Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2000-07-26
2002-04-16
Ford, John M. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
C540S483000
Reexamination Certificate
active
06372903
ABSTRACT:
Polyazamacrocyclic compounds are of considerable interest in the field of coordination chemistry. These ligands in particular form stable complexes with transition elements and heavy metals (Bradshaw J. S, Krakowiak K. E, Izatt R. M, Aza-crown Macrocycles in
The Chemistry of Heterocyclic Compounds
; edited by Taylor E. C, John Wiley & Son Inc.: New York, 1993, pp. 1-885; Izatt R. M, Pawlak K, Bradshaw J. S, Bruening R. L,
Chem. Rev
., 1995, 95, 2529-2586). The dimensions of the macrocyclic cavity, the shape and the rigidity of the ring, the size of the chelated ring, and the number and the nature of the substituents carried by the nitrogen atoms are all factors which influence the affinity of the ligand with respect to a given metal ion and thus the selectivity with respect to other elements. These properties have made possible the use of these compounds in fields as varied as the selective coordination of atmospheric dioxygen (Cabani S.
React. and Funct. Polym
., 1996, 167-182; Machida R, Kimura E, Kodama M,
Inorg. Chem
., 1983, 22, 2055-2061), medical imaging (Alexander V,
Chem. Rev
., 1995, 95, 273-342) or the extraction of metal elements (Guilard, R, Chollet H, Guiberteau P, Cocolios P, WO 96/11189, published on Apr. 18, 1996, FR 2725382 published on Apr. 12, 1996; Izatt R. M, Bruening R. L, Borup M. B,
Water Sci. Technol
., 1991, 23, 301-308).
In the field of the extraction of heavy metals and of the purification of effluents, the major disadvantage of these nitrogenous macrocycles is their solubility both in water and organic solvents, which results in a loss of the ligand when it is used in a liquid—liquid extraction process. On the other hand, the immobilization of the ligand on a solid support makes possible the development of a solid-liquid extraction process which exhibits numerous advantages, such as a reduced cost (no loss of the ligand), the noncontamination of the solvents to be purified, and easy use and regeneration of the columns. In the context of gas separation or purification, it is known, for example, that tetraazamacrocyclic cobalt complexes exhibit a high affinity with respect to dioxygen. However, the superoxide oxygen-comprising species formed can change in the direction of species of &mgr;-peroxo type which have a limited lifetime in solution, where they undergo irreversible decomposition reactions (Martell A. E, Basak A. K, Raleigh C. J,
Pure Appl. Chem
., 1988, 60, 1325-1329). The attachment of the active complex to a solid matrix results in the superoxide species, which promotes the reversibility of the reaction and limits the decomposition of the oxygen-comprising species. Thus, absorption/desorption cycles might be carried out by lowering the pressure and/or raising the temperature.
Some industrial sectors, for example electronics, use liquids or gases of very high purity and environmental standards are becoming increasingly strict. Consequently, the development of processes which make it possible to remove trace amounts constitutes a priority. To this end, numerous modified polymers possessing selective chelating properties have been developed. Silica gels are among the most widely used supports (Biernat J. F, Konieczka P, Tarbet B. J, Bradshaw J. S, Izatt R. M,
Sep. Purif. Methods
, 1994, 23, 77-348). This is because they exhibit numerous advantages with respect to organic polymers: they are inexpensive, mechanically and thermally stable, inert with respect to numerous chemicals and insoluble in most organic solvents and can be easily modified.
