CS227027B2 - Method of separating sulphuric acid from the reaction mixture left after paraffine sulphoxidizing - Google Patents

Abstract

1. A process for the removal of sulfuric acid from the reaction mixture formed in the sulfoxidation of paraffins, which process is characterized by adding an organic amine of the formula see diagramm : EP0054851,P5,F2 in which R**1 denotes C3 -C18 -alkyl, C5 -C8 -cycloalkyl or phenyl which can be substituted by 1 to 3 C1 -C4 -alkyl groups or by a C1 -C9 -alkyl group, or, if R**3 represents a group of the formula -X-NR**1 R**2 , also denotes hydrogen, R**2 has the same meaning as R**1 and additionally denotes hydrogen, R**3 has the same meaning as R**1 and additionally denotes hydrogen or a group of the formula -X-NR**1 R**2 and X denotes phenylene or C8 -C12 -alkylene, to the reaction mixture and removing the phase, composed of water and sulfuric acid, which then separates out.

Description

The invention relates to a process for separating sulfuric acid from the reaction mixture resulting from the sulfoxidation of paraffins.

The sulfoxidation of the linear paraffins by the light-water process, i.e. the sulfur dioxide and oxygen process in the presence of water and ultraviolet light, produces a mixture consisting of paraffin, water, alkanesulfonic acid and sulfuric acid after separation of the insoluble paraffin. The composition of this mixture is dependent on the chain length of the paraffin used. In the sulfoxidation of a paraffin chain having a chain length of 12 to 18 carbon atoms and a maximum chain length of 14 to 17 carbon atoms, a mixture of approximately the following composition is obtained, for example, after the sulfur dioxide ejection: 37.5% water, 32% paraffin, 23% alkanesulphone. acid and 7.5% sulfuric acid.

This mixture is a completely clear solution and is hereinafter referred to as an extract. This is probably a microemulsion of paraffin in aqueous sulfuric acid, where the alkanesulfonic acid acts as a solubilising agent.

In order to obtain pure alkanesulphonic acid sodium salt, which is of great importance as a readily biodegradable surfactant, the presence of sulfuric acid has a very disruptive effect, since the corresponding fraction of sodium sulphate is formed during the ne2 trazilization.

Therefore, attempts have been made in the past to influence this extract so that sulfuric acid can be separated. Thus, for example, it is known that heating the extract to about 90 ° C leads to a partial separation of the sulfuric acid. However, the technically achievable separation is only about 35% of the total sulfuric acid. It is also known to add weakly polar alcohols having at least 5 carbon atoms to the extract in order to obtain a separation of the mixture into an organic phase containing sulfonic acid and an aqueous phase containing almost all sulfuric acid. it consists, on the one hand, of a considerable amount of alcohol which must be added to the extract (between 20 and 80 g of alcohol per 100 g of extract) and, on the other hand, of the difficult separation of alcohol from paraffin. Finally, it is known to add weakly polar organic solvents such as ethers, ketones, esters and aliphatic ketoesters to the extract. A disadvantage of this process is also the considerable amount of solvents that must be used to separate the sulfuric acid. The amounts used are between 30 and 100 g per 100 g of extract.

The object was therefore to achieve as little as possible a quantitative separation of sulfuric acid from the addition of as little as possible of the monovalent reagent. It has now been found that this object can be achieved by the process according to the invention.

The process for separating sulfuric acid from the reaction mixture resulting from the sulfoxidation of paraffins according to the invention consists in adding to the reaction mixture at a temperature of 20 to 130 ° C, preferably at a temperature of 90 to 100 ° C, an organic amine of the formula

R1 \

N - R ³ / R 2 wherein

R 1 represents a C 3 -C 18 alkyl group, a C 5 -C 8 cycloalkyl group, a phenyl group optionally substituted by 1 to 3 C 1 -C 4 alkyl groups or one C 1 -C 9 alkyl group, or if R3 represents a group —X — _N RR2 then also represents hydrogen,

R2 has the same meaning as R1 and is additionally hydrogen,

R 3 has the same meaning as R 1 and additionally represents hydrogen or a group of the formula -X-NR 1 R 2, wherein

X represents a phenyl group or an alkylene group having 8 to 12 carbon atoms.

in an amount of 1 to 5 parts by weight, preferably in an amount of 2 to 4 parts by weight,. to 100. The separated phase consisting of water and sulfuric acid is separated.

