F:Flammable;
75-65-0Relevant articles and documents
Electrocatalytic features of a heme protein attached to polymer-functionalized magnetic nanoparticles
Krishnan, Sadagopan,Walgama, Charuksha
, p. 11420 - 11426 (2013)
Direct electron-transfer and electrocatalytic kinetics of covalently attached myoglobin (MB) films on magnetic nanoparticles (MB-MNP covalent), in comparison to the corresponding physisorbed films and individual components, are reported for the first time. MB-MNP covalent ("-" denotes a covalent linkage) was adsorbed onto a cationic poly(ethyleneimine) layer (PEI) coated high-purity graphite (HPG) electrode. Similarly, films of myoglobin physisorbed on magnetic nanoparticles (MB/MNPadsorbed, "/" denotes a noncovalent nature), only MB, or only MNP were constructed on HPG/PEI electrodes for comparison. The observed electron-transfer rate constants (ks, s-1) were in the following order: MB-MNPcovalent (69 ± 6 s -1), MB/MNPadsorbed (37 ± 2 s-1), only MB (27 ± 2 s-1), and only MNP (16 ± 3 s-1). The electrocatalytic properties of these films were investigated with the aid of tert-butylhydroperoxide as a model reactant, and its reduction kinetics were examined. We observed the following order of catalytic current density: MB-MNPcovalent > MB/MNPadsorbed > only MNP > only MB, in agreement with the electron-transfer (ET) rates of MB-MNP covalent and MB/MNPadsorbed films. The crucial function of MNP in favorably altering the direct ET and electrocatalytic properties of both covalently bound MB and physisorbed MB molecules are discussed. In addition, the occurrence of a highly enhanced electron-hopping mechanism in the designed covalent MB-MNPcovalent films over the corresponding physisorbed MB/MNPadsorbed film is proposed. The enhanced electron-transfer rates and catalytic current density suggest the advantages of using metalloenzymes covalently attached to polymer-functionalized magnetic nanoparticles for the development of modern highly efficient miniature biosensors and bioreactors.
Correlation of the product E/Z framework geometry and O/O vs O/N regioselectivity in the dialkylation of hyponitrite
Arulsamy, Navamoney,Bohle, D. Scott,Imonigie, Jerome A.,Sagan, Elizabeth S.
, p. 5539 - 5549 (2000)
The products from the alkylation of silver hyponitrite with tert-butyl bromide, tert-amyl bromide, p-tert-butyl benzylbromide, and chlorotriethylsilane have been determined. In the reaction of tert-butyl bromide the formation of three new products, namely
Kinetics of Oxidation of Hydrazine and of t-Butylhydrazine using Tris(dimethylglyoximato)nickelate(IV) in the Presence of Added Cu(2+) (aq)
Acharya, Sridhara,Neogi, Gautam,Panda, Rama Krushna,Ramaswamy, Dorai
, p. 1477 - 1484 (1984)
The kinetics of the oxidation of hydrazine and t-butylhydrazine using tris(dimethylglyoximato)nickelate(IV), (2-), in the presence of added Cu(2+)(aq), and in the pH range 5.0 - 7.0 at 35 deg C and I = 0.25 mol dm-3 in aqueous medium, follow pseudo-first-order and pseudo-zero-order disappearance of the NiIV complex, respectively.Results of the Cu(2+) (aq)-promoted oxidation of hydrazine by (2-) are consistent with a probable scheme involving pH-dependent equilibrium formation of intermediate adducts between the NiIV and CuII-hydrazine complex species present in the solution and subsequent rate-determining electron transfer(s) to the adduct(s) from the hydrazine species in the presence of H(1+).Results of the Cu(2+) (aq)-catalyzed oxidation of t-butylhydrazine are interpreted in terms of a probable mechanism involving a rate-determining decomposition of the 1:1 intermediate complex between the CuII and t-butylhydrazine species in the solution, with a concomitant electron transfer.While the oxidation of hydrazine leads to nitrogen, the main products of the t-butylhydrazine oxidation are nitrogen and t-butyl alcohol.
