927-07-1Relevant articles and documents
Continuous synthesis of tert-butyl peroxypivalate using a single-channel microreactor equipped with orifices as emulsification units
Illg, Tobias,Hessel, Volker,L?b, Patrick,Schouten, Jaap C.
, p. 392 - 398 (2011)
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).
Bu4NI-Catalyzed, Radical-Induced Regioselective N-Alkylations and Arylations of Tetrazoles Using Organic Peroxides/Peresters
Ghosh, Subhendu,Mir, Bilal Ahmad,Patel, Bhisma K.,Rajamanickam, Suresh,Sah, Chitranjan,Sethi, Garima,Venkataramani, Sugumar,Yadav, Vinita
, p. 2118 - 2141 (2020/03/13)
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.
Iron-Catalyzed Vinylic C?H Alkylation with Alkyl Peroxides
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)
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.
