Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfonic acids or salts thereof
Reexamination Certificate
2001-05-04
2002-05-07
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfonic acids or salts thereof
C562S058000
Reexamination Certificate
active
06384271
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for sulfonating, sulfating, or sulfamating an organic compound.
BACKGROUND OF THE INVENTION
Sulfonation of organic compounds represents a major synthetic reaction. Sulfonations commonly use sulfuric acid and sulfur trioxide as the sulfonating agents. While sulfur trioxide presents major problems in terms of corrosivity, toxicity, and the consequences of leakage, it provides certain advantages. For example, sulfonation with sulfur trioxide can result in different and advantageous ratios of sulfonated isomers compared with the use of sulfuric acid and avoid safety problem with handling sulfuric acid.
The importance of the ratio of sulfonated isomers is conveniently described by the synthesis of p-cresol, extensively used in disinfectants and in the manufacture of resins. The sulfonation of toluene provides essentially a mixture of o- and p-toluene sulfonic acids, which are fused with sodium hydroxide to yield the corresponding o- and p-cresols (o- and p-methylphenols). Since the o-cresol is largely an unwanted byproduct, maximizing the ratio of para:ortho is highly advantageous in terms of ease of purification of the desired p-cresol, minimizing byproduct and waste streams, and minimizing energy use in the purification steps. The term regiospecificity is used to describe the ability of, in this application, a sulfonating agent, to affect the para:ortho ratio.
The sorption of sulfur trioxide by some basic organic compounds is well known. For instance, certain polyvinylpyridine resins form addition compounds with sulfur trioxide that can be used in sulfation reactions. See U.S. Pat. No. 3,057,855 disclosing use of a sulfur trioxide-poly(2-vinylpyridine) polymer for sulfation. See also W. Graf, in Chemistry and Industry, p 232, 1987 disclosing a pyridine-sulfur trioxide complex bound to a cross-linked polystyrene polymer and its use for the sulfation of alcohols and amines. However, the sulfur trioxide is sufficiently deactivated in the complexes that it does not sulfonate aromatics. Furthermore, U.S. Pat. No. 4,490,487 discloses SO
3
adducts with imides and the use of the adducts as sulfonating agents for aromatic compounds.
In all such complexes or adducts, SO
3
is deactivated. Some deactivate SO
3
enough that they become somewhat unreactive to sulfonate compounds that are relatively resistant to sulfonation. For instance, the sulfur trioxide-pyridine complexes described above have uses limited to the sulfation of alcohols, sugars, polysaccharides, etc.
It would be desirable to develop: new sulfur trioxide complexes in which the sorbent is substantially insoluble to facilitate product isolation, which sulfonate aromatic compounds in a regiospecific manner, and which provide a more active solid sulfonating, sulfating, and sulfamating agent effective in a wider range of sulfonation, sulfation, and sulfamation processes.
An advantage of the invention is that it can be used industrially for the manufacture of detergents, dye intermediates, and sulfonated oils. For example, detergents can be made by using the SO
3
complexes disclosed below for either sulfating alcohols or sulfonating polyalkyl benzenes. Another advantage is that the use of the SO
3
complexes provides substantial safety and product isolation advantages over the prior art.
SUMMARY OF THE INVENTION
A process comprises contacting an organic compound with sulfur trioxide under a condition sufficient to effect the sulfonation, sulfation, or sulfamation of the organic compound in which the organic compound is selected from the group consisting of an aromatic compound, alcohol, carbohydrate, amine, amide, protein, and combinations of two or more thereof, and the sulfur trioxide is present in a complex comprising an inorganic support selected from the group consisting of zeolite, silicalite, silica, titanosilicate, borosilicate, clay, and combinations of two or more thereof.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, any organic compounds that can be sulfurized with SO
3
can be used. The term “sulfurized” refers to being added a sulfur atom or sulfur-containing functionality. Examples of suitable organic compounds include, but are not limited to, aromatic compounds, alcohols, carbohydrates, amines, amides, proteins, or combinations of two or more thereof.
The aromatic compound is preferably an activated aromatic compound. An activated aromatic compound has no substituents on the arylene ring or contains at least one electron-donating group on the arylene ring. Examples of electron-donating groups include alkyl, alkoxy, alkylthio, hydroxy, amino, amide such as —NHCOCH
3
, phenyl, or combinations of two or more thereof. Specific examples of activated aromatic compounds include, but are not limited to, benzene, naphthalene, biphenyl, toluene, aniline, benzylamine, methylaniline, dimethylaniline, diphenylamine, triphenylamine, anisidines, acetanilide, benzanilide, toluidine, phenol, hydroxymethyl benzene, biphenyl, or combinations of two or more thereof. Many of these compounds such as, for example, aniline, benzylamine, methylaniline, dimethylaniline, toluidine, phenol, and hydroxymethyl benzene can also be sulfated or sulfamated. The presently preferred aromatic compound is toluene. See generally, Everett Gilbert, in “Sulfonation and Related Reactions”, Interscience Publishers, John Wiley and Sons, 1965, p. 65.
The process of the invention is also useful for selectively sulfonating an aromatic compound. The term “selective or selectively” used herein, unless otherwise indicated, refers to the sulfonation of suitable aromatic compound to produce substantially higher para:ortho ratio. Such selective sulfonation is also referred to as improving “regiospecificity”, which is disclosed in the BACKGROUND OF THE INVENTION section.
For example, with sulfonation of toluene using the invention process, the toluene sulfonic acid produced has an enhanced para:ortho ratio. Also, sulfonation of biphenyl, biphenyl-4-sulfonic acid production is enhanced. Further for example, selective sulfonation suppresses undesired multiple sulfonations in reactive aromatic compounds such as naphthalene.
Wishing not to be bound by theory, the mechanism for the regiospecificity is believed to be due to steric restrictions for a reaction within the inorganic support or sorbent pores. The pore dimensions are believed to orient the organic molecule as it contacts the sulfur trioxide. For instance, in the sulfonation of biphenyl, the biphenyl enters the pore constrained or oriented to present the 4-position to the reactant SO
3
. The pore dimension creates a constraint against presentation of the 2- postion to the sorbed reactant; a constraint that is absent in conventional fluid phase reactions.
The preparation of p-cresol via the sulfonation of toluene and subsequent alkali metal hydroxide fusion discussed above is an example of sulfonation, which improves regiospecificity of the sorbed sulfur trioxide. The higher ratio of p-toluene sulfonic acid to o-toluene sulfonic acid results in a higher yield of the desired p-cresol and reduced isolation costs. A second example is the sulfonation of biphenyl, to give a sulfonation more regiospecific in the production of the preferred biphenyl-4-sulfonic acid, a source of various 4-substituted biphenyl compounds, including 4-phenylphenol.
Any alcohols that are substantially liquid or are soluble in an inert solvent under ambient conditions can be used. Examples of suitable alcohols include, but are not limited to, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, octanol, decanol, or combinations of two or more thereof.
Any carbohydrates that are substantially soluble in a solvent, which is inert to SO
3
such as super critical CO
2
, can be used in the invention. Examples of suitable carbohydrates include, but are not limited to, glucose, fructose, sucrose, or combinations of two or more thereof.
Similarly, proteins suitable for use in the invention are substantially soluble in an inert solvent. Examples of suitabl
Corbin David Richard
Jacobson Stephen Ernest
E.I. du Pont de Nemours and Company
Vollano Jean F.
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