Chelate effect, definition

Cone angle concepts, 2,1012-1028 chelate effects, 2,1012 definitions, 2,1015 models, 2,1015 phosphines chiral, 2,1014 polydentate, 2,1013 solubility effects, 2,1014 use, 2,1028... 

It was a hue shock to Astrid and myself when we learned last Sunday night that Hitoshi has passed away. This is a tremendous loss for our whole community. As yon correctly state, we had seen him in Tokyo twice, namely at October 12 and 13, when he attended both of my lectures. He was in good mood and spirit and we had in fact intense scientific discnssions about the chelate effect and this continued until November 3, when he sent me his last mail. We all definitely lost a veiy dear friend. Of conrse, Astrid and I have immediately written to his wife Ei... and as you say, at this time we can only pray for his sonl. 

Concanavalin, 773 Cone angle concepts, 1012-1028 chelate effects, 1012 definitions, 1015 models, 1015 phosphines chiral, 1014 polydentate, 1013 solubility effects, 1014 use, 1028... 

The second very important entropy-induced effect is the great stability of metal chelates (see definition of chelate in Section 1.3). Both ammonia and ethylenediamine (en) coordinate with metals through amine nitrogens in terms of the heat evolved in the complexation reaction two molecules of NH3 have been shown to be about equivalent to one en molecule. However, en eomplexes are considerably more stable than their NH3 eounterparts for example, [Ni(NH3)6], KiK2 = 6x 10 K3Ki = 5 x 10 KsK = 3. [Ni(en)3f, Ki = 5x 10 K2 = 2.2 X 10 K2 = 3.6x 10 ). It has been experimentally demonstrated that the unusual stability of the en compounds is due to a more favorable entropy associated with their formation. 

Edmondson et al (1971), who studied the enrichment of whole milk with iron, found that ferrous compounds normally caused a definite oxidized flavor when added before pasteurization. Aeration before addition of the iron reduced the off-flavor. The authors recommended the addition of ferric ammonium citrate followed by pasteurization at 81 °C. Kurtz et al. (1973) reported that iron salts can be added in amounts equivalent to 20 mg iron per liter of skim milk with no adverse flavor effects when iron-fortified dry milk is reconstituted to skim milk or used in the preparation of 2% milk. Hegenauer et al. (1979A) reported that emulsification of milk fat prior to fortification greatly reduced lipid peroxidation by all metal complexes. These researchers (Hegenauer et al. 1979B) concluded that chelated iron and copper should be added after homogenization but before pasteurization by a high-temperature-short-time process. 

It has been observed that vanadium has insulin-like effects on the main organs targeted by insulin — skeletal muscles, adipose, and liver — and vanadium has been shown to reduce blood glucose to normal levels in rats that have diabetic conditions. In considering the potential of vanadium to treat diabetes in humans, the toxicity of vanadium is a definite consideration. Several organically chelated forms of vanadium have been found to be more effective in treating diabetes symptoms and less toxic than inorganic vanadium.4... 

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