Conversion Of Β-pinene Research Articles

Discovering Circular Process Solutions through Automated Reaction Network Optimization

The transition toward a circular and biobased chemical industry is needed to cut global CO2 emissions and limit the chemical industry’s overall impact on the environment. However, the development of circular chemical reaction systems is challenging as it requires symbiotic sets of novel chemical reaction pathways and involves unconventional processing steps. We present a methodological pipeline for automated reaction network optimization. The tools can guide the development of circular processes on the reaction pathway level. Chemical big data combined with energetic assessment metrics and state-of-the-art decision-making has the potential to efficiently identify the most promising reaction systems. We mine large-scale chemical reaction data from Reaxys database and automate the screening of pathways based on chemical rules. We then approximate thermodynamic properties for exergy calculations of the prescreened pathways and formulate the optimization problem as linear programming and mixed-integer linear programming problem. The methodological workflow is illustrated in a case study on the conversion of β-pinene to citral. Our results show that the tools are well suited to model circular process interactions within different environment scenarios.

Metabolic conversion of β-pinene to β-ionone in rats

Exposure to or ingestion of turpentine can alter the scent of urine, conferring it a flowery, violet-like scent. Turpentine’s effect on urine was initially noticed after its use either as medicine or as a preservative in winemaking. Regardless of the source of exposure, the phenomenon requires metabolic conversion of turpentine component(s) to ionone, the molecule mainly responsible for the scent of violets. The purpose of this study was to identify the presence of ionone in the urine of rats that received β-pinene, and thus to demonstrate that the postulated conversion occurs. We treated rats intraperitoneally with normal saline (negative control), β-ionone (positive control), low-dose β-pinene (1/3 of LD50), and high-dose β-pinene (1/2 of LD50). Urine samples were collected up to 72 h after administration of the compounds, followed by gas chromatography/mass spectrometry identification of the presence of ionone. β-Ionone was found in the urine of rats exposed to both low and high doses of β-pinene. In contrast, α-ionone appears unlikely to have been formed in rats exposed to either low or high doses of β-pinene. β-pinene was converted to β-ionone, followed by partial excretion in the urine of rats. β-Ionone is a minor metabolite of β-pinene.

Epoxidation of β-pinene with a highly-active and low-cost catalyst

As β-pinene is one of the main compounds of turpentine oil, its epoxidation is of academic and industrial interest. In the present work, the activity of a low-cost calcium material and magnesium oxide was compared with that of hydrotalcites for the catalytic epoxidation of β-pinene. FTIR, XRD, nitrogen adsorption/desorption isotherms, BET and TPD-CO2 analyses were used for identifying the influence of basicity and textural properties of the materials on β-pinene epoxidation. Materials with medium-strength basic sites showed the highest activity; a complete conversion of β-pinene and 74% selectivity towards β-pinene epoxide was reached over magnesium oxide. A mechanism for this reaction over magnesium oxide is proposed based on the deprotonation and hydration of the catalyst, which favored the formation of an intermediate oxidant and the activation of the substrate. Purification of the reaction product by filtration, liquid–liquid extraction, drying and simple distillation leads to a final β-pinene epoxide concentration higher than 90% wt; the stability of the epoxide was verified by measuring its composition during 20 days.

Evaluation of nopol production obtained from turpentine oil over Sn/MCM-41 synthesized by wetness impregnation using the Central Composite Design

A face-centered Central Composite Design (CCD) was used for nopol synthesis from turpentine oil over Sn/MCM-41 catalyst synthesized with sodium silicate as silicon source and incorporating Sn by wetness impregnation using SnCl2.2H2O as metal source. The catalyst was characterized by XRD, NH3-TPD and UV–vis-DRS. The catalyst was used four times without an apparent loss of catalytic activity and with no leaching of Sn. The CCD was constructed from 24 factorial points, eight axial points and seven central points, with time, paraformaldehyde to β-pinene molar ratio, catalyst concentration and solvent to β-pinene ratio as factors. Three response variables were selected (β-pinene conversion, nopol selectivity and nopol yield), and second order models were obtained taking into account all possible effects and identifying the non statistically significant effects. The optimal values found by response surface methodology were 71 %, 99 % and 61 % for conversion, selectivity and yield, respectively. The reactions were carried out under the established optimal conditions and the error varied between 2.14 and 2.63 %. Finally, the assumptions of independence, normality and homoscedasticity for each of the models were satisfactorily validated.

