Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-11-15
2004-09-28
Wilson, James O. (Department: 1623)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C536S004100, C536S018500
Reexamination Certificate
active
06797773
ABSTRACT:
BACKGROUND AND PREVIOUS KNOWLEDGE
Most (>90%) of the industrial chemical processes are catalytic [J. M. Thomas, W. J. Thomas, Principles and Practice of Heterogeneous Catalysis, VCFL Weinheim, 1997]. Of these, a percentage higher than 75% makes use of heterogeneous catalysts [J. H. Clark, Catalysis of organic Reactions by Supported Inorganic Reagents, VCH, Weinheim, 1994]. Heterogeneous catalysts are widely used in the petrochemical industry in several chemical processes including hydrocarbon cracking (on zeolites), olefin hydrogenations (on precious metals) and stereospecific polymerizations [J. H. Clark, Catalysis of Organic Reactions by Supported Inorganic Reagents, VCH, Weinheim, 1994]. On the other hand, many of the chemical synthesis of interest to the pharmaceutical and secondary chemical industries are liquid-phase homogeneous catalytic or stoichiometric processes [G. Sironi, La Chim. and l'Ind., 79 (1997) 1173-1177; M. Hudlicky oxidations in Organic Chemistry, Acs Monograph, No. 186, 1990]. The interest is high in converting homogeneous processes into efficient and clean heterogeneous catalytic conversions. The oxidation of alcohols to carbonyl derivatives is a typical fine chemical production process in need for such conversion [G. Sironi, La Chim. and l'Ind., 79 (1997) 1173-1177]. Due to the urgent demand of new oxidative technologies mentioned above, very recently Sheldon and colleagues were terming “philosophers' stones” efficient heterogeneous catalysts for liquid-phase oxidations in widely known international publication [R. A. Sheldon, m, Wallau, I. W. C. E. Arends, U. Schuchardt, Acc. Chem. Res., 31 (1998) 485-433]. Apart from industrial, large-scale high temperature (600° C.) catalytic dehydrogenations (equation 1) and oxidative dehydrogenations (equation 2) carried out on Ag and Cu catalysts [M. Muhler in: Handbook of Heterogeneous Catalysis, VCH, Weinheim, 1997],
R
1
—CHOH—R
2
→R
1
—CO—R
2
+H
2
(1)
R
1
—CHOH—R
2
+O
2
→R
1
—CO—R
2
+H
2
O (2)
alcohol oxidations are carried out with stoichiometric amounts of oxidants (periodinanes, Dess-Martin reagent, chromium and manganese salts, mineral acids) or by electrochemical reactions. Environmental, economical and technological reasons make of primary importance the substitution of these homogeneous processes with heterogeneous catalytic oxidations carried out with clean oxidants such as O
2
, HO
2
O
2
or hypochlorite [J. A. Cusumano, J. Chem. Ed., 72 (1995) 959-964]. In general, however, the selectivity required in fine chemicals production is much higher as compared to that of classical large-scale heterogeneous catalysis.
Traditionally, heterogeneous catalysts are obtained by supporting the active species onto an inert solid of high surface area (silica, celite, carbon, alumina, clays etc.) in order to maximise the dispersion of the active species. The solid carrier can be an inorganic oxide or an organic polymer. Phase separation between the catalytic species and the reagents in the reaction mixture permits the facile separation of the catalyst and—in principle—either to reuse the catalyst in a subsequent reaction or its employment in a continuous process in which the reaction product is separated while the reactant is processed. Typically, heterogeneous catalysts ate prepared by impregnation of the inorganic support with a solution of the active species (i.e. metals ions) or by derivatising the surface of the solid in a heterogeneous reaction between the surface reactive groups (hydroxyl) and an organoderivate of the catalytic molecule.