Temperature dependence of the rate and activation parameters for tert-butyl chloride solvolysis: Monte Carlo simulation of confidence intervals
Sung, Dae Dong,Kim, Jong-Youl,Lee, Ikchoon,Chung, Sung Sik,Park, Kwon Ha
, p. 378 - 382 (2004)
The solvolysis rate constants (kobs) of tert-butyl chloride are measured in 20%(v/v) 2-PrOH-H2O mixture at 15 temperatures ranging from 0 to 39°C. Examination of the temperature dependence of the rate constants by the weighted least squares fitting to two to four terms equations has led to the three-term form, lnkobs=a1+a 2T-1+a3lnT, as the best expression. The activation parameters, ΔH? and ΔS ?, calculated by using three constants a1, a 2 and a3 revealed the steady decrease of ≈1 kJmol -1 per degree and 3.5 JK-1mol-1 per degree, respectively, as the temperature rises. The sign change of ΔS ? at ≈20.0°C and the large negative heat capacity of activation, ΔCp?=-1020 JK -1mol-1, derived are interpreted to indicate an S N1 mechanism and a net change from water structure breaking to electrostrictive solvation due to the partially ionic transition state. Confidence intervals estimated by the Monte Carlo method are far more precise than those by the conventional method.
Decomposition of tert-butyl hydroperoxide into tert-butyl alcohol and O2 catalyzed by birnessite-type manganese oxides: Kinetics and activity
Qi, Lin,Qi, Xingyi,Wang, Lili,Feng, Lili,Lu, Shupei
, p. 6 - 9 (2014)
Birnessite-type manganese oxides (M-OL-1s, M = K, Mg, Fe, Ni and Cu) are first reported to efficiently catalyze the decomposition of tert-butyl hydroperoxide (TBHP) into tert-butyl alcohol (TBA) and O2 with a 100% selectivity towards TBA under heterogeneous conditions. The same form of overall second-order kinetic equations is fitted out for the M-OL-1s and explained by the proposed mechanism. Life tests and XRD analyses demonstrate no losses in both the activity and the birnessite-type structure after the reaction.
Possible Role of Non-hydrogen-bonded Units in the Chemistry of Liquid Water
Pay, Nicholas G. M.,Symons, Martyn C. R.
, p. 2417 - 2422 (1993)
Pure liquid water is thought to contain ca. 8 molpercent of non-hydrogen-bonded (free) OH groups and lone-pair (LP) groups.It is suggested that, as well as playing important roles in the physical and spectroscopic properties of liquid water, these groups are important in controlling solvation and in certain chemical reactions.The postulate is that if a reaction that makes a significant contribution to the overall rate involves (OH)free groups, then solutes that increase or decrease the free> will increase or decrease the rate.Conversely, if (LP)free groups are reactants, than changes in free> will similarly affect the reaction rate.The hydrolysis of tert-butyl iodide in binary solvent systems has been measured spectrophotometrically at 7 deg C, and it is shown that the results can be reasonably understood in terms of the above theory.It is clearly established that basic aprotic cosolvents lead to rapid decreases in the rates of SN1 reactions and our results are in good agreement.For simple 1:1 electrolytes the salt effect results in rate enhancement, as expected for an 'ionisation' process.However, tetra n-butylammonium bromide causes a dramatic fall in the rate of hydrolysis.This is expected, if the key reaction involves (OH)free groups, as is indicated by the rate decreases caused by basic solutes.Thus, for simple salts, cations and anions have similar solvation numbers and so induce only small changes in the concentration of 'free' water groups.However R4N+ ions do not form bonds to water so the anions, which solvate by hydrogen bonding to OH units, cause a large fall in free>, and hence there is a large negative contribution to the rate of hydrolysis.Taking the primary solvation number of Br- as 6, the results agree well with those for solvents such as dimethylformamide, which has a solvation number ca. 2.Finally, it is pointed out that reactions involving attack by oxygen via an electron pair, such as the extraction of H+ from an organic reactant should behave in just the opposite manner.This is indeed the case.
A search for mode-selective chemistry: The unimolecular dissociation of t-butyl hydroperoxide induced by vibrational overtone excitation
Chandler, David W.,Farneth, William E.,Zare, Richard N.
, p. 4447 - 4458 (1982)
The use of optoacoustic spectroscopy permits both the monitoring of the overtone excitation of t-butylhydroperoxide (t-BuOOH) and the in situ detection of the resulting reaction product t-butanol (t-BuOH).The sample is contained in a reaction cell, equippedwith a microphone, in which all surfaces have been specially passivated.The cell is placed inside the cavity of a dye laser tuned to excite the 5-0 O-H stretch of the t-BuOOH at 619.0 nm.The dissociation process yields directly OH and t-BuO, and the latter readily abstracts a hydrogen atom from a parent molecule to form t-butanol (t-BuOH).The appearance rate of t-BuOH is obtained by ratioing the area under the 5-0 O-H stretch of tBuOH to that of a combination band of t-BuOOH.At low pressures, below 40 Torr, a plot of the reciprocal of the t-BuOH appearance rate versus total pressure shows near linear behavior.This linearlity can be well described by a statistical model (RRKM) when careful averaging of the dissociation rate over the thermal energy distribution of the photoactivated molecules is included.At pressures above 40 Torr, a marked deviation from linearity appears.This deviation is fit to a kinetic model in which the dissociation rate of an energy nonrandomized molecule competes with the rate of intramolecular energy relaxation.This places a lower bound of >= 5.0*1011 s-1 on the rate of energy randomization.A discussion of this model in the context of other possible kinetic schemes as well as other photoactivated and chemically activated systems is presented.