Particularly preferred are those amines of the above general formula which contain only alkyl or alkylene groups, in particular straight alkyl or alkylene groups.

Suitable amines of this type are aliphatic monoalkylamines, dialkylamines and trialkylamines, wherein the alkyl radicals can have both straight and branched chains. Corresponding cycloaliphatic mono-, di- and trialkylamines are also suitable. Also aromatic amines such as. xylidine or ethylaniline have the desired effect as well as long chain aliphatic diamines.

Amines which exhibit particularly good activity are heptylamine, hexylamine, octylamine, diisobutylamine, dibutylamine, dipentylamine, dihexylamine, tributylamine, dibutylmethylamine, tripentylamine, trihexylamine, cyclohexylamine, dicyclohexylamine, dicyclohexylamine, tricyclohexylamine, tricyclohexylamine, dicyclohexylamine, triacylamine, p-toluidine, xylidine,

2-ethylanilium, o-diaminobenzenene, amino2-ethylamine, o -diaminobenzene, aminodiphenyl and p-nonylaniline.

parts by weight, preferably 2 to 4 parts by weight, based on 100 parts by weight of the crude sulfonation mixture extract (extract). Prior to this, the extract was freed from the sulfur dioxide residues which had been removed. are '. dissolved in it. Lower Department. the phase consisting of water and sulfuric acid takes place at room temperature with the addition of the amine. In order to achieve a complete separation of sulfuric acid, it is preferred to heat the extract to about 20 to 130. ° C, in particular 90 to 95 ° C. After addition of the amine, the mixture is allowed to stand for about 30 to 60 minutes and then formed. the bottom phase is separated, the bottom phase consisting of about 20% aqueous sulfuric acid and containing virtually all the amount of sulfuric acid originally present in the extract. This sulfuric acid can be further processed by a special process. The remainder of the upper phase consists of an unreacted residue of paraffin and an alkanesulfonic acid, a part of which. The alkanesulfonic acid is present in the form of a salt with an amine added as a phase separation agent. -

In particular, the process described above is characterized in that complete separation is achieved. sulfuric acid, the amount of amine being for. for this purpose, it is of the order of ten times lower than the amount of weakly polar solvents used hitherto for this purpose. Another advantage is that the organic amines do not migrate with the acid. sulfuric. into the water bottom. phase, but remain entirely with the alkanesulfone. acid in the upper phase. The process according to the invention is used. especially k. division of raw sulphonation. . mixtures derived from. .sulfoxida.ce n-. paraffins having 7 to 30 carbon atoms, preferably 10 to 30 carbon atoms; to 20 carbon atoms.

The invention. illustrate, but in no way. the following examples do not limit:

P FiklaHl у

Ke 100. parts by weight extract. gas-free with the following composition:

water 37.5% paraffin 32% alkanesulfonic acid 23% sulfuric acid 7.5% were added with stirring 3 parts by weight of di-n-pentylamine at 95 ° C and the mixture was further stirred for 5 minutes. The mixture is then held in a heated separating funnel for about 45 minutes, the extract being separated into two phases. The colorless aqueous sulfuric acid is then separated as the lower phase. . 35 parts by weight are obtained. about 20% sulfuric acid, the content of which is determined by filtration. Based on the sulfuric acid leak present in the extract, 92% was separated.

Example 1 a d 2

To 100 parts by weight of the degassed extract of Example 1, 3.5 parts by weight of tri-n-butylamine are added at room temperature and the mixture is stirred for 10 minutes. The mixture was then transferred to a heatable separatory funnel and the appropriate procedure as in Example 1 was used ^; separates sulfuric acid as the aqueous bottom phase. 35.5 parts by weight of aqueous sulfuric acid are obtained which contains 94.6% of the amount of sulfuric acid initially present in the extract.

