Mass spectrometric characterization of isomeric terpenoic acids from the oxidation of α-pinene, β-pinene, d-limonene, and Δ3-carene in fine forest aerosol

In this study, we present liquid chromatographic and mass spectral data for predominant terpenoic acids formed through oxidation of α-pinene, β-pinene, d-limonene, and Δ(3)-carene that occur in fine forest aerosol from K-puszta, Hungary, a rural site with coniferous vegetation. Characterization of these secondary organic aerosol tracers in fine ambient aerosol is important because it allows one to gain information on monoterpene precursors and source processes such as oxidation and aging processes. The mass spectral data were obtained using electrospray ionization in the negative ion mode, accurate mass measurements, and linear ion trap tandem mass spectrometric experiments. Emphasis is given to the mass spectrometric differentiation of isobaric terpenoic acids, such as, e.g. the molecular weight (MW) 186 terpenoic acids, cis-pinic, cis-caric, homoterpenylic, ketolimononic, and limonic acids. Other targeted isobaric terpenoic acids are the MW 184 terpenoic acids, cis-pinonic and cis-caronic acids, and the MW 204 tricarboxylic acids, 3-methyl-1,2,3-butanetricarboxylic and 3-carboxyheptanedioic acids. Fragmentation pathways are proposed to provide a rational explanation for the observed isomeric differences and/or to support the suggested tentative structures. For the completeness of the data set, data obtained for recently reported lactone-containing terpenoic acids (i.e. terpenylic and terebic acids), related or isobaric compounds (i.e. norpinic acid, diaterpenylic acid acetate, and unknown MW 188 compounds) are also included, the rationale being that other groups working on this topic could use this data compilation as a reference.     

The photometric determination of silicon as α-silicomolybdic acid

A photometric method for the determination of silicon based on the yellow color of α-silicomolybdic acid is described. The pH must be kept within the range 3.0–3.7, and the equilibrium state is established by beating the solution. Since the color of this modification is remarkably stable and reproducible, a high degree of precision can be attained.     

The condensation reaction of methylphosphonic acid with α,ω-diethoxydimethylsiloxanes

Russian Chemical Bulletin -     

Reactions of 3-carene, limonene, and α-pinene nitrosochlorides with imidazole, benzotriazole, and indole

The reactions of terpene nitrosochlorides derived from 3-carene, ??-pinene, and limonene, with simplest azaheterocycles (imidazole, benzotriazole, and indole) were studied. On the base of these transformations, preparative procedures to access chiral oximes bearing azaheterocyclic moieties in the ??-position to the oxime fragment, namely, ??-(1H-imidazol-1-yl)-, ??-(1H-benzo-[d][1,2,3]triazol-1-yl)-, and ??-(1H-indol-3-yl)-substituted terpenic oximes, were developed. Transformations of the studied monoterpene nitrosochlorides into ??-substituted oximes proceeded stereoselectively to give in the moderate yields (30?C60%) the only stereoisomer arising from the attack of the heterocyclic anion from the less hindered side of the intermediate nitroso olefin generated in situ from nitrosochloride.     

The thermolysis of α-pinene and verbenone epoxides in supercritical solvents

Thermal transformations of α-pinene and verbenone epoxides were studied in supercritical solvents with complex compositions, including CO₂, lower alcohols (ethanol and isopropanol), and water, over the temperature and pressure ranges 387–575 K and 135–215 atm. The main product from α-pinene epoxide in a supercritical solvent containing water was campholenic aldehyde and pinocamphone; the total content of these products in the reaction mixture was 80%. Suggestions concerning the mechanism of the thermal isomerization of α-pinene epoxide depending on the acidity of supercritical solvents were made. The direction of verbenone epoxide transformations was independent of the presence of water in the mixture. The main identified products were ketoalcohols with para-menthane and camphane frameworks.     