Heterogeneous Mo/W/Zn–SiO2 based catalysts in nopol (2-(6,6-dimethyl-2-bicyclo[3.1.1]hept-2-enyl)ethanol) synthesis

Nopol (2-(6,6-dimethyl-2-bicyclo[3.1.1]hept-2-enyl)ethanol) is an important fragrant compound, which synthesis is widely studied. Possibility of the use of heterogeneous catalysts instead of commonly used zinc (II) chloride can offer environmentally friendly process with possible catalyst reuse and avoiding wastewater production. Several metal modified SiO2 materials (mostly molybdenum, tungsten and zinc) were prepared and tested in nopol synthesis. Molybdenum and zinc modified material (with 25 wt% of MoO3 resp. ZnO loading) showed to possess a high activity in nopol synthesis accompanied by high selectivity of nopol formation. Under optimal reaction conditions (solvent benzonitrile, 80 °C, molar ratio β-pinene:paraformaldehyde = 1:2, 24 h) following results were observed: using catalyst 25 wt% MoO3–SiO2 (20 wt% to β-pinene) 77% β-pinene conversion and 98.7% selectivity of nopol formation was obtained (24 h), using catalyst 25 wt% ZnO–SiO2 (40 wt% to β-pinene) 72% β-pinene conversion and 96.3% selectivity of nopol formation was obtained (24 h). Molybdenum or zinc modified SiO2 can be successfully used in nopol synthesis from β-pinene and paraformaldehyde as heterogeneous catalysts, after material regeneration, the catalyst reuse is possible.

Turpentine valorization by its oxyfunctionalization to nopol through heterogeneous catalysis

Turpentine is a mixture of monoterpene hydrocarbons obtained as a by-product in the paper industry. In this contribution we present its transformation process towards an alcohol named nopol, that is an important household product and fragrance raw material. Reaction conditions were established for the oxyfuntionalization of crude turpentine oil over Sn-MCM-41 catalyst for the selective conversion of β-pinene to nopol. Synthesized materials were characterized by XRD, N2 adsorption, FT-IR, TEM and chemical absorption. The reaction was tested in 2 mL glass reactor with a sample of commercial turpentine with α-pinene (55.5% w/w) and β-pinene (39.5% w/w) as main components and scaled up into a 100 mL Parr reactor, getting 92% conversion of β-pinene and a nopol selectivity of 93%. The reusability tests showed that the catalyst can be reused 4 times without loss of activity. The results showed that 86% less solvent and 37.5% less paraformaldehyde can be used with turpentine, compared to the conditions used with β-pinene for getting similar catalysts activity.

Exploring the Keggin-Type Heteropolyacid-Catalyzed Reaction Pathways of the β-Pinene with Alkyl Alcohols

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.

Superior Activity of Isomorphously Substituted MOFs with MIL-100(M=Al, Cr, Fe, In, Sc, V) Structure in the Prins Reaction: Impact of Metal Type.

The catalytic behavior of isomorphously substituted MIL-100(M) (M=Al, Cr, Fe, In, Sc, V) is investigated for the synthesis of nopol through the Prins condensation of β-pinene with paraformaldehyde. The large mesoporous cages of the metal-organic frameworks provide a sustainable confinement for the formation of the target product (100 % selectivity for nopol over all materials studied). MIL-100(Sc) and MIL-100(V) exhibit the highest yields (up to 90 %) of nopol after just 20 min from the beginning of the reaction, owing to their high concentrations of accessible Lewis sites possessing intermediate acidity. The high catalytic activity (reaching almost 90 % β-pinene conversion) even upon decreasing the amount of catalyst from 100 to 25 mg (0.025 and 0.0063 gcatalyst mmolsubstrate -1 , respectively), the stability of its structure, and the possibility to use it several times, make MIL-100(V) a promising material for applications in acid-catalyzed reactions under mild reaction conditions.

