- Continuous synthesis of tert-butyl peroxypivalate using a single-channel microreactor equipped with orifices as emulsification units
-
The two-step synthesis of tert-butyl peroxypivalate is performed in a single-channel microreactor. The first step, the deprotonation of tert-butyl hydroperoxide, is done in a simple mixer tube setup. The residence time section for the second reaction step is equipped with orifices for interfacial area renewal, needed for ensuring mass transfer between the two immiscible phases. The strong dependence of the reaction performance on the size of the interfacial area is demonstrated by using a setup with 4 orifices (distance of 52 cm), giving a HPLC yield of 71% at a residence time of 8 s and a reaction temperature of 23°C. A further shortening of orifice distances helped to shorten the residence time down to 1.5 s and 0.5 s (using 9 orifices and 3 orifices with a distance of 5 cm). When using these setups, the produced heat could not be removed from the system sufficiently quickly (δT=38 K). The achieved yields (ca. 70% by HPLC) are close to the state of the art (cascaded batch processing) and provide an indication that the tert-butyl peroxypivalate synthesis can be performed at higher temperatures or at least, a more flexible process control can be allowed compared to high-volume batch reactors. Processing at higher reaction temperatures up to 70 °C shows a slight optimum at reaction temperatures between 40°C to 50 , depending on the setup used. Knowing this novel process window as well as the optimum orifice geometry and distance will allow for tailored design of the microreactor. For the processing in the single-channel microreactor setup using 9 orifices (distance of 5 cm) and a reaction temperature of 40 °C a space-time-yield of 420 000 gL-1h-1 was reached which is higher than the space-time-yield for the industrial 3 cascaded batch reactor process (190 gL-1h-1).
- Illg, Tobias,Hessel, Volker,L?b, Patrick,Schouten, Jaap C.
-
-
Read Online
- Stereoselective Alkylation of Chiral Titanium(IV) Enolates with tert-Butyl Peresters
-
Here, we present a new stereoselective alkylation of titanium(IV) enolates of chiral N-acyl oxazolidinones with tert-butyl peresters from Cα-branched aliphatic carboxylic acids, which proceeds through the decarboxylation of the peresters and the subsequent formation of alkyl radicals to produce the alkylated adducts with an excellent diastereoselectivity. Theoretical calculations account for the observed reactivity and the outstanding stereocontrol. Importantly, the resultant compounds can be easily converted into ligands for asymmetric and catalytic transformations.
- Pérez-Palau, Marina,Sanosa, Nil,Romea, Pedro,Urpí, Fèlix,López, Rosa,Gómez-Bengoa, Enrique,Font-Bardia, Mercè
-
supporting information
p. 8852 - 8856
(2021/11/17)
-
- Bu4NI-Catalyzed, Radical-Induced Regioselective N-Alkylations and Arylations of Tetrazoles Using Organic Peroxides/Peresters
-
Bu4NI-catalyzed regioselective N2-methylation, N2-Alkylation, and N2-Arylation of tetrazoles have been achieved using tert-butyl hydroperoxide (TBHP) as the methyl source, alkyl diacyl peroxides as the primary alkyl source, alkyl peresters as the secondary and tertiary alkyl sources, and aryl diacyl peroxides as the arylating source. These reactions proceed without pre-functionalization of tetrazole and in the absence of any metal catalysts. Here, peroxides serve the dual role of oxidants as well as alkylating or arylating agents. Based on DFT calculations, it was found that spin density, transition-state barriers (kinetic control), and thermodynamic stability of the products (thermodynamic control) play essential roles in the observed regioselectivity during N-Alkylation. This radical-mediated process is amenable to a broad range of substrates and provides products in moderate to good yields.
