Tert-butyl Peracetate Research Articles

Reaction mechanism and process safety assessment of acid-catalyzed synthesis of tert-butyl peracetate

Esterification during the synthesis of tert-butyl peracetate (TBPA) is highly exothermic. Since peroxides (tert-butyl hydroperoxide TBHP and TBPA) are intrinsically thermosensitive, this synthesis process is potentially dangerous. In this work, the exothermic process and mechanism of TBPA synthesis using acetic anhydride (Ac2O) and TBHP under the catalysis of sulphuric acid (H2SO4) were clarified by calorimetry, infrared spectroscopy, and high-performance liquid chromatography. To substantially alleviate the thermal risk of the reaction, and to feasibly select appropriate synthesis conditions for ensuring the process safety of the synthesized products, several sets of isothermal and isoperibol experiments were performed using calorimetry. The intermediates formed and concentration changes during the reaction were monitored using in-situ Fourier-transform infrared spectroscopy. Differential scanning calorimetry and adiabatic calorimetry were used to assess the thermal hazard of the materials during the synthesis process. The reaction mechanism was verified using density functional theory calculations. The results revealed that a controlled increase in exothermicity could be achieved by adding aqueous TBHP to Ac2O in semi-batch experiments in isothermal mode, and accordingly, the highest yield was 95.71%. Experiments combined with theoretical calculations revealed that the primary exothermic event was the TBPA formation reaction, and the removal of a large amount of water from TBHP prior to this is favourable for the reaction. The criticality classes of this reaction were of Grade 2.

The modified Stoessel criticality diagram for process safety assessment

The modified Stoessel criticality diagram was present in this research. The final temperature under adiabatic condition was considered for thermal hazard assessment. We reported the systematic thermal hazard assessment of synthesis of tert-butyl peracetate, preparation of hydroxylamine and synthesis of 2,6-diethyl-4-methylPhenylpropanamide and discussed their classification according to the modified Stoessel criticality diagram. The process temperature, maximum temperature of synthesis reaction, maximum temperature for technical reasons, temperature at which TMRad is 24h and the final temperature under adiabatic condition(Tp, MTSR, MTT, TD24, Tf) were obtained by experiments and calculation. The evaluation results by the modified Stoessel criticality are more rational and conforms to reality.

New Thermal Runaway Risk Assessment Methods for Two Step Synthesis Reactions

In this study, in order to assess thermal runaway risk of two step synthesis reactions, two new risk assessment methods were proposed by combining the new assessment procedure with the risk matrix and the Stoessel criticality diagram. The thermal runaway risks of the tert-butyl peroxybenzoate (TBPB) synthesis process and the tert-butyl peracetate (TBPA) synthesis process, and the influence of the use of the pure target products on the assessment results were also studied by the new methods. The results showed that the new methods could obtain more accurate assessment results of two step synthesis reactions. Some measures should be taken to reduce the thermal runaway risks of the two synthesis processes. Furthermore, the use of the pure target products in the new methods would exaggerate the thermal runaway risks of the two step synthesis reactions.

Process safety evaluation of the synthesis of tert-butyl peracetate

To explore the thermal hazard of tert-butyl peracetate (TBPA), various instruments were applied to investigate the synthesis and decomposition of TBPA. Reaction calorimeter (RC1e) was used to analyze the exothermic characteristics during synthesis of TBPA in acid and alkaline medium, respectively. The thermal parameters, such as adiabatic temperature rise (ΔTad,r) and maximum temperature of the synthesis reaction (MTSR), were calculated for assessing the thermal hazard of TBPA synthesis. Differential scanning calorimetry (DSC) and Phi-TEC II adiabatic calorimeter were used to understand thermal characteristics of TBPA decomposition. According to the exothermic curves from the interruption and rescanning experiments and isothermal experiments by DSC, TBPA decomposed following the nth-order law. Thermal parameters of TBPA decomposition at different heating rates were obtained from non-isothermal experiments and the corresponding apparent activation energy (Ea) was calculated by Kissinger method and Starink method. Phi-TEC II was, in turn, used to obtain the thermokinetic parameters of TBPA decomposition under adiabatic conditions. The thermokinetic parameters, such as Ea, the pre-exponential factor (A) and reaction order (n), were used to calculate the time to maximum rate under adiabatic conditions (TMRad) and TD24 (Temperature at which TMRad is 24.0 h). To further understand the decomposition process, thermal decomposition products were studied using gas chromatography/mass spectrometry (GC/MS). Then the reaction scheme of TBPA decomposition was proposed. The thermal hazard of TBPA synthesis was evaluated according to the risk matrix and the Stoessel criticality diagram. Results shows that compared to synthesis in acid medium, TBPA synthesis in alkaline medium was preferred. However, the operating conditions of synthesis also need to be redesigned to improve the process safety level. These studies were considered to have potential applications in inherently safer operating measures and safer storage and transportation.

