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Koleksiyon Organik Kimya Anabil ...
167251

Some synthetic cyclitol derivatives alleviate the effect of water deficit in cultivated and wild-type chickpea species

Yıldızlı Aytunç, Güzel Değer Ayşin

Cyclitols were prepared from corresponding allylic hydroperoxides, synthesized by photooxygenation of the appropriate cyclic alkenes. These hydroperoxides were then separately treated with a catalytic amount of OsO4. Synthesized dl-cyclopentane-1,2,3-triol 9 (A), dl-cyclohexane-1,2,3-triol 12 (B), and dl-cycloheptane-1,2,3-triol 15 (C) were used in the investigation of plant stress. Antioxidants, lipid peroxidation, and water status of chickpea species exposed to synthetic cyclitols under water deficit were examined. Cyclitol derivatives significantly decreased leaf water potential, lipid peroxidation and H2O2 levels of wild and cultivated species under water deficit. Cyclitol treatments affected antioxidant enzyme activities differently in both species under water deficit. The highest SOD...

167243

Oxidation of Alchols to Carbonyl Compounds Benzylic Carbons to their Ketones and Arenes to their Quinones with Molecular Oxygen in Subcritical Water

Özen Recep, Şimşek Kuş Nermin

Molecular oxygen is used as an efficient oxidant for the conversion of alcohols into carbonyl compounds, benzylic carbons to their ketones, and arenes to their quinones in subcritical water in the absence of catalysts. The procedure utilizes water and does not require support materials and metal salts.

167242

OXIDATION OF TOLUENES TO AROMATIC ALDEHYDES WITH MOLECULAR OXYGEN IN SUBCRITICAL WATER

Recep Özen, Ahmet M. Gizir & N. Simsek Kus

Oxidations are important transformations in organic synthesis. In general, many oxidations are carried out with a large excess of chromium or manganese reagents. The metal residues are environmentally undesirable and often cause problems during work-up.2 In addition organic oxidations in the chemical industry have traditionally been performed in either aromatic or halogenated solvents.' One of the most attractive oxidants is molecular oxygen? since oxygen is highly soluble in subcritical water. Molecular oxygen has been used as the reagent for the oxidation of alkyl aromatic compounds in the presence of different catalysts, such as MnBr.

167244

A Mild and Effective Method for the Conversion of Alkenes into Alcohols in Subcritical Water

Özen Recep, Şimşek Kuş Nermin

lkenes were oxidized to alcohols in subcritical water. A number of alkenes were oxidized directly to their alcohols in excellent yields. The syntheses were performed in 215 cm3 stainless steel high pressure reactor at 120 ºC in 150 cm3 water. The yields of alcohols increased with the nitrogen pressure.

166783

Corrosion inhibition of indole-3-acetic acid on mild steel in 0.5 M HCl

Avcı, Gülşen

Corrosion inhibition of indole-3-acetic acid on mild steel in acidic medium (0.5 M HCl) containing the desired amount of inhibitor has been investigated at different temperatures by using potentiodynamic polarization, electrochemical impedance spectroscopy, and polarization resistance measurements. The experimental results showed that corrosion potential shifted toward a more negative potential region in the presence of indole-3-acetic acid than that of blank solution. According to the obtained results from all measurements, inhibition efficiency was about 77% with 1.7 × 10−3 M inhibitor present, increasing to about 93% at the 1 × 10−2 M inhibitor concentration. Potentiodynamic polarization measurements showed that the current at anodic and cathodic regions obtains a smaller value in the p...

167252

Diels Alder reactions The effects of catalyst on the addition reaction

Yılmaz Özgür, Şimşek Kuş Nermin

The reaction between 2,3-dimethyl-1,3-butadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3dicarboxylate is efficiently achieved with small amounts of catalyst, i.e. phenol, AcOH, nafion, and b cyclodextrin. Exo-diastereoselective cycloaddition reactions were observed both without catalyst and different catalysts for 48 days. As a result, different products (tricyclicmolecule 5, retro-DielseAlder product 6, and oxidation product 7) were obtained with different catalysts. In addition, we synthesized DielseAlders product 8 and tricyclocyclitol 10 via DielseAlder reaction. The structures of these products were characterized by 1H NMR, 13C NMR, MS and IR spectroscopy.

167250

Simple and convenient preparation of some bicyclic alcohols and epoxide derivatives promising antibiotic activities of rac dimethyl 3 8 dioxatricyclo 3 2 1 02 4 oct 6 ene 6 7 dicarboxylate

Yılmaz Özgür, Şimşek Kuş Nermin

The biological activity of alcohol and epoxide groups containing bicyclic skeletal structures was investi- gated in terms of antibiotic and toxic effects at cellular level. The present protocol, which utilizes readily available starting materials and mild reaction conditions, provides an attractive approach to a series of functionalized bicyclic alcohol and epoxide derivatives with promising biological applications. In this protocol, while some of the bicyclic compounds were synthesized as in the literature, the other bicyclic compounds were synthesized by new synthetic methods. The antibiotic and toxic properties of the syn- thesized bicyclic compounds were investigated, and some of their biological activities were tested in prokaryotic and eukaryotic systems. (rac)-Dimethyl 3,8-dioxatric...

