Greener Synthesis of Pristane by Flow Dehydrative Hydrogenation of Allylic Alcohol Using a Packed-Bed Reactor Charged by Pd/C as a Single Catalyst

Abstract

Our previous work established a continuous-flow synthesis of pristane, which is a saturated branched alkane obtained from a Basking Shark. The dehydration of an allylic alcohol that is the key to a tetraene was carried out using a packed-bed reactor charged by an acid–silica catalyst (HO-SAS) and flow hydrogenation using molecular hydrogen via a Pd/C catalyst followed. The present work relies on the additional propensity of Pd/C to serve as an acid catalyst, which allows us to perform a flow synthesis of pristane from the aforementioned key allylic alcohol in the presence of molecular hydrogen using Pd/C as a single catalyst, which is applied to both dehydration and hydrogenation. The present one-column-two-reaction-flow system could eliminate the use of an acid catalyst such as HO-SAS and lead to a significant simplification of the production process.

Pictorial Mechanistic Views on the Chemical History of Withaferin A: The Structural Determination of the Side Chain, the Organic Chemistry Notebook Series, a Didactical Approach, Nº 16

“…19). Electronic Impact Mass Spectrometry analysis EIMS assays were performed on Withaferin A (1), dihydridesoxywithaferin A (4) and dihydridesoxywithaferin A monoacetate (6), the results confirmed the structural elucidation discussed previously [2] and analyzed in the present paper.…”

“…Compound 5 was submitted to ozonolysis following the same procedure than 6 [cf. Ozonolysis of dihydrodesoxywithaferin A acetate (6)] [2]. The product obtained was similar to that from the ozonolysis of 6, see Fig.…”

“…The proposed mechanism for this reaction is shown in Fig. 4 [6]. The authors mentioned regarding the composition of the side chain of 1 the following after the third hydrogenation:…”