- Merging Halogen-Atom Transfer (XAT) and Copper Catalysis for the Modular Suzuki-Miyaura-Type Cross-Coupling of Alkyl Iodides and Organoborons
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We report here a mechanistically distinct approach to achieve Suzuki-Miyaura-type cross-couplings between alkyl iodides and aryl organoborons. This process requires a copper catalyst but, in contrast with previous approaches based on palladium and nickel
- Górski, Bartosz,Leonori, Daniele,Zhang, Zhenhua
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supporting information
(2022/02/01)
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- Determination of silyl peroxides by ultra-performance liquid chromatography/electrospray ionisation mass spectrometry
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Rationale: Residual initiators in polymers are a concern in the case of products that come directly into contact with the human body or food. Due to low concentrations and difficulties in the sample preparation, highly sensitive and selective methods are required. Methods: A series of bis-silyl- and alkyl-silyl peroxides were analysed by electrospray ionisation mass spectrometry (ESI-MS) on an ultra-performance liquid chromatography/time-of-flight (UPLC/TOF) instrument. Li, Na, K, and NH4 acetates were used to promote the formation of [M + Me]+ ions. The sample preparation involved only dissolution of the polymer sample in 0.1 mL of acetonitrile, followed by precipitation with 1 mL of water. A portion of 0.1–1 μL of the solution was then analysed without further treatment by UPLC/ESI-MS. Results: Limits of detection (LODs) were in the range of 0.06–9 pmol, depending on the peroxide structure. On average, the signal intensity increased with the number of phenyl groups in a peroxide and decreased in the order Na > Li > K > NH4. Peroxides that did not contain phenyl groups could not be detected. Collision-induced dissociation experiments can be used for structural investigations of alkyl-silyl peroxides. It was possible to detect 2 × 10?4% (LOD = 7 × 10?5%) of unreacted Ph3SiOOt-Bu in the poly(methyl methacrylate) sample. Conclusions: The method is suitable for the analysis of trace peroxide initiators in polymers and for other purposes where LODs in the pmol range are required.
- Krawczyk, Tomasz,Zalewski, Mariusz,Szo?tysik, Rafa?,Korytkowska-Wa?ach, Anna
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p. 2040 - 2046
(2018/11/10)
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