Highly selective isomerization of biomass β-pinene over hierarchically acidic MCM-22 catalyst

Hierarchical MCM-22 material with microporous-mesoporous structure is found to be a highly efficient solid acid catalyst for the liquid phase isomerization of β-pinene, which can achieve 100% conversion of β-pinene and 93.7% yield for main products inclusive of 76.2% limonene and 17.5% camphene under mild reaction conditions. The excellent catalytic activity of the catalyst is ascribed to hierarchical pore structure and suitable Brønsted/Lewis ratio of surface acidity on the material, widely characterized by XRD, SEM, TEM, N2 adsorption, ICP, NH3-TPD, and pyridine-IR analyses. More importantly, this catalyst can be regenerated by simple MeOH-washing without calcination, different from traditional recovery by calcination at high temperature, and reused 7 times without an appreciable decrease of both the conversion of β-pinene and the selectivity of camphene and limonene, implying its excellent recyclable stability.

Highly Active and Recyclable Metal Oxide Catalysts for the Prins Condensation of Biorenewable Feedstocks

Metal oxides such as Nb2O5, Cr2O3, and especially a ZnIICrIII mixed oxide are demonstrated to be highly active and recyclable heterogeneous catalysts for Prins condensation, which provides a clean, high-yielding route for the synthesis of nopol through the condensation of biorenewable β-pinene with paraformaldehyde. ZnCr mixed oxide with an optimum Zn/Cr atomic ratio of 1:6 gave 100 % nopol selectivity at 97 % β-pinene conversion, with the catalyst easily recovered and recycled. The acid properties of Nb2O5 and ZnCr mixed oxide were characterized by the diffuse reflectance IR Fourier transform spectroscopy of adsorbed pyridine and ammonia adsorption microcalorimetry. An appropriate combination of acid–base properties of ZnCr mixed oxide is believed to be responsible for its efficiency.

Ring-Opening Reactions of α- and β-Pinenes in Pressurized Hot Water in the Absence of Any Additive

Reactions of α- and β-pinenes in pressurized hot water were examined in a batch reactor made of a SS316 1/2-in. tube at temperatures of 250–400 °C, pressures of 4–30 MPa, and reaction times of 1–30 min in the absence of any additive under an argon atmosphere. The maximum yields of limonene from α-pinene were ca. 70% in 20 min at 300 °C or 1 min at 400 °C. Limonene was obtained from β-pinene in ca. 16% yield for 30 min at 300 °C and 1 min at 400 °C. Reversible production of myrcene in 14% yield and formation of unidentified C20 dimer fractions were noted for 1 min at 370 °C from β-pinene. The conversion of α-pinene to limonene took place under anhydrous conditions, albeit at slightly lower yield of 65% compared to processes conducted in the presence of water, where increased limonene yield of 70% was observed for 1 min at 400 °C. The conversion of β-pinene to limonene under anhydrous conditions was limited to 6.1% in contrast to 11.9% in the presence of water for 7 min at 370 °C. In the presence of oxygen, p-cymene was formed in 23% and 24% yield at the expense of limonene from α- and β-pinenes, respectively, for 30 min at 400 °C.

Nanosized sulfated zinc ferrite as catalyst for the synthesis of nopol and other fine chemicals

A nanosized highly ordered mesoporous zinc ferrite (ZnFe2O4; ZF) was synthesized via co-precipitation method, further sulfated with ammonium sulfate solution to obtain sulfated ZF (SZF) and have been used for the synthesis of nopol by Prins condensation of β-pinene and paraformaldehyde. The NH3-TPD and pyridine sorption DRIFT-IR studies revealed the significant enhancement in Lewis acidic sites of the zinc ferrite on sulfatation. The influence of various reaction parameters such as reaction temperature, effect of substrate stoichiometry and catalyst loading has been investigated. It gave 70% conversion of β-pinene with 88% selectivity to nopol. The spent catalyst was regenerated and reused successfully up to four cycles with slight loss in catalytic activity. The nanosized SZF catalyst was found to be highly active towards several other commercially important acid catalyzed reactions such as isomerization, acetalization and aldol condensation.

