Epoxidation Of Terpenes Research Articles

Supported Co‐based catalytic systems for the epoxidation of terpenes using O2 as oxidant

We synthesized and characterized a range of cobalt‐based catalyts supported on mesoporous silica (SBA‐15 and SBA‐16), commercial silica and functionalized carbon nanotubes (CNT), investigated their efficiency in the aerobic epoxidation of terpenes, specifically limonene and α‐pinene. Cobalt deposition was achieved by impregnation with cobalt(II) acetylacetonate and the resulting systems were characterized by XPS, ICP‐OES, N2 adsorption‐desorption, TEM, STEM‐HAADF and EDX. Variations in pore structure, cobalt dispersion, and oxidation states depending on the support used were observed. Catalytic tests demonstrated that Co/SBA‐15 (1.6% Co) exhibited superior catalytic activity in the oxidation of limonene compared to Co/SBA‐16, Co/SiO2c, and Co/CNT, achieving 90% conversion with a 68% selectivity towards 1,2‐limonene oxide. In contrast, for α‐pinene oxidation, Co/SBA‐15 showed lower activity, while other catalysts achieved full conversion. The study also explored the effect of cobalt loading on catalytic performance, indicating that higher loadings generally led to rapid catalyst deactivation due to the formation of larger cobalt oxide particles. The findings underscore the critical role of support structure and cobalt dispersion in enhancing catalytic efficiency for terpene epoxidation. Additionally, we demonstrated the potential for 3 recycling and scale up to the gram level while maintaining high activity and selectivity.

Environment-friendly epoxidation of limonene using tungsten-based polyoxometalate catalyst

Terpene epoxides play a vital role as chemical intermediates in industries such as flavourings, fragrances, paints, and polymers manufacturing. However, current methods for limonene epoxidation suffer from low selectivity and environmental concerns. To address these limitations, we aimed to develop a highly selective and environmentally benign process for limonene epoxidation. Our approach involved employing hydrogen peroxide (H2O2) as an oxidant in the presence of tungsten-based polyoxometalates as catalysts. A novel catalyst was synthesized using sodium tungstate dihydrate (Na2WO4·2H2O), phosphoric acid (H3PO4), sulfuric acid (H2SO4), and sodium sulfate (Na2SO4) as an inorganic salt. We investigated the influence of various process variables, including the limonene:H2O2 molar ratio, reaction time, temperature, and solvent type, to optimize the epoxidation process. Through systematic screening, we achieved remarkable results, attaining 96% limonene conversion, 80% selectivity to limonene-1,2-epoxide, and 19% selectivity to limonene bis-epoxide within a short reaction time of 15 min. Notably, this high performance was accomplished by introducing H2O2 in a single step. To mitigate the hydrolysis of the epoxide, we employed sodium sulphate (Na2SO4) to saturate the reaction mixture. Furthermore, we proposed a comprehensive mechanism for the limonene epoxidation process using tungsten-based polyoxometalates as catalysts. Our kinetic study revealed a first-order reaction with respect to both limonene and the catalyst. Importantly, the decomposition of H2O2 was negligible under the investigated operating conditions, confirming the stability and efficiency of our approach. Our findings present eco-friendly, scalable, and catalytic epoxidation methods as valuable synthetic tools for converting inexpensive bio-renewable terpene feedstocks into essential chemical building blocks. The implications of our work extend to the synthesis of useful chemical products in a biorefinery setting, promoting a more sustainable and efficient utilization of terpenes.

Synthesis of Biorenewable Terpene Monomers Using Enzymatic Epoxidation under Heterogeneous Batch and Continuous Flow Conditions.

A commercially available Lipase B from Candida antarctica immobilized onto a macroporous support (Novozym 435) has been employed in the presence of H2O2 as a benign oxidant for the epoxidation of various biorenewable terpenes. This epoxidation protocol was explored under both heterogeneous batch and continuous flow conditions. The catalyst recyclability was also investigated demonstrating good activity throughout 10 cycles under batch conditions, while the same catalyst system could also be productively used under continuous flow operation for more than 30 h. This practical and relatively safe sustainable flow epoxidation of di- and trisubstituted alkenes by H2O2 allows for the production of gram quantities of a range of terpene epoxides. As a proof of principle, the same protocol can also be applied to the epoxidation of biobased polymers as a means to post-functionalize these macromolecules and equip them with cross-linkable epoxy groups.

Recent advances in catalytic and non-catalytic epoxidation of terpenes: a pathway to bio-based polymers from waste biomass.

