1068-55-9Relevant articles and documents
Absolute kinetic rate constants and activation energies for the formation of Grignard reagents
Beals, Bridget J.,Bello, Zainab I.,Cuddihy, Kathleen P.,Healy, Ethan M.,Koon-Church, Stephanie E.,Owens, Jane M.,Teerlinck, Cynthia E.,Bowyer, Walter J.
, p. 498 - 503 (2002)
This paper reports the first absolute rate constants for the formation of Grignard reagents from magnesium metal and organohalides. The theory that allows calculation of heterogeneous rate constants from the rate of growth of individual pits is described. By monitoring the reaction of individual reactive sites on the magnesium surface using photomicrography, it is possible to determine the rate of reaction and the active surface area; rate constants then are calculated from those data. Rate constants are on the order of 10-4 cm/s and vary relatively little between various organohalides. By measuring rate constants over a range of temperatures, Arrhenius parameters are determined for the reaction. The magnitudes of the enthalpic and entropic barriers are not consistent with electron transfer as the rate-limiting step. Rather, the data suggest that the rate-limiting step is reaction of the organohalide at the magnesium surface with partial insertion of a magnesium atom into the carbon-halide bond in the transition state.
Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides
Adamo, Andrea,Berton, Mateo,McQuade, D. Tyler,Sheehan, Kevin
supporting information, p. 1343 - 1356 (2020/07/10)
Magnesium organometallic reagents occupy a central position in organic synthesis. The freshness of these compounds is the key for achieving a high conversion and reproducible results. Common methods for the synthesis of Grignard reagents from metallic magnesium present safety issues and exhibit a batch-to-batch variability. Tubular reactors of solid reagents combined with solution-phase reagents enable the continuous-flow preparation of organomagnesium reagents. The use of stratified packed-bed columns of magnesium metal and lithium chloride for the synthesis of highly concentrated turbo Grignards is reported. A low-cost pod-style synthesizer prototype, which incorporates single-use prepacked perfluorinated cartridges and bags of reagents for the automated on-demand lab-scale synthesis of carbon, nitrogen, and oxygen turbo magnesium bases is presented. This concept will provide access to fresh organomagnesium reagents on a discovery scale and will do so independent from the operator’s experience in flow and/or organometallic chemistry.
Ledipasvir key intermediate and preparation method thereof
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Paragraph 0040-0043; 0065; 0086, (2018/04/26)
The invention discloses a ledipasvir key intermediate LD-J, a structure of the ledipasvir key intermediate LD-J and a preparation method of the ledipasvir key intermediate LD-J. The preparation methodcomprises the following steps: (A1) preparing LD-G; (A2) preparing LD-H; (A3) preparing LD-I; (A4) preparing a Grignard reagent; and (A5) preparing LD-J. The ledipasvir key intermediate LD-J and thepreparation method thereof have the advantages that the process is mature and stable, the product is stable in quality, the production process is safe and reliable, and the preparation method is suitable for industrial production.
