25571-13-5Relevant academic research and scientific papers
Monoterpenes etherification reactions with alkyl alcohols over cesium partially exchanged Keggin heteropoly salts: effects of catalyst composition
da Silva, Márcio José,Lopes, Neide Paloma Goncalves,Ferreira, Sukarno Olavo,da Silva, Rene Chagas,Natalino, Ricardo,Chaves, Diego Morais,Texeira, Milena Galdino
, p. 153 - 168 (2020/07/21)
In this work, cesium partially exchanged Keggin heteropolyacid (HPA) salts were prepared, characterized, and evaluated as solid catalysts in monoterpenes etherification reactions with alkyl alcohols. A comparison of the activity of soluble HPAs and their insoluble cesium salts showed that among three different Keggin anions the phosphotungstate was the most efficient catalyst. Assessments on the effects of the level of the protons exchange by cesium cations demonstrated that Cs2.5H0.5PW12O40 solid salt was the most active and selective phosphotungstate catalyst, converting β-pinene to α-terpinyl methyl ether. The influences of the main reaction parameters such as reaction temperature, time, catalyst load, substrate nature (i.e., alcohols and monoterpenes) were investigated. We have demonstrated that the simultaneous presence of the cesium ions and protons in the catalyst plays an essential role, being the 2.5–0.5 the optimum molar ratio. The Cs2.5H0.5PW12O40 salt was efficiently recovered and reused without loss of catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
Exploring the Keggin-Type Heteropolyacid-Catalyzed Reaction Pathways of the Β-Pinene with Alkyl Alcohols
Polo, Henrique Priori,Lopes, Neide Paloma Goncalves,da Silva, Márcio José
, p. 2844 - 2853 (2019/05/28)
Abstract: In this work, we investigated the activity of Keggin heteropolyacid catalysts (i.e., H3PW12O40, H3PMo12O40 and H4SiW12O40) in β-pinene reactions with alkyl alcohols (i.e. methyl, ethyl, propyl, sec-propyl, butyl and sec-butyl alcohols), and exploring the different aspects that drive the selectivity of this process. We have found that carbon skeletal rearrangements and isomerization providing intermediate carbocations that controlling the reaction selectivity. β-pinene was preferentially converted to α-terpinyl ion which undergoes a nucleophilic attack of alcohol providing alkyl alcohol. Bornyl ion was converted to bornyl and fenchyl ethers. The other secondary products were β-pinene isomers obtained from bornyl and α-terpinyl carbocations. Phosphotungstic acid (i.e., H3PW12O40) was the most active catalyst and selective toward the main product (α-terpinyl alkyl ether); the highest conversion (ca. 96%) and ether selectivity (ca. 61%) was achieved in the reactions with β-pinene. Although having also been alkoxylate, α-pinene was less reactive (ca. 40%), while camphene and limonene remained unreactive under reaction conditions studied. An increase of temperature resulted in an improvement on conversion of β-pinene and selectivity toward α-terpinyl methyl ether. Similarly, the H3PW12O40 concentration played a crucial role on reaction selectivity. This work presents positive features such as a short reaction time, high atom economy, mild reaction conditions (i.e., low temperature and room pressure). Even though soluble the catalyst was easily recovered by liquid -liquid extraction and efficiently reused. Graphical Abstract: [Figure not available: see fulltext.].
Fe(III)-catalyzed α-terpinyl derivatives synthesis from β-pinene via reactions with hydrogen peroxide in alcoholic solutions
Da Silva,Carari,Manoel Da Silva, Adalberto
, p. 10529 - 10536 (2015/01/30)
In this study, a novel and environmentally benign Fe(iii)-catalyzed terpinyl derivatives synthesis using hydrogen peroxide in alcohol solutions (i.e. methyl, ethyl, propyl, isopropyl and butyl alcohols) was investigated. The use of Bronsted acid catalysts was avoided and β-pinene was used as the starting reactant. High conversions (ca. 90%) and combined selectivities for the α-terpineol and terpinyl alkyl ethers (ca. 70-73%) were obtained when Fe(NO3)3 was used as the catalyst. The role of each component catalyst system was studied with special focus on the solvent. The use of a biodegradable and renewable origin solvent (ethyl alcohol), which was added to an inexpensive and mildly toxic catalyst and a green oxidant are the main positive features of this process.
Hydroalkoxylation of non-activated olefins catalysed by Lewis superacids in alcoholic solvents: an eco-friendly reaction
Lemechko, Pierre,Grau, Fanny,Antoniotti, Sylvain,Du?ach, Elisabet
, p. 5731 - 5734 (2008/02/09)
Lewis superacids such as tin(IV) triflate catalyse the intermolecular addition of primary alcohols to non-activated olefins under mild conditions.
SOLVOLYTIC DISPLACEMENT OF ALKYL HALIDES BY METAL SALTS. PREPARATIVE PROCEDURES FOR ALLYL-, BENZYL- AND TERTIARY ALKYL-OXY DERIVATIVES USING THE ZINC SALTS
Gurudutt, K. N.,Ravindranath, B.,Srinivas, P.
, p. 1843 - 1846 (2007/10/02)
Reaction of allylic, benzylic and tertiary alkyl halides with zinc oxide in protic solvents leads to the formation of the corresponding alcohols, ethers and esters in good yields.The scope and limitations of this reaction have been examined.The possible involvement of ion quadruplets in the reaction is suggested.
Cyclobutane Ring Opening of Pin-2(10)-ene with Mercury(II) Salts. A New, High-yield Synthesis of p-Mentha-1,8-dien-7-ol
Bluthe, Norbert,Ecoto, Jules,Fetizon, Marcel,Lazare, Sylvain
, p. 1747 - 1751 (2007/10/02)
The nucleophilic attack of pin-2(10)-ene-mercury(II) complex systems by water results in the opening of the four-membered ring leading to an allylic organomercury(II) derivative (11) with the p-menthane skeleton.This intermediate can be reduced by hydride to p-menth-1(2)-en-8-ol (6a) or can undergo an in situ SE2' elimination yielding p-menth-1(7)-en-8-ol (9a), in high yields. (-)-2,10-Epoxypinane (15) reacts with mercury(II) salts at room temperature, giving the diol (16) in a quantitative yield.Compound (16) is a suitable intermediate for convenient preparation of p-mentha-1,8-dien-7-ol (17) and its derivatives.