Temperature dependence of the kinetic isotope effect inβ-pinene ozonolysis

[1] The temperature dependence of the kinetic isotope effect (KIE) of β-pinene ozonolysis was investigated experimentally at 258, 273 and 303 K in the AIDA atmospheric simulation chamber. Compound specific carbon isotopic analysis of gas phase samples was performed off-line with a Thermo Desorption-Gas Chromatography-Isotope Ratio Mass Spectrometry (TD-GC-IRMS) system. From the temporal behavior of the δ13C of β-pinene a KIE of 1.00358 ± 0.00013 was derived at 303 K, in agreement with literature data. Furthermore, KIE values of 1.00380 ± 0.00014 at 273 K and 1.00539 ± 0.00012 at 258 K were determined, showing an increasing KIE with decreasing temperature. A parameterization of the observed KIE temperature dependence was deduced and used in a sensitivity study carried out with the global chemistry transport model MOZART-3. Two scenarios were compared, the first neglecting, the second implementing the KIE temperature dependence in the simulations. β-Pinene stable carbon isotope ratio and concentration were computed, with emphasis on boreal zones. For early spring it is shown that when neglecting the temperature dependence of KIE, the calculated average age of β-pinene in the atmosphere can be up to two times over- or underestimated. The evolution of the isotopic composition of the major β-pinene oxidation product, nopinone, was examined using Master Chemical Mechanism (MCM) simulations. The tested hypothesis that formation of nopinone and its associated KIE are the determining factors for the observed δ13C values of nopinone is supported at high β-pinene conversion levels.

Activation parameters of supercritical and gas-phase β-pinene thermal isomerization

New data on enthalpy and entropy contributions to the energy barrier of β-pinene thermal isomerization were obtained. The rate of β-pinene conversion is higher in supercritical EtOH (P = 120 atm) than in the gas phase (P ≤ 1 atm, without solvent, or for inert carrier gas N2) at equal temperatures. The highest activation energy EΣ of total β-pinene conversion is also observed in reactions in the supercritical (sc) condition. Activation parameters ΔHΣ#, ΔSΣ#, and ΔGΣ# depend strongly on the reaction pressure. Thus, at P ≤ 1 atm (gas-phase reaction) the values of ΔSΣ# are negative, while at sc conditions at P = 120 atm is positive. The linear dependences lnkΣ0 − EΣ and ΔSΣ# − ΔSΣ# indicate an isokinetic relation (IKR) and enthalpy-entropy compensation effect (EEC). The isokinetic temperature was calculated (Tiso = 605.5 ± 22.7 K). It was shown that elevation of temperature reduces the value of ΔGΣ#(T) upon sc thermolysis only, whereas in all gas-phase reactions ΔGΣ#(T) increases. At equal reaction temperatures, the greatest values of Keq#(T) proved to be typical for thermolysis in sc-EtOH. We hypothesize that the rate of total β-pinene conversion increases dramatically due to a considerable shift in equilibrium toward higher concentrations of activated complex yTS#. A detailed analysis of activation parameters shows that the IKR and EEC coincide, evidence of a common mechanism of β-pinene conversion observed under different reaction conditions, including thermolysis in sc-EtOH.

Acidity and porosity modulation of MWW type zeolites for Nopol production by Prins condensation

Abstract Prins condensation of β-pinene with paraformaldehyde was carried out over MCM-22, delaminated ITQ-2 and silica pillared MCM-36. The mesopore-containing MCM-36 and ITQ-2 catalysts exhibit higher conversion of β-pinene due to more exposed acid sites. Lewis acid sites are responsible for Prins condensation while Bronsted acid sites favor the isomerization of pinene. The Bronsted acid sites can be removed mostly by ion-exchanging the zeolites with sodium cations. Thus, NaMWW zeolites had a higher selectivity towards Nopol. Of these, NaITQ-2 showed the highest activity and selectivity, and is a stable and reusable catalyst for production of Nopol.

