Esterification of camphene over heterogeneous heteropoly acid catalysts: Synthesis of isobornyl carboxylates

Activities of Heterogeneous Acid-Base Catalysts for Fragrances Synthesis: A Review

“…Silica-supported H3PW12O40 (PW) was also used as a solid acid catalyst for the liquid-phase esterification of camphene [14]. The results on camphene (9) esterification with acetic acid (5-10 fold excess) in the presence of PW/SiO2 in cyclohexane solution at 40-80 o C have been reported.…”

“…The reaction occurred with 100% selectivity to isobornyl acetate (10), with no other products being observed. The application of H3PW12O40 (PW), the strongest HPA in the Keggin series was used as the catalyst for the liquid-phase acetoxylation of β-caryophyllene in homogeneous and heterogeneous systems for producing of βcaryolanyl acetate (14) and β-caryolanol (15) (Scheme 7). β-caryophyllene is one of the most abundant sesquiterpenes found in many essential oils.…”

One-pot synthesis at room temperature of epoxides and linalool derivative pyrans in monolacunary Na7PW11O39-catalyzed oxidation reactions by hydrogen peroxide

“…However, they are strong Brønsted acids, a feature that compromises their use as a catalyst in oxidations of monoterpenes, which are substrates susceptible to acid-catalyzed concurrent reactions such as carbon skeletal rearrangement and nucleophilic addition. 18,19 To circumvent this drawback, a rarely explored approach is to convert Keggin HPAs to neutral salts, exchanging their acidic protons by metal cations. 20,21 Moreover, the removal of one MO unit of heteropolyanions (i.e., WO or MoO) results in a lacunar salt catalyst that may be more active than its precursor with saturated anion.…”

Heteropoly acid catalyzed cyclization of nerolidol and farnesol: Synthesis of α-bisabolol

“…Previously, we have applied HPA catalysts in a variety of liquidphase reactions of terpenic compounds, such as isomerization [28][29][30][31][32], hydration, etherification and esterification [33][34][35], and cycloaddition [36]. Within our program on the valorization of natural ingredients of essential oils by catalytic transformations, we report now the application of tungstophosphoric heteropoly acid H 3 PW 12 O 40 (HPW), the strongest HPA in the Keggin series, as a homogeneous catalyst for the isomerization of nerolidol (1) and farnesol (2) aiming to obtain ␣-bisabolol (3).…”