- Ghosh, Subhendu,Mir, Bilal Ahmad,Patel, Bhisma K.,Rajamanickam, Suresh,Sah, Chitranjan,Sethi, Garima,Venkataramani, Sugumar,Yadav, Vinita
-
p. 2118 - 2141
(2020/03/13)
-
- Decarboxylative Borylation of mCPBA-Activated Aliphatic Acids
-
A decarboxylative borylation of aliphatic acids for the synthesis of a variety of alkylboronates has been developed by mixing m-chloroperoxybenzoic acid (mCPBA)-activated fatty acids with bis(catecholato)diboron in N,N-dimethylformamide (DMF) at room temperature. A radical chain process is involved in the reaction which initiates from the B-B bond homolysis followed by the radical transfer from the boron atom to the carbon atom with subsequent decarboxylation and borylation.
- Wei, Dian,Liu, Tu-Ming,Zhou, Bo,Han, Bing
-
supporting information
p. 234 - 238
(2020/01/02)
-
- Iron-Catalyzed Vinylic C?H Alkylation with Alkyl Peroxides
-
A variety of alkyl peresters and alkyl diacyl peroxides, which are readily accessible from carboxylic acids, are utilized as general primary, secondary, and tertiary alkylating reagents for iron-catalyzed vinylic C?H alkylation of vinyl arenes, dienes, and 1,3-enynes. This transformation affords olefinic products in up to 98 % yield with high E/Z values. A broad range of functionalities, including carboxyl, boronic acid, methoxy, ester, amino, and halides, are tolerated. This protocol provides a facile approach to some olefins that are difficult to access, and hence, offers an alternative to existing systems. The synthetic utility of this method is demonstrated by late-stage functionalization of selected natural-product derivatives.
- Ge, Liang,Jian, Wujun,Zhou, Huan,Chen, Shaowei,Ye, Changqing,Yu, Fei,Qian, Bo,Li, Yajun,Bao, Hongli
-
supporting information
p. 2522 - 2528
(2018/08/01)
-
- Iron-Catalyzed Dehydrative Alkylation of Propargyl Alcohol with Alkyl Peroxides to Form Substituted 1,3-Enynes
-
This paper reports a new method for the generation of substituted 1,3-enynes, whose synthesis by other methods could be a challenge. The dehydrative decarboxylative cascade coupling reaction of propargyl alcohol with alkyl peroxides is enabled by an iron catalyst and alkylating reagents. Primary, secondary, and tertiary alkyl groups can be introduced into 1,3-enynes, affording various substituted 1,3-enynes in moderate to good yields. Mechanistic studies suggest the involvement of a radical-polar crossover pathway.
- Ye, Changqing,Qian, Bo,Li, Yajun,Su, Min,Li, Daliang,Bao, Hongli
-
supporting information
p. 3202 - 3205
(2018/06/11)
-
- Iron-catalyzed C-H alkylation of heterocyclic C-H bonds
-
An efficient, iron-catalyzed C-H alkylation of benzothiazoles by using alkyl diacyl peroxides and alkyl tertbutyl peresters which are readily accessible from carboxylic acids to synthesize 2-alkylbenzothiazoles is developed. This reaction is environmentally benign and compatible with a broad range of functional groups. Various primary, secondary, and tertiary alkyl groups can be efficiently incorporated into diverse benzothiazoles. The effectiveness of this method is illustrated by late-stage functionalization of biologically active heterocycles.
- Babu, Kaki Raveendra,Zhu, Nengbo,Bao, Hongli
-
supporting information
p. 46 - 49
(2017/11/28)
-
- Aminopyridine-Borane Complexes as Hydrogen Atom Donor Reagents: Reaction Mechanism and Substrate Selectivity
-
Lewis base-borane complexes are shown to be potent hydrogen atom donors in radical chain reduction reactions. Results obtained in 1H, 11B, and 13C NMR measurements and kinetic experiments support a complex reaction mechanism involving the parent borane as well as its initial reaction products as active hydrogen atom donors. Efficient reduction reactions of iodides, bromides, and xanthates in apolar solvents rely on initiator systems generating oxygen-centered radicals under thermal conditions and pyridine-borane complexes carrying solubilizing substituents. In contrast to tin hydride reagents, the pyridine-boranes reduce xanthates faster than the corresponding iodides.
