Polymerization

Details Polymerization Polymerization

2001-04-06

2002-10-08

Dang, Thuan (Department: 1764)

Chemistry of hydrocarbon compounds

Aromatic compound synthesis

By condensation of entire cyclic molecules or entire...

C585S425000, C585S427000, C585S429000

Reexamination Certificate

active

06462245

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the catalytic use of molecular sieves, especially actinide—containing molecular sieves, and, more particularly, to their use in organic synthesis.
DESCRIPTION OF RELATED ART
A molecular sieve, i.e. a material which is porous at the molecular level, has a three dimensional open framework providing cages or pores or, alternatively, gaps between adjacent layers. Depending upon the pore size or the interlayer spacing, molecular sieves are categorised into three groups: (1) microporous materials having a pore size or interlayer spacing of less than 20 Å (2×10
−9
m); (2) mesoporous materials having a pore size or interlayer spacing of from 20 Å to 50 Å (2×10
−9
m to 5×10
−9
m); and (3) macroporous materials having a pores size or interlayer spacing of greater than 50 Å (5×10
−9
m). For convenience, however, molecular sieve materials are sometimes referred to as “microporous” even though they may have a pore size or interlayer spacing of more than 20 Å (2×10
−9
m). Thus, the term “microporous” should not in all contexts be interpreted as being restricted to materials having a pore size or interlayer spacing of less than 20 Å (2×10
−9
m).
Intense interest, both academic and industrial, in the synthesis of new open framework materials (e.g. microporous materials) has stemmed from their great utility as catalysts, sorbents, ion-exchange reagents and as host materials for inclusion complexes (P B Venuto
Microporous Mater.
1994, 2, 297). This has stimulated the search for new materials with novel layered and open-framework structures. Following the synthesis of microporous aluminophosphates in 1982, much interest has focused on the synthesis of other microporous metal phosphates. Research into the synthesis of metal phosphates has been driven by three main potential advantages that they have over aluminosilicate zeolites. Firstly, the ability of main group and transition metals to exist in five, six, seven or higher co-ordination environments, as opposed to zeolites and aluminophosphates which only contain tetrahedrally co-ordinated units, allows the synthesis of new more complex framework architectures. Secondly, the sheer number of different possible elements that may be incorporated into a phosphate framework means the potential for the synthesis of new materials is huge. Finally, the incorporation of transition metals capable of existing in a variety of different oxidation states within an open-framework structure offers the possibility of combining the shape-selectivity of zeolites with the catalytic, magnetic and photo-chemical properties associated with d-block elements. These potential advantages have led many groups to study the synthesis of these materials over recent years, and a vast number of different metals have been incorporated into microporous phosphate frameworks, including Be, Ga, In, Mo, V, Zn, Co, Cr, Mn and Fe. Many of these materials have unusual structures and properties.
Molecular sieve materials are generally synthesised under hydrothermal conditions in the presence of organic molecules which act as templates in the crystal growth process (see R M Barrer. “Hydrothermal Chemistry of Zeolites”, Academic Press, 1982).
Actinide—containing molecular sieves are described in an International patent application No WO 98/50307 entitled “Actinide—Containing Molecular Sieves” in the name of British Nuclear Fuels plc et al. The content of International application No WO 98/50307 is intended to be included in this application. However, WO 98/50397 has the same filing date as the priority date for the present application. The molecular sieves described in WO 98/50307 contain an actinide in combination with atoms selected from the group consisting of oxygen, fluorine, phosphorus, transition metals and mixtures thereof. The actinide is preferably uranium. The molecular sieve material may contain a template species, which suitably comprises an organic template molecule and/or a cationic metal species; it may also contain water. Additionally, it may contain a dopant, usually in a minor amount; suitable dopants include transition metals to modify the catalytic properties of the materials. Preferred molecular sieves comprise layered structures in which layers containing actinide in combination with atoms selected from the group consisting of oxygen, fluorine, phosphorus, transition metals and mixtures thereof have organic templates and/or cationic metal species located between them. In one class of materials, the layers consist essentially of an actinide species and an oxoanion (preferably a phosphate, notably orthophosphate, or a transition metal oxoanion); in this class, the actinide may usually be represented as an oxo ion, especially an oxocation. In another class of materials, the layers consist essentially of actinide and fluorine.
Many of the actinide—containing molecular sieves, therefore, have an actinide/phosphorus/oxygen framework, which may additionally contain fluorine and/or a dopant. Others of the molecular sieves have an actinide/fluorine framework and yet others have an actinide
on-actinide metal/oxygen framework.
A suitable strategy for making actinide—containing molecular sieves, especially for making the phosphorus—containing materials, is to adapt the techniques used previously to synthesise microporous metal phosphates, and make use of the same types of templating agents that have proved so successful in the synthesis of zeolites and other types of molecular sieve materials. In preferred embodiments, the synthesis mixture consists of four components: an actinide source, a phosphorus source, water and an organic template. The concept of a template as a species which acts as a structure directing agent during the crystallisation of molecular sieves is not completely understood, but their use is very familiar in the synthesis of open framework materials. Generally, the actinide source, phosphorus source and water are mixed, the templating reagent added and then the resulting mixture is heated under autogenous hydrothermal conditions at temperatures of at least 100° C. (and often of >150° C.) to 175° C. or sometimes more, for a prolonged duration typically of less than 24 hours to several days.
The synthetic technique may use fluoride as a mineralising agent. The use of fluoride as a mineralising agent in hydrothermal syntheses was originally pioneered by Flanigen and Patton as a new method of synthesising zeolites (E. M. Flanigen, R. L. Patton U.S., 1978). The technique was then further developed by Guth and Kessler (J. L. Guth, H. Kessler, R. Wey:
Stud. Surf. Sci. Catal.
1986, 28, 121; J. L. Guth, H. Kessler, J. M. Higel, J. M. Lamblin, J. Patarin, A. Sieve, J. M. Chezcau, R. Wey;
ACS Symp. Ser.
1989, 398, 17). Replacement of OH° ions by F° ions allows the crystallisation of zeolites to be performed in neutral or acidic conditions which, in turn, allows the synthesis of heteroatom (e.g. B, Al, Fe, Ga, Ti) substituted high silica zeolites. These cannot be synthesised under high pH conditions because many transition metal ions are not stable under such conditions.
Of most importance to the present invention, however, is the application of the fluorine method to the synthesis of microporous metal phosphates, since the used of fluorine appears to aid the crystallisation of metal phosphates.
Hydrothermal synthesis using fluorine and phosphate may also be used to synthesise the actinide/fluorine frameworks. Such procedures suitably use U
3
O
8
, H
3
PO
4
, HF and a template as the starting materials.
SUMMARY OF THE INVENTION
The present invention provides a new class of oxidation reactions and a novel class of polymers obtained thereby. The method of the invention is particularly suited for polymerising alkyl-substituted aromatic compounds and comprises oxidising the compound in the presence of a molecular sieve.
Thus, according to the invention, we provide a method for polymerising an alkyl-subs

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