CuCrS

CuCr (Corten) Rust-resisting steels for structural applications. 

Table 1 shows that methyl dodecanoate is easily converted into amine in the presence of CuCr deposited on alumina or on titania. Nevertheless one can observe that the methylation reaction is rather difficult and favoured by alumina. Moreover, a significant increase of N-dimethyl dodecylamine is obtained when the reaction is carried out with a large excess of hydrogen. Due to the mechanism of the reaction this is unexpected indeed it is generally considered that the methylation of primary amine with methanol requires i) the dehydrogenation of alcohol into a carbonyl compound and ii) a further reaction of this compound with primary amine or secondary amine via imine or enamine intermediates. 

The effect of adding Ca or Mn to CuCr/A Oj (TiC ) catalysts presented in Table 2 demonstrate that i) the selectivity in N-dimethyldodecylamine is much enhanced, the effect being rather more significant with alumina than with a titania support ii) the total amine selectivity is particularly high, above 98% instead of 80% without promoter. 

Anions BrClj cucr CIF4 i2ci3- IFf- ClFg IF8 ... 

V3+ cations have been incorporated along with Mg or Ni as the divalent cations [51, 52], Although CuM3+-LDHs have been reported, including CuAl-, CuMgAl- and CuCr-LDHs, in general they are poorly crystallized and contain impurity phases (such as malachite, Cu20H2C03) [53-55]. The instability of Cu2+ (d9) towards LDH formation may be attributed to a Jahn-Teller distortion... 

Fig. 55 (continued), (d) Crystallographic and magnetic data for the system CuCr Fe2 (04 (after Ohnishi and Teranishi (488).)... 

Although there is a change from tetragonal (c/a > 1) to tetragonal (c/a < 1) symmetry in the system CuCr Fe2 04 (see Fig. 55(b)), the changes reported by Ohnishi and Teranishi (488) are due, at least partially, to the fact that J3-site Cu2+ is also a Jahn-Teller ion. 

Another example [58] is given by NBu4[CuCr(ox)3], which has a ferromagnetic transition at Tc = 1 K and exhibits remnant magnetization and a hysteresis loop below Tc. 

CuCr,0,.4NH3.2H20 CuCr,0.. KCsIIsNHa) Cuervo,. KCjITsN) ... 

Methyl ester Hydrogen CuCr Fatty alcohol Methanol... 

Fatty acid Hydrogen CuCr Fatty alcohol Water... 

Moreover, the catalysts promoted by alkaline or alkaline-earth species are more stable than the unpromoted CuCr. For example, barium impregnated on copper chromite increases the stability of the active CuCr02 phase (13). Furthermore, the presence of barium or calcium on copper chromite catalysts influences strongly the selectivity to the methylation of amines N-alkylation/N-methylation. 

Fig. 8. Structures of CuFe(fsa)2enCi(H20) CH3OH and [CuCr(fsa)2en(H20)2]+ (from Ref. 49)...

In [CuCr], the three unpaired electrons around Cr(III) in octahedral surroundings occupy the three t2g-type magnetic orbitals transforming as ax(x2 - y2), a2(yz) and b2(xy). All three are orthogonal to the bx magnetic orbital around Cu(II). Therefore, in the expression of J ... 

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