- Barth, Florian,Achrainer, Florian,Pütz, Alexander M.,Zipse, Hendrik
-
supporting information
p. 13455 - 13464
(2017/10/05)
-
- Method for producing acyl peroxides
-
The invention relates to a method for producing acyl peroxides. According to said method, an acyl compound is reacted with an organic hydroperoxide and a base, the pH of the two-phase mixture so obtained is adjusted to 6 to 13, the obtained organic phase is extracted with an aqueous solution of a base and the aqueous extract is recirculated to the reaction step. The method according to the invention allows the recirculation of unreacted hydroperoxide to the reaction step.
- -
-
Page/Page column 4
(2010/02/17)
-
- METHOD FOR THE PRODUCTION OF ORGANIC PEROXIDES BY MEANS OF A MICROREACTION TECHNIQUE
-
The invention provides a process for efficient and reliable preparation of organic peroxides, preferably dialkyl peroxides, peroxycarboxylic acids, peroxycarboxylic esters, diacyl peroxides, peroxycarbonate esters, peroxydicarbonates, ketone peroxides and perketals with the aid of at least one static micromixer and an apparatus for performing the process.
- -
-
Page/Page column 6-7
(2009/03/07)
-
- Process for the preparation of a tertiary perester
-
The invention relates to a process for the preparation of a tertiary perester by contacting an acyl compound with a tertiary hydroperoxide in the presence of an enzyme catalyst. The acyl compound has the formula R1[C(O)OR2]n, wherein R1is a linear or branched, saturated or unsaturated C1-C22group, optionally containing one or more hetero atoms, R2represents hydrogen or has the same meaning as described for R1, and n is 1-5, or a polyalcohol ester of R1C(O)OH, wherein R1has the same meaning as described above. The tertiary hydroperoxide has the formula [HOOCR3R3]mR4, wherein R3represents either a methyl or an ethyl group, R4has the same meaning as described for R1, and m is 1-5.
- -
-
-
- Thermal decomposition mechanisms of tert-alkyl peroxypivalates studied by the nitroxide radical trapping technique
-
The thermolysis of a series of tert-alkyl peroxypivalates 1 in cumene has been investigated by using the nitroxide radical-trapping technique. tert-Alkoxyl radicals generated from the thermolysis underwent the unimolecular reactions, β-scission, and 1,5-H shift, competing with hydrogen abstraction from cumene. The absolute rate constants for β-scission of tert- alkoxyl radicals, which vary over 4 orders of magnitude, indicate the vastly different behavior of alkoxyl radicals. However, the radical generation efficiencies of 1 varied only slightly, from 53 (R = Me) to 63% (R = Bu(t)), supporting a mechanism involving concerted two-bond scission within the solvent cage to generate the tert-butyl radical, CO2, and an alkoxyl radical. The thermolysis rate constants of tert-alkyl peroxypivalates 1 were influenced by both inductive and steric effects [Taft-Ingold equation, log(rel k(d)) = (0.97 ± 0.14)Σσ* - (0.31 ± 0.04)ΣE(s)(c), was obtained].
- Nakamura,Busfield,Jenkins,Rizzardo,Thang,Suyama
-
-
- D-Galactofuranosylphosphonates. First Synthesis of UDP-C-D-galactofuranose
-
The chemical synthesis of two phosphono analogues of D-galactofuranosyl phosphate was performed. The natural phosphate seemed to be too labile to allow the chemical synthesis of UDP-Galf, these C-galactofuranosides are stable pharmacophores, and the α-phosphono analogue has been easily converted into UDP-C-Galf. UDP-C-Galf was tested as a competitive inhibitor of UDP-galactopyranose mutase and showed inhibition of Galf formation. Thus, it is of potential interest as an antimycobacterial agent; as an active molecule against Trypanosoma cruzi, the causative agent of South American trypanosomiasis (Chagas' disease), and as a stable analogue for use in UDP-galactopyranose mutase crystallization studies.