Epoxides derived from waste biomass are a promising avenue for the production of bio-based polymers, including polyamides, polyesters, polyurethanes, and polycarbonates. This review article explores recent efforts to develop both catalytic and non-catalytic processes for the epoxidation of terpene, employing a variety of oxidizing agents and techniques for process intensification. Experimental investigations into the epoxidation of limonene have shown that these methods can be extended to other terpenes. To optimize the epoxidation of bio-based terpene, there is a need to develop continuous processes that address limitations in mass and heat transfer. This review discusses flow chemistry and innovative reactor designs as part of a multi-scale approach aimed at industrial transformation. These methods facilitate continuous processing, improve mixing, and either eliminate or reduce the need for solvents by enhancing heat transfer capabilities. Overall, the objective of this review is to contribute to the development of commercially viable processes for producing bio-based epoxides from waste biomass.

Continuous process for the epoxidation of terpenes using mesoscale oscillatory baffled reactors

Continuous epoxidation of terpenes with H2O2 was carried out using mesoscale oscillatory baffled reactors (meso-OBRs) in a solvent-free environment. The performance of the new 3D-printed single, tri- and multi-orifice baffles was compared with helical and integral baffles. The performance investigated includes mixing intensity, induction period, steady-state attainment, and heat removal capability of the meso-OBR. Moreover, passive isothermalisation was also investigated using meso-OBR in a heat pipe assembly. The tri- and multi-orifice baffles were able to overcome mixing limitations and achieved a comparable rate of reaction to batch at mixing conditions of Reo > 850 and Reo > 500, respectively. Both baffles exhibited rapid steady-state attainment, shorter induction period (t = 1.5τ) and better reproducibility with product variation of ∼1.3%. The meso-OBR designs demonstrated effective heat transfer capability, allowing the reaction to being operated isothermally with ±1 °C temperature variation in solvent-free conditions. This removes the need for a solvent, thus reducing reaction volume by a 5-fold. The timescale for the reaction was reduced from ∼8 h in a conventional process to 30 min in the multi-orifice meso-OBR, a 16-fold reduction. A better process has been developed for a continuous epoxidation of terpenes with H2O2 using multi-orifice meso-OBRs, with a potential intensification factor of ∼80.

Epoxidation of limonene and pinenes by dimethyldioxirane in microemulsions

Terpene epoxides such as limonene dioxide are known as a very important intermediates for developing biological resins such as non-isocyanate polyurethanes. Recently, the dimethyldioxirane (DMDO) epoxidation technique has attracted attention and studies are being carried out to epoxidize terpenes. This study focuses on the epoxidation of hydrophobic terpene such as limonene and pinene by DMDO generated in-situ in a microemulsion system, examining the efficacy of cetyltrimethylammonium hydrogen sulfate (CTAHS) as a surfactant to homogenize the limonene and pinene in the aqueous reaction medium. The application of CTAHS showed a significant advantage for the epoxidation reaction. 100% limonene dioxide (LDO) and α-pinene oxide yields are obtained with molar ratios of only 1.6 for oxone/limonene and 0.9 for oxone/α-pinene respectively, after 30 min. The application of CTAHS resulted in a significant reduction in acetone content so that it just plays the role of a catalyst; Only an acetone/water volume ratio of up to 1:9 was sufficient to obtain these results. The reaction volume is therefore completely reduced and the amount of oxone required is almost 50% less than with the conventional biphasic organic solvent/water reaction medium. The separation of the epoxides from the aqueous medium and the surfactant (CTAHS) is easily done by liquid-liquid extraction. The main advantages of this technology are the use of acetone as a catalyst, which can be recycled indefinitely, the high selectivity of the epoxides without any by-products and the exclusion of the use of any organic solvent.

The Influence of Hop Latent Viroid (HLVd) Infection on Gene Expression and Secondary Metabolite Contents in Hop (Humulus lupulus L.) Glandular Trichomes.

