen and X is chlorine, and n-butyl amine, that is to say the product in which Rx is hydrogen and R2 is n-butyl.

In stage a) it is essential to use an excess of alkylamine, that is to say more than one mole of amine is used for one mole of halide.

This excess is advantageously 20 % in moles, that is to say 1.2 moles of amine per mole of halide involved, and preferably 5 to 15 %. The use of a large excess is not outside the scope of the invention but necessitates recycling large quantities of amine at the end of the reaction.

Alkali metal or alkaline-earth metal hydroxides, carbonates, bicarbonates and alcoholates, for example, may be used as an alkaline agent in aqueous solution. It is advantageous to use sodium hydroxide (soda) or potassium hydroxide and preferably sodium hydroxide. Although the concentration of the sodium or potassium hydroxide is unimportant, it is convenient to use aqueous solutions of 10 to 30 % by weight. The necessary quantity of alkaline agent is a function of the quantity of sulphonyl halide involved in a), the stoichiometric quantity being one alkaline equivalent for one mole of sulphonyl halide, that is to say if sodium or potassium hydroxide are used at least one mole is required for one mole of sulphonyl halide. An excess of alkaline agent must be used, relative to the stoichiometric quantity that has just been defined. It is advantageous to use a molar excess of up to 10 % and preferably from l to 5 %. The use of a large excess of sodium hydroxide is not outside the scope of the invention but the process is tnen complicated by the large quantities of excess product to be eliminated.

The operation may be continuous or noncontinuous and the arylsulphonyl halide, alkylamine and aqueous solution of alkaline agent may be added in any order or partly in one order and partly in another order. The only condition to be respected is that the arylsulphonyl halide should not be destroyed by reaction with the alkaline agent. The arylsulphonyl halide may, for example, be placed in contact with the alkylamine before adding the alkaline agent. The arylsulphonyl halide may also be run into a stirred mixture of alkaline agent in aqueous solution and alkylamine. The expression stirred mixture is used because the alkaline solution and the alkylamine are not generally miscible, and a sort of unstable emulsion is formed by stirring. According to another alternative the arylsulphonyl halide and aqueous solution of alkaline agent may also be run into the alkylamine with a slight lag for the alkaline solution. The lag -7is reckoned in number of moles of alkaline agent relative to the number of moles of arylsulphonyl halide.

It is essential in the invention to have an arylsulphonyl halide, an alkylamine, water and an alkaline agent in contact; the use of an anhydrous alkaline agent and water or an anhydrous alkaline agent and an alkylamine in aqueous emulsion is not outside the scope of the invention. An arylsulphonyl halide may be used just as it is or in solution in a solvent; the alkylamine may also be just as it is or possibly in a solvent, for example toluene.

Although stage a) may be carried out at any temperature and pressure, provided of course that the products are not decomposed, it is preferred to operate at or close to ambient temperature and at or close to atmospheric pressure, so that the halide is liquid and the amine is liquid too. If it is impossible to combine these conditions a zone of temperature and pressure should be selected in which the halide is liquid and the amine is gaseous. These conditions are advantageously a temperature not exceeding 150°C and a relative pressure not exceeding 5 bars.

It is preferred to operate at atmospheric pressure at a temperature close to room temperature, that it to say from 0° to 50°C. -8The duration of stage a) is unimportant, but the reaction is generally instantaneous and its duration is determined by the practical conditions linked to the apparatus and the quantities handled.

This duration is usually of the order of 15 minutes to a few hours.

This bringing into contact is an operation known per se and may be carried out in any apparatus used in the chemical industry; stirred apparatus is used with advantage.

When all the reactants in this stage a) have been brought into contact it is advantageous to maintain the stirred reaction mixture at a temperature of 20 to 100°C, and preferably 40° to 70° for, say, a few minutes to a few hours and preferably from one hour to three hours. The reaction mixture obtained at the end of stage a) is subsequently separated into a aqueous phase and an organic phase essentially containing the arylsulphonylalkylamide, some alkylamine and a few percent of water. This separation of the two phases is an operation known per se.

Stage b) comprises eliminating the water and the alkylamine from this organic phase. This is advantageously achieved by distillation. This may be done under vacuum or up to a few bars so long as the temperature does not exceed that at which the organic phase begins to degrade, or to produce coloured products or products of decomposition.

This temperature usually does not exceed 180°C. It is advantageous to operate from 130° to 170°C. To operate -9at a higher temperature is not outside the scope of the invention, but there is a risk of degrading the products, whereas it is simpler to operate at a lower temperature.

The duration of the operation is unimportant; it is determined by the practical conditions linked to the apparatus and the quantities of water and alkylamine to be eliminated.

This stage.b), like all the other stages in the present invention, may be carried out continuously or noncontinuously. When all the water and alkylamine have been eliminated, an organic residue is obtained, esentially containing the required amide. Stage c) can be carried out by any known means of separation. A distillation is used with advantage or one or more flash evaporations or evaporation from a film or thin layer and operating under vacuum.

In the following Examples the heat stability test consists in maintaining the arylsulphonylalkylamide for 3 hours at 250°C under nitrogen; the colour at the end of the test must be less that 250 Hazen. The product may then be used as a plasticizer.

