Microwave assisted synthesis of imine derivates

In this study, a series of imine derivatives were synthesized by condensation of some carbonyl compounds such as acetyl acetone, benzoin and benzil with some substituted anilines and aliphatic diamines. All the synthesis were done in a modified domestic microwave oven. The reactions were performed in different reaction conditions such as neat, in solution, and at solid phase and optimum conditions were investigated in microwave conditions for the shorter reaction time and higher yields. Structures of the compounds were identified by using IR, 1H-NMR and 13C-NMR techniques. Microwave assisted synthesis of the imines in ethanol from acetyl acetone were achieved in shorter time than literature values. In our study, at classical heating conditions 4-(5-chloro-2-hydroxyphenylamino)-3-pentene–2-one (III) were obtained in 180 minute with 71% yield whereas in microwave 82% yield was obtained in 10 minutes. The reaction time is 18 fold less than classical heating. b-Ethoxyethanol was used as wetting solvent to obtain neat form of the reagent mixture for the synthesis of imines from benzoine. In microwave oven reaction time and yields for the 1,2-diphenyl-2-(phenylimino)ethanol (VI) and 1,2- diphenyl-2-(ptolylimino) ethanol (VII) are 90 minutes, 71% , and 60 minutes, 91% respectively. For this reactions anhydrous Mg(ClO4)2 were also used to facilitate the nucleophilic attack in first step of the imine formation and help to removal of the water in second step. While compound VI was obtained in 90 minutes with 71% yield, by adding catalytic amount of Mg(ClO4)2 into neat reaction mixture reduced reaction time from 90 minutes to 25 minutes and increased yield from 71% to 83%. Synthesis of imines from benzyl and diamines were tried at three different conditions, in ethanol, at solid phase and with excess diamines. 5,6-Diphenyl-2,3-dihydropyrazine (XI) were synthesized conventionally in 660 minutes with 91 % yield. In microwave irradiation condition same compound was obtained in 75 minutes with 94% yield in ethanol and at solid phase in 15 minute with 97% yield and in the presence of excess diamine in 15 minutes afforded 99% yield. The results obtained in our study were compared regarding reaction time and yield. It has been seen that the formation of imines is not only accelerated upon exposure to microwave irradiation also shortening its reaction time.Bu çalısmada, asetilaseton, benzoin ve benzil gibi karbonil bilesiklerinin anilin türevleri ve bazı alifatik diaminlerle reaksiyonuyla bir seri imin türevleri sentezlenmistir. Sentezler ev tipi, bir takım degisiklikler yapılmıs (modifiye edilmis) bir mikrodalga fırında gerçeklestirilmistir. Bilesiklerin mikrodalga sentezleri, çözücü içerisinde, katı fazda ve kaynama noktası yüksek bir miktar çözücü ile ıslatılarak yapılmıs, reaksiyon zamanı ve verim açısından uygun sartlar belirlenmistir. Sentezlenen imin türevlerinin yapıları IR, 1H-NMR ve 13C-NMR spektroskopik teknikleri ile aydınlatılmıstır. Etanol içerisinde asetilaseton’dan çıkılarak sentezlenen iminler, mikrodalga fırında literatürde belirtilen zamandan daha kısa sürede elde edildi. 4-(5-Klor-2-hidroksifenilamino)-3-penten–2-on (III) bilesigi literatürde klasik ısıtma sartlarında 180 dakikada % 71 verimle elde edilirken, çalısmamızda mikrodalga ısıtma ile 10 dakikada % 82 verimle elde edilmistir. Reaksiyon için gerekli süre 18 kat kadar azalmıstır. Benzoin’den elde edilen iminlerin sentezinde ise reaktifler b-etoksietanol ile ıslatılarak reaksiyonlar gerçeklestirilmistir. 1,2-Difenil-2-(fenilimino)etanol (VI) bilesigi 90 dakikada % 71 verimle ve 1,2-Difenil-2-(p-tolilimino)etanol (VII) bilesigi 60 dakikada % 91 verimle elde edilmistir. Ayrıca imin olusumunda hem birinci adımdaki nükleofilik saldırıyı, hem de son adımdaki suyun uzaklastırılmasını kolaylastıran susuz magnezyum perklorat kullanılmıstır. VI Bilesigi b-etoksietanol ile ıslatma yöntemiyle 90 dakikada % 71 verimle elde edilebilirken Mg(ClO4)2 ilavesiyle 25 dakikada % 83 verimle elde edilmistir. Benzil ve diaminlerden elde edilen iminler de etanol içerisinde, katı fazda ve diamin reaktifinin asırısı kullanılarak üç farklı yöntemle sentezlenmistir. 5,6-Difenil-2,3- dihidropirazin (XI) bilesigi klasik ısıtma ile etanol içerisinde 660 dakikada % 91 verimle elde edilmistir. Aynı bilesik mikrodalga ısıma ile etanol içerisinde 75 dakikada % 94, katı fazda 15 dakikada % 97 ve amin reaktifinin asırısının kullanılmasıyla 15 dakikada % 99 verimle sentezlenmistir. Çalısmamızda elde edilen sonuçlar zaman ve verim açısından karsılastırılmıstır. Mikrodalga ısımanın imin sentezinde reaksiyon süresini kısalttıgı gibi verimlerinde de artıslara sebep oldugu görülmüstür

The efficacy of vestibular electrical stimulation on patients with unilateral vestibular pathologies

WOS: 000422785900006Objectives: This study aims to investigate the efficacy of vestibular electrical stimulation (VES) in unilateral vestibular lesions including benign paroxysmal positional vertigo (BPPV). Patients and methods: Between June 2007 and August 2007, a total of 19 patients diagnosed with BPPV were included in this study and they were randomized into two groups using the 1: 1 method. Ten patients were administered medical treatment plus VES (treatment group; 1 male, 9 females; mean age 55.8 years; range 27 to 74 years), whereas nine patients were only administered medicine (control group; 2 males, 6 females; mean age 54.9 years; range 34 to 73 years). Both groups received the same medical treatment throughout the study. Vestibular electrical stimulation was performed for 30 min long twice a day, three times a week; 12 sessions in total with 80 Hz high-frequency Transcutaneous Electrical Nerve Stimulation (TENS). Before and after the treatment, patients' severity of dizziness was assessed with Visual Analog Scale (VAS) and daily life activities with Dizziness Handicap Inventory (DHI), and their duration (sec) of single leg stance with eyes open and closed was recorded. Results: Compared to prior to the treatment, VAS-dizziness and DHI scores, and the duration of single leg stance on one foot with eyes open and closed at the end of the treatment showed statistically significant improvement in both groups; however, although VES provided a positive contribution, we did not find a statistically significant difference between the two groups. Conclusion: It can be concluded that VES has positive contribution to medical treatment of patients with dizziness due to unilateral vestibular lesions; however the results of this study should be further investigated with larger groups of patients

Synthesis, spectroscopic characterization and DFT calculations of N-Methyl-2-(2 '-hydroxyphenyl)benzimidazole derivatives

1-Methy1-2-(2'-hydroxyphenyl)benzimidazole (1) and 1-Methy1-2-(2'-hydroxy-4'-methylphenyl)benzimidazole (2) compounds have been synthesized and characterized by XRD, IE-MS