The invention is directed to ruthenium-based metathesis catalysts of the Grubbs-Hoveyda type. The new 2-aryloxy-substituted ruthenium catalysts described herein reveal rapid initiation behavior. Further, the corresponding styrene-based precursor compounds are disclosed. The catalysts are prepared in a cross-metathesis reaction starting from styrene-based precursors which can be prepared in a cost-effective manner.

The new Grubbs-Hoveyda type catalysts are suitable to catalyze ring-closing metathesis (RCM), cross metathesis (CM) and ring-opening metathesis polymerization (ROMP). Low catalyst loadings are necessary to convert a wide range of substrates including more complex and critical substrates via metathesis reactions at low to moderate temperatures in high yields within short reaction times.

The present disclosure is directed to a cleavable agent for enhanced magnetic resonance generally corresponding to the formula Y-L-R, wherein Y represents a catalyst-binding moiety having at least one isotopically labeled heteroatom, L represents a cleavable bond, and R represents a hyperpolarized payload having at least one isotopically labeled carbon. Also disclosed herein is a method of cleaving the cleavable agent for enhanced magnetic resonance.

This invention relates generally to olefin metathesis catalysts, to the preparation of such compounds, compositions comprising such compounds, methods of using such compounds, and the use of such compounds in the metathesis of olefins and in the synthesis of related olefin metathesis catalysts. The invention has utility in the fields of catalysis, organic synthesis, polymer chemistry, and in industrial applications such as oil and gas, fine chemicals and pharmaceuticals.

A highly efficient, Z-selective ring-closing metathesis system for the formation of macrocycles using a stereoretentive, ruthenium-based catalyst supported by a dithiolate ligand is reported. This catalyst is demonstrated to be remarkably active as observed in initiation experiments showing complete catalyst initiation at −20° C. within 10 min. Using easily accessible diene starting materials bearing a Z-olefin moiety, macrocyclization reactions generated products with significantly higher Z-selectivity in appreciably shorter reaction times, in higher yield, and with much lower catalyst loadings than in previously reported systems. Macrocyclic lactones ranging in size from twelve-membered to seventeen-membered rings are synthesized in moderate to high yields (68-79% yield) with excellent Z-selectivity (95%-99% Z).

This invention relates to novel hydrogenation catalyst compositions obtainable from reacting metal-based complex hydrogenation catalysts with specific co-catalysts and to a process for selectively hydrogenating nitrile rubbers in the presence of such novel hydrogenation catalyst compositions.

Embodiments in accordance with the present invention encompass compositions encompassing a latent organo-ruthenium compound, a photosensitizer and one or more monomers which undergo ring open metathesis polymerization (ROMP) when said composition is exposed to suitable actinic radiation to form a substantially transparent film or a three dimensional object. Surprisingly, the compositions are very stable at ambient conditions to temperatures up to 80° C. for several weeks and undergo mass polymerization only when subjected to actinic radiation under inert atmosphere such as for example a blanket of nitrogen. Accordingly, compositions of this invention are useful in various opto-electronic applications, including as 3D printing materials, coatings, encapsulants, fillers, leveling agents, among others.

The invention discloses a mixed Ni(II) complex containing bisoxazoline-derived nitrogen heterocyclic carbene ligand and phosphite ligand and application thereof; the chemical formula of the mixed Ni(II) complex is Ni(NHC)[P(OR).sub.3]X.sub.2, wherein R is ethyl or isopropyl, X is bromine or chlorine, and NHC is a bisoxazoline-derived nitrogen heterocyclic carbene ligand. In the presence of magnesium shavings, the mixed Ni(II) complex containing bisoxazoline-derived nitrogen heterocyclic carbene ligand and phosphite ligand of the present invention can catalyze low-activity chlorinated aromatic hydrocarbons and fluorinated aromatic hydrocarbons with chlorinated benzyl compounds, respectively, reductive cross-coupling reaction at a single temperature, generating a diarylmethane compound in one step, providing a new method for the synthesis of diarylmethane compounds.

A method for preparing formamide compounds via hydrogenation of carbon dioxide catalyzed by porous materials includes the following steps: by taking porous organometallic polymers as catalysts, reacting amine compounds with carbon dioxide and hydrogen under an air atmosphere to prepare formamide compounds. The method has the advantages of high reaction efficiency, good selectivity, mild conditions, economy, environmental protection, and simple operation. The catalysts are solid organometallic polymers with large specific surface area, strong carbon dioxide adsorption, hierarchical pore distribution, and uniformly dispersed metal centers. They are designed and synthesized as the reaction catalysts by changing the proportion of the cross-linked comonomer. The catalysts can be especially used for catalytic synthesis of fine chemical N, N-dimethylformamide (DMF) without addition of any additional solvent, alkali, or other additives, which is convenient for separation and purification of DMF.

The present invention relates to a process for preparing nitrile rubbers having reduced molecular weight by metathesis of a first nitrile rubber in the presence of specific ruthenium complex catalysts that have particular N-heterocyclic carbene ligands.

The disclosure provides a catalyst system and a method for ethylene oligomerization using this. The catalyst system contains: ligand a, containing carbene groups of imidazole ring type; transition metal compound b, that is one of IVB˜VIII group metal compounds; activator c, that is a compound containing III A group metals; the ligand a contains at least one group as shown in general formula I: ##STR00001##
in which, bridging group A contains a main chain including alkyl, alkenyl, aryl groups or the combination of them and the first heteratom; E is a linear or cyclic group containing the second heteroatom; R is a hydrocarbyl group. The catalyst system is especially used for trimerization and tetramerization of ethylene. The catalyst system has high selectivity for 1-hexene and 1-octene, low selectivity for 1-butene and 1-C.sub.10+, and the total percent content of C.sub.6˜C.sub.8 linear □α-olefin in the product is more than 90% by mass.