- Kovensky, Jose,McNeil, Michael,Sinay, Pierre
-
p. 6202 - 6205
(2007/10/03)
-
- Initiation mechanisms for radical polymerization of methyl methacrylate with tert-butyl peroxypivalate
-
The reaction of tert-butyl peroxypivalate (2) with methyl methacrylate (3) has been studied by the radical trapping technique employing 1,1,3,3-tetramethyl-2,3-dihydro-1H-isoindol-2-yloxyl (1) as a scavenger. Thermolysis of 2 generated tert-butoxyl, tert-butyl, and methyl radicals in the ratios of 48:50:2 at 60 °C in 3. Both alkyl radicals underwent selective tail addition to 3. tert-Butyl radicals reacted about twice as fast as methyl radicals with 3. The absolute rate constant for addition of tert-butyl radicals to 3 was estimated to be 2.3 x 106 M-1 s-1 at 60 °C. The overall ratio of addition to H abstraction in the reaction of 2 with 3 was 5:1.
- Nakamura, Tomoyuki,Busfield, W. Ken,Jenkins, Ian D.,Rizzardo, Ezio,Thang, San H.,Suyama, Shuji
-
p. 10824 - 10828
(2007/10/03)
-
- The Influence of Steric Constraints on the Conformational Properties and on the 17O NMR Shielding of ortho-Substituted Perbenzoates
-
The 17O chemical shifts and band widths for tert-butyl peresters of ortho-substituted benzoic acids have been measured in benzene solution.Two signals are observed, of different line-width, and that at higher field is broader.The two signals shift to lower field with an increase in the number and size of ortho substituents (methyl and tert-butyl groups were chosen), and the signal at lower field is the one more significantly affected.Correlations with a fair degree of linearity are found for each set of chemical shifts with the twist angle of the carbonyl group from the phenyl plane.Twist angles were calculated from molecular mechanics.From the screening constants estimated theoretically at a semi-empirical level with the Karplus-Pople formula and from line-width arguments based on quadrupole relaxation, it is possible to advance the reasonable conclusion that the signal at lower field of these molecules represents two oxygen nuclei and the other the remaining peroxidic oxygen.For the 2,4,6-tri-But derivative which is solid at room temperature and can be obtained in a suitable crystal form, the crystal and molecular structure has been determined by X-ray diffraction.The structure is built up of one crystallographically independent molecule, affected by statistical disorder due to two alternative orientations of all the tert-butyl groups bonded to the ring.The peroxycarboxyl group is planar and nearly perpendicular (80.8) to the benzene ring plane.
- Antolini, Luciano,Benassi, Rois,Ghelli, Stefano,Folli, Ugo,Sbardellati, Silvia,Taddei, Ferdinando
-
p. 1907 - 1913
(2007/10/02)
-
- Homolytic Decomposition of t-Alkyl 2,2-Dimethylperoxypropionates
-
Decomposition rates and products of t-alkyl 2,2-dimethylperoxypropionates were measured in cumene at several temperatures.The peroxyesters decomposed homolitycally, depending on the structure of the t-alkyl moiety.The relative rates of the t-alkyl moieties to the 1,1-dimethylethyl one were: 1,1-dimethylbutyl (1.14), 1,1-dimethylpropyl (1.19), 1,1,2-trimethylpropyl (1.85), 1,1,3,3-tetramethylbutyl (2.10), and 1,1-dimethyl-2-phenylethyl (2.34).The decomposition showed an isokinetic relationship and the importance of stabilization by hyperconjugation.Based on these data, the decomposition mechanism, which contains a slight stretching of the Cα-Cβ bond to the peroxyl oxygen at the transition state is, discussed.
- Komai, Takeshi,Matsuyama, Kazuo,Matsushima, Masaru
-
p. 1641 - 1646
(2007/10/02)
-
- Batch process for manufacturing and purifying liquid organic peroxide by distillation
-
A batch process for the manufacture of liquid organic peroxides, such as peroxy esters and diacyl peroxides, by reacting an acid chloride, a hydroperoxide and an alkali metal hydroxide uses a countercurrent, packed distillation column for recovering a purer, drier product with higher yield than previous batch drying processes.
- -
-
-
