Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Reexamination Certificate
1995-02-14
2001-02-13
Reamer, James H. (Department: 1614)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
C568S021000
Reexamination Certificate
active
06187960
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing organic polysulfide compounds from organic disulfides.
BACKGROUND OF THE INVENTION
Organic polysulfides containing two to five or even more sulfur atoms in the molecules have been found useful for many purposes such as additives for elastomers, antioxidants for lubricating oils, intermediates for the production of organic chemicals, insecticides, germicides and as an additive to diesel fuels to improve the octane number and ignition qualities of these fuels. These compounds have also been found useful in the compounding of extreme pressure lubricants and in the acceleration of rubber treating processes.
Such polysulfide compounds can be prepared by reacting mercaptans with elemental sulfur in the presence of a basic catalyst. For example, Biensan et al (U.S. Pat. No. 3,308,166) discloses that polysulfides can be prepared from a mercaptan and sulfur catalyzed by an amine using an alcohol promoter.
It has been shown that an alkyl polysulfide can also be produced by direct addition of sulfur to an alkyl disulfide in the presence of alkali, ammonia, amine, or zinc oxide. For example, sulfur is taken up by a warm, stirred solution of ethyl disulfide containing 1% of triethylamine. See generally E. Reid, Organic Chemistry of Bivalent Sulfur, Vol. III, 1960.
However, it has been discovered that the addition of sulfur to an alkyl disulfide caused substantially incomplete reaction partly due to the low reactivity and solubility of sulfur in alkyl disulfide. Therefore, there is a need to develop an improved process for producing organic polysulfide compounds.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing organic polysulfide compounds. Another object of the invention is to provide a process for producing organic polysulfide compounds under mild conditions. A further object of the present invention is to provide a process for producing polysulfide compounds at an increased reaction rate. Still another object of the invention is to produce an organic trisulfide compound. Yet still a further object of the present invention is to provide a process for producing an organic polysulfide from a mixture containing an organic disulfide. One of the advantages of the present invention is that an organic polysulfide can be produced in high yield at a mild condition. Other objects and advantages will become more apparent as the invention is more fully disclosed hereinbelow.
According to the present invention, a process which can be used to produce organic polysulfide compounds is provided. The process comprises contacting, in the presence of a catalyst, an organic disulfide with sulfur under conditions sufficient to produce the organic polysulfide. The organic disulfide, sulfur, and catalyst are each present in an amount effective to produce an organic polysulfide, and the catalyst comprises a basic catalyst and a surfactant.
DETAILED DESCRIPTION OF THE INVENTION
According to the first embodiment of the present invention, an organic polysulfide compounds having the formula of R—S
n
—R, wherein each R can be the same or different and is each a hydrocarbyl radical having 1 to about 30, preferably about 1 to about 20, and most preferably 1 to 15 carbon atoms and n is a number greater than 2 but less than about 10, preferably in the range of from about 3 to about 8, more preferably from 3 to 5, and most preferably 3, can be produced by the process of the present invention. The hydrocarbyl radical can be linear or branched and can be alkyl, aryl, cycloalkyl, alkaryl, aralkyl, alkenyl radicals, or combinations of any two or more thereof. Preferably the hydrocarbyl radical is an alkyl radical.
According to the present invention, a process for producing an organic polysulfide is provided which comprises contacting an organic disulfide with elemental sulfur in the presence of a catalyst which comprises a basic catalyst and a surfactant. The basic catalyst can be any catalyst, which is not an alkylamine, that can catalyze the reaction of an organic disulfide and sulfur to form an organic polysulfide compound as defined hereinabove. The presently preferred catalyst comprises a basic catalyst which can be an inorganic base, an organic base, or combinations of any two or more thereof.
Suitable organic bases include, but are not limited to, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetramethylammonium bisulfide, tetraethylammonium bisulfide, and combinations of any two or more thereof. Suitable inorganic bases include, but are not limited to, lithium hydroxide, sodium hydroxide, sodium hydrosulfide, sodium bisulfide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium bicarbonate, sodium carbonate, sodium oxide, sodium sulfide, magnesium oxide, calcium oxide, calcium carbonate, sodium phenoxide, barium phenoxide, calcium phenoxide, R
1
ONa, R
1
OK, R
1
SNa such as sodium methanethiolate, R
1
SK, and combinations of any two or more thereof; where R
1
is a C
1
-C
18
alkyl radical, or combinations of any two or more thereof. Among the bases, sodium hydroxide, sodium hydrosulfide, and sodium methanethiolate are preferred because they exert some synergistic effect with a surfactant and they are readily available and inexpensive.
The catalyst useful in the production of an organic polysulfide also comprises a surfactant. According to the present invention, any surfactant that facilitates the mixing of reactants into substantially a single phase can be used.
Generally, the surfactant comprises one or more compounds which exhibit surface-active properties. A preferred surfactant for use in the reaction system of the instant invention is selected from the group consisting of alkoxylated compounds, quaternary ammonium salts, alkali metal alkyl sulfates, alkali metal salts of alkanoic acids, alkali metal salts of alkaryl sulfonic acids, 1-alkyl pyridinium salts, and combinations of any two or more thereof.
The presently preferred surfactant is an alkoxylated compound. Examples of suitable alkoxylated compounds include, but are not limited to, alkoxylated alcohols, alkoxylated mercaptans, sulfates of alkoxylated alcohols, alkoxylated phenols, sulfates of alkoxylated phenols, and combinations of any two or more thereof.
The alkoxylated alcohol useful in the present invention has a general formula of R
2
O[CH
2
CH(R
3
)O]
q
H where R
2
is a C
1
-C
20
hydrocarbyl radical selected from the group consisting of alkyl radical, alkylaryl radical, aryl radical, cycloalkyl radical, alkenyl radical, and combinations of any two or more thereof; Preferably R
2
is a C
6
-C
18
alkyl radical. Most preferably R
2
is a C
10
-C
16
alkyl radical; R
3
is selected from the group consisting of hydrogen, C
1
-C
16
alkyl radicals, C
2
-C
16
alkenyl radicals, and combinations of any two or more thereof; and q is a number of from 1 to about 20, preferably from about 2 to about 12, most preferably from 5 to 10. Generally R
3
can contain from 0 to about 16 carbon atoms. Preferably R
3
is a hydrogen or a C
1
-
3
alkyl radical. Most preferably R
3
is hydrogen. An example of suitable alkoxylated alcohol is TERGITOL 15-S-7 which is an ethoxylated alcohol, is manufactured and marketed by Union Carbide Corporation, and has the formula of R
2
O(CH
2
CH
2
O)
7
H where R
2
is a secondary alkyl radical having 11-15 carbon atoms and 7 is the averaged number of the ethylene oxide units. Another example is an ethoxylated phenol having the same number of ethylene oxide units. Other suitable alkoxylated alcohols are also available from Union Carbide Corporation.
The sulfate of alkoxylated alcohol useful in the present invention has a general formula of R
2
O[CH
2
CH(R
3
)O]
q
SO
3
M where R
2
and R
3
are the same as those described above and M is an alkali metal or an alkaline earth metal or combinations of any two or more thereof. An example of suitable sulfate of alkoxylated alcohol is sodium sulfate of an ethoxylated alcohol having th
Phillips Petroleum Company
Reamer James H.
Richmond, Hitchcock, Fish & Dollar
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