Synthesis of nopol via Prins condensation of β-pinene and paraformaldehyde catalyzed by sulfated zirconia

The present work describes the novel application of sulfated zirconia (SZ) solid acid catalysts for the synthesis of nopol via Prins condensation of β-pinene and paraformaldehyde. SZ catalysts with different percentages of sulfur loadings have been synthesized and characterized using various physico-chemical techniques like PXRD, FT-IR, surface area analysis and NH 3–TPD studies. The influences of various reaction parameters such as sulfur loading, reaction temperature, molar ratio of reactants, reaction time, solvent effect and reusability of the catalyst have been investigated. SZ catalyst synthesized by impregnation of 2N sulfuric acid solution over Zr(OH) 4 was found to be a highly selective catalyst for β-pinene conversion (>99%) with ∼99% selectivity to nopol. The catalyst could be reused up to five cycles with minor loss in catalytic activity for β-pinene conversion, while the nopol selectivity remains unaffected.

Nopol production over Sn-MCM-41 synthesized by different procedures – Solvent effects

Nopol production over impregnated Sn-MCM-41 under several reaction conditions was examined and compared with Sn-MCM-41 materials previously synthesized by CVD or hydrothermal procedures. The effect of solvent on catalytic activity of Sn-MCM-41 materials and leaching tests of impregnated samples were also assessed. Selected materials were characterized by BET, XPS and H 2-TPR. The effect of solvent was explained in terms of polarity by the solvatochromic parameter, E T(30), and paraformaldehyde solubility by the Hansen solubility parameter (HSP). Nopol selectivity was enhanced at intermediate values of E T(30), and the highest β-pinene conversion was obtained when the HSP was close to 18.2 MPa 0.5. Leaching experiments confirmed that the reaction was truly heterogeneous. Catalysts characterization suggested that tin was deposited as tin oxide nanoparticles, when MCM-41 was modified by CVD and impregnation with stannic and stannous chloride, respectively. Conversely, most of the tin hydrothermally incorporated is presumably present as aggregates in the inner walls of MCM-41 and a small fraction of tin isomorphously substituted silicon atoms.

Synthesis of nopol from β-pinene using ZnCl 2 impregnated Indian Montmorillonite

The ZnCl 2 impregnated Montmorillonite catalyst prepared by wet impregnation technique were used for the synthesis of nopol from β-pinene. Furthermore, the reaction conditions over this catalyst for this reaction were optimized to obtain 75% conversion of β-pinene with 97% selectivity for nopol.

Síntesis de nopol con Sn-SBA-15 y Sn-MCM-41

Se comparó la actividad de Sn-MCM-41 y Sn-SBA-15 para la síntesis de nopol a partir de β-pineno yparaformaldehído. Los materiales se prepararon por los métodos hidrotérmico y el de impregnaciónhúmeda incipiente, utilizando cloruro estañoso como sal precursora de Sn. Los catalizadores sintetizados por impregnación presentaron mayor actividad y fueron más selectivos a nopol que los materialesobtenidos por el método hidrotérmico. La conversión de β-pineno obtenida con Sn-MCM-41 fue similar ala obtenida con Sn-SBA-15. Mediante síntesis hidrotérmica, se obtuvo especies de Sn(IV) en forma deagregados de SnO y substituyendo isomórficamente Si en la MCM-41 y la SBA-15, respectivamente.

Conversion of β-Phellandrene into a Derivative of α-Phellandrene

RECENT observations1,2,3 of the co-existence of α-and β-phellandrenes in certain essential oils suggest a possible biogenetic relationship between these two terpenes. So far as we are aware no evidence of such an interconversion has been put forward although this might be anticipated from the apparently analogous conversion of β-pinene into α-pinene4. Since this lack of evidence may be due to the difficulty in detecting small quantities of one isomer in the presence of the other, it may be of interest to note that by condensation of maleic anhydride with lβ-phellandrene we have obtained a product which, from its melting point, mixed melting point and rotation, is apparently identical with the compound obtained from lα-phellandrene3. The lβ-phellandrene employed was obtained from Canada balsam oil which has been shown to be free from α-phellandrene3.