167240

High temperature bromination XIII Bromination of dimethyl 7 oxabicyclo 2 2 1 hepta 2 5 diene 2 3 dicarboxylate

Kuş, Nermin Şimşek

The electrophilic addition of bromine to dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate 10 at 0 and −60°C led in high yield to the formation of dibromide 11. However, high-temperature bromination of 10 in carbon tetrachloride at 77°C gave four products 12–15, three of them with nonrearranged skeleton. Similarly, bromination of the dibromides 14 and 15 at 77°C yielded the nonrearranged tetrabromides 13 and 16, respectively. The structure of the tetrabromide 13 was solved by single-crystal X-ray analysis. The formation mechanism is discussed and supported by calculations

167249

One-step synthesis of substituted isobenzofuran-1(3H)-ones and isobenzofuran-1,3-diones from indane derivatives in subcritical media

Kuş, Nermin Şimşek

Molecular oxygen is one of the most attractive oxidants in organic synthesis because it is highly soluble in subcritical water. In this study, indane derivatives were oxidized to the corresponding isobenzofuran-1(3H)-one with molecular oxygen and isobenzofuran-1,3-dione with a mixture of molecular oxygen and H2O2 in subcritical water. This paper describes a simple, economic, environmentally benign,and general procedure that can be used for the synthesis of substituted isobenzofuran-1(3H)-ones and isobenzofuran-1,3-diones in only one step and without catalyst.

167276

28. Ulusal kimya Kongresi özet kitabı

Şimşek Kuş Nermin,

28. Ulusal kimya Kongresi özet kitabı

167275

ORGANİK KİMYA "YAŞAMIN KALBİ"

Kuş, Prof. Dr. Nermin Şimşek

KARBOKSİLİK ASİTLER

166230

Yemler Bilgisi Yem Teknolojisi ve Balık Besleme

Bilgüven, Murat

Her havuz alanında ya da yetiştirme biriminden elde edilen balık ve dolayısıyla balık yetiştiriciliğinin kârlılığı, büyük ölçüde kullanılan yemin miktarına bağlıdır. Su ürünleri sistemi ne kadar yoğun olursa yemlemenin önemi o kadar fazla olur ve toplam üretim maliyetinde yem maliyetinin payı da o kadar artar. Bilindiği üzere alabalık başta olmak üzere bazı balıkların yetiştiriciliği için akarsu sistemli tesisler kullanılmakta yada sıcaklığın, su bileşiminin ve akıntının dolayısıyla oksijen yoğunluğunun daha iyi olduğu tatlı su ve kıyılarda ise yüzer ağ kafeslerde yetiştiricilik yapılmaktadır. Su ürünleri yetiştiriciliğinin ileri durumda olduğu ülkelerde entansif yetiştiricilik uygulanmakta ve yetiştirme alanlarında birim hacimde maksimum ürün yetiştirilmeye çalışılmaktadır. Bu tür yetişti...

Kitap2002Akademisyen 268 | 7 Erişime Açık
167247

Concise preparation of azenes by oxidation of aromatic amines with molecular oxygen in subcritical water

Nermin, Şimşek Kuş

Reaction of organic substrates with molecular oxygen, the most abundant and accessible oxidant, has always been an attractive method for preparation of target molecules. In terms of green chemistry, non-metal-catalyzed oxidation of organic substrates is very attractive. This paper describes a general procedure for synthesis of azenes by oxidation of primary aromatic amines with molecular oxygen (3O2) in subcritical water. The reactions afforded the corresponding azenes in moderate to good yield.

167266

Oxidation of Toluenes to Aromatic Aldehydes With Molecular Oxygen in Subcritical Water

Özen Recep, Gizir Ahmet Murat

Oxidation of Toluenes to Aromatic Aldehydes With Molecular Oxygen in Subcritical Water

167274

Chemistry and Alternative Usage of Missile Propellants Stored in Azerbaijan

Zir Ahmet Murat, Şimşek Kuş Nermin

Chemistry and Alternative Usage of Missile Propellants Stored in Azerbaijan

167316

Role of antioxidant defense system and biochemical adaptation on stress tolerance of high mountain and steppe plants

Keleş, Yüksel

Eleven species were collected from Northwest Anatolian mountains (1500–2000 m) and 18 species were collected from the Central Anatolian steppes (850–1000 m) in June 1998 and 1999. In all the species investigated, the water and dry matter percentages and solute contents were measured. The chlorophyll, b-carotene, ascorbate and a-tocopherol contents and catalase (CAT), superoxide dismutase (SOD) andglutathione reductase (GR)enzymeactivities oftheplants werealsodetermined.Thesteppeplantshadlowerwatercontentcomparedwith alpine plants. The chlorophyll contents of the plants investigated did not change with altitude. However, the carotenoid/chlorophyll ratio of alpine plants was found to be significantly higher. The antioxidant/chlorophyll ratio of the trees and shrubs was higher than that of he...

Makale2004Acta Oecologica 35 | 0 Erişime Açık
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