Iron-Based ICAR ATRP of Styrene with ppm Amounts of FeIIIBr3 and 1,1'-Azobis(cyclohexanecarbonitrile).

A successful ICAR (initiators for continuous activator regeneration) ATRP (atom transfer radical polymerization) of styrene was conducted with iron(III) bromide and 1,1'-azobis(cyclohexanecarbonitrile) (ACHN) as the thermal initiator. A polymerization, started with 50 ppm of FeBr3 and 50 mol equivalents of ACHN in 33% (v/v) anisole at 90 °C, reached 70% conversion in 24 h and was well controlled, giving a polymer with a narrow molecular weight distribution (Mw/Mn = 1.15). The number average molecular weight (Mn) corresponded well to theoretical values, as conversion increased. The rate of polymerization was dependent on the amount of ACHN initially added to the reaction. A polymer with a relatively narrow molecular weight distribution, Mw/Mn = 1.29 at 65% of conversion, was obtained with 5 ppm of FeBr3 and the appropriate amount of ACHN. This procedure therefore provides an efficient controlled polymerization in addition to creating a robust, cheap, and environmentally friendly catalytic system. Control of polymerization with ACHN was better than with tert-butyl peracetate as a thermal initiator or tin(II) 2-ethylhexanoate, Fe0, or Zn0 wire as reducing agents.

Kinetics of the Reactions of Cu(0) and Cu2O in Hexanes or Condensed Carbon Dioxide by tert-Butyl Peracetate and 1,1,1-Trifluoro-2,4-pentanedione

The oxidation and removal of copper(0) foil and copper(I) oxide (Cu2O) powder were studied in hexanes or condensed CO2 (at a constant density of 0.8 g/cm3) using excess tert-butyl peracetate (t-BuPA), as the oxidant, and excess 1,1,1-trifluoro-2,4-pentanedione (tfacH), as the chelating agent from 19 to 68 °C. Concentration and temperature effects were used to develop kinetic models. Under our conditions, independent of solvent choice, the reaction of Cu2O was first order with respect to t-BuPA and tfacH while for Cu(0) foil the reaction was independent of t-BuPA concentration and second order with respect to tfacH. The calculated effects of stir rate and reaction temperature on the mass transfer coefficient derived from a correlation for flow past a sphere were used to confirm that the reaction was kinetically controlled along with the fact that the reaction rates and orders were independent of stirring rate. Copper removal rates were calculated from the kinetic expressions (at 40 °C using 0.78 M tfacH and t-BuPA): copper from the foil was removed at 2.7 nm/min in hexanes and 140 nm/min in condensed CO2 while the Cu2O powder, based on initial surface area, was consumed at 120 nm/min in hexanes and 7.0 nm/min in condensed CO2. The Arrhenius expressions were determined by the temperature-dependent kinetics of the product, Cu(tfac)2, formation. While hexanes and condensed CO2 have similar solvent properties in many respects, the apparent activation energies, Ea, for Cu(0) foil were 88 kJ/mol in hexanes and 49 kJ/mol in CO2. The apparent Ea for Cu2O were 30 kJ/mol in hexanes and 53 kJ/mol in CO2. The differences in the activation energies are attributed to a complex combination of solvent properties and the energetics of the reacting species.

Supercritical-carbon dioxide-assisted cyclic deposition of metal oxide and metal thin films

Thin films of aluminum oxide and palladium were deposited on silicon at low temperatures (70–120°C) by a cyclic adsorption/reaction processes using supercritical CO2 solvent. Precursors included Al(hfac)3, Al(acac)3, and Pd(hfac)2, and aqueous H2O2, tert-butyl peracetate, and H2 were used as the oxidants or reductants. For the precursors studied, growth proceeds through a multilayer precursor adsorption in each deposition cycle, and film thickness increased linearly with the number of growth cycles.