Reactions of N,N′-diphenyl-p-quinonediimine with hydroquinone, α-tocopherol,and other antioxidants

Phenols (hydroquinone and -tocopherol) and heterocyclic aminophenols (2,2,4-trimethyl-6-ethoxy-1,2-dihyroquinoline) reduce N,N-diphenyl-p-quinonediimine (A) to the diamine. With difunctional hydrogen atom donors, the reaction rate is proportional to the concentrations of the reactants. The effective rate constants have been determined over a range of temperatures. In the reaction of A with -tocopherol, plots of rate versus initial concentrations are nonlinear, 2,6-Di-tert-butyl-4-methylphenol and 2,2,4-trimethyl-6-ethoxy-1,2-dihyroquinoline do not react with A under the same conditions.N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 417–420, February, 1992.     

Inclusion complexes of α- andβ-cyclodextrin with α-lipoic acid

A UV spectroscopic study has been performed in neutral aqueous solution to give the complex stability constants. Data analyses assuming 1:1 stoichiometry were successfully applied to both of the host-guest combinations employed, where 1:1 host-guest complex formations were observed at lower concentration of cyclodextrins (CDs). X-ray powder diffraction and IR spectroscopy measurements also demonstrated that inclusion complexes were formed in the solid state. Furthermore, thermogravimetry and DTA were used to investigated the thermal properties of these complexes. The differential thermal analysis, as well as temperature variation experiments below 100°C, indicated that after complexing the 1,2-thiolane moiety of -lipoic acid (LP) penetrated into the cavity of the CD and the S-S linkage was protected against heat.     

The Reaction of α,α-Dichlorobenzyltrimethylsilane with Aldehydes and Ketones

The reaction of α,α-dichlorobenzyltrimethylsilane with carbonyl compounds in the presence of fluoride ion fails to give reasonable yields of the α,α-dichlorobenzyl adducts except when carried out in the presence of zinc iodide and in HMPA as solvent. Under these conditions moderate yields of the adducts can be obtained with cyclohexanone, cyclohexenone, benzaldhyde and trans cinnamaldehyde. These reactions were compared with those of α,α-dichlorobenzyllithium.     

Binding behaviors of scutellarin with α-, β-, γ-cyclodextrins and their derivatives

A series of cyclodextrin/scutellarin inclusion complexes were prepared from α-cyclodextrin, β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin with scutellarin (SCU), and their inclusion complexation behaviors, such as stoichiometry, complex stability constants and inclusion mode, were investigated by means of UV/Vis spectroscopy, ¹H NMR and 2D NMR. The results showed that the SCU could be efficiently encapsulated in the cyclodextrin cavity in aqueous solution to produce complexes that were more soluble than free SCU. The enhanced binding ability of cyclodextrins towards SCU was discussed from the viewpoint of the size/shape-fit and multiple recognition mechanism between host and guest.     

Host–guest complexation of antioxidative caffeic and ferulic acid amides with a functionalized cyclophane

Host?guest complexation has been studied by ¹H NMR on the benzyl and phenethyl amides of ferulic and caffeic acids as the guests in chloroform and acetonitrile; the counter host is a cyclophane which integrates four phenylene rings, amino and amide groups in the macrocyclic framework and bears four pendant methyl acetate ester arms. CAPE, one of the best known natural antioxidants, also has been studied for comparison. Among the guests studied, ferulic acid benzyl amide shows NMR shifts due to the formation of a host?guest complex in chloroform. The complexation occurs in two steps with the formation constants K ₁?=?[HG]/[H][G]?=?6?M^?1 and β ₂?=?[HG₂]/[H][G]²?=?87?M^?2. Two guest molecules are bound on the surface of the macrocyclic framework of a host molecule by two hydrogen bonds, NH(host amide)···O=C(guest amide) and C=O(host ester)···HO(guest phenol). The latter hydrogen bond may protect the bioactive site, i.e., phenol OH, of guest molecules captured in the complex against undesirable oxidation. This feature is observed only for ferulic acid benzyl amide in chloroform; the cyclophane ester interacts with this amide, distinctively from the other hydroxycinnamic acid derivatives.     

Reaction of α-cyanoacrylic acid and cyanoacrylates with dialkyl and diaryl phosphites

-Cyanoacrylic acid and -cyanoacrylates add dialkyl and diaryl phosphites and diethyl thiophosphite at the C=C double bond in the absence of catalyst. This is an anti-Markovnikov reaction, which yields the corresponding phosphonates and thiophosphonates.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1913–1915, August, 1992.     

