Reactions of CuiG with the aliphatic-free radicals *CH2CO;, CH3qHCO;, O;CCHCH(OH)CO;, *CC13, $'H2CH20H and -CH,C(CH,),OH in aqueous solutions were studied.In these reactions the formation of unstable intermediates absorbing in the U.V. range was observed. This absorption is attributed to compounds with copper-carbon u bonds. The kinetics of formation and decomposition of these intermediates are reported and discussed. No intermediates were observed when Cu& reacts with *CR,R,OH-free radicals. Cu:, is one of the final products in all systems studied.Copper salts have been shown to affect a variety of reactions involving aliphatic free radicals including many catalytic processes in aprotic and protic media.l The results indicated that aliphatic free radicals react with many Cu" complexes via a mechanism involving the formation of " short lived " intermediates having a coppercarbon bond R* + CU" + Cu"'-R.It was suggested2 that the lifetime of the CU~~I-R intermediate is too short to be physically observable. The mechanisms of decomposition of CuI1'-R differ depending on the nature of -R, though in all cases the reaction can be summed up bywhere R(-H) is an oxidized form of the radical which lost one proton. In systems having a " good bridging " ligand on the Cu" the reaction scheme is often better described byIn some systems the results suggest an outer sphere redox mechanism However, the latter mechanism seems to be limited to unusual cases.
Bromine is a very good electro active species, with fast and reversible kinetics. However, it possesses a high vapor pressure and reactivity which require stabilization via complexing agents, which reduce reactivity and vapor pressure without changing its electrochemical properties. Currently, bromide based batteries like the Zinc/ Bromine cell, use as Bromide complexing agents, either Methyl Ethyl Morpholinium Bromide (MEM) or Methyl Ethyl Pyrrolidinium Bromide (MEP) or their mixture. Both complexing agents have been well known in the field for about 40 years. A possible drawback of their use as complexing agents for bromine is that they are not always compatible with different bromide chemistries. ICL-IP has developed a family of new effective Bromide complexing agents that are compatible with various bromide based chemistries and applications.
Helium-saturated solutions containing copper sulphate and an aliphatic alcohol (methanol, ethanol or propan-2-01) were pulse irradiated. The kinetics of the reactions thus initiated were followed by the spectrophotometric and conductometric techniques. The results indicate that all three radicals, -CR1R20H, react with Cuii to yield Cu&+ CRlR20+ H,O+. =CH20H radicals react with Cu&, according to CuAq+4M20H CuIl-CH,OH+, K = 5 x 10 dm" rnol-'.? The corresponding equilibrium constants for CulI-CH(CH3)OH+ and CUI~-C(CH~)~OH+ are too low to be measured and the corresponding intermediates are not observed. Cuk, reacts with the p radicals, =CH2CH20H and -CH2CH(CH3jOH, according to Cu&The latter intermediates decompose via acid catalysed reactions to yield C u j i + H2C=CR1R2 + H20.Copper salts were shown to affect a variety of reactions involving aliphatic free radicals including many catalytic processes in aprotic and protic media.Ib The results indicate that aliphatic free radicals react with cuprous, as well as with cupric ions via a mechanism involving the formation of " short-lived " intermediates having a copper-carbon bond(2) Recently while studying the kinetics of formation and decomposition of several CUI~~--R intermediates in aqueous solutions, we found that when Cu,', ions are t In writing CuII--R + or CuIII---R*+ we follow the accepted nomenclature for organometallic compounds. This notation does not imply that the nature of the chemical bond is ionic. Furthermore, the results, see discussion, indicate that the Cu-C bond has at least partially a covalent nature.* Clearly one cannot prepare solutions which contain Cug ions but no Cu&+ ions.
The radical *CH,CO,-reacts with Cu2+ (aq) forming an unstable intermediate with a specific rate of (6.4 f 1.5) x 10s 1 mol-l s-I; the intermediate, Cu-CH,-CO,+, decomposes via a first-order process with K 2.8 f
The effect of CdS04 and NiS04 on the radiolytic hydrogen yield and its isotopic composition in the systems H,O + CH30H, HzO + CD30H, DzO + CH30D, HzO + (CHd2CHOH, HzO + (CH& CDOH and D20 + (CH3)XHOD are reported.The results suggest that hydrogen atoms and aliphatic radicals oxidize Cdzq and Ni&. Furthermore it is suggested that the reaction Cd-C(CH&OH+ -+ CdH++ (CH3)C=CH2 occurs in aqueous solutions. The implications of these observations on earlier results are discussed. /OH ' A.
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