7789-89-1Relevant articles and documents
Chemically induced dynamic nuclear polarization and the mechanism of the reaction of Et3Al with CCl4 in the presence of transition metal complexes
Sadykov,Safina,Teregulov,Paramonov
experimental part, p. 497 - 501 (2011/01/10)
Integral effects of chemically induced 1H and 13C nuclear polarization are reported for the reaction of Et3Al with CCl4 catalyzed by Pd(acac)2, Cu(acac)2, and Cp2TiCl2; for the reaction of (n-C8H 17)3Al with CCl4 in the absence of a catalyst and in the presence of Ni(acac)2; and for the reaction of the cyclic organoaluminum compound 1-ethyl-3-butylaluminacyclopentane with CCl4 in the presence of Pd(acac)2. A scheme of the catalytic cycle of this reaction predicting the formation of both radical and nonradical products is derived from the observed chemically induced dynamic nuclear polarization (CIDNP) effects and from data on the products of the reaction between Et 3Al and CCl4 in the presence of Pd(acac)2. According to the results of qualitative analysis of the CIDNP effects, the reactions of the trialkylalanes and the cyclic organoaluminum compound with CCl4 in the presence of various metal complexes proceeded via similar mechanisms.
CINDP study of the Ni(acac)2-catalyzed reaction of triethylaluminum with chloroform
Sadykov,Dzhemilev
, p. 995 - 997 (2007/10/03)
CIDNP effects were found in the Ni(acac)2-catalyzed reaction of Et3Al with CHCl3. The effects appear in the products of transformation of the diffusion radical pair of the ethyl and dichloromethyl radicals. The radical route is a side process in this reaction, and the main products, Et2AlCl, ethane, and ethylene, are formed by a nonradical route. A general mechanism of the reactions of Et3Al with CHCl3 and CCl4 including radical and ion-coordination processes was suggested.
REACTIVITY OF TRIETHYL PHOSPHITE WITH TETRACHLOROMETHANE : ELECTRON TRANSFER VERSUS IONIC SUBSTITUTION ON "POSITIVE" HALOGEN
Bakkas, Salem,Julliard, Michel,Chanon, Michel
, p. 501 - 512 (2007/10/02)
The reaction of triethyl phosphite (1) with tetrachloromethane (2) has been studied from a mechanistic point of view. 1 reacts at 80 deg C with 2 to form diethyltrichloromethanephosphonate (3) (85-90percent yield) and chloroethane (4) (80percent yield).Several results hint at a radical chain mechanism (like SRN1).Trichloromethyl radical is trapped by 2,6-di-t-butyl-4-cresol (BHT), the reaction may be initiated with UV radiation (254 nm) and a charge transfer complex (CTC) is formed between 1 and 2 ; furthermore, the reaction is inhibited by 7,7',8,8' tetracyanoquinodimethane (TCNQ).Tris(cyclopropylmethyl)phosphite (12a) and tri(1-hexene-6-yl) phosphite (7a) are used as potential radical clocks in these reactions.The first leads inter alia to 3-chloro-1-butene (17) and the second to 5-chloro-1-hexene (11), the first therefore suggests a radical mechanism but not the second.However in this particular case even the results obtained with the tris(cyclopropylmethyl)phosphite may be rationalized also by an ionic mechanism.For the photostimulated reaction , the overall quantum yield is 0.1.The electrochemical oxidation of 1 with added CCl4 does not account for a radical chain process as the main pathway.Furthermore, the application of Marcus analysis to reaction viewed as an electron transfer leads to a calculated rate constant in the range of 10-20 M-1s-1.The synergy of the techniques that we used lead us to conclude that the thermal reaction is in fact an SNCl+ substitution.The radical intermediates would mainly be derived from the electron-transfer reaction between CCl3- and CCl4 the importance of which increases when special conditions such as hν activation are applied.Reaction therefore provides an example where the observed paramagnetic species during a D/A interaction could deceptively suggest an electron-transfer between D and A whereas they originate from an interaction between A and an electron donor formed after or during the first step of the reaction.
