1664-98-8Relevant articles and documents
Stepwise photocatalytic dissociation of methanol and water on TiO 2(110)
Guo, Qing,Xu, Chenbiao,Ren, Zefeng,Yang, Wenshao,Ma, Zhibo,Dai, Dongxu,Fan, Hongjun,Minton, Timothy K.,Yang, Xueming
, p. 13366 - 13373 (2012)
We have investigated the photocatalysis of partially deuterated methanol (CD3OH) and H2O on TiO2(110) at 400 nm using a newly developed photocatalysis apparatus in combination with theoretical calculations. Photocatalyzed products, CD2O on Ti5c sites, and H and D atoms on bridge-bonded oxygen (BBO) sites from CD3OH have been clearly detected, while no evidence of H2O photocatalysis was found. The experimental results show that dissociation of CD3OH on TiO2(110) occurs in a stepwise manner in which the O-H dissociation proceeds first and is then followed by C-D dissociation. Theoretical calculations indicate that the high reverse barrier to C-D recombination and the facile desorption of CD2O make photocatalytic methanol dissociation on TiO2(110) proceed efficiently. Theoretical results also reveal that the reverse reactions, i.e, O-H recombination after H2O photocatalytic dissociation on TiO2(110), may occur easily, thus inhibiting efficient photocatalytic water splitting.
Olofson,Zimmermann
, p. 5057 (1967)
Concerted Grob Fragmentation in N-Halo-α-amino Acid Decomposition
Armesto, X. L.,Canle L., M.,Losada, M.,Santaballa, J. A.
, p. 4659 - 4664 (1994)
The Grob fragmentation of N-halo-α-amino acids in aqueous solution has been studied, being first order in N-halo-α-amino acid and pH-independent.The substituents on the C2 and N atoms strongly affect the reaction rate.Structure reactivity correlations for C2 substituents provide ρ* values of -3.9 and -4.1 for N-Cl and N-Br compounds, respectively.The same correlations for N substituents lead to ρ* values of -2.1 and -1.9 for N-Cl and N-Br compounds.The transition state (TS) can be generally described as product-like, its structure and characteristics being significantly affected by the substituents on the C2 and on the N atoms.In conclusion, the reaction is a DEDN concerted and slightly nonsynchronous two-stage process.
-
Bannard et al.
, p. 351,358 (1953)
-
Hydrogen atom abstraction reactions independent of C-H bond dissociation energies of organic substrates in water: Significance of oxidant-substrate adduct formation
Ishizuka, Tomoya,Ohzu, Shingo,Kotani, Hiroaki,Shiota, Yoshihito,Yoshizawa, Kazunari,Kojima, Takahiko
, p. 1429 - 1436 (2014)
Detailed kinetic studies on the oxidation reactions of organic substrates such as methanol with RuIVO complexes as oxidants, formed electrochemically in water, have been conducted to elucidate the reaction mechanism. The rate constants of the oxidation reactions exhibited saturation behaviours relative to the substrate concentration, regardless of the oxidants and the substrates employed. This indicates the existence of a pre-equilibrium process based on the adduct formation between the RuIVO oxidant and the substrate. Herein, we have experimentally confirmed that the driving force of the adduct formation is the hydrogen bonding between the oxidants and alcohols even in water. In addition, we have investigated the kinetic isotope effects (KIE) on the oxidation reaction using methanol and its deuterated derivatives and as a result observed moderate KIE values for the C-H bond of methanol. We have also revealed the independency of the reaction rates from the bond dissociation enthalpies of the C-H bonds of the substrates. This independency is probably derived from the tightly condensed transition state, whose energy level is strongly controlled by the activation entropy but less sensitive to the activation enthalpy.
-
Breuer et al.
, p. 452 (1970)
-
Formaldehyde O-Methylide, +-C--H2>: The Parent Carbonyl Ylide
Prakash, G. K. Surya,Ellis, Robert W.,Fellberg, Jeff D.,Olah, George A.
, p. 1341 - 1342 (1986)
-
Photodecomposition of Methyl Nitrite Trapped in Solid Argon
Jacox, Marilyn E.,Rook, Frederick L.
, p. 2899 - 2904 (1982)
The threshold wavelength for the photolysis of methyl nitrite isolated in solid argon at 14 K has been determined to be near 370 nm.Photolyzed samples show prominent infrared absorptions of H2CO and HNO, which are perturbed by the hydrogen-bonding interac
Catalytic oxidation of alcohols using Fe-bTAML and NaClO: Comparing the reactivity of Fe(V)O and Fe(IV)O intermediates
Jana, Sandipan,Thomas, Jithin,Sen Gupta, Sayam
supporting information, p. 476 - 482 (2018/11/23)
We demonstrate the selective oxidation of secondary alcohols and activated primary alcohols to their corresponding aldehydes or ketones using Fe-bTAML as the catalyst and sodium hypochlorite (NaClO) as the oxidant. Good to excellent yields of 80%–99% for the carbonyl compounds and turnover numbers up to ～500 was obtained with this catalytic system. The reactions are clean, performed under mild conditions (air, room temperature) and yielded sodium chloride as the only by-product. The yield and turnover number were dependent on the pH of the reaction and this difference was attributed to the different reactive intermediates that was formed at pH 7 and pH 12 (FeV(O) and FeIV(O) respectively). Reactions involving the FeV(O) intermediate oxidize secondary alcohols more efficiently than its FeIV(O) analog. This trend was reversed for the oxidation of activated primary alcohols where reactions involving FeIV(O) afforded much higher TON's. This reactivity trend can be explained from the differences in bond dissociation energy (BDE) of their corresponding one electron reduced species ([FeIV-OH], ～99 kcal/mol; [FeIII-OH], ～83 kcal/mol) as well as their relative stabilities in the solvent during reaction. This catalytic system was found to be unsuitable for nonconjugated primary alcohol due to the formation of the inactive FeIV(OMe) intermediate after one catalytic cycle.
A hydrogen-atom transfer mechanism in the oxidation of alcohols by [FeO4]2- in aqueous solution
Xie, Jianhui,Lo, Po-Kam,Lam, Chow-Shing,Lau, Kai-Chung,Lau, Tai-Chu
, p. 240 - 245 (2017/12/27)
The ferrate(vi) ion, [FeO4]2-, has attracted much interest in recent years because of its potential use as a green oxidant in organic synthesis and water treatment. Although there have been several reports on the use of ferrate(vi) for the oxidation of alcohols to the corresponding carbonyl compounds, the mechanism remains unclear. In this work, the kinetics of the oxidation of a series of alcohols with α-C-H bond dissociation energies ranging from 81 to 95 kcal mol-1 have been studied by UV/Vis spectrophotometry. The reactions are first-order in both [FeO4]2- and [alcohol]. The deuterium isotope effects for the oxidation of methanol/d4-methanol, ethanol/d6-ethanol and benzyl alcohol/d7-benzyl alcohol are 18.0 ± 0.1, 4.1 ± 0.1 and 11.2 ± 0.1, respectively. A linear correlation is found between the second-order rate constants and the α-C-H bond dissociation energies (BDEs) of the alcohols, consistent with a hydrogen atom transfer (HAT) mechanism. The proposed HAT mechanism is supported by DFT calculations.
