One Alkenylphenol and Steroids from the Aquatic Plant Monochoria Vaginalis

Two new compounds have been isolated from the whole plant of Monochoria vaginalis and characterized as: (10Z)‐1‐(2,6‐dihydroxyphenyl)octadec‐10‐en‐1‐one ( 1 ) (20R, 24R)‐campest‐5‐ene‐3β, 4β‐diol ( 2 ) together with nine known ones. The structures of these compounds were elucidated on the basis of spectral data and chemical evidence.     

Convenient and High-Yielding Preparations of Mono(5-carboxy-2-ethylpentyl) Phthalate and its Ring-Deuterated Isomer – The “Third” Major Metabolite of Bis(2-ethylhexyl) Phthalate

Summary. The synthesis of an oxidative major metabolite of bis(2-ethylhexyl) phthalate is described. The target molecule and its ring-deuterated isomer were obtained via acylation of the appropriate -hydroxy benzyl ester or the corresponding carboxylate with phthalic anhydride or phthalic anhydride-d₄. All transformation steps proceed with high yields.     

Structure elucidation of triglycerides by chromatographic techniques. Part 1: Capillary GC of ozonized triglycerides

Structure determination of triglycerides according to their number of unsaturated fatty acids (N.U.F.A.) is more easily achieved after ozonolysis of their mixtures (fats and oils) than by capillary gas chromatographic analysis of the mixture as such. Analyses performed before and after ozonolysis of cocoa buttel, hazelnut oil, and a mixture of both fats illustrate the potential of this approach to the structure elucidation of triglycerides by chromatographic techniques.     

Synthesis of Chiral Cyclohexenones from α-Campholenic,Fencholenic, and β-Campholenic Derivatives

Summary. Optically active dimethylcyclohexenones, potential building blocks for enantioselective syntheses of various naturally active substances, were prepared. These compounds were obtained by oxidation with KMnO₄/Pb(OAc)₄ or ozonolysis of the corresponding cyclopentenic precursors, followed by aldol condensation. During the course of the preparation intermediate diols and chiral polyfunctional carbonyl derivatives were separated and identified analytically.     

Vacuum Ultraviolet Free-Electron Laser Photoionization Mass Spectrometry of Alpha-pinene Ozonolysis

\begin{document}$\alpha$\end{document}-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds. Molecular identification of key transient compounds during the \begin{document}$\alpha$\end{document}-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved. Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study the \begin{document}$\alpha$\end{document}-pinene ozonolysis. The experiments of \begin{document}$\alpha$\end{document}-pinene ozonolysis are performed in an indoor smog chamber, with reactor having a volume of 2 m\begin{document}$^3$\end{document} which is made of fluorinated ethylene propylene film. Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction of \begin{document}$\alpha$\end{document}-pinene with O\begin{document}$_3$\end{document}. With the aid of quantum chemical calculations, plausible mechanisms for the formation of these new compounds are proposed. These findings provide crucial information on fundamental understanding of the initial steps of \begin{document}$\alpha$\end{document}-pinene oxidation and the subsequent processes of new particle formation.     

Micro-droplet Trapping and Manipulation: Understanding Aerosol Better for a Healthier Environment

Understanding the physicochemical properties and heterogeneous processes of aerosols is key not only to elucidate the impacts of aerosols on the atmosphere and humans but also to exploit their further applications, especially for a healthier environment. Experiments that allow for spatially control of single aerosol particles and investigations on the fundamental properties and heterogeneous chemistry at the single-particle level have flourished during the last few decades, and significant breakthroughs in recent years promise better control and novel applications aimed at resolving key issues in aerosol science. Here we propose graphene oxide (GO) aerosols as prototype aerosols containing polycyclic aromatic hydrocarbons, and GO can behave as two-dimensional surfactants which could modify the interfacial properties of aerosols. We describe the techniques of trapping single particles and furthermore the current status of the optical spectroscopy and chemistry of GO. The current applications of these single-particle trapping techniques are summarized and interesting future applications of GO aerosols are discussed.     

A short and concise route to total synthesis of Dendrodolide L

A short and efficient method for the stereoselective synthesis of Dendrodolide L has been developed from inexpensive and commercially available starting material. This convergent synthesis utilizes Jacobsen kinetic resolution, regioselective ring-opening of epoxide and Yamaguchi macrolactonization as key steps.     

Unusual reactivity of bicyclo[2.2.1]heptene derivatives during the ozonolysis. Part 2

The ozonation of four bornene derivatives, prepared from (R)-(+)-pulegone, which possess a particularly hindered double bond, led to the formation of unexpected products depending on the nature of the solvent. The formation of the corresponding epoxides, ketones with the same skeleton, various lactones and even an allyl alcohol and an allyl chloride (allylic functionalisation) was observed. In two cases, products presenting a pulegone modified skeleton resulting from a Wagner-Meerwein rearrangement were obtained. The structure of three products was confirmed by crystallographic X-ray analysis. Mechanisms taking into account the rigid and congested structure of the reactants explain these results. The most striking steps were backed up by theoretical calculations.     

Random low vinyl styrene-isoprene copolymers

The present work is to the syntheses and characterization of random, low vinyl copolymers containing styrene and isoprene (SIR’s). The content of these SIR’s ranged from 10% styrene/90% isoprene to 60% styrene/40% isoprene, and all were soluble in hexane solvent. The anionic polymerization of these SIR’s was initiated by a catalyst system of various sodium dodecylbenzene sulfonate (SDBS) to n-butyllithium (n-BuLi) ratios. The SDBS allowed for styrene to become randomly incorporated onto the polyisoprene chain without any increase in the 3,4-unit of the isoprene. The glass transition temperature of the resulting polymers could be controlled by the styrene content and microstructure (blocky versus random) in the polymer chain. Kinetic data confirmed that styrene and isoprene have similar reaction kinetics. NMR and ozonolysis confirmed that random, low vinyl SIR’s were indeed being synthesized. The unique features of this system are that it does not metallate the polymers as was seen in the previous publication using the sodium and potassium alkoxides. Molecular weight differences due to SDBS are discussed. Finally, rubber process analyzer (RPA) results were presented for various styrenes content SIR’s.