Identification of insecticidal constituents of the essential oils of Dahlia pinnata Cav. against Sitophilus zeamais and Sitophilus oryzae

The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata, their insecticidal activity against Sitophilus zeamais and Sitophilusoryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as d-limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD₅₀ values ranging from 132.48 to 828.79 μg/cm² against S. zeamais and S. oryzae. Essential oils possessed fumigant toxicity against S. zeamais and S. oryzae with LC₅₀ from 14.10 to 73.46 mg/L. d-Limonene (LC₅₀ = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d-limonene (87 ± 5%) showed the strongest repellency against S. zeamais and S. oryzae, respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.     

Chemical bonding in refractory transition metal compounds with 8, 9, and 10 valence electrons

The chemical bonding in the refractory transition metal compounds TiC, TiN, and VN is investigated by experimental and theoretical techniques. High-precision X-ray diffraction is used to determine the electron densities in these three compounds experimentally. The X-ray structure factors and the respective valence electron densities are used twice, once to understand the chemical bonding and once to relate the experimental charge densities to those obtained from band structure calculations. These calculations, which in general are in very good agreement with experimental data, utilize the linearized augmented plane wave (LAPW) method. Theory and experiment lead to a detailed analysis of the chemical bonding in these compounds with 8, 9, and 10 valence electrons. By decomposition of the theoretical charge density into contributions from different states (energy regions), it was possible to show the strong covalent nonmetal p-metal d interaction, which is otherwise apparent only in TiC, but not in TiN or VN. In the latter two compounds the additional electrons occupy mainly metal d states with t_2g symmetry, so that in the total valence charge densities the most important bonding feature is covered. In addition to covalent interactions all compounds have a metallic bonding contribution as well as a considerable charge transfer from the metal to the nonmetal site. This mixture in chemical bonding accounts for the unusual combination of properties such as ultrahardness, high melting points, and good conductivity.     

Effects of water and alcohol on the formation of inclusion complexes of d-limonene and cyclodextrins

Abstract

Systematic studies have been carried out on the role of water and alcohol in the formation of inclusion complexes between d-limonene and α-, β- and γ-cyclodextrin (CD) by a micro-aqueous method. The inclusion complex was barely formed at zero water content for all CDs. Above the specific water content for each CD, formation of the inclusion complex correlated well with an equation which was derived on the autocatalytic assumption for the inclusion phenomenon. The inclusion complex correlated well with an equation which was derived on the autocatalytic assumption for the inclusion phrnomenon. The minimum water content, which was defined as 1% of the maximum concentration of the inclusion complex formed, coincided with the number of water molecules inside the cavity of the CD. In the presence of ethanol, a significant amount of the inclusion complex was formed for β- and γ-CD/limonene systems, particularly at lower moisture content. However, for α-CD the inclusion fraction decreased significantly in the presence of ethanol. This means that ethanol inhibits the formation of the inclusion complex between x-CD and d-limonene. For other linear alcohols, the formation of the inclusion complex between d-limonene and β-CD increased with decreasing alkyl chain length. This suggests that the more hydrophilic and the smaller (in molecular size) the alcohol is, the more enhanced is the inclusion of d-limonene to β-CD.     

Selective Catalytic Synthesis of 1,2- and 8,9-Cyclic Limonene Carbonates as Versatile Building Blocks for Novel Hydroxyurethanes

The selective catalytic synthesis of limonene-derived monofunctional cyclic carbonates and their subsequent functionalisation via thiol–ene addition and amine ring-opening is reported. A phosphotungstate polyoxometalate catalyst used for limonene epoxidation in the 1,2-position is shown to also be active in cyclic carbonate synthesis, allowing a two-step, one-pot synthesis without intermittent epoxide isolation. When used in conjunction with a classical halide catalyst, the polyoxometalate increased the rate of carbonation in a synergistic double-activation of both substrates. The cis isomer is shown to be responsible for incomplete conversion and by-product formation in commercial mixtures of 1,2-limomene oxide. Carbonation of 8,9-limonene epoxide furnished the 8,9-limonene carbonate for the first time. Both cyclic carbonates underwent thiol–ene addition reactions to yield linked di-monocarbonates, which can be used in linear non-isocyanate polyurethanes synthesis, as shown by their facile ring-opening with N-hexylamine. Thus, the selective catalytic route to monofunctional limonene carbonates gives straightforward access to monomers for novel bio-based polymers.     