Save where otherwise indicated, the operation is carried out in a glass reactor equipped with a stirrer, a thermometric jacket, an injector for purging with nitrogen, a vertical condenser and cooling by cold water or brine bath. The materials were blanketed with nitrogen during the distillations (stages b) and c)). -10EXAMPLE 1 a) 3 moles of benzenesulphonyl chloride (C6H5SO2C1) are run in the course of 1 hour and 30 minutes into a mixture containing 3.051 moles of sodium hydroxide as an aqueous solution at a concentration of 19.37 % by weight and 3.3 moles of n-butylamine (CH3CH2CH2CH2NH2) . The temperature of the reactor is maintained at 20°C. Then the temperature is raised to between 60 and 65°C for 2 hours. After phase separation 675 g of an organic phase are obtained containing 3 x 0.9959 moles of N-(n-butyl)benzenesulphonamide (C6H5SO2NHCH2CH2CH2CH3) (BBSA) . b) This organic phase is distilled to eliminate water and n-butylamine, the temperature at the foot of the column being maintained at 20 to 145°C under a vacuum of 740 to 10 mm Hg for 1 hour. c) The residue obtained is distilled under vacuum (0.5 mm Hg) and 96 % of the BBSA contained in the organic phase at the end of stage a) is thus collected. The heat test shows a colour of 50 Hazen.

EXAMPLE 2 The procedure of Example 1 is followed save that the temperature is maintained at 50°C during the addition of benzenesulphonyl chloride. The results are identical to those in Example 1.

EXAMPLE 3 a) 0.6 mole of benzenesulphonyl chloride is run into 3.3 moles of n-butylamine, the reactor being maintained -1 1at 50°C. Then 3.051 moles of sodium hydroxide in the form of an aqueous solution at a concentration of 19.37 % by weight and 2.4 moles of benzenesulphonyl chloride are run in simultaneously in the course of 1 hour and 30 minutes, the reactor being maintained at 50°C. 7 g of water are added to rinse the sodium hydroxide dropping funnel. The reactor is then heated to between 60 and 65°C for 2 hours.

After phase separation 669 g of an organic phase are obtained containing 3 x 0.9939 moles of BBSA. b) Distillation is carried out as in Example 1. c) The residue obtained is distilled under a vacuum of 0.5 mm Hg and 95 % of the BBSA contained in the organic phase at the end of stage a) is thus collected. The heat test shows a colour of 50 Hazen.

EXAMPLE 4 The procedure of Example 2 is followed but using a stainless steel reactor whose bottom is made of grade 304 L and the rest of grade 316 L. Identical results are obtained.

EXAMPLE 5 a) 3 moles of benzenesulphonyl chloride are run into 3.3 moles of n-butylamine in the course of 30 minutes; the temperature of the reactor is maintained at 50°C. Then 3.15 moles of sodium hydroxide as a 19.91 % strength aqueous solution are run in during the course of 1 hour and 30 minutes. -12The sodium hydroxide dropping funnel is rinsed with 13.5 g of water. The reactor is heated to between 60 and 70°C for 2 hours. After phase separation 671.8 g of an organic phase are obtained containing 3 moles of BBSA. b) The water and amine are distilled out as in Example 1. 6.1 % of the mass involved in b) is observed to have been lost during this distillation. c) The residue obtained is distilled under vacuum (0.5 mm Hg) and 92 % of the BBSA contained in the organic phase at the end of stage a) is thus collected. The heat test shows a colour of 175 Hazen.

EXAMPLE 6 a) The procedure followed is the same as in Example 3 save that the reactor is maintained at 20°C instead of 50°C during the two operations of running in reactants. After phase separation 671.8 g of an organic phase are obtained containing 3 x 0.998 moles of BBSA. b) The water and amine are distilled out as in Example 1. A loss of mass of 6.07 % is observed during this distillation. c) The residue obtained is distilled under vacuum (0.5 mm Hg) and three fractions are collected corresponding to distillation foreruns, middles and tailings (the % are by weight) Fl = 4.9 % F2 = 84.2 % F3 = 7.1 % -133.8 % remains in the flask (% of the mass involved in stage c)).

The heat test on F2 gives a colour below 50 Hazen and 100 Hazen on Fl + F2 + F3. .5 EXAMPLE 7 The procedure followed is the same as in Example 2 save that 3.75 moles of n-butylamine are used. 702.6 g of an organic phase are obtained containing 3 x 0.9924 moles of BBSA. Identical results are obtained.

EXAMPLE 8 The procedure followed is the same as in Example 2 save that 3.15 moles of n-butylamine are used. 659.8 g of an organic phase are obtained containing 3 x 0.9915 moles of BBSA. Identical results are obtained.

Claims (8)

1. Process for the synthesis of arylsulphonylalkylamide, by reacting an arylsulphonyl halide with an alkylamine, of formula (I) CLAIMS 5 in which R x represents a hydrogen atom or an alkyl group of 1 to 10 carbon atoms, R 2 represents an alkyl group of 1 to 10 carbon atoms and R 3 represents one or more identical or different substituents which are halogen, hydrogen and C x alkyl comprising: 10 a) mixing arylsulphonyl halide with an excess of alkylamine and an aqueous solution of an alkaline agent, the quantity of alkaline agent being in excess relative to the arylsulphonyl halide involved; b) removing water and the alkylamine from the 15 organic phase obtained in a); and, -15c) separating the arylsulphonylalkylamide from the residue obtained in b).

2. Process according to Claim 1 in which the molar excess of alkylamine relative to the stoichiometric quantity of arylsulphonyl halide is from 5 to 15%.

3. Process according to Claims 1 or 2, in which the alkaline agent is sodium hydroxide.

4. Process according to any one of Claims 1 to 3, in which the molar excess of alkaline agent is from 1 to 5%.

5. Process according to any one of Claims 1 to 4, in which stage b) is performed by distillation.

6. Process according to any one of Claims 1 to 5 in which the arylsulphonylalkylamide is N-(n-butyl) benzene-sulphonamide: SO 2 NHCH 2 CH 2 CH 2 CH

7. Process according to Claim 1 substantially as described in any one of the Examples 1 to 8.

8. An arylsulphonylalkylamide of formula I as defined in Claim 1 whenever synthesised by the process of any one of Claims 1 to 7.