Viroids are small infectious pathogens, composed of a short single-stranded circular RNA. Hop (Humulus lupulus L.) plants are hosts to four viroids from the family Pospiviroidae. Hop latent viroid (HLVd) is spread worldwide in all hop-growing regions without any visible symptoms on infected hop plants. In this study, we evaluated the influence of HLVd infection on the content and the composition of secondary metabolites in maturated hop cones, together with gene expression analyses of involved biosynthesis and regulation genes for Saaz, Sládek, Premiant and Agnus cultivars. We confirmed that the contents of alpha bitter acids were significantly reduced in the range from 8.8% to 34% by viroid infection. New, we found that viroid infection significantly reduced the contents of xanthohumol in the range from 3.9% to 23.5%. In essential oils of Saaz cultivar, the contents of monoterpenes, terpene epoxides and terpene alcohols were increased, but the contents of sesquiterpenes and terpene ketones were decreased. Secondary metabolites changes were supported by gene expression analyses, except essential oils. Last-step biosynthesis enzyme genes, namely humulone synthase 1 (HS1) and 2 (HS2) for alpha bitter acids and O-methytransferase 1 (OMT1) for xanthohumol, were down-regulated by viroid infection. We found that the expression of ribosomal protein L5 (RPL5) RPL5 and the splicing of transcription factor IIIA-7ZF were affected by viroid infection and a disbalance in proteosynthesis can influence transcriptions of biosynthesis and regulatory genes involved in of secondary metabolites biosynthesis. We suppose that RPL5/TFIIIA-7ZF regulatory cascade can be involved in HLVd replication as for other viroids of the family Pospiviroidae.

Epoxidation of Terpenes

Terpene epoxides are considered as potential primary intermediates in the synthesis of numerous green polymers including epoxy resins, polycarbonates, nonisocyanate polyurethanes and even some polyamides. In this chapter we describe recent efforts from our group to develop catalytic and noncatalytic processes for terpene epoxidation using a variety of oxidizing agents and process intensification methods. Most experimental tests deal with limonene epoxidation with applicability to some other terpenes also demonstrated.

Synthesis of the fragrance terpene epoxides and selective monocyclization promoted by camphor and oxone®

AbstractA high level of regio‐selectivity in the epoxidation of monoterpenes with camphor and oxone® at pH 7 has been observed. This methodology when applied to acyclic terpenes such as citronellyl acetate, geranyl acetate yielded mainly chiral 6(S),7‐epoxides. Similarly, farnesyl acetate yielded 10(S),11‐epoxide. Alternatively, unsaturated monocyclic terpene alcohol such as (‐)‐α‐terpineol, 6‐methyl‐hept‐5‐en‐2‐ol, when treated with camphor and oxone® at pH ~4‐5 led to one‐pot oxidative‐cyclization to yield (‐)‐trans‐2‐(S)‐hydroxy‐1,8‐cineole and (+)‐2,2,6‐trimethyl‐tetrahydropyran‐3‐ol respectively. In addition, the epoxides, trans‐2‐hydroxyl‐cineole and its acetate synthesized herein have good perfumery value with woody and sweet aromas. Copyright © 2016 John Wiley & Sons, Ltd.

Isomerization of bicyclic terpene epoxides into allylic alcohols without changing of the initial structure

A novel method of (1S,2R,3R,5R)-6,6-dimethyl-4-methylenebicyclo[3.1.1]heptane-2,3-diol synthesis, which is a valuable intermediate in the synthesis of a perspective potent anti-Parkinson drugs, in the presence of TiO2 was proposed. Catalytic activity of TiO2 in the bicyclic terpene epoxides isomerization to corresponding allylic alcohols without changing of the initial structure was demonstrated, contrary to titania-supported Au catalysts which promoted rearrangement with predominant formation of a cyclopentene α-hydroxy ketone.

Effective immobilization of Candida antarctica lipase B in organic-modified clays: Application for the epoxidation of terpenes

The use of three smectite nanoclays (Laponite, SWy-2 and Kunipia) organic-modified with octadecyl-trimethyl-ammonium surfactant, as suitable host matrices for the immobilization of lipase B from Candida antarctica (CaLB) was demonstrated. The resulting hybrid biocatalysts were characterized by a combination of powder X-ray diffraction, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy and infrared spectroscopy. The experimental results confirmed the remarkable binding capacity of the three organoclays for CaLB . Activity and operational stability of immobilized CaLB were determined for the chemo-enzymatic epoxidation of terpenes ( α-pinene and d-limonene) in organic media using various oxidizing agents. The immobilized enzyme retains a significant part of its activity after repeated use under drastic reaction conditions originating from the use of oxidants.

ChemInform Abstract: An Effective Catalytic Epoxidation of Terpenes with Hydrogen Peroxide under Organic Solvent‐Free Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An Effective Catalytic Epoxidation of Terpenes with Hydrogen Peroxide ­under Organic Solvent-Free Conditions

A catalytic system that operates well for the epoxidation of α-pinene,a very challenging substrate, at near-neutral pH and ambient temperaturewithout organic solvent was developed. With hydrogen peroxide asa terminal oxidant, combination of Na 2 WO 4 , PhP(O)(OH) 2 ,and [Me( N-C 8 H 17 ) 3 N]HSO 4 successfullycatalyzed the epoxidation of α-pinene to give α-pineneoxide in 95% selectivity at 91% conversion, whilethe previously published conditions that use NH 2 CH 2 P(O)(OH) 2 asa promoter provide no epoxide. The method is also well applicableto the epoxidation of the other acid-sensitive terpenes.

