Diamines cobalt catalyst

Diagnostic imaging techniques non-invasive gamma rays, 965 Dialkyl sulfides solvent extraction gold and silver, 807 palladium, 807 Diamines cobalt catalysts hydrogenation, 237 ligands... 

Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

The nitrile can be converted to hexamethylene diamine by reduction in the presence of liquid ammonia at 125 C under 600 to 625 atmospheres pressure together with a copper-cobalt catalyst. 

A new process for synthesis of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) has been investigated. The reaction was performed in two steps. In the first step bis (3-cyano-3,5,5 trimethylcyclohexylidene) azine (IPNA) was synthesized from 3-cyano-3,5,5 trimethyl- 1 oxo cyclohexane (IPN) and hydrazine hydrate in solvent. The reaction yield was nearly quantitative. In the second step the azine (IPNA) was hydrogenated under mild conditions on a Raney nickel or cobalt catalyst in the presence of a small amount of ammonia. Isophorone diamine (IPDA) was obtained at high yields (90-95 %). But the main interest of a such process is to minimize the production of byproducts (aminoalcohol, azabicyclic compound, secondary amine) and to use less severe pressure conditions than those generally employed. 

A direct synthesis of substituted pyridines in yields of about 50% is found in the treatment of acetylene and an alkyl nitrile in the presence of a cobalt catalyst. A general method for the synthesis of 3- and 3,4-substituted furans from ketones has been developed. A new route to various heterocycles with 2 or more heteroatoms has been presented, as well as a procedure involving 1,3- or 3,3-cyclization on difunctional nucleophiles, such as hydrazine, hydroxylamine, alkyl and aryl-diamines. 76 77... 

Isophorone diamine is synthesized traditionally by aminoreduction of iso-phoronenitrile. Raney cobalt was used for this process. More recently, a new two-step process was patented. The first step consists of synthesizing the imine and the second one of hydrogenating the latter. Ra-Ni was used as catalyst at 150°C and 60 bar hydrogen pressure. Under these conditions, the catalyst reduces the nitrile groups and is able to cleave the N-N bonds, too. Ammonia is required to promote primary amine formation during nitrile hydrogenation (Scheme 4.151).554... 

A series of diaquatetraaza cobalt(III) complexes accelerated the hydrolysis of adenylyl(3 -50adenosine (ApA) (304), an enhancement of 10 -fold being observed with the triethylenetetramine complex (303) at pH 7. The pentacoordinated intermediate (305), which is formed with the complex initially acting as an electrophilic catalyst, then suffers general acid catalysis by the coordination water on the Co(III) ion to yield the complexed 1,2-cyclic phosphate (306), the hydrolysis of which occurs via intracomplex nucleophilic attack by the metal-bound hydroxide ion on the phosphorus atom. Neomycin B (307) has also been shown to accelerate the phosphodiester hydrolysis of ApA (304) more effectively than a simple unstructured diamine. 

Other possible catalysts for the reaction of various alkyl bromides with allyhnagnesium hahdes in THF are cobaltbis(l,3-diphenylphosphino)propane complex (equation 70) or cobalt chloride in combination with a diamine (equation 71) °. Cyclization products can... 

Among several chiral cyclic and acyclic diamines, (R,R)-cyclohexane-l,2-diamine-derived salen ligand (which can adopt the gauche conformation) was most effective in providing high enantioselectivity [38]. Further, the introduction of substituents at the 3,4, 5 and 6 positions on the aromatic ring of catalyst 39c was not advantageous, and resulted in low enantioselectivity [32,37,39]. The metal ions from first-row transition metals - particularly copper(II) and cobalt(II) - that could form square-planar complexes, produced catalytically active complexes for the asymmetric alkylation of amino ester enolates [38]. 

FIG. 22. Preparation of a cyanocobalt(II)-chiral diamine catalyst solution. The cobalt species in solution may resemble the ethylenediamine complex (VI). 

The basic approach to prepare Co(II)-complexes of salen (N,lSr-bis(salicylidene)ethylene-diamine)-type molecules is the flexible ligand method [9]. In this process the Schiffbase ligand can diffuse by twisting into the zeolite where it becomes too large to exit by complexation with the cobalt ion. The flexible ligand method, however, was not usefiil for the preparation of Co-salophen/ zeolite catalyst, because the product was inactive in the oxidation reactions. The salophen molecule does not seem to be flexible enough and can not get into the zeolite to produce the suitable complex in the supercage. 

Recently, another cobalt(II)/camphor-derived complex was developed for performing the asymmetric cyclopropanation of olefins [38]. The complex 18 was prepared by reacting the ligand 17, synthesized by condensation of (lR)-3-hydroxymethylenebornane-2-thione and the corresponding diamine, with co-balt(II) dichloride hexahydrate in degassed ethanol (Scheme 11). The cyclopropane derivatives were obtained in 50-60% yield using 3 mol % of the catalyst 18 and ethyl diazoacetate in styrene or 1-octene as solvent. The diastereomeric ratios were low for both styrene and 1-octene. 

Isophoronenitrile azine is quickly converted to partially hydrogenated azines (X3 and X4) during the first hour. The hydrogenation rate is faster with cobalt, that is confirmed by H2 consumption. Moreover we observed only one isomeric form of the intermediate diamine with Raney cobalt. As we previously described, we can see a different behaviour between these 2 intermediates. For one of them (at the present time we are unable to distinguish between cisoide and transoide) hydrogenation rate is low. Another characteristic of this process relates to IPDA isomeric composition. Usually by reductive amination of isophoronenitrile, the isomeric ratio cis/trans is about 80/20 but in our case the proportion of trans isomer increased considerably to reach a ratio of 50/50 to 44/56, depending on the nature of the catalyst (table 2). 

A key step in the large-scale production of isophorone diamine (IPDA, Degussa) is simultaneous hydrogenation of a nitrile group and reductive amination of a keto function from isophoronenitrile (IPN) to give the corresponding diamine using a catalyst based on cobalt, nickel or ruthenium or mixtures thereof (Eq. 8-15) [4] ... 

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