Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-03-23
2002-12-31
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S363000
Reexamination Certificate
active
06500964
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for preparing alditol acetals, such as dibenzylidene sorbitols, monobenzylidene sorbitols, and the like, through the reaction of unsubstituted or substituted benzaldehydes with alditols (such as sorbitol, xylitol, and ribitol) in the presence of a mineral acid and at least one surfactant having at least one pendant group of 6 carbon chains in length. Such a reaction provides a cost-effective, relatively safe procedure that provides excellent high yields of alditol acetal products, particularly those which have heretofore not been readily available due to processing limitations, such products including bis(5-indanylidene)sorbitol. Furthermore, such a specific reaction is also the best known procedure for the production of certain compounds which can be easily separated from other formed isomers. Additionally, such a procedure facilitates the production of certain asymmetric alditol acetal compounds and compositions in acceptable yields as well. Such alditol acetals are useful as nucleating and clarifying agents for polyolefin formulations and articles, as one example.
BACKGROUND OF THE PRIOR ART
All U.S. Patent documents and other publication discussed below are herein entirely incorporated by reference.
Dibenzylidene sorbitol (“DBS”), substituted DBS's, such as can be made with alkyl substituted aromatic aldehydes, and related acetals have found utility as nucleating agents, clarifying agents, gelling agents, processing aids, and strength modifiers in polyolefin resins, polyester resins, deodorant, and antiperspirant compositions; hydrocarbon fuels; waste liquids, especially those containing organic impurities; and paint.
Alditol acetals, such as DBS derivative compounds, are typically prepared by the condensation reaction of an aromatic aldehyde with a polyhydric alcohol, for example, without limitation, sorbitol, xylitol, ribitol, and the like. For DBS structures, such reactions involve two moles of the aldehyde and one mole of the alcohol. Examples of suitable processes may be found in Uchiyama, U.S. Pat. No. 4,267,110, Murai et al., U.S. Pat. No. 3,721,682; Murai et al., U.S. Pat. No. 4,429,140; Machell, U.S. Pat. No. 4,562,265; Kobayashi et al., U.S. Pat. No. 4,902,807; Salome et al., U.S. Pat. No. 5,023,354; and Scrivens et al., U.S. Pat. No. 5,731,474.
Unfortunately, these previous reaction procedures all suffer significant drawbacks for utilization within a greater breadth of reactions. The first procedure taught was by Uchiyarna solely for the production of limited DBS compounds of the unsubstituted benzaldehyde type. The lack of versatility of such a procedure has severely limited its implementation within different DBS compound producing methods. Solvent-based systems have been developed for higher yield and greater versatility of DBS formation, for instance, within the Murai et al., Scrivens et al, and Kobayashi et al. patents, which all concerned reactions for the production of un-, mono-, or di-substituted dibenzylidene sorbitols. Although these reactions are highly effective in producing high yield, high purity DBS compounds, the solvents needed are expensive and the energy required to effectuate necessary mixing and high temperatures is also expensive. In an effort to reduce such solvent costs, low temperature low temperature aqueous procedures have been developed, such as in the Machell and Salome et al. patents. Machell requires the utilization of a mineral acid as the catalyst alone for acetalization; Salome et al. specifically exclude any mineral acids from their procedure and instead rely solely upon the presence of relatively large amounts of arylsulfonic acid catalysts to effectuate acetalization of the benzaldehyde and alditol components. Machell thus requires large amounts of mineral acids whereas Salome et al. require expensive arylsulfonic compounds (such as para-toluenesulfonic acid, naphththalene sulfonic acid, and the like). More importantly, however, it has now been found that there are key problems with both types of procedures which require improvement. For instance, the previous uses of acid alone, as in Machell, or with arylsulfonic acids alone, as in Salome et al., as acetalization catalysts have proven very difficult for a number of reasons. The Machell method of acid alone has suffered from a lack of effectiveness in producing highly-substituted DBS derivatives, apparently, and without intending to be limited to any specific scientific theory, from the lack of contacting a sufficient amount of catalyst with the reactants themselves to permit combination and thus acetalization. In the past, such mineral acids have proven to be excellent catalysts alone for un- or certain minimally-substituted benzaldehydes (e.g., p-methylbenzaldehyde). Apparently, di-substituted benzaldehydes and above are more hydrophobic and thus do not solubilize well within aqueous acid formulations. In such a situation, the catalysis of di-substituted (or higher)benzaldehydes with alditol is nearly nonexistent due to a lack of effective contact between all three components (e.g., acid, benzaldehyde, and alditol). Benzaldehyde and p-methylbenzaldehyde, on the other hand, are much more soluble within such an aqueous acid formulation and thus more easily contact the acid catalyst, thereby permitting a more effective acetalization of the alditol for very high yields. Thus, from a versatility standpoint, the use of mineral acids alone, although the best catalyst for acetalization procedures, does not effectively contact with certain reactants due to solubility considerations. The Salome et al. method requires a very large amount of very expensive arylsulfonic compounds (Salome et al. require a molar ratio of benzaldehyde to arylsulfonic acid of at least 1:0.6) as catalysts alone within the reaction mixture. Although such large amounts of arylsulfonic acid catalyst have proven to be effective for certain reactions of benzaldehydes with alditols, a combination of both costs and lack of versatility has been problematic from a large-scale industrial production standpoint. The arylsulfonic acids alone either do not contact sufficiently (as with p-toluenesulfonic acid) or are not strong enough acid catalysts alone to provide the needed reactivity for greater versatility with different benzaldehyde reactants at lower levels at concentration within the reaction mixture. Thus, the cost of such arylsulfonic acids, being relatively high and extremely high in comparison with the more effective mineral acids, pose considerable economic problems for the user.
Clearly, the utilization of less expensive mineral acids, which are better catalysts at lower amounts, is a preferred method from a cost perspective; however, the lack of versatility has been a hindrance to widespread use and effectiveness of such a method. The yield offered by both teachings is acceptable, however the versatility of producing large variations of different DBS compounds is questionable. There has been a need to provide a procedure which permits production of not only standard p-methyldibenzylidene sorbitol (MDBS), 3,4-dimethyldibenzylidene sorbitol (DMDBS), and dibenzylidene sorbitol (DBS), but other compounds which heretofore have been impossible to produce either at all or at least in any acceptable yield and/or purity. As a few examples, 1,3:2,4-bis(5-indanylidene)sorbitol has been unavailable as a product due to the lack of production of such a compound in any yield acceptable on an industrial scale or without the need for using excess amounts of the reactive benzaldehyde. Such a compound is known to provide excellent clarifying and nucleating benefits within polypropylene formulations, but, again, has not been readily utilized in such a market because of the lack of effective production methods for large-scale reliable availability. Also, other types of compounds, such as certain symmetrical compounds [e.g., 1,3:2,4-bis(3-ethyl-4-methylbenzylidene)sorbitol and 1,3:2,4-bis(3,4-diethylbenzylidene) sorbitol] have not been available as pure
Anderson John D.
Dotson Darin L.
Jones Jeffrey R.
Lever John G.
Sheppard Shawn R.
Covington Raymond
Milliken & Company
Moyer Terry T.
Parks William S.
Rotman Alan L.
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