Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-01-11
2001-07-17
Lambkin, Deborah C. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S506000, C549S505000
Reexamination Certificate
active
06262280
ABSTRACT:
FIELD OF THE INVENTION
The functionalization of compounds containing carbon-hydrogen bonds utilizing platinum compounds in Shilov-type reactions is improved by using hydrogen peroxide or selected Pt[IV] compounds as an oxidant. The products of the various processes are useful in many ways, for example as chemical intermediates, solvents, and as monomers for polymers.
BACKGROUND OF THE INVENTION
The conversion of carbon-hydrogen bonds, especially unactivated carbon-hydrogen bonds, into other functional groups in organic compounds has always been a difficult challenge for chemists, and few methods for doing this which are selective and/or well controlled have been developed. One of these methods is the so-called Shilov-type reaction, which classically involves the combined use of a Pt[II] compound such as PtCl
2
and a Pt[IV] compound, almost always the PtCl
6
−2
anion, especially to create oxygen functional compounds, see for instance A. E. Shilov, et al., Coordination Chemistry Reviews, vol. 24, p. 97-143 (1977); L-C. Kao, et al., J. Chem. Soc., Chem. Commun., 1991, p. 1242-1243; A. C. Hutson, et al., J. Organometal. Chem., vol. 504, p. 69-74 (1995); G. A. Luinstra, et al., J. Organometal. Chem., vol. 504, p. 75-91 (1995); L. Wang, et al., J. Mol. Catal. A, vol. 116, p. 269-275 (1997); A. E. Shilov,
Activation of Saturated Hydrocarbons by Transition Metal Complexes,
D. Reidel Publishing Co., Dordrecht (1984); A. E. Shilov, et al., Chem. Rev., vol. 97, p. 2879-2932 (1997); and S. S. Stahl, et al., J. Am. Chem. Soc., vol. 118, p. 5961-5976 (1996). However, this reaction has two major disadvantages, namely it is not often as selective as desired, for example organic chlorine compounds are often generated, and the expensive Pt[IV] compound must be used in stoichiometric, not catalytic, quantities. Therefore, methods for overcoming one or both of these problems would enhance the usefulness of this reaction.
The mechanism of the Shilov-type reaction is well studied, and it is believed that the Pt[IV] compound acts as an oxidant, that is when the organic compound is functionalized with, for example, hydroxyl group, the organic compound is oxidized, and the Pt[IV] is the oxidant. It has been suggested by a number of authors, see for instance S. S. Stahl, et al., Angew. Chem. Int. Ed., vol. 37, p. 2180-2192 (1998), that the use of a cheaper oxidant would make the Shilov reaction more attractive, but such an oxidant has not been found. It has been pointed out that when Pt[IV] acts as an oxidizing agent it becomes Pt[II], which is one of the reactants. Numerous attempts have also been made to diminish the by-products associated with the Shilov reaction, especially the chlorinated organic by-products, but these attempts have been only partially successful.
N. Basickes, et al., Polyhedron, vol. 14, p. 197-202(1995) describes the synthesis of tetrahydrofuran and butanediols from 1-butanol using a platinum catalyst system. No mention is made of making 3-methyltetrahydrofuran.
M. S. Freund, et al., J. of Mol. Catal., vol. 87, p. L11-L15 (1994), use electrochemical methods to oxidize p-toluenesulfonic acid in the presence of a Pt[II] compound. J. A. Labinger, et al., Organometallics, vol. 12, p. 895-905 (1993) report on the use of phosphomolybdic acid or peroxydisulfate anion as an oxidant in the oxidation of p-toluenesulfonic acid in the presence of Pt[II]. No mention is made of hydrogen peroxide in either of these references.
What are needed are improved Shilov-type processes that do not have the disadvantages and/or deficiencies inherent in the prior art.