DESIGNING CATALYSTS FOR CLEAN TECHNOLOGY, GREEN CHEMISTRY, AND SUSTAINABLE DEVELOPMENT

▪ Abstract There is a pressing need for cleaner fuels (free or aromatics and of minimal sulfur content) or ones that convert chemical energy directly to electricity, silently and without production of noxious oxides and particulates; chemical, petrochemical and pharmaceutical processes that may be conducted in a one-step, solvent-free manner and that use air as the preferred oxidant; and industrial processes that minimize consumption of energy, production of waste, or the use of corrosive, explosive, volatile, and nonbiodegradable materials. All these needs and other desiderata, such as the in situ production and containment of aggressive and hazardous reagents, and the avoidance of use of ecologically harmful elements, may be achieved by designing the appropriate heterogeneous inorganic catalyst, which ideally should be cheap, readily preparable and fully characterizable, preferably under in situ reaction conditions. A range of nanoporous and nanoparticle catalysts that meet most of the stringent demands of sustainable development and responsible (clean) technology is described. Specific examples that are highlighted include the production of adipic acid (precursor of polyamides and urethanes) without the use of concentrated nitric acid nor the production of greenhouse gases such as nitrous oxide; the production of caprolactam (precursor of nylon) without the use of oleum and hydroxylamine sulfate; and the terminal oxyfunctionalization of linear alkanes in air. The topic of biocatalysis and sustainable development is also briefly discussed for the epoxidation of terpenes and fatty acid methyl esters; for the generation of polymers, polylactides, and polyesters; and for the production of 1,3-propanediol from corn.

Regio- and stereoselectivity of diethylaluminum azide opening of trisubstituted epoxides and conversion of the 3 degrees azidohydrin adducts to isoprenoid aziridines.

The regioisomer ratios (3 degrees,2 degrees /2 degrees,3 degrees ), and in some cases the stereochemistry, of vicinal azidohydrins formed in reactions of 11 trisubstituted terpene epoxides with Et(2)AlN(3) in toluene are reported. The more highly substituted azide usually predominated (3 degrees,2 degrees /2 degrees,3 degrees ratios >or= 40:1 to 2.5-1) in accord with a Markovnikov orientation and an S(N)1-like transition state. Reversed regioisomer ratios were observed with 6,7-epoxygeranyl acetate (1:2.5) and cis-1,2-epoxylimonene (1:3.3 to 1:10). The tertiary azido diols from 2,3-epoxygeraniol, 2,3-epoxyfarnesol, and 2,3-epoxynerol were formed as single isomers with inversion of configuration at C3 (>or= 35-40:1 for the C(10) azido diols). The regioselectivity was affected by the presence and proximity of oxy functional groups on the epoxide substrate (OH, OAc, and OSi-tBuMe(2)), the equivalents of Et(2)AlN(3), and additives (EtOAc or EtOH). The results and trends are rationalized by consideration of the structural and stereoelectronic characteristics of proposed diethylaluminum epoxonium ion intermediates and transition states, together with the nucleophilicity of the azide donor. Six of the 3 degrees,2 degrees azidohydrins were converted to the corresponding aziridines by primary-selective silylations of four azido diols, mesylations, and reductive cyclizations with LiAlH(4).

A Heterogeneous Tungsten Catalyst for Epoxidation of Terpenes and Tungsten-Catalyzed Synthesis of Acid-Sensitive Terpene Epoxides

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTA Heterogeneous Tungsten Catalyst for Epoxidation of Terpenes and Tungsten-Catalyzed Synthesis of Acid-Sensitive Terpene EpoxidesAída L. Villa de P, Bert F. Sels, Dirk E. De Vos, and Pierre A. JacobsView Author Information Center for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Heverlee, Belgium Cite this: J. Org. Chem. 1999, 64, 19, 7267–7270Publication Date (Web):August 31, 1999Publication History Received13 May 1999Published online31 August 1999Published inissue 1 September 1999https://doi.org/10.1021/jo990790zCopyright © 1999 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1642Altmetric-Citations79LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (44 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Catalysts,Ethers,Hydrocarbons,Organic reactions,Selectivity Get e-Alerts