Metal Oxide Thin Films Deposited from Metal Organic Precursors in Supercritical CO2 Solutions

This work demonstrates a novel method for deposition of metal oxide thin films, including Al2O3, ZrO2, MnOx, and RuOx where the metal−organic precursors and oxidizing agents are delivered in liquid and supercritical CO2. A cyclic deposition process is presented where reactants are introduced sequentially to control surface adsorption and byproduct removal steps. Reactions are studied in a hot wall reactor at pressures ranging from 1600 to 3600 psi at 80−200 °C, and X-ray photoelectron spectroscopy and infrared transmission confirmed metal oxide formation. We show that hydrogen peroxide is a viable O source for oxide deposition, whereas tert-butyl peracetate, which is a good electron acceptor, is less suited for oxygen donation. Capacitance versus voltage analysis of resulting Al2O3 films show good dielectric properties after post-deposition anneal. We believe that the good solvation properties of supercritical CO2 can aid in the delivery of precursors and in the removal of byproducts for advanced low-temp...

Electrode reaction mechanisms for the reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide

The reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide has been investigated at platinum and glassy carbon electrodes in DMF. It is known from the studies of Maran et al. that peroxides reduction mechanisms generally involve at first a slow electron transfer concerted with the scission of the peroxide bond. Then the radical produced at the electrode is immediately reduced, which leads to a two electrons consumption. Similar results were obtained in this study for tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide. Besides, the determination of the number of electrons involved in the reduction at different time scales gave a number of two for lauryl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate and di- tert-butyl peroxide and showed that this transfer is followed, in the case of tert-butyl peracetate, by a subsequent chemical reaction consuming a part of the substrate.

Oxidative Dissolution of Copper and Zinc Metal in Carbon Dioxide with tert-Butyl Peracetate and a β-Diketone Chelating Agent

A series of beta-diketone ligands, R(1)COCH(2)COR(2) [tmhdH (R(1) = R(2) = C(CH(3))(3)); tfacH (R(1) = CF(3); R(2) = CH(3)); hfacH (R(1) = R(2) = CF(3))], in combination with tert-butyl peracetate (t-BuPA), have been investigated as etchant solutions for dissolution of copper metal into carbon dioxide solvent. Copper removal in CO(2) increases in the order tfacH < tmhdH < hfacH. A study of the reactions of the hfacH/t-BuPA etchant solution with metallic copper and zinc was conducted in three solvents: scCO(2) (supercrical CO(2)); hexanes; CD(2)Cl(2). The etchant solution/metallic zinc reaction produced a diamagnetic Zn(II) complex, which allowed NMR identification of the t-BuPA decomposition products as tert-butyl alcohol and acetic acid. Gravimetric analysis of the amount of zinc consumed, together with NMR studies, confirmed the 1:1:2 Zn:t-BuPA:hfacH reaction stoichiometry, showing t-BuPA to be an overall two-electron oxidant for Zn(0). The metal-containing products of the copper and zinc reactions were characterized by elemental analysis, IR spectroscopy, and, as appropriate, NMR spectroscopy and single-crystal X-ray diffraction [trans-M(hfac)(2)(H(2)O)(CH(3)CO(2)H) (1, M = Cu; 2, M = Zn)]. On the basis of the experimental results, a working model of the oxidative dissolution reaction is proposed, which delineates the key chemical variables in the etching reaction. These t-BuPA/hfacH etchant solutions may find application in a CO(2)-based chemical mechanical planarization (CMP) process.

Intramolecular homolytic displacements. Part 22. Polar effects in the homolytic induced decompositions of allyl peroxides

The products of the decomposition of allyl peroxides 1–5, initiated by tert-butyl peracetate, in three solvents—cyclohexane, dimethyl malonate and benzene—were analysed. The formation of epoxides proved the existence of an homolytic induced decomposition of the unsaturated peroxides by a chain process involving a free radical addition to the double bond and an intramolecular homolytic substitution on the peroxide linkage. The balance of the reaction's products indicated a second way of degradation of the peroxides: allylic hydrogen abstraction followed by the breaking of the peroxide bond by β-elimination. The relative ratios of the products generated by the eliminated alkoxy radicals YO˙ and of the different epoxides produced in these reactions showed the influence of the polar factors in the various steps of the homolytic induced decomposition: i.e. hydrogen abstraction to the solvent or to the peroxide and addition to the double bond.