Evaluation of ionization techniques for mass spectrometric detection of contact allergenic hydroperoxides formed by autoxidation of fragrance terpenes

Hydroperoxides formed by autoxidation of common fragrance terpenes are strong allergens and known to cause allergic contact dermatitis (ACD), a common skin disease caused by low molecular weight chemicals. Until now, no suitable methods for chemical analyses of monoterpene hydroperoxides have been available. Their thermolability prohibits the use of gas chromatography and their low UV-absorption properties do not promote sensitive analytical methods by liquid chromatography based on UV detection. In our study, we have investigated different liquid chromatography/mass spectrometry (LC/MS) ionization techniques, electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI), for detection of hydroperoxides from linalool and limonene.Flow injection analysis was used to evaluate the three different techniques to ionize the monoterpene hydroperoxides, linalool hydroperoxide and limonene hydroperoxide, by estimating the signal efficacy under experimental conditions for positive and negative ionization modes. The intensities for the species [M+H]+ and [M+H-H2O]+ in positive ionization mode and [M-H]- and [M-H-H2O]- in negative ionization mode were monitored. It was demonstrated that the mobile phase composition and instrumental parameters have major influences on the ionization efficiency of these compounds. ESI and APCI were both found to be appropriate as ionization techniques for detection of the two hydroperoxides. However, APPI was less suitable as ionization technique for the investigated hydroperoxides.     

Minor antifungal aromatic glycosides from the roots of Gentiana rigescens （Gentianaceae）

Two new phenolic glycosides,2,3-dihydroxybenzoic acid methyl ester 3-O-β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside(1) and 2,5-dihydroxylbenzofuran 5-O-β-D-xylopyranosyl-(1-6)-O-β-D-glucopyranoside(2),were isolated as the minor chemical constituents from the roots of Gentiana rigescens,along with 15 known compounds.Their structures were elucidated by detailed spectroscopic analysis,including 1D,2D NMR and chemical method.All of these compounds were isolated for the first time from the title plant.Moreove...     

Experimental and estimated saturated vapour pressures of aroma compounds

The saturated vapour pressure of d-linalool, 2-nonanone, d-limonene and isoamyl acetate were measured using a static method at different temperatures from 223 to 468 K. From the experimental values, Antoine's constants were determined to enable the calculations of the saturated vapour pressures at a given temperature. The saturated vapour pressure of the four aroma compounds at 298 K were respectively 27, 59, 200 and 733 Pa. These results were compared with those obtained using different estimation methods (Antoine–Grain, Watson, Lee–Kesler, Gomez–Thodos, Grain and Mackay). Gomez–Thodos' model was found to be the most accurate method for the estimation of the saturated vapour pressure of these aroma compounds. The importance of accurate saturated vapour pressures for the calculation of other thermodynamic properties used in the study of vapour–liquid equilibria of aroma compounds is discussed.     

Synthesis of allylic hydroperoxides and EPR spin-trapping studies on the formation of radicals in iron systems as potential initiators of the sensitizing pathway

Many terpenes used as fragrance compounds autoxidize when exposed to air, forming allylic hydroperoxides that have the potential to be skin contact allergens. To trigger the immunotoxicity process that characterizes contact allergy, these hydroperoxides are supposed to bind covalently to proteins in the skin via radical pathways. We investigated the formation of reactive radical intermediates from 7-hydroperoxy-3,7-dimethylocta-1,5-dien-3-ol and 2-hydroperoxylimonene, responsible for the sensitizing potential acquired by autoxidized linalool and limonene. Both compounds were synthesized through new short and reproducible synthetic pathways. The hydroperoxide decomposition catalyzed by Fe(II)/Fe(III) redox systems, playing a key role in degradating peroxides in vivo, was examined by spin-trapping-EPR spectroscopy. Alkoxyl and carbon-centered free radicals derived from the hydroperoxides were successfully trapped by the spin-trap 5,5-dimethyl-1-pyrroline N-oxide, whereas peroxyl radicals were characterized by spin-trapping studies with 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide. Using liquid chromatography combined with mass spectrometry, we demonstrated the formation of adducts, via radical mechanisms induced by Fe(II)/Fe(III), between the hydroperoxides and N-acetylhistidine methyl ester, a model amino acid that is prone to radical reactions. Free radicals derived from these hydroperoxides can thus induce amino acid chemical modifications via radical mechanisms. The study of these mechanisms will help to understand the sensitizing potential of hydroperoxides.     

Synthesis of New Isoxazolo[4,5‐d]pyrimidines as Antitumor Agents

The present paper (publication) concerns the synthesis of new isoxazole[4,5‐d]pyrimidine derivatives. There are only a few publications in the chemical literature that report the derivatives of the [4,5‐d] isomer. Our new compounds, the derivatives of this isomer, were obtained using a new manner that differs from those reported in the aforementioned publications in that we used the tautomers of 3‐arylo‐4‐imino‐5‐carbethoxy isxazole 3 and 4 as the starting compounds instead of using their 4‐amino forms. Their tautomeric form proved chemically stable, and, as a result of ammonolysis, we obtained the compounds 5 and 6 . The cyclization of the amides of 5 and 6 with various aldehydes yielded new derivatives, 10 – 19 , with good yields. As a by‐product, the 4‐amino tautomer form in by degrees and was reacted also with aldehydes, and we isolated Schiff bases 20 – 25 with low yields. Some of these compounds were tested for their antitumor activity at National Cancer Institute, Bethesda, MD, USA.     

