Determination of Phytosterols in vegetable oils by GC-MS method

In this study, a method for determination of six phytosterols by gas chromatography-mass spectrometry with derivatization in vegetable oils was validated. The samples were hydrolyzed in an alkaline media at 70°C for 60 min. Then, the samples were performed liquid-liquid extraction with toluene. The phytosterols are derivatized to trimethylsilyl ethers and then analyzed by gas chromatography-mass spectrometry. The limit of detection and limit of quantification was 5 and 15 mg/kg, respectively. Recoveries of six phytosterols were between 93.5% and 101%.

Cyanosilylation of Aldehydes Catalyzed by Ag(I)- and Cu(II)-Arylhydrazone Coordination Polymers in Conventional and in Ionic Liquid Media

The novel Ag(I) and Cu(II) coordination polymers [Ag(μ3-1κO;2:3κO′;4κN-HL)]n∙n/2H2O (1) and [Cu(en)2(μ-1κO;2κN-L)]n∙nH2O (2) [HL− = 2-(2-(1-cyano-2-oxopropylidene)hydrazinyl)benzene sulfonate] were synthesized and characterized by IR and ESI-MS spectroscopies, elemental and single crystal X-ray diffraction analyses. Compounds 1 and 2 as well as the already known complex salt [Cu(H2O)2(en)2](HL)2 (3) have been tested as homogenous catalysts for the cyanosilylation reaction of different aldehydes with trimethylsilyl cyanide, to provide cyanohydrin trimethylsilyl ethers. Coordination polymer 2 was found to be the most efficient one, with yields ranging from 76 to 88% in methanol, which increases up to 99% by addition of the ionic liquid [DHTMG][L-Lactate].

Iron-Catalyzed Grignard Cross-Couplings with Allylic Methyl Ethers or Allylic Trimethylsilyl Ethers

We have found that cross-coupling between aryl Grignard reagents and allylic methyl ethers proceeded well in the presence of a catalytic amounts of Fe(acac)3 to afford the corresponding allylic substitution products in good yields. Under the same conditions, allylic trimethylsilyl ethers also reacted with Grignard reagents to give the corresponding cross-coupling products.

Sugar profile determination of four pure Greek honeys by gas-chromatography

Honey sugar determination was performed by using a combination of two methods (Iverson & Bueno, 1981 and Pierce no. 16, 1990) with some modifications. The proposed by Pierce method no.16, has been designed to assist in the routine determination of sugars in food products and syrups. Sugars are treated with hydroxylamine hydrochloride and the resulting oximes are converted to trimethylsilyl ethers by direct silylation with TMS. The derivatives are then determined by gas-chromatography with flame ionization detector and sugar oxime-TMS derivatives are quantitative and reproducible. This reaction is fast and simple, the results are quantitatively reproducible and multiple peaks due to the tautomeric forms of reducing sugars, which produced by direct TMS derivatization, are eliminated. From the honey samples analyzed it has been determined that only fir-tree honey contains trisaccharides with higher percentages that of melezitose.

Cyanosilylation of Aldehydes Catalyzed by Iron(III) Arylhydrazone-β-Diketone Complexes

Two known iron(iii) complexes, [Fe(H2O)3(L1)]·xH2O (x = 4 (1), 5 (2)) and [Fe(H2O)3(L2)]·3H2O (3), bearing the basic forms of 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxybenzenesulfonic acid (H3L1) and 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonic acid (H3L2), were prepared and used as homogeneous catalysts for cyanosilylation of a variety of aldehydes with trimethylsilyl cyanide leading to the corresponding cyanohydrin trimethylsilyl ethers. High yield (up to 98 %) was observed in the reaction catalyzed by 3 at room temperature in methanol.