The solvent effect in β-pinene oxide rearrangement

Sulfonated Hyper‐cross‐linked Porous Polyacetylene Networks as Versatile Heterogeneous Acid Catalysts

“…The temperature programmed desorption (TPD) of pyridine was used to determine the surface acidity of P(1,4‐DEB)‐SO 3 H and P(1,3‐DEB)‐SO 3 H. Considering the results of TGA measurements, P(1,4‐DEB)‐SO 3 H and P(1,3‐DEB)‐SO 3 H were thermally pre‐treated at 160 °C (for 1 h). The saturation by pyridine was performed at the temperature of 150 °C . The pyridine desorption provided the following concentrations of the acid centres: 1.30 mmol ⋅ g −1 for P(1,4 ‐DEB)‐SO 3 H and 1.23 mmol ⋅ g −1 for P(1,3‐DEB)‐SO 3 H. As can be seen, the acid centre concentrations were virtually identical for both sulfonated networks.…”

“…A comparison of the concentration of the acid centres determined by the TPD method and the concentration of SO 3 H groups in P(1,4‐DEB)‐SO 3 H and P(1,3‐DEB)‐SO 3 H (2.7 mmol ⋅ g −1 by elemental analysis, see Table ) showed that about 45 % of the SO 3 H groups of the sulfonated networks were accessible for pyridine molecules. It should, however, be noted that P(1,4‐DEB)‐SO 3 H and P(1,3‐DEB)‐SO 3 H exhibited a higher concentration of acid centres than classical heterogeneous catalysts of the zeolite‐type . Due to the reduced thermal stability of P(1,4‐DEB)‐SO 3 H and P(1,3‐DEB)‐SO 3 H the desorption of pyridine (proceeding at temperature >150 °C) was accompanied by the decomposition of the sulfonated networks ( vide supra ).…”

New Sustainable Synthetic Routes to Cyclic Oxyterpenes Using the Ecocatalyst Toolbox

“…The synthesis of myrtenol 3 based on the opening of ß-pinene oxide 2 has not been extensively reported in the literature. Indeed, myrtenol 3 is mostly considered a side-product of the formation of perillyl alcohol 5 by the action of a Brønsted acid on ß-pinene oxide 2 [ 24 , 25 , 26 , 27 ]. Several Brønsted acid catalysts were tested to favour the formation of myrtenol 3 instead of perillyl alcohol 5 ( Table 4 ).…”

“…The selective epoxidation of ß-pinene is challenging because of the tensions of the pinane ring system and the exo position of the double bond on the one hand, and the high reactivity of the corresponding epoxide on the other hand [ 24 ]. Thus, the oxidation of β-pinene can lead to several oxidation products, including epoxy, [ 25 ] which can itself rearrange into several by-products [ 26 , 27 , 28 ]. Indeed, β-pinene oxide is very reactive due to the many steric constraints imposed by the three rings.…”

Selective Catalytic Isomerization of β‐Pinene Oxide to Perillyl Alcohol Enhanced by Protic Tetraimidazolium Nitrate

“…In general, perillyl alcohol occurs as a byproduct of the isomerization of β-pinene oxide to myrtenol. Despite its antibacterial importance, only a few reports [7,8] have investigated the selective synthesis of perillyl alcohol from βpinene oxide. The highest reported yield of perillyl alcohol in the isomerization of β-pinene oxide over solid acid catalysts is 66 %, but achieving this yield takes a long time.…”