Homolytic cleavage of the O-Cu(II) bond: XAFS and EPR spectroscopy evidence for one electron reduction of Cu(II) to Cu(i)
Yi, Hong,Zhang, Guanghui,Xin, Jie,Deng, Yi,Miller, Jeffrey T.,Kropf, Arthur J.,Bunel, Emilio E.,Qi, Xiaotian,Lan, Yu,Lee, Jyh-Fu,Lei, Aiwen
, p. 6914 - 6917 (2016)
The investigation into the active copper(i) catalysts from copper(ii) precursors has become a fundamental and important task in copper catalysis. In this work, we demonstrate that the tBuO- anion serves not only as a base but also as a mediator to promote the reduction of Cu(ii) to Cu(i) in copper catalysis. XAFS and EPR spectroscopy evidence the [Cu(OtBu)3]- ate complex as the key intermediate which undergoes homolytic-cleavage of the O-Cu(ii) bond generating [Cu(OtBu)2]- ate complex.
Enhanced catalytic performance of porphyrin cobalt(II) in the solvent-free oxidation of cycloalkanes (C5~C8) with molecular oxygen promoted by porphyrin zinc(II)
Shen, Hai-Min,Zhang, Long,Deng, Jin-Hui,Sun, Jing,She, Yuan-Bin
, (2019)
Dual-metalloporphyrins catalytic system based on T(p-Cl)PPCo and T(p-Cl)PPZn was presented to enhance the oxidation of cycloalkanes, especially for cyclohexane, the selectivity towards KA oil increasing from 90.7% to nearly 100.0%, meanwhile the conversion increasing from 3.42% to 4.29%. Enhancement on conversion and selectivity was realized simultaneously. In the dual-metalloporphyrins system, T(p-Cl)PPCo served the role to activate molecular oxygen and promote the decomposition of cyclohexyl hydroperoxide, and T(p-Cl)PPZn catalyzed the decomposition of cyclohexyl hydroperoxide to avoid unselective thermal decomposition. This protocol is also very applicable to other cycloalkanes and will provide a applicable strategy to enhance the oxidation of alkanes.
CHANGE IN THE REACTIVITY OF DI-tert-BUTYL PEROXIDE DURING HOMOLYSIS WITH AN INCREASE IN THE DEGREE OF CONVERSION AND PRESSURE
Zhulin, V. M.,Khueidzha, I.,Koreshkov, Yu. D.
, p. 643 - 649 (1992)
It was found that the differential reactivity (kd') of di-tert-butyl peroxide (DTBP) in a solution of 2-methoxy- (1) and 2-ethoxytetrahydropyran (2) at 130 deg C and pressures p = 20 and 1000 MPa is a periodic function of the degree of conversion, arbitrarily measured by the concentration of tert-butyl alcohol (TBA) formed.The function kd' = F() was calculated with the spline approximation (SA) of the experimental as a function of the reaction time τ, giving a continuous curve of d/dτ as a function of τ.The integral reactivity kd = G() calculated with the kinetic equation for a first-order reaction for decomposition of DTBP in 1, 2, 1+ C6H6 and 2 + C6H6 in three segments of τ in the range of p = 20-1000 MPa changes differently with an increase in the degree of conversion for different p.The volume activation effects (ΔVp) determined by SA of the experimental ln kd as a function of p were calculated for close degrees of conversion, = 0.1-0.14 M.The ΔVp as a function of p obtained were compared with the similarly processed published data on decomposition of DTBP in n-heptane and dicumyl peroxide (DCP) in different aromatic solvents.The results were attributed to the effect of the type of packing of the solvent molecules surrounding the reacting molecule on the reactivity of the peroxide and not to the effect of radical recombination in the primary cage. Keywords: di-tert-butyl peroxide, homolysis, high pressure, role of solvent.