Synthesis of α,β-epoxyesters by homolytically induced decomposition of derivatives of ethyl 2-(1-hydroperoxyethyl)propenoate

Decomposition of small amounts of tert-butyl peracetate at 110 °C in benzene solutions of derivatives of ethyl 2-(1-hydroperoxyethyl)propenoate afforded α,β-epoxyesters in good yields.

Kinetics and mechanism of carbon-8 methylation of purine bases and nucleosides by methyl radical.

The kinetics of homolytic methylation of the model purine compound caffeine at carbon-8 were determined as a function of several reaction variables. The methyl radical was generated from tert-butyl peracetate (BPA) either thermally (65 to 95/sup 0/C) or photochemically (greater than 300 nm, 25/sup 0/C). The thermal reaction k (25/sup 0/C) was found to be 3.09 x 10/sup -8/ s/sup -1/ from the linear log k (pseudo-first-order) vs. l/T plot. The light reactions using the 450- and 1200-W mercury lamps proceeded with k (25/sup 0/C) 450- and 2160-fold greater, respectively. The derived activation energies are consistent with an S/sub E/Ar reaction. Increasing the concentration of caffeine from 0.25 M to 1.67 M in the presence of 3 molar equiv of BPA did not cause any side reaction. The pH-rate profile can be predicted by rate equations, which are derived on the basis of an electrophilic substitution occurring on the free base and conjugate acid of a heteroaromatic system. A competition study using tetrahydrofuran reveals the presence of a radical sigma complex IIIa and a charge transfer complex IIIb as intermediates for methylation under neutral and acidic conditions, respectively. Their rate-determining nature was indicated by the small positive kinetic isotope effectmore » and the inverse solvent isotope effects: k/sub H/sub 3/O/sup +///k/sub D/sub 3/O/sup +// = 0.87 and k/sub H/sub 2/O//k/sub D/sub 2/O/ = 0.32. Thus, in acidic medium, a preequilibrium proton transfer to form the caffeine conjugate acid precedes the rate-controlling formation of IIIb. In neutral solution, the rate-determining step appears to be the protonation of the radical nitrogen in IIIa converting it to III. The acid-catalyzed caffeine-BPA reaction was shown to be general for other purines such as adenine, adenosine, guanine, guanosine, hypoxanthine, and inosine.« less

Synthetic routes to nucieoside analogs of N-substituted 1-oxa-4-azacyclohexanes and 1-thia-4-azacyclohexanes. 13C nuclear magnetic resonance spectra of six-membered, cyclic amides

Nucleoside analogs, namely 6-chloro-9-(4-benzoyl-1-oxa-4-azacyclohexan-2-yl)-9H-purine 6 and 6-chloro-9-(4-benzoyl-1-thia-4-azacyclohexan-2-yl)-9H-purine 7, were obtained by treatment of 4-benzoyl-2-hydroxy-1-oxa-4-azacyclohexane 13 and 4-benzoyl-2-hydroxy-1-thia-4-azacyclohexane18, respectively, with 6-chloropurine, methyldiphenylphosphine, and diethyl azodicarboxylate in refluxing tetrahydrofuran. Compounds 13 and 18 were obtained by O-deacetylation of the corresponding 2-acetoxy derivatives 11 and 16 with a catalytic amount of sodium methoxide in chloroform. 2-Acetoxy-4-benzoyl-1-oxa-4-azacyclohexane 11 was obtained from 4-benzoyl-1-oxa-4-azacyclohexane 10 by treatment with tert-butyl peracetate, cuprous chloride, and benzene, whereas 2-acetoxy-4-benzoyl-1-thia-4-azacyclohexane 16 was prepared by a Pummerer reaction with 4-benzoyl-1-thia-4-azacyclohexane 1-oxide 15. The13C nmr spectra of all the compounds are reported; the spectra provided unambiguous proof of structure.

Secondary deuterium isotope effects in radical-forming reactions. V. tert-Butyl peracetate and substituted tert-butyl phenylperacetates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSecondary deuterium isotope effects in radical-forming reactions. V. tert-Butyl peracetate and substituted tert-butyl phenylperacetatesThomas W. Koenig, J. Huntington, and R. CruthoffCite this: J. Am. Chem. Soc. 1970, 92, 18, 5413–5418Publication Date (Print):September 1, 1970Publication History Published online1 May 2002Published inissue 1 September 1970https://doi.org/10.1021/ja00721a020RIGHTS & PERMISSIONSArticle Views50Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (722 KB) Get e-Alerts Get e-Alerts