Total Lipid Extraction of Food Using d-Limonene as an Alternative to n-Hexane

A useful and green method for the extraction of fats and oils with a new procedure combining Soxhlet extraction and Clevenger distillation using d-limonene (bio-solvent) as a substitute for n-hexane (petroleum solvent) is reported. This method using green solvent is a laboratory exercise which easily teaches fundamental green analytical chemical lessons and successfully incorporates green “analytical chemistry” into the teaching and the research laboratory to both developed and developing nations.     

Synthesis of Precursors of Heterocyclic cis-β-Amino Alcohols by Intramolecular Amidoalkylation of 4-Hydroxyoxazolidin-2-ones

The reaction of intramolecular amidoalkylation of 4-hydroxyoxazolidin-2-ones leads to formation of novel and rare heterocyclic systems: substituted 1,5,6,10b-tetrahydro[1,3]oxazolo[4,3-a]isoquinolin-3-ones, 3a,4,5,10b-tetrahydro[1,3]dioxolo[4',5':6,7]naphtho[1,2-d][1,3]oxazol-2(1H)-ones, and 5,6,10,10a-tetrahydro-1H-di[1,3]oxazolo[3,4-d:4,3-g][1,4]diazepine-3,8-diones. Mild reaction conditions and the simplicity of isolation of the compounds formed make it possible to obtain the indicated heterocycles in high yields.     

Short chain acyclic crown ethers

A series of short chain acyclic crown ethers such as (1,2), (1,3), (1,4)-phenylenediethers and some symmetric or assymmetrico-substituted phenyl ethers were prepared. The complexation studies of these compounds were carried out by a) direct UV titration method, b) picrate extraction method and c) isolation of crystalline complex.Taken in part from the master's thesis ofMaria Cecilia Bastos Vieira de Souza, Instituto Militar de Engenharia, 1978.     

Effects of gamma irradiation on the yields of volatile extracts of Angelica gigas Nakai

The study was carried out to determine the effects of gamma irradiation on the volatile flavor components including essential oils, of Angelica gigas Nakai. The volatile organic compounds from non- and irradiated A. gigas Nakai at doses of 1, 3, 5, 10 and 20 kGy were extracted by a simultaneous steam distillation and extraction (SDE) method and identified by GC/MS analysis. A total of 116 compounds were identified and quantified from non- and irradiated A. gigas Nakai. The major volatile compounds were identified 2,4,6-trimethyl heptane, α-pinene, camphene, α-limonene, β-eudesmol, α-murrolene and sphatulenol. Among these compounds, the amount of essential oils in non-irradiated sample were 77.13%, and the irradiated samples at doses of 1, 3, 5, 10 and 20 kGy were 84.98%, 83.70%, 83.94%, 82.84% and 82.58%, respectively. Oxygenated terpenes such as β-eudesmol, α-eudesmol, and verbenone were increased after irradiation but did not correlate with the irradiation dose. The yields of active substances such as essential oil were increased after irradiation; however, the yields of essential oils and the irradiation dose were not correlated. Thus, the profile of composition volatiles of A. gigas Nakai did not change with irradiation.     

Influence of synthetic perfumes on stability of O/W emulsion in sodium dodecyl sulfate–n-dodecane–water ternary systems

Influence of synthetic perfumes having diverse chemical structures such as eugenol, linalool, benzyl acetate, α-ionone, α-hexylcinnamaldehyde, and d-limonene on stability of oil-in-water (O/W) emulsion composed of sodium dodecyl sulfate, n-dodecane, and water is investigated. Turbidity measurements of the O/W emulsion indicate that the emulsion is stabilized by adding the synthetic perfume, except for d-limonene, and that this tendency is remarkable in adding eugenol. The addition of the perfume, especially eugenol, shrinks oil droplets in the O/W emulsion, which inhibits coagulation and/or creaming of oil droplets. When adding eugenol, moreover, ζ-potential of oil droplets increases negatively, and viscosity of the external water phase of the emulsion rises drastically. The increment in ζ-potential and viscosity by the addition of eugenol also prevents oil droplets from coagulation and/or creaming and makes the O/W emulsion still more stable.     