Four polymethylsqualene epoxides and one acyclic tetraterpene epoxide from Botryococcus braunii

New terpene epoxides have been isolated from two strains of the green microalga Botryococcus braunii. Polymethylsqualene epoxides C 32, C 33 and C 34 are 10,11-epoxysqualene derivatives with non-isoprenoid methyls at C-3, C-7, C-18 and (or) C-22; they were isolated from a strain producing large amounts of triterpene hydrocarbons ( B. braunii, B race). Epoxylycopaene is an acyclic tetraterpene with a trans epoxide occurring at C-14, C-15 and a trans unsaturation at C-18; it was obtained from a strain characterized by the production of trans, trans-lycopadiene, a tetraterpene hydrocarbon ( B. braunii, L race). The structures were determined by NMR and mass spectrometry. Chemical degradation and application of Mosher ester methodology allowed us to establish the absolute stereochemistry of epoxylycopaene. In addition, 14,15-dihydroxy lycopa-18-ene has been isolated from the L race.

Purification and properties of alpha-pinene oxide lyase from Nocardia sp. strain P18.3.

alpha-Pinene oxide is an intermediate in the degradation of alpha-pinene by Nocardia sp. strain P18.3 and some Pseudomonas strains. The epoxide is cleaved by a lyase which catalyzes a concerted reaction in which both rings of the bicyclic structure are cleaved with the formation of cis-2-methyl-5-isopropylhexa-2,5-dienal. The enzyme has been purified to homogeneity from Nocardia sp. strain P18.3. It was induced by growth with alpha-pinene and constituted 6 to 7% of the soluble protein of cell extracts. The apparent molecular weight of the native enzyme was 50,000 by ultracentrifugal analysis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave two dissimilar subunits with apparent molecular weights of 17,000 and 22,000. The enzyme was devoid of prosthetic groups, had no cofactor requirement, and had a broad pH activity range, a Km for alpha-pinene oxide of 9 microM, and a turnover number of 15,000. Inhibitors included sulfhydryl reactive compounds, terpene epoxides, and pinane derivatives with substituent groups at carbon 3. A mechanism for the concerted reaction has been proposed in which decyclization is initiated by donation of a proton from the catalytic center to the oxygen of the epoxide with consequent destabilization. In vitro the enzyme was inactivated during catalysis, and a reactive cationic intermediate may be responsible for this phenomenon. The enzyme should be classified as a lyase EC 4.99.-.-.

Epoxidation and hydration of prenyl pyrophosphates by plant extracts

Cell-free extracts of Tanacetum vulgare, Artemisia annua, and Santolina chamaecyparissus contain seasonally-dependent enzyme systems that convert IPP§, DMAPP, GPP and NPP into water-soluble products in up to 96% yield. 3-Methyl-3,4-oxidobutan-1-ol; 3-methylbutan-1,3,4-triol; 3,7-dimethyl-6,7-oxido-octa- trans-2-en-1-ol; and 3,7-dimethylocta- trans,trans-2,5-dien-1,7-diol were major products when IPP and GPP respectively were substrates and several other terpene epoxides and their ring-opened products were tentatively identified. 2-CEPA blocked formation of diols from the epoxides. The occurrence of these enzymes accounts for some hitherto puzzling observations that have arisen in studies of monoterpene biosynthesis both in vivo and in vitro.

A novel ring contraction during the vapor phase pyrolysis of substituted [formula omitted]-1-hydroxy-2-acetoxycyclohexanes

Tetrahedron Letters No.23, pp. 2G03-2006, 1970. Pergamon Press. Printed i n Great Britain. A NOVEL RING CONTRACTION DURING THE VAPOR PHASE PYROLYSIS OF SUBSTITUTED TRANS-1-HYDROXY-2-ACETOXYCYCLOHEXANES John C. Leffingwell and Ronald E. Shackelford (Research and Development Departments, R. J. Reynolds Tobacco Company Winston-Salem, North Carolina 27102) (Received in USA 25 February 1970; r eceived in UK for publi cation 20 April 1970) The vapor phase pyrolysis of a number of terpene hydroxyacetates derived from terpene epoxides has been reported by Royals and Leffingwell to give terpenoid allylic alcohols.1 During a reinvestigation and extension of this earlier work, we have discovered that pyrolytic ring contractions which produce ketonic products accompany the formation of the previously reported allylic alcohols. We have now demonstrated the generality of such pyrolytic ring contractions by the pyrolysis of five substituted trans-1-hydroxy-2-acetoxycyclohexanes. On pyrolysis these systems all follow the general equation: