Cyanide cobalt compounds

Char formation and reduced monomer production are observed for all of these additives upon reaction with PMMA. Char formation increases as a function of temperature, for the hydrido cobalt compound, there is 5% char at 262°, 8.5% at 322°, 15% at 338°, and 19% at 375°C the cobalt(lll) cyanide produces 3% char at 338° and 11% at 375°C the cobalt(ll) cyanide yields 11% char at 375°C. At the highest temperature, 375°C, the amount of monomer formation is 22% for K3Co(CN)5, 11% for K3Co(CN)6, and 10% for HCo[P(OPh)3]4. Ideally one would hope to observe no monomer formation and complete char production. Such is not the case here, these materials probably have no utility as flame retardant additives for PMMA since monomer formation, even at a reduced level, will still permit a propagation of the burning process. While somewhat positive results for these three additives do not prove the validity of the hypothesis, we take this to be a starting point in our search for suitable additives, further work is underway to refine the hypothesis and to identify other potential hydrogenation catalysts and other additives that may prove useful as flame retardants for PMMA... 

Cyanide s binding to metallic ions is also employed in a reaction with cobalt-containing compounds that yields cyanocobalamin (see Section 2.6). Cobalt compounds generally are not used because of their toxicity however, Co2EDTA (Klimmek et al. 1983) and hydroxocobalamin (Benabid et al. 1987 Mengel et al. 1989 Mushett et al. 1952) have been used as antidotes both in clinical and laboratory trials. Cardiac toxicity from Co2EDTA use under clinical conditions has raised caution in its clinical use, as the cardiac... 

Patients who are critical and do not satisfactorily respond to supportive therapy should be administered specific cyanide antidotes as outlined in Table 19.5. Cyanide antidotes have been classified into three main groups based on their mechanism of action (1) methemoglobin inducers, (2) sulfur donors, and (3) cobalt compounds. The definitive treatment of cyanide poisoning differs in various countries due to different medical practices and guidelines. The safety... 

Cobaltic ion is unstable, and an attempt to oxidize cobaltous ion usually leads to the precipitation of cobaltic hydroxide, Co(OH)3. The covalent cobaltic compounds are very stable. The most important ot these are potassium cobaltinitrite, KgCo(N02)6> and potassium cobalti-cyanide, K3Co(CN). ... 

Klimmeck, R., Faderer, M., and Weger, N., Circulation, respiration and blood homeostasis of dogs during slow cyanide poisoning and after treatment with 4-dimethylaminophenol or cobalt compounds. Arch. Toxicol., 3, 121-133, 1979. 

B. Treatment. Successful treatment for acute cyanide poisoning depends upon rapid fixation of the cyanide ion, either by methemoglobin (metHB) formation or by fixation with cobalt compounds. Drug treatments include, compounds producing Methemoglobin, Hydroxyocobalamin, and Dicobalt edetate. Any casualty who is fully conscious and breathing... 

Antimony compounds Arsenic compounds Beryllium compounds Cadmium compounds Chromium compounds Cobalt compounds Coke oven emissions Cyanide compounds Glycol ethers Lead compounds Manganese compounds Mercury compounds Fine mineral fibers... 

The drawback of cobalt compounds is their rather severe toxicity. Cardiac effects such as angina pectoris and ventricular arrhythmias, edema around the eyes, vomiting, and death have been observed.71 A clinical caveat is that severe toxicity from cobalt can be seen even after initial recovery from acute cyanide poisoning. 

Dicobalt edentate Hydroxocobalamin Cobalt compounds Forms stable metal complexes with cyanide... 

Successful antidotes for acute cyanide poisoning are available. Sodium thiosulfate, a sulfur donor, can detoxify HCN by promoting its conversion to thiocyanate when catalyzed by the enzyme rhodanase (Baumeister et al., 1975 Egekeze and Oehme, 1980) however, the detoxification effect is slow. Another procedure utilizes cobalt compounds (hydroxoco-balamine) to bind directly with cyanide to form physiologically inactive cyanocobalamine (Offterdinger and Weger, 1969). 

Many of these cobalt complexes will catalyze the reduction of organic compounds by borohydride, hydrazine, thiols, etc. Cobalt cyanide complexes will catalyze the reduction of a,j8-unsaturated acids by borohydride (105) DMG complexes the reduction of butadiene and isoprene by borohydride, but not by H2 (124) Co(II) salen, the reduction of CHCI3 and CH3CCI3 to the dichloro compounds by borohydride (116) and cyanocobalamin, the selective reduction of -CCI2- by borohydride to -CHCl- in compounds such as aldrin, isodrin, dieldrin, and endrin without... 

Alkali metal boratabenzenes may be liberated from bis (boratabenzene) cobalt complexes 7 and 13 by reductive degradation with elemental Li, sodium amalgam, or Na/K alloy (60), or alternatively by degradation with cyanides (61). The latter method has been developed in detail (Scheme 4). It produces spectroscopically pure ( H-NMR control) solutions of the products 26 the excess alkali metal cyanide and the undefined cyanocobalt compounds produced are essentially insoluble in acetonitrile. 

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