Ion exchange resins as catalyst for the isomerization of α-pinene to camphene

Properties of Desilicated ZSM-5, ZSM-12, MCM-22 and ZSM-12/MCM-41 Derivatives in Isomerization of α-Pinene

“…Various acidic catalysts, such as oxides [2,3], oxides treated with acids [4], zeolites [5][6][7][8][9][10][11][12], mesoporous materials [12][13][14], activated clays [15][16][17][18][19], resins [20,21] and heteropolyacids [22], have been explored in isomerization of a-pinene. Currently, the acid-impregnated TiO 2 is used as an industrial catalyst for this purpose, but due to the low rate of the reaction, there is still a great interest in developing novel, viable contacts for the process.…”

Synthesis of Camphene by α-Pinene Isomerization Using W2O3–Al2O3 Catalysts

“…It has been reported that the selectivity to bicyclic and monocyclic products in presence of a solid catalyst is related to Brönsted and Lewis acid sites and their strength [13]. Severino et al [2] studying the a-pinene isomerization catalyzed by zeolites, established that Lewis acid sites, which are weaker than Brönsted acid sites, are beneficial for the formation of bicyclic compounds, whereas Brönsted sites are responsible for the production of monocyclic compounds.…”

ZrO2–SiO2 Mixed Oxides Xerogel and Aerogel as Solid Acid Catalysts for Solvent Free Isomerization of α-Pinene and Dehydration of 4-Methyl-2-Pentanol

“…It indicated that formation of camphene and limonene requires moderate acidity, whereas tricyclene and a-terpinene need higher acidity. The formation of various mono-, bi-and tricyclic products by the isomerization of a-pinene occurred through the carbocation formation by the interaction of the proton of the acid catalyst with the double bond of a-pinene [17]. It is reported that in the presence of high acidic conditions, camphene and isomeric bi-and tricyclic compounds are transformed to monocyclic compounds [17].…”

“…The formation of various mono-, bi-and tricyclic products by the isomerization of a-pinene occurred through the carbocation formation by the interaction of the proton of the acid catalyst with the double bond of a-pinene [17]. It is reported that in the presence of high acidic conditions, camphene and isomeric bi-and tricyclic compounds are transformed to monocyclic compounds [17]. This may be the reason that we found lower camphene selectivity with sulfated samples having higher acid site density compared to non-sulfated samples having lower acid site density.…”

“…a-pinene undergoes acid-catalyzed isomerization reaction resulting into valuable products such as camphene, limonene, mono-, bi-and tricyclic hydrocarbons, p-cymene, and oligomers [16]. Camphene is used in the production of camphor and limonene is widely employed in the synthesis of oxygenated compounds of perfumery industry [17]. The selectivity of various products strongly depends on the structural, textural and catalytic features of the catalyst along with the reaction conditions [18,19].…”