97860-69-0Relevant articles and documents
Kinetics and Mechanism of Oxygen Transfer in the Reaction of p-Cyano-N,N-dimethylaniline N-Oxide with Metalloporphyrin Salts. 7. Oxygen Atom Transfer to and from (meso-Tetrakis(pentafluorophenyl)porphinato)iron(III) Chloride
Ostovic, Drazen,Knobler, Carolyn B.,Bruice, Thomas C.
, p. 3444 - 3451 (1987)
The decomposition of p-cyano-N,N-dimethylaniline N-oxide (NO) in the presence of (meso-tetrakis(pentafluorophenyl)porphinato)iron(III) chloride ((F20TPP)FeIIICl) provides p-cyano-N,N-dimethylaniline (DA) in 32 +/- 3percent, p-cyano-N-methylaniline (MA) in 50 +/- 5percent, 4-cyano-7-(dimethylamino)-2-benzofuranone-3-spiro-2'-cyano-5'-(dimethylamino)cyclopentadiene (BF) in 16 +/- 2percent, and formaldehyde in 30 +/- 3percent yield based upon (NO)i.Material balance may be accounted for in all components.Appearance of products is first order in both NO and (F20TPP)FeIIICl, and the second-order rate constant for the reaction has been determined to be (2.0 +/- 0.5) x 102 M-1 s-1.The observation that the formation of products DA, MA, and BF is associated with the same rate constant establishes the commitment step to be the bimolecular reaction of NO with (F20TPP)FeIIICl.It is proposed that this reaction directly yields DA and the iron(IV)-oxo porphyrin ?-cation radical ((+.F20TPP)FeIVO).That the formation of (+.F20TPP)FeIVO + DA is rate controlling is substantiated by use of the reagents 2,4,6-tri-tert-butylphenol (TBPH), N,N-dimethylaniline (DMA), and N,N-dimethyltoluidine (DMT) as traps for the (+.F20TPP)FeIVO species.The rates of oxidation of these trapping agents are independent of their concentration, and the rate constants calculated for the appearances of their oxidation products correspond to the turnover rate constant for the reaction of NO with (F20TPP)FeIIICl in the absence of trapping agents.Formation of the products MA and BF must then be attributed to the rapid oxidation of DA by (+.F20TPP)FeIVO.The formation of MA occurs by the oxidative demethylation of DA, and formation of BF is logically accounted for by the hydroxylation of DA to yield 2-hydroxy-4-cyano-N,N-dimethylaniline (DMP) which, on further stepwise oxidation, provides BF (much as in the stepwise 1 e- oxidation of p-cresol to yield Pumerer's ketone).Increase in the concentrations of DMA and DMT results in exponential increase in the percentage yield of DA and decrease in the percentage yield of MA.In each case the asymptotic percentage yields of 68 +/- 7percent DA and 17 +/- 2percent MA are approached.The percentage yield of BF (17 +/- 2percent) is not changed by the presence of DMA or DMT at various concentrations or by their absence.These results show that a substantial portion of the immediate products DA and (+.F20TPP)FeIVO reacts in a solvent-caged /(+.F20TPP)FeIVO*DA/ pair prior to their diffusion apart.Once free from the caged pair, the (+.F20TPP)FeIVO species oxidizes the traps DMA and DMT in preference to DA.The asymptotic yield of MA represents the percentage yield of MA obtained by oxidation of DA within the solvent caged pair.Since the percentage yield of BF is not influenced by the presence of DMA or DMT, all hydroxylation of DA must occur within the /(+.F20TPP)FeIVO*DA/ species.By this reasoning, both the caged oxidative demethylation and hydroxylation of DA occur in ca. 17percent yields.Thus, within the ....
The Kinetics and Mechanisms of Oxygen Transfer in the Reaction of p-Cyano-N,N-dimethylaniline N-Oxide with Metalloporphyrin Salts. 4. Catalysis by meso-(Tetrakis(2,6-dimethylphenyl)porphinato)iron(III) Chloride
Woon, T. C.,Dicken, C. Michael,Bruice, Thomas C.
