The zirconium catalyst refers to metal zirconium or zirconium compound which has a catalytic function. The zirconium is light grey metal. Zirconium is relatively reactive chemically. At room temperature, the surface of zirconium is easy to form a glossy oxide film. Zirconium reacts with many nonmetallic elements at high temperatures. The reaction of zirconium and halogen has the properties of Lewis acid, which can catalyze many chemical reactions. The valence of zirconium is 0, +2, +3 and +4. The valence of zirconium in zirconium catalysts is usually 0 or +4.
Zirconium catalyst is widely used in the field of organic synthesis and industry because of its strong coordination ability, high catalytic activity, low toxicity and low cost.
- Polymerization: Ultra-high molecular weight polyethylene (UHMWPE) has excellent impact resistance, wear resistance, chemical corrosion resistance, self-lubrication and other characteristics, and is widely used in various fields of national life. Zirconium phenoximide complex has the characteristic of single active center, which can catalyze ethylene polymerization to get UHMWPE with narrow molecular weight distribution. Better catalytic activity can be obtained by combining phenoxyimide zirconium complexes with some co-catalysts. Ethylene polymerization catalyzed by zirconium catalyst has the characteristics of low cost and high activity. Zirconium catalysts are often used in industrial ethylene polymerization.
- Addition reaction: Zirconium catalyst can catalyze many kinds of addition reactions, including Michael addition reaction, Aldol reaction, Strecker reaction, carbene metallization reaction and so on. For example, under mild reaction conditions, zirconium tetrachloride catalyzes the Michael conjugate addition of 1, 3-dicarbonyl compounds and alpha, beta-unsaturated ketones, with high yield. Carbene metallization can add organometals to the C-C multiple bonds. As a catalyst, ZrCl4 can catalyze addition reaction between tributylallyl tin and aromatic acetylene, so as to obtain cis or trans products with high yield.
Figure 1. Zirconium catalyst catalyzes addition reaction
- Reduction reaction: Reduction of aromatic nitrocompounds to aniline is very important in organic chemistry. As a catalyst, ZrCl4 can effectively catalyze the reduction of aromatic nitro compounds and aliphatic nitro compounds to primary amine compounds. Among them, aromatic nitro groups and hetero-aromatic nitro compounds can be reduced to primary amines with high yield by reflux in THF solution for 6-8 h, while fatty nitro compounds can be reduced to corresponding fatty amino products by reaction at room temperature for 8-9 h. In addition, the C=O, C=N and C≡N bonds can be reduced with ZrCl4 as the catalyst. The reaction is still conducted at room temperature with THF as the solvent. Most aldehydes, ketones, carboxylic acids, acyl chlorides, amides, oxime, and nitrile can be reduced.
Figure 2. Zirconium catalyst catalyzes reduction reaction
- Rearrangement reaction: Zirconium catalysts are widely used in rearrangement reactions. Among the zirconium compounds, ZrCl4 as a zirconium catalyst can catalyze Ferrier rearrangement, Beckmann rearrangement, Fries rearrangement. In addition, some zirconium complexes formed by the coordination of zirconium and ligand also have catalytic activity and can catalyze rearrangement reactions. For example, zirconium complex Zr-(S)-BINOL as a catalyst can catalyze the Baeyer-Villiger rearrangement of 3-phenylcyclobutanone to form lactone structures. Zr-MMT catalysts can be prepared by loading zirconium on montmorillonite and can also be used to catalyze Baeyer-Villiger rearrangement reactions.
Figure 3. Zirconium catalyst catalyzes rearrangement reaction
- Lowe, Miranda Y. (2017). "Investigation of redox switchable titanium and zirconium catalysts for the ring opening polymerization of cyclic esters and epoxides." Inorganic Chemistry Frontiers 4(11), 1798-1805.
- Cimino, Alessandro. (2016), "Novel yttrium and zirconium catalysts featuring reduced Ar-BIANH2 ligands for olefin hydroamination (Ar-BIANH2= bis-arylaminoacenaphthylene).." New Journal of Chemistry 40(12), 10285-10293.
- Kobayashi S. (2000), "Novel binuclear chiral zirconium catalysts used in enantioselective strecker reactions" Chirality 12(5-6), 540-3.
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