Few mild catalytic oxidative processes are available. Catalysts of platinum and palladium supported on carbon are used at room temperature for alcohol oxidative dehydrogenation (equation 2) in batch reactors containing a suspension of the catalyst particles in a solution of the alcohol through which air is bubbled. The mild reaction conditions make it possible to oxidise sensitive compounds including carbohydrates [M. Besson, F. Lahmer, P. Gallezot, P. Fuertes, G. Flèche, J. Catal, 152 (1995) 116-122] and steroids, [T. Akihisa et al., Bull. Chem. Soc. Jpn. 59 (1986) 680-685), but reaction conditions need to be strictly controlled in order to avoid substrate overoxidation and rapid catalyst deactivation (by metal particles oxidation, sintering etc,). An efficient commercial oxidation catalyst is the inorganic oxide titanium silicalite (TS-1) used with aqueous H
2
O
2
(30% w/w) for the catalytic oxidation of primary and secondary alcohols as described in [R. Murugawel. H. W. Roesky, Angew Chem. Int. Ed. Engl., 36 (1997) 477-479]. Selectivity of TS-1, however, is not high and different oxidisable groups such as double bonds and primary or secondary alcohol groups in a substrate are all rapidly oxidised as well.
There exists high demand of new, selective and efficient catalysts of oxidative processes and intense research efforts are devoted towards this aim both in industrial and in academic laboratories world-wide. Recently for instance, a new aerobic selective oxidative process has been described which uses diazo complexes of Cu (I) supported on K
2
CO
3
. Alcohols dissolved in apolar organic solvent can be dehydrogenated into carbonyl compounds by using oxygen contained in air as primary oxidant [I. E. Markó, P. R. Giles, M. Tsukazaki, S. M. Brown, C. J. Urch, Science, 274 (1996) 2044-2046]. Reactions temperatures employed are high (70-90° C.) and—due to low surface area of the inorganic support—an excess of K
2
CO
3
(2 equiv.) is needed for optimum catalytic activity. The Authors therefore suggest the use of di-t-but-azodicarboxylate (DBAD) as a better primary oxidant affording less carbonate burden (10% equiv.) [I. E. Markó, P. R. Giles, M. Tsukazaki, S. M. Brown, C. J. Urch, Angew. Chem. Int. Ed. Engl., 36 (1997) 2208-2210]. Another novel catalytic reaction system has been introduced in Japan where alcohols are oxidised with 30% H
2
O
2
in the presence of catalytic tungsten complexes with high turnover numbers [R. Nogori, K. Sato, M. Aoki, J. Takahi, J. Am. Chem. Soc., 119 (1997) 12386-12390].
Higly promising candidates suitable for the preparation of efficient heterogeneous catalysts may originate from stable organic nitroxyl radicals. These are di-tertiary-alkyl nitroxyl radicals (FIG. 1) with A representing a chain of two or three atoms (methylene groups) or a combination of one or two atoms with an oxygen or nitrogen atom as described in International patent application PCT/NL94/00217. Typically, the preferred radicals employed belong to the family of the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO, 1) and its derivatives substituted in position 4 (4-oxo-TEMPO, 2).
These species are highly efficient and versatile catalysts suitable for highly selective oxidation of hydroxyl containing compounds either to carbonyl or to carboxyl compounds, depending an applied reaction conditions. Their use as catalytic mediators in alcohol oxidations has been recently reviewed in depth in [A. E. J. de Nooy, A. C. Besemer, H. van Bekkum, Synthesis, (1996) 1153-1174]. Reactions can be carried our both at acidic and alkaline pH's with important difference in the selectivity observed. Furthermore, the oxidation reaction can be performed in different reaction media, i.e. in organic solvent, in biphasic water-organic solvent system and in water. In these catalytic oxidations, the active species (oxidant) is the (cyclic) nitrosonium ion which is generated in situ by adding an active primary oxidant including, among the others, Cu (II), NaOCl, NaOBr, NaBrO
2
, N
2
O
4
, K
3
Fe(CN)
6
. It is believed that positive nitrogen of the cyclic nitrosonium ion attacks the alcoholic oxygen, with subsequent hydride abstraction in a bielectronic oxidative step involving carbonyl formation and acid release in the reaction mixture.
The hydroxylamine formed in the oxidative step disproportiona
Avnir David
Blum Jochanan
Deganello Giulio
Pagliaro Mario
Browdy and Neimark , P.L.L.C.
Consiglio Nazionale delle Ricerche
Lewis Patrick
Wilson James O.
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