, p. 7990 - 7995 (2007/10/02)
meso-(Tetrakis(2,6-dimethylphenyl)porphinato)iron(III) chloride ((Me8TPP)Fe(III)Cl) is a catalyst for the conversion of p-cyano-N,N-dimethylaniline N-oxide (NO) to p-cyano-N,N-dimethylaniline (DA), p-cyano-N-methylaniline (MA), p-cyano-N-formyl-N-methylaniline (FA), p-cyanoaniline (A), N,N'-dimethyl-N,N'-bis(p-cyanophenyl)hydrazine (H), N,N'-bis(p-cyanophenyl)-N-methylmethylenediamine (MD), and CH2O.All evidence supports these reactions to occur by equilibrium ligation of NO to iron(III) porphyrin followed by rate-detrmining oxygen transfer to yields as intermediate products DA and the iron(IV)-oxo porphyrin ?-cation radical.Stepwise oxidation of DA by the higher valent iron-oxo porphyrin species is responsible for the formation of the other products (i.e., DA-->-->FA, DA-->MA-->A, 2MA-->MD, and 2MA-->H).The oxidation potentials of (Me8TPP)Fe(III)OCH3 are comparable to those of the unsubstituted meso-(tetraphenylporphinato)iron(III) methoxide ((TPP)Fe(III)OCH3).The following results are, therfore, not surprising: (i) The second-order rate constant (kakb/k-a) for reaction of (Me8TPP)Fe(III)Cl with NO is but 3.3-fold smaller than in the case of the reaction of NO with (TPP)Fe(III)Cl; (ii) the percentage yields of products (DA, 53percent; MA, 24percent; A, 3percent; FA, 8percent; H, 7percent; MD, 5percent) are comparable to when (TPP)Fe(III)Cl is employed; and (iii) oxidation and epoxydation of added substrates are not rate-determining.Of considerable interest is the finding that epoxidation reactions using NO with (Me8TPP)Fe(III)Cl occur in much higher yield (80percent to 100percent) than when (TPP)Fe(III)Cl is used as the catalyst.
Kinetics and Mechanisms of Oxygen Transfer in the Reaction of p-Cyano-N,N-dimethylaniline N-Oxide with Metalloporphyrin Salts. 2. Amine Oxidation and Oxygen Transfer to Hydrocarbon Substrates Accompanying the Reaction of p-Cyano-N,N-dimethylaniline N-Oxide with meso-(Tetraphenylporphi...
Dicken, C. Michael,Lu, Fu-Lung,Nee, Michael W.,Bruice, Thomas C.
, p. 5776 - 5789 (2007/10/02)
The catalysis of the decomposition of p-cyano-N,N-dimethylaniline N-oxide (NO) with meso-(tetraphenylporphinato)iron(III) chloride IIICl> has been studied at 25 deg C in CH2Cl2 with i = 5.0E-4 to 8.0E-3 M > IIICl>i = 3.0E-5 to 5.0E-4 M.The iron(III) porphyrin catalyst was shown to be unaltered in catalytic efficiency to 120 turnovers (the highest examined).The influence of O2 and the purity of solvent upon the kinetics of the reactions and products obtained have been assessed.In the absence of an oxidizable substrate, NO gives way to the following products: p-cyano-N,N-dimethylaniline (DA), 52percent yield; p-cyano-N-methylaniline (MA), 25percent yield; N-formyl-p-cyano-N-methylaniline (FA), 4percent yield; p-cyanoaniline (A), 2percent yield; N,N'-dimethyl-N,N'-bis(p-cyanophenyl)hydrazine (H), 12percent yield; N,N'-bis(p-cyanophenyl-N-methylmethylenediamine (MD), 6percent yield; and CH2O, 11percent yield.The major portion of the products (i.e., DA, MA, H and MD) absorb appreciably at 320 nm where absorbance by (TPP)FeIIICl is minimal.The formation of products was followed spectrophotometrically at 320 nm and by HPLC at 280 and 320 nm.Both means were found to be in quantitative agreement.Spectral monitoring of the increase in A320 showed that the first-order decomposition of the N-oxide was independent of i but increases with an increase in IIICl>i.The appearance of DA, MA, FA, MD, and CH2O also followed the first-order rate law, while the formation of the products H and A are characterized by a lag period followed by a constantly accelerated formation ending abruptly with the consumption of the N-oxide.Of the various products, only A exhibited inhibition of the kinetics for decomposition of N-oxide by (TPP)FeIIICl.At the concentration formed in the kinetic experiment, however, A is not inhibiting.The rate constant for "oxygen" transfer from NO to (TPP)FeIIICl to form IV=O>+. was determined by trapping this species with 2,4,6-tri-tert-butylphenol (TBPH).In the presence of TBPH trap, DA is formed in 100percent yield, showing that the other decomposition products of the N-oxide arise via stepwise oxidation of DA by IV=O>+..An intermolecular deuterium kinetic isotope effect of unity was obtained by comparison of the initial rate contants for the reactions of p-NCC6H4N+(CH3)2O-/p-NCC6H4N+(CD3)2O-.A discriminatory intramolecular deuterium isotope effect of 4.5 was observed when p-NCC6H4N+(CH3)(CD3)O- was used and the formation of p-NCC6H4NH(CD3)/p-NCC6H4NH(CH3) was monitored.The isotope effects are in agreement with the finding that rate-determining oxygen transfer from NO to (TPP)FeIIICl is followed by demethylation of DA.A variety of alkenes and cyclohexane are shown to compete with DA as substrates.With these, the yields of epoxidation and/or hydroxylation products are comparable to those reported previously when iodosylbenzene was used as the oxygen source under similar conditions.The stereospecifity seen with iodosylbenzene is also evidenced with NO.At 1.0 M 2,3-dimeth...
