Claims
- 1. A process for the preparation of aromatic sulfonyl chlorides of the formula I ##STR5## in which R.sub.1, R.sub.2 and R.sub.3 are identical or different and are hydrogen, fluorine, chlorine, bromine or iodine atoms, alkyl (C.sub.1 -C.sub.4), acetamido, nitro or carboxyl groups, or R.sub.1 and R.sub.2 together form an aromatic ring having 5 to 6 ring members or form an oxazolone ring which comprises reacting aromatic compounds of the formula II ##STR6## in which R.sub.1, R.sub.2 and R.sub.3 have the abovementioned meanings, with chlorosulfonic acid in excess or with chlorosulfonic acid or oleum and thionyl chloride in the presence of about 0.1 to about 20% by weight of sulfamic acid relative to the aromatic compound of said formula II as a catalyst at a temperature in the range of from -10 to 150.degree. C.
- 2. The process as claimed in claim 1, which comprises reacting in the presence of about 0.5 to about 5% by weight of sulfamic acid, relative to the aromatic compound of said formula II.
- 3. The process as claimed in claim 1, which process is carried out at normal or elevated pressure.
- 4. The process as claimed in claim 1, wherein the sulfamic acid is completely added to the chlorosulfonic acid at the start of the reaction.
- 5. The process as claimed in claim 1, wherein the sulfamic acid is only partially added to the chlorosulfonic acid at the start of the reaction and further sulfamic acid is metered in during the course of the reaction.
- 6. The process as claimed in claim 1, wherein, when using chlorosulfonic acid or oleum as the sulfonating agent, the sulfamic acid is added to the reaction mixture obtained after reaction of the aromatic compound of said formula II with said sulfonating agent and the mixture is then reacted with thionyl chloride to give arylsulfonyl chloride.
Priority Claims (1)
| Number |
Date |
Country |
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| 3919840 |
Jun 1989 |
DEX |
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Parent Case Info
This application is a continuation of our copending application Ser. No. 07/538,115, filed Jun. 14, 1990, now abandoned.
The invention relates to the preparation of aromatic sulfonyl chlorides in a manner known per se by reaction of aromatic compounds with excess chlorosulfonic acid or with chlorosulfonic acid or oleum and thionyl chloride, the reaction being carried out in the presence of sulfamic acid as a catalyst.
It is known that the sulfonation and sulfochlorination of aromatic compounds can be improved by adding so-called sulfone inhibitors to suppress the sulfone formation observed as a secondary reaction [Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., vol. A.3, p. 513]. Examples of such sulfone inhibitors which may be mentioned are ammonium sulfate, sodium carbonate or potassium carbonate [DE 3,501,754], and sodium chloride or ammonium chloride [DE 3,306,597]. A large number of other sulfonating agents are mentioned in EP 0,001,275.
It is known from Helv. Chimica Acta 42, 1653 (1959) that dialkylformamides act as catalysts in the preparation of naphthalenesulfonyl chlorides from the corresponding sulfonic acids.
Reference is made in DE 2,938,744 to the toxicological problems in the use of dimethylformamide in particular, and substitutes, such as, for example, pyridine, substituted pyridines, tertiary aliphatic amines and quaternary ammonium salts, preferably tertiary amines, are proposed.
The compounds proposed as catalysts or auxiliaries for the sulfonation or sulfochlorination of aromatic compounds are not satisfactory for industrial use, in particular for reasons of occupational hygiene , and thus capable of improvement .
It has now been found that sulfamic acid is a novel, advantageous auxiliary for the sulfochlorination of aromatic compounds to give the corresponding arylsulfonyl chlorides.
The invention thus relates to an improved process, with respect to attainable yields and quality, for the preparation of aromatic sulfonyl chlorides of the general formula I ##STR3## in which R.sub.1, R.sub.2 and R.sub.3 are identical or different and are hydrogen, fluorine, chlorine, bromine or iodine atoms, alkyl(C.sub.1 -C.sub.4), acetamido, nitro or carboxyl groups, or R.sub.1 and R.sub.2 together form an aromatic or heteroaromatic ring having 5 or 6 ring members, which can be substituted by fluorine, chlorine, bromine or iodine atoms, alkyl(C.sub.1 -C.sub.4), acetamido, nitro or carboxyl groups, by reaction of aromatic compounds of the general formula II ##STR4## in which R.sub.1, R.sub.2 and R.sub.3 have the abovementioned meanings, in a manner known per se with chlorosulfonic acid in excess or with chlorosulfonic acid or oleum and thionyl chloride, which comprises reacting in the presence of sulfamic acid as a catalyst.
The sulfamic acid employed according to the invention as a catalytically active auxiliary cannot be classified in any of the known compound classes of auxiliaries or catalysts for the sulfochlorination of aromatic compounds.
The aromatic sulfonyl chlorides are prepared from the aromatic compounds by methods known per se, for example by reaction of the aromatic compounds of the abovementioned general formula II with excess chlorosulfonic acid [cf. Winnacker-Kuchler, Chemische Technologie (Chemical Technology), volume 6, 4th edition, page 181, Carl-Hauser-Verlag Munich Vienna]or chlorosulfonic acid (or oleum) and thionyl chloride [DE 3,302,647].
In this connection, a procedure is expediently used in which the sulfamic acid is partially or completely added to the chlorosulfonic acid and, in the case of only partial addition at the beginning of the reaction, further sulfamic acid is metered in during the reaction.
However, it is also possible to convert the aromatic starting compound into the aromatic sulfonic acid first using chlorosulfonic acid or oleum, to add the sulfamic acid to the reaction mixture produced in this case and then to react further to give the arylsulfonyl chloride with thionyl chloride.
The sulfamic acid is expediently added in an amount of about 0.1 to about 20% by weight, preferably about 0.5 to about 5% by weight, relative to the aromatic compound of said general formula (II), to the chlorosulfonic acid, which is used in excess (when working without thionyl chloride), or after completion of the sulfonation in the first step and before addition of the thionyl chloride in the second step. Addition of sulfamic acid in larger amounts is admittedly possible, but possesses no advantages. As far as the temperatures are concerned, those in the known sulfochlorination of aromatic compounds with an excess of chlorosulfonic acid, i.e. temperatures of about -10.degree. C. to about 150.degree. C., preferably of about 20.degree. C. to about 120.degree. C., or those in the known sulfonation of aromatic compounds with chlorosulfonic acid or oleum in the first step, i.e. temperatures of about -10.degree. C. to about 150.degree. C., preferably of about 20.degree. C. to about 130.degree. C., and those in the subsequent known sulfochlorination with thionyl chloride in the second step, i.e. temperatures of about 30.degree. C. to about 150.degree. C., preferably about 50.degree. C. to about 130.degree. C., can be used.
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| Entry |
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Continuations (1)
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| Parent |
538115 |
Jun 1990 |
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Patent Grant
5136043
