Thallium salt metathesis

The chemical reactivity of the Tl—C bond is also the lowest in the group, especially for ionic compounds of the type R2TlX.

Thallium salt metathesis

The use of acid with these catalysts allows for reactions with a wide range of olefins in a variety of solvents, including acid-initiated RIM processes and living ROMP reactions of water-soluble monomers in water. Lynn, Bernhard Mohr, and Eric L. Dias This application claims the benefit of U.

Thallium salt metathesis

Government has certain rights in this invention pursuant to Grant No. GM awarded by the National Institutes of Health. Field of the Invention The invention relates to highly active and stable ruthenium metal carbene complex compounds and their use as catalysts for olefm metathesis reactions.

Description of the Related Art The formation of carbon-carbon bonds via olefin metathesis is of considerable interest and commercial utility, and considerable research efforts have been undertaken to develop olefin metathesis catalysts and systems. Both classical and well-defined olefin metathesis catalysts based on ruthenium have been shown to exhibit good tolerance to a variety of functional groups, as has been reported by, e.

Eds; Kluwer Academic Publishers: Boston, ; Novak, B. In particular, as reported by Lynn, D. Organometallics15,both of which are incorporated herein by reference, the robust nature of the ruthenium-carbon bonds in these complexes has enabled olefin metathesis reactions to be carried out in protic media.

However, slow reaction rates and low yields have limited the application of these catalysts for a variety of olefin monomers and reaction conditions. As an example, there is a need for homogeneous polymerization systems that are living in water and that will polymerize water-soluble monomers.

In living polymerization systems, polymerization occurs without chain transfer or chain termination, giving greater control over polydispersity of the resultant polymers. Such polymerization systems are highly desirable as they would allow the controlled synthesis of water-soluble polymers and would enable precise control over the composition of block copolymers for use, for example, in biomedical applications.

However, such polymerization systems represent a formidable challenge. For example, the addition of water to traditional living anionic or cationic systems results in rapid termination. The advent of late transition metal catalysts tolerant of numerous polar and protic functionalities has recently enabled living ring-opening metathesis polymerizations ROMPfree-radical polymerizations, and isocyanide polymerizations in aqueous environments, as reported by Lynn, D.

Tetrahedron,53, ; Manning, D. Macromolecules30, ; Deming, T. Macromolecules,24,each of which is incorporated herein by reference. Although these examples represent significant advances toward entirely aqueous systems, the catalysts themselves are insoluble in water and the polymerization reactions basically occur in "wet" organic phases.

Aqueous ring-opening metathesis polymerization of strained, cyclic olefins initiated by Group VIII salts and coordination complexes is well-documented.

We recently reported the synthesis of well-defined, water soluble ruthenium alkylidenes which serve as excellent initiators for olefin metathesis reactions in water, methanol, and aqueous emulsions.

Organometallics,15,incorporated herein by reference. Further investigation of these complexes, however, revealed that potential applications could be limited by relatively fast termination reactions.

Similar ruthenium alkylidene complexes are disclosed in U. For these reasons, there is a need for well-defined olefin metathesis catalysts and systems with improved efficiencies that provide for increased reaction rates, increased product yields, and that allow for metathesis of a wider range of olefins in a broader range of solvents than previously possible.

In other embodiments of the invention, the ruthenium catalyst compounds have the general formulas: These ruthenium catalysts contain acid-labile ligands and the addition of inorganic or organic acids to olefin metathesis reactions employing these catalysts results in substantially enhanced activities relative to systems in which acid is not present.

Substantial rate increases in the presence of acid have been observed for olefin metathesis reactions in aqueous, protic and organic solvents in methods according to the present invention.

In another aspect of the invention, acid is used to activate ruthenium alkylidene complexes that are otherwise unreactive with olefins.

Thallium salt metathesis

This aspect of the invention allows for greater control in reaction injection molding RIM processes, as the catalyst and monomer can be stored together, either in solution or in neat monomer, and then acid is added to initiate polymerization.

Similar processes can be applied to photoinitiated-ROMP PROMP systems and to photomasking applications using photoacid generators photoacid generators are compounds that are not themselves acids, but which break down into acids and other products upon exposure to light energy.

The invention is further directed to living polymerization reactions taking place in aqueous solutions in the absence of any surfactants or organic cosolvents. In another embodiment of the invention, water-soluble ruthenium alkylidene complexes initiate living ROMP of water-soluble monomers in the presence of acid.

The ruthenium alkylidenes of the present invention are not only stable in the presence of polar or protic functional groups or solvents, but the catalytic activities of these alkylidenes are are enhanced by the deliberate addition of specific amounts of acid not present as a substrate or solvent.

A number of ruthenium alkylidenes of the present invention are otherwise inactive absent the addition of acid to the reaction mixture. Such acidic conditions would destroy alkylidenes based on earlier transition metals. Olefin monomers that can be reacted according to the processes of the present invention include acyclic olefins, cyclic olefins, both strained and unstrained, dienes and unsaturated polymers.

These olefins can be functionalized as well, and can include functional groups either as substituents of the olefins or incorporated into the carbon chain of the olefm.The use of photoacid generators (PAG) in conjunction with acid-activated ruthenium olefin metathesis catalysts has been explored.

The hydrochloric acid () with thallium (Tl) acac salts (Figure ). Silver (Ag) acac salts could also be used in some. Thallium is a constituent of the alloy in the anode plates of magnesium seawater batteries.

Soluble thallium salts are added to gold plating baths to increase the speed of plating and to reduce grain size within the gold layer.

Reaction of Thallium(III) Salts with Homoallylic Alcohols: Ring Contraction vs. Dimethoxylation Luiz F. Silva, Jr* and Marcus V. Craveiro Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, the metathesis occurs only partially.

TTP is a stable white solid and its thallium(I) content was zero. Apr 29,  · Thallium(I) iodide is a chemical compound with the formula TlI. It is unusual in being one of the few water-insoluble metal iodides, along with AgI, SnI, SnI, PbI and HgI.

Chemistry TlI can be formed in aqueous solution by metathesis of any soluble thallium salt with iodide ion. The lithium (1) and thallium (2) salts of five new tert-butyl-tris(3-hydrocarbylpyrazolyl)borate ligands [t-BuTpR]- (R = H, a; Me, b; i-Pr, c; t-Bu, d; Ph, e) have been synthesized and characterized.

Ruthenium-initated Ring Opening Metathesis Polymerization of O-containing Norbornene Derivatives based initiators on the ring opening metathesis polymerization of O-containing norbornene derivatives.

MATERIALS AND METHOD thallium salt used without further purification.

Thallium - an overview | ScienceDirect Topics