Various silica gels modified by polyazamacrocyclic ligands have already been synthesized (Gros C, Rabiet F, Denat F, Brandes S, Chollet H, Guilard R,
J. Chem. Soc. Dalton Trans
., 1996, 1209-1214; Subba Rao Y. V, De Vos D. E, Bein T, Jacobs P. A,
Chem. Commun
., 1997, 355-356; Bagnoud M. A, Haerdi W, Veuthey J. L,
Chromatographia
, 1990, 29, 495-499; Izatt R. M, Bruenig R. L, Tarbet B. J, Griffin L. D, Bruening M. L, Krakowiak K. E, Bradshaw J. S,
Pure Appl. Chem
., 1990, 62, 1115-1118; Dudler V, Lindoy L. F, Sallin D, Schlaepfer C. W,
Aust. J Chem
., 1987, 40, 1557-1563). The most commonly used synthetic route (route A) is represented diagrammatically as follows:
During a first stage, a spacer arm carrying an electrophilic ending is attached to the silica gel by reaction of the appropriate silylated reactant (generally an alkoxysilane) with the silanol sites. Various assembling groups, such as those which appear hereinabove, can thus be used. The unreacted silanol sites can optionally be protected by the action of trimethylchlorosilane, in order to increase the selectivity of the gel or the hydrophobic nature of the latter. The desired macrocycle is subsequently condensed onto the modified silica gel. In a final stage, the grafted macrocycle can be N-substituted by the action of an appropriate electrophilic reactant. The amount of macrocycle grafted according to this synthetic scheme is approximately 0.35-0.40 mmol/g of material.
Another possible route of access to modified silica gels of this type (route B) consists, in a first stage, in functionalizing the macrocycle with the spacer arm, the grafting onto the silica subsequently taking place in a final stage: Bradshaw et al. (Izatt R. M, Bruening R. L, Tarbet B. J, Griffin L. D, Bruening M. L, Krakowiak K. E, Bradshaw J. S,
Pure Appl. Chem
., 1990, 62, 1115-1118, Bradshaw J. S, Krakowiak K. E, Tarbet B. J, Bruening R. L, Griffin L. D, Cash D. E, Rasmussen T. D, Izatt R. M,
Solv. Extract Ion Exch
., 1989, 7, 855-864) have thus developed a method which makes it possible to graft pentaazamacrocycles and various mixed (oxygen-nitrogen) macrocycles onto a silica gel, represented diagrammatically as follows:
In a first stage, a substituent carrying a terminal ethylene unit is attached to the desired macrocycle. The compound is subsequently hydrosilylated and the product thus obtained is condensed onto the silica gel.
However, the first synthetic route (A) exhibits two major disadvantages:
Only 30 to 50% of the spacer arms grafted in the first stage react with the macrocycle. The amount of grafted macrocycles is thus greatly reduced thereby and the residual presence of the unreacted functional groups can prove to be harmful during the implementation of a process using these materials for a given application.
The N-functionalization of the grafted tetraazamacrocycle, the final stage in the synthesis, is not quantitative as only one to two secondary amine functional groups of the three available react with the electrophilic reactant. In addition, some macrocycles may be bonded by two nitrogen atoms to the silica gel. This heterogeneity is harmful to the effectiveness and to the selectivity of the modified silica gel.
The synthetic route (B), while it makes it possible to control the substitution of the grafted ligand, is problematic to carry out, however, and it requires the use of expensive catalysts, such as hexachloroplatinic acid. The subject-matter of the present invention provides an unexpected solution to the problems set out hereinabove.
A subject-matter of the invention is a process for the preparation of a polyazacycloalkane, immobilized on a silica gel, from a polyazacycloalkane of formula (A):
in which
R
1
and R
2
, which are identical or different, each represent, independently of one another, a hydrogen atom, a linear or branched alkyl radical comprising from 1 to 15 carbon atoms,
W
1
, W
2
and W
3
, which are identical or different, represent, independently of one another, a divalent radical chosen from those represented by the general formula (B):
—[(CT
1
T
2
)
n
—[N(R
3
)]
p
—(CT
3
T
4
)
m
]
1
— (B)
in which
p represents an integer equal to 1 or equal to 0,
l represents an integer equal to 1 or to 2,
n and m, which are identical or different, each represent, independently of one another, an integer less than or equal to 3 and greater than or equal to 1,
T
1
, T
2
, T
3
and T
4
, which are identical or different, either each represent, independently of one another, a hydrogen atom, a linear or
Barbette Frédéric
Denat Franck
Guilard Roger
Lagrange Gilles
Mehdi Ahmad
Commissariat a l'Energie Atomique
Ford John M.
Young & Thompson
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