Correction to: Effect of varying biogas mass flow rate on performance and emission characteristics of a diesel engine fuelled with blends of n‑butanol and diesel

Journal of Thermal Analysis and Calorimetry - In the original publication of the article, Figs. 6 and 7 were published incorrectly without test fuel D80/nb20+BG (0.5 kg/h).     

The reduction of α,β-unsaturated nitriles and α-halonitriles with sodium hydrogen telluride

Sodium hydrogen telluride reacts chemoselectively with α,β-unsaturated nitriles and α-halonitriles linked to aromatic and aliphatic substituents to give the corresponding saturated nitriles with good yields.     

Diphenylparabanic acid as a synthon for the synthesis of α-diketones and α-ketocarboxylic acids

Diphenylparabanic acid was found to react with >2 equiv of organolithiums at -78 °C to effectively give the corresponding symmetrical α-diketones. However, upon treatment with 1 equiv of organolithium, the parabanic acid gave mainly 5-substituted 5-hydroxyimidazolidine-2,4-diones. On the other hand, Grignard reagents were less reactive toward the parabanic acid at low temperature, and selectively gave the corresponding 5-hydroxyimidazolidine-2,4-diones even if more than 1 equiv of the reagents was used. A tandem process in which the parabanic acid was first reacted with a Grignard reagent and then reacted in one-pot with an organolithium effectively gave the unsymmetrical α-diketone. 5-Substituted 5-hydroxyimidazolidine-2,4-diones were useful as versatile precursors for preparing α-ketocarboxylic acids as well as unsymmetrical α-diketones.     

Exergetic and exergoeconomic analyses of a diesel engine fueled with binary and ternary blends of diesel–palm oil biodiesel–diethyl ether for various injection timings

Journal of Thermal Analysis and Calorimetry - In this study, ten different blends were prepared with binary and ternary combinations of diesel, palm oil biodiesel (0 vol%,...     

Reaction of unsymmetrical α,β-unsaturated ketones with thiobarbituric acid

Carbocyclization of unsymmetrical 1,5-diarylpenta-1,4-dien-3-ones with thiobarbituric acid afforded previously unknown 7,11-diaryl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-triones with high regio- and stereoselectivity. The same spiro compounds were also synthesized by three-component condensation of thiobarbituric acid with the corresponding aromatic aldehydes and 4-arylbut-3-en-2-ones.     

Syntheses of carbocyclic analogues of α-D-glucosamine, α-D-mannose, α-D-mannuronic acid, β-L-idosamine, and β-L-gulose

A versatile synthesis of orthogonally protected derivatives of carba-α-D-glucosamine, carba-α-D-mannose, carba-α-D-mannuronic acid, carba-β-L-idosamine, and carba-β-L-gulose from methyl α-D-mannoside is described. Our synthetic strategy utilizes the palladium-promoted Ferrier carbocyclization and persistent butane-2,3-diacetal protection to produce a key chiral cyclohexanone intermediate, from which all five carbasugar derivatives can readily be obtained.     

Structural and thermal properties of rare earth complexes with 2,2′-biphenyldicarboxylic acid

Rare earth complexes with 2,2′-biphenyldicarboxylic acid (diphenic acid = H₂dpa) were obtained as hydrated precipitates of the general formula Ln₂(C₁₄H₈O₄)₃∙nH₂O, where n = 3 for the of Y(III) and Ce(III)–Er(III) and n = 6 for La(III), Tm(III), Yb(III) and Lu(III) complexes. On heating in air atmosphere complexes lose all water molecules in the temperature range 30–210 °C in one step and form anhydrous compounds, which are stable up to 315–370 °C. During further heating they decompose to oxides. The trihydrated compounds are crystalline powders whereas the hexahydrated are amorphous solids. The trihydrated complexes crystallize in the monoclinic (Pr(III) and Ce(III) complexes) and triclinic (Y(III) and Nd(III)–Er(III) complexes) crystal systems.     

Synthesis of arylglycine and mandelic acid derivatives through carboxylations of α-amido and α-acetoxy stannanes with carbon dioxide

Incorporation reactions of carbon dioxide (CO(2)) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO(2) pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO(2) pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α-amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.