Sur le calcul a priori des déplacements chimiques de 1H et de 19F

We propose a new method for calculating ¹H and ¹⁹F chemical shifts in saturated organic compounds. Results show that the shifts are a balance of several contributions and allow an evaluation of these effects: a diamagnetic contribution d(—?) proportional to the net charge ? of the electronic environment of the nucleus considered and paramagnetic contributions p_X of each of substituents, constant attached to the substituent X in any molecule. For both nuclei, d values were deduced from a theoretical calculation of the screen in the free atom. This method, using a restricted number of parameters obtained from experiment, lead to the observed chemical shifts with a mean accuracy of ± 0,32 ppm for ¹H and ± 11 ppm for ¹⁹F. Therefore this method gives a simple quantitative relation between chemical shift and structure from which precise indications about the origin of the contributions from neighbouring electronic surroundings can be obtained.     

A sensitive method for determination of allergenic fragrance terpene hydroperoxides using liquid chromatography coupled with tandem mass spectrometry

Different compositions of monoterpenes are utilized for their pleasant scent in cosmetics and perfumes. However, the most commonly used fragrance terpenes easily oxidize upon contact with air, forming strongly skin‐sensitizing hydroperoxides. Due to their thermolability and low UV absorbance, detection methods for hydroperoxides are scarce. For the first time, a simple and sensitive method using LC/ESI‐MS/MS was developed to quantitatively determine hydroperoxides from the common fragrance compounds linalool, linalyl acetate, and limonene. The method was applied to autoxidized petitgrain oil and sweet orange oil. A separation was accomplished using a C₃ column. The method LOD for the investigated hydroperoxides in the essential oils was below 0.3 μg/mL, corresponding to 0.3 ppm. For prevention purposes and according to EU regulations, concentrations in cosmetics exceeding 100 ppm in “rinse‐off” and 10 ppm in “stay‐on” products of linalool and limonene must be labeled. However, the products may still contain allergens, such as hydroperoxides, formed by oxidative degradation of their parent terpenes. The sensitivity and selectivity of the presented LC/MS/MS method enables detection of hydroperoxides from the fragrance terpenes linalool, linalyl acetate, and limonene. However, for routine measurements, the method requires further validation.     

Release Behavior of Flavor Encapsulated CD in Slurry Solution Under Boiling Conditions

Cyclodextrin (CD) can control flavor release rate and protect the flavor from volatilization by the formation of inclusion complex with flavor compounds. However, the flavor release rate during cooking, particularly in boiling water has hardly been understood. In this study, flavor release rate of flavor encapsulated CD in slurry or turbid solution under boiling condition was investigated. The release rate constants of methyl caproate and d-limonene depended on the CD concentration, whereas, those of phenyl ethanol hardly did. The plot of a reciprocal number of apparent release rate constant to CD concentration for d-limonene stability constant under boiling condition was obtained. Stability constants for d-limonene in α-CD and β-CD were 185 and 38 M⁻¹, respectively. These stability constants were smaller than the order of 1000 M⁻¹ at room temperature. These results suggested that the addition of CD for protection of flavors in boiling water might have small effect in comparison to that at room temperature. The behavior of flavor release in the boiling water correlated well with the first-order release rate equation, which can be described by the film theory of the interfacial mass transfer.     

Etude théorique des déplacements chimiques du phosphore en RMN

Phosphorus chemical shifts have been evaluated by means of the perturbation theory using CNDO/S wave functions in phosphine, phosphite, phosphonate and phosphate derivatives. The necessity of introducing 3d orbitals of phosphorus and of using Z_eff3d as an adjustable parameter for each family of compounds is shown. Calculated values agree with experimental ones.     

Synthesis and cyclization reactions with pyrazolopyrimidinyl keto esters part I. Reactivity of pyrazolopyrimidinyl β-keto ester and pyrazolopyrimidinyl α,β-unsaturated ketones

5-Acetyl-4,5-dihydro-1-phenylpyrazolo[3,4-d]pyrimidin-4-one was prepared and subjected to various chemical transformations to give novel 5-heterocyclic pyrazolopyrimidinone derivatives of expected important biological activity. Then, the latter compounds were used to obtain β-keto ester and α,β-unsaturated carbonylpyrazolopyrimidinones which were used as alternate precursors to produce new pyrazolopyrimidinones substituted with five-membered heterocycles such as pyrazole and isoxazole. The structure of these compounds was identified on the basis of their chemical behaviour as well as elemental and spectral analysis.     

Glycoconjugates of amines: alkylation of primary and secondary amines withN-chloroacetyl-β-glycopyranosylamines

Efficient monoalkylation of a series of primary and secondary amines was demonstrated with the use ofN-chloroacetylglycosylamines derived fromd-glucose,d-galactose,d-mannose,N-acetyl-d-glucosamine, and lactose. The reaction was shown to be useful for incorporation of carbohydrate residues into physiologically active compounds. Glycoconjugates of some derivatives of piperazine, 2-phenylethylamine, tryptamine, and important biogenic amines (norephedrine, octopamine, dopamine) were prepared. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 6, pp. 1244–1247, June, 1998.