Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
1999-12-29
2002-09-03
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S300000, C508S581000, C549S016000
Reexamination Certificate
active
06444623
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods for the production of sulfurized diphenyloxides and compositions made therefrom. In particular, the present invention relates to methods for the production of sulfurized diphenyloxides from the reaction of diphenyloxides with elemental sulfur in the presence of a solid acid catalyst. The solid acid catalyst can be a zeolite or a catalytic amount of a Friedel-Crafts compound. Compositions made from the sulfurized diphenyloxides are useful as lubricant base stocks and additives thereto.
BACKGROUND OF THE INVENTION
Sulfurized diphenyloxides are beneficial as lubricant additives, lubricant base stocks, or intermediates to lubricant base stocks. Sulfurized diphenyloxides include, for example, phenoxathiin, bis(diphenyloxide) sulfides, diphenyloxide phenoxathiin sulfides, and bis(phenoxathiin) sulfides having the structures shown below. Alkylated phenoxathiin is a high-performance synthetic lube base stock with excellent viscometrics, oxidative stability, and antiwear properties. In addition, the bis(diphenyloxide) sulfide has been reported as a high-performance fluid.
Sulfurized diphenyloxides can be prepared from the reaction of diphenyloxide with sulfur using stoichiometric amounts of AlCl
3
at low temperatures. The reaction is believed to proceed through an aromatic electrophilic substitution mechanism. The acid catalyst enhances the electrophilicity of sulfur via the formation of positively charged sulfur intermediates. These intermediates are believed to be produced by the formation of a Lewis acid-base adduct between sulfur and the Lewis acid or by the protonation of sulfur by a Bronsted acid. However, the use of stoichiometric amounts of AlCl
3
does not provide an adequate commercial source of sulfurized diphenyloxides. Rather, the known process suffers from numerous drawbacks, including, for example, the use of corrosive reactants (e.g., halogenated hydrocarbons), the production of corrosive by-products (e.g., gaseous hydrochloric acid), poor selectivity (e.g., the production of significant amounts of higher sulfurized diphenyloxides, such as diphenyloxide phenoxathiin sulfide), and the need for extensive downstream separations (e.g., separation of catalyst from the product stream).
These drawbacks have negative implications for the commercial use of sulfurized diphenyloxides. The commercial use of sulfurized diphenyloxides has been hampered by the need to purify the sulfurized diphenyloxide prior to use. In particular, the presence of high concentrations of corrosive by-products has made it imperative that the sulfurized diphenyloxides be removed from the product stream prior to use. However, the purification of the sulfurized diphenyloxides is expensive and time consuming.
Accordingly, it would be highly beneficial to provide methods for the large scale production of sulfurized diphenyloxides. The method should provide for the production of sulfurized diphenyloxides in large yield without the use of highly corrosive reactants. Further, the method should produce little or no corrosive and/or undesired by-products. In addition, the method should utilize readily available reactants and be selective.
SUMMARY OF THE INVENTION
The drawbacks associated with the known method for producing sulfurized diphenyloxides is overcome, to a large extent, by methods in accordance with the present invention. The present invention provides a method for producing sulfurized diphenyloxides wherein a diphenyloxide and elemental sulfur are reacted in the presence of a solid acid catalyst. The reaction is very clean and produces little undesirable by-products. Usually, high sulfur conversion and selectivity to specific sulfurized diphenyloxides can be obtained under mild reaction conditions. The method can be used to produce sulfurized diphenyloxides in large scale and at economical prices.
In one of its aspects, the present invention relates to methods for the production of a sulfurized diphenyloxide wherein a diphenyloxide is reacted with elemental sulfur in the presence of a solid acid/oxide catalyst. In one embodiment, the diphenyloxide is alkylated prior to reaction with sulfur. Alternatively, alkylation is performed after sulfurization of the diphenyloxide. Preferably, however, the sulfurization and alkylation occur concurrently. In one embodiment, the acid catalyst comprises a molecular sieve, preferably a zeolite such as MCM-56, ZSM-5, MCM-22, MCM-68, and USY. Alternatively, the catalyst comprises a catalytic amount of a Friedel-Crafts compound, such as AlCl
3
. When the catalyst comprises a Friedel-Crafts compound, the reaction is preferably conducted at a temperature above about 75° C., more preferably at a temperature above about 120° C., and even more preferably at a temperature above about 180° C.
In another of its aspects, the present invention relates to a composition comprising between about 40 and about 80 weight percent diphenyloxide; no more than about 15 weight percent diphenyloxide thiol; between about 5 and about 45 weight percent phenoxathiin; and between about 3 and about 50 weight percent total of bis(diphenyloxide) sulfide, diphenyloxide phenoxathiin sulfide, and bis(phenoxathiin) sulfide.
Additional features and embodiments of the present invention will become apparent to those skilled in the art in view of the ensuing disclosure and appended claims.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to methods for the production of sulfurized diphenyloxides. The sulfurized diphenyloxides are produced by reacting a diphenyloxide with elemental sulfur in the presence of a solid acid catalyst according to reaction Scheme 1 below. It will be appreciated by those skilled in the art that the diphenyloxide can be optionally alkylated on one or both of the phenyl groups prior to reaction with the sulfur. The methods enable the production of a variety of sulfurized diphenyloxides, including phenoxathiin, bis(diphenyloxide) sulfide, diphenyloxide phenoxathiin sulfide, and bis(phenoxathiin) sulfide. Additionally, the methods can be used to produce substituted sulfurized diphenyloxides, including alkylated phenoxathiins.
The sulfur is in its elemental form and can be used without further purification. The sulfur can be combined with the diphenyloxide to form a saturated sulfur solution. Toward that end, the sulfur can be dissolved within a liquid solution containing the diphenyloxide. For example, an appropriate amount of sulfur can be dissolved directly in an appropriate amount of diphenyloxide to provide a diphenyloxide/sulfur solution having the desired mole ratio of diphenyloxide to sulfur. Preferably, the diphenyloxide/sulfur solution is saturated with sulfur.
The reaction between the diphenyloxide and the sulfur is carried out in the presence of solid acid catalyst. The acid catalyst can be aluminum chloride (AlCl
3
), BF
3
, AlBr
3
, solid zeolite, a layered catalyst, or any of a variety of other molecular sieves. Examples of suitable zeolite catalysts include MCM-56, ZSM-5, MCM-22, MCM-68, and USY. Zeolites may be used with framework metal elements other than aluminum such as, for example, boron, gallium, iron, and chromium.
When a zeolite is used, the zeolite preferably has a pore size of at least 5 Å. Large pore size zeolite catalysts are usually preferred, although less highly constrained medium or intermediate pore size zeolites may also be used. Generally, the large pore size zeolites are characterized by a pore structure with a ring opening of at least about 7 Å and the medium or intermediate pore size zeolites with a ring structure of 10 membered oxygen ring systems will have a pore opening smaller than about 7 Åbut larger than about 5.6 Å. Examples of suitable large pore size zeolites include faujasite, synthetic faujasites (zeolite X and Y), zeolite L, ZSM4, ZSM-18, ZSM-20, mordinite and offretite which are characterized by the presence of a 12-membered oxygen ring system in the molecular structure as described in Chen et al., “Shape-Selective Catalysis in
LaPierre Rene B.
Trotto Philip
Wu Margaret M.
ExxonMobil Chemical Patents Inc.
McAvoy Ellen M.
LandOfFree
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