Example 3

100 parts by weight of the gas-free extract according to Example 1 are mixed with 3.5 parts by weight of dicyclohexylamine in the form of 9.5 parts by weight of alkanesulfonic acid dicyclohexylammonium salt at 90 DEG C. and then treated as in Example 1. After separation, 35.2 parts by weight of aqueous sulfuric acid are obtained which contains 93% of the amount of sulfuric acid initially present in the extract.

Example 4

100 parts of the gas-free extract according to Example 1 were pre-separated by heating to 90 ° C, with 33% of the sulfuric acid present remaining in the form of about 23% of the sulfuric acid in the lower phase which was separated. Subsequently, 4 parts by weight of n-hexylamine are added and the mixture is treated as described in Example 1. An additional 60% sulfuric acid is obtained as the lower phase so that 93% of the amount of sulfuric acid originally present in the mixture is separated.

Further examples, which were carried out in analogy to the above-described examples 1-4, are summarized below in the form of a table. The amount of amine reported in all examples was chosen so that the residual sulfuric acid content was in accordance with the current specification for commercially available alkane sulfonates. By adding more amine, this residual content can be further reduced in all cases.

the amine used parts by weight of amine per 100 parts by weight of extract % by weight of the separated sulfuric acid n-pentylamine .......... 3,5 92 n.-heptylamine. 3,5 ....... 91 cyclohexylamine 4 . 93 n-octylamine i 4 92 n-laurylamine ....... 4 .. '. 90 n-stearylamine 4. . . 90 isohexylamine 4 92 isoheptýlamine .......... 3.5 89 isoxtytylamine. .  3.5 89 išótridecylamine ; 3,5 ... 90, dibuty lamin 3.0 93 diisobutylamine 3.0 92 di-n-hexylamine 3.5 91 distearylamine 4 89 dibutylmethylamine 3.0 92 1,8-diaminoctane 3.5 88 1,11-diaminoundecane 4.0 92 aniline 4.0 88 o-toluidine 3.5 89 p-toluidine 3.5 89 1,3-xylidine 3.5 91 p-nonylaniline 3.5 92 2-ethylaniline 3.0 93 o-diaminobenzene 3.5 89 aminodiphenyl 3.5 90

Claims (3)

I will invent the subject Process for separating sulfuric acid from the reaction mixture resulting from the sulfoxidation of paraffins, characterized in that an organic amine of the general formula (I) is added to the reaction mixture at a temperature of 20 to 130 ° C, preferably 90 to 100 ° C. Ri \ ' N — R ³ OF R ² in which R ¹ is C 3 -C 18 alkyl, C 5 -C 8 cycloalkyl, phenyl optionally substituted with 1 to 3 C 1 -C 4 alkyl, or one C 1 -C 9 alkyl, or when R ³ is a group -X-NR1R ^2, it is also hydrogen, R ² has the same meaning as R ¹ and additionally denotes hydrogen, R ³ has the same meaning as R 1 and in addition represents hydrogen or a group of the formula -X-NR ¹ R ² , wherein X is a phenylene or C8-C12 alkylene group in an amount of 1 to 5 parts by weight, preferably in an amount of 2 to 4 parts by weight, per 100 parts by weight of the extract, and the excluded phase consisting of water and sulfuric acid, is separated. 2. The process of claim 1, wherein an organic amine of formula (I) is added to the reaction mixture R ¹ \ N — R ³ OF R ² in which R 1 is C 3 -C 18 alkyl, or when R ³ is - X - NR ¹ R ² , it is also hydrogen, R ² has the same meaning as R ¹ and additionally denotes hydrogen, R ³ has the same meaning as R ¹ and additionally represents hydrogen or a group of the formula -X-NR ¹ R ² and X represents an alkylene group having 8 to 12 carbon atoms. 3. The process of claim 1 wherein an organic amine of formula (I) is added to the reaction mixture Ri \ N — R ³ OF R ² in which R 1 is a straight C 3 -C 18 alkyl group or when R ³ is -X-NR ¹ R ² , it is also hydrogen, R ² has the same meaning as R, and additionally represents hydrogen, R ³ has the same meaning as R 1 and, moreover, represents hydrogen or a group of the formula -X- NR ¹ R ² and X represents a straight alkylene group having 8 to 12 carbon atoms.