SUMMARY OF THE INVENTION
This invention discloses an improved Shilov-type process utilizing platinum salts for producing functionalized organic compounds, wherein the improvement comprises, using at a pH of about 2.0 or less, hydrogen peroxide as an oxidant.
Also disclosed in this invention is an improved Shilov-type process for producing functionalized organic compounds, using a Pt[II] salt and an oxidant which is a Pt[IV] salt, wherein the improvement comprises, using as said Pt[IV] salt PtCl
3
X.Q
n
, PtCl
4
.Q
n
or APtCl
5
.Q
n
, wherein Q is a neutral molecule which may coordinate to the Pt atom, n is zero, 1, 2 or 3, X is a monovalent anion, and A is a monovalent cation.
Another disclosure of this invention concerns a process for the production of 3-methyltetrahydrofuran, comprising: contacting at a temperature of about 0° C. to about 400° C., a compound selected from the group consisting of 2-methylbutane, 3-methyl-1-butanol and 2-methyl-1-butanol, or a mixture thereof, a Pt[II] salt, and a suitable oxidant.
A further disclosure of the present invention is a process for the simultaneous production of tetrahydrofuran and 3-methyltetrahydrofuran, comprising: contacting, at a temperature from about 0° C. to about 400° C., a mixture of n-butanol and one or both of 3-methyl-1-butanol and 2-methyl-1-butanol, in the presence of a Pt[II] compound and a suitable oxidant.
DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise noted, all of the general description of the Shilov-type reactions apply to all four processes above. Herein, Roman numbers in brackets, refer to the oxidation state of a metal such as Pt.
One of the ingredients in a Shilov-type reaction is an organic compound containing at least one hydrogen bound to carbon, and preferably that carbon atom is a saturated carbon atom. In the Shilov-type reaction at least one of those hydrogen atoms is converted to a functional group, preferably an oxygen containing functional group such as a hydroxyl group, or in some cases an ether group. Sometimes the oxygen functional group is further oxidized to an oxo (keto) group, an aldehyde or a carboxylic acid.
The organic compound to be functionalized may simply be a hydrocarbon such as an alkane, but the organic compound may also initially contain one or more other functional groups. In the Shilov-type reaction such an organic compound is further functionalized. In some instances one or more of the functional groups already present may take part in the reaction. For example, as reported herein, 3-methyl-1-butanol reacts in the Shilov-type reaction to form 3-methyltetrahydrofuran, whose formation may be rationalized (although not necessarily the actual mechanism) by the initial formation of 2-methyl-1,4-butanediol, and subsequent cyclization to form the tetrahydrofuran ring.
Typically the source of the oxygen atom for the functionalized organic compound is water, so it is preferred that at least some water be present in the Shilov-type reaction. This water may be added as one of the ingredients, or in some cases, may be generated during the oxidation. The water may also be added in the form of a hydrate, such as a hydrate of one or more Pt compounds. The presence of water also often helps to dissolve some of the other reaction ingredients such as the Pt compound(s), and this is also often advantageous.
One of ingredients necessary for the Shilov-type reaction is a Pt[II] compound or salt. This may be added directly to the reaction or may be formed in situ, as by the reduction of higher valent Pt, such as Pt[IV]. Although a number of different Pt[II] compounds are useful in the Shilov-type reaction, some of the most commonly used Pt compounds are PtCl
2
and its hydrate, or an alkali metal salt (or its hydrate) of the PtCl
4
−2
anion, and these Pt[II] compounds are preferred herein. Since the Pt[II] compound acts in a catalytic way, its concentration in the reaction is not critical, and the typical amounts used in Shilov reactions are applicable herein.
In the first and second processes herein other process conditions useful for Shilov-type reactions may be employed, and these are known in the art, see for instance many of the references listed in the “Background of the Invention” section above; the contents of which are incorporat
De Vries Nadine Henriette Caroline
Garnett Donald Irwin
Thorn David Lincoln
E. I. Du Pont de Nemours and Company
Lambkin Deborah C.
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