Ionic liquid effects on the reaction of β-enaminones and tert-butylhydrazine and applications for the synthesis of pyrazoles

In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF₄], [BMIM][Br], [OMIM][BF₄], [BMIM][PF₆], [DBMIM][Br], [DBMIM][BF₄], [BMIM][OH], [BMIM][SCN], [HMIM][HSO₄] and [HMIM][CF₃CO₂]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CHCHNMe₂, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO₂-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF₄].     

Effect of dicationic ionic liquids on cloud points of tergitol surfactant and the formation of aqueous micellar two-phase systems

Journal of Materials Science - A cloud point evaluation was performed for the nonionic surfactant Tergitol 15-S-7 in aqueous solutions of McIlvaine buffer (pH 7.0). Cloud point temperatures of the...     

Fractionation of citronella (Cymbopogon winterianus) essential oil and concentrated orange oil phase by batch vacuum distillation

The aim of this work was to assess the performance of a vacuum fractionating column for the fractionation of citronella essential oil and concentrated orange oil phase during batch mode operation at different pressures, from 20 to 1 mbar and reflux ratios from 1:1 to 10:1. Fractions from column top and bottom were analyzed by gas chromatography (GC/FID) using authentic standards of major constituents of the oils. Good fractionation results for citronella essential oil were achieved, affording complete removal of limonene, with a rich citronellal fraction and an output stream constituted mainly by citronellol and geraniol. Likewise, the use of the vacuum fractionation column allowed almost complete removal of limonene (∼0.7 wt% at column bottom) from the orange oil phase at the lowest operating pressure, 1 mbar, while the higher valencene content (20.5 wt%) was obtained at 10 mbar and reflux ratio of 1:1.     

Catalytic oxidation of concentrated orange oil phase by synthetic metallic complexes biomimetic to MMO enzyme

BACKGROUND: This paper reports the catalytic oxidation of the concentrated orange oil phase using the complexes [Fe^III(BMPP)Cl(µ‐O)Fe^IIICl₃], [Cu^II(BTMEA)₂Cl]Cl and [Co^II(BMPP)]Cl₂ biomimetic to methane monooxygenase enzyme as catalysts and hydrogen peroxide as oxidant. RESULTS: The reaction products of oil oxidation, mainly nootkatone, were identified by gas chromatography/mass spectrometry. A screening of catalysts was performed through a full 2³ experimental design, varying the temperature from 30 to 70 °C, the catalyst concentration from 7.0 × 10^?4 to 1.5 × 10^?3 mol L^?1 and the oxidant/substrate molar ratio from 1:1 to 3:1. The results of reaction kinetics employing the most promising catalysts showed that conversions to nootkatone of up to 8% were achieved after 16 h at 70 °C. CONCLUSION: The results obtained in this study in terms of nootkatone production should be considered encouraging, since a real, industrially collected, raw material, instead of pure valencene, was employed in the reaction experiments, with a final content about ten times that present in the original concentrated oil. Copyright © 2010 Society of Chemical Industry     

Synergic Effects of Ionic Liquid and Microwave Irradiation in Promoting Trifluoromethylpyrazole Synthesis

Abstract  

The synthesis of 5-trifluoromethyl-1-phenyl-1H-pyrazoles from the reactions of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF₃C(O)CH=C(R¹)OR, where R = Me, Et; R¹ = H, Me, Bu, i-Bu, Ph, 4-MeC₆H₄, 4-FC₆H₄, 4-ClC₆H₄, 4-BrC₆H_4, 4-IC₆H_4, fur-2-yl] with phenyl hydrazine in the presence of ionic liquid [BMIM][BF₄] is reported. Synergic effects of ionic liquid and microwave irradiation in promoting pyrazole synthesis have been shown for the first time.     

Ionic Liquids Promoted the C-Acylation of Acetals in Solvent-free Conditions

The synthesis of a series of fourteen 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (2,3) [CX₃COC(R²)=C(R¹)OMe, where X = Cl, F; R¹/R² = Me/H, Bu/H, i-Bu/H, Ph/H, Thien-2-yl/H, –(CH₂)₄–, –CH(CH₂)₄CH(CH₂)₂–] from the acylation reactions of acetals (1) with trichloroacetyl chloride or trifluoroacetic anhydride in the presence of equimolar amounts of pyridine and imidazolium based ionic liquid ([BMIM][BF₄] or [BMIM][PF₆]) is reported. The reaction time, yields and IL recyclation are also investigated and this method showed advantages over the methods described in the literature.     

Lead content of dietary calcium supplements available in Brazil.

The lead and calcium content of calcium supplements available in Brazil were determined by graphite furnace and flame atomic absorption spectrometry, respectively. Samples were microwave-digested in concentrated HNO(3). Citric acid was used as a chemical modifier in the lead analysis. Supplements were classified into six categories: oyster industrialized (OI, n=4), oyster prepared in pharmacy (OP, n=3), refined industrialized (RI, n=6), refined prepared in pharmacy (RP, n=3), bone meal (B, n=3), and dolomite (D, n=4). Lead levels (microg g(-1) of measured calcium) were higher in D products (2.33), followed by OI, RP, OP, and RI products (1.46, 1.32, 1.29, 0.75), while B products had levels lower than the limit of quantification (0.02 microg g(-1) unit weight). Daily lead intake of eight supplements exceeded the limit of California, USA (1.5 microg g(-1) calcium), but none exceeded the federal limit of USA (7.5 microg g(-1) calcium) or the provisional tolerable lead intake by FAO/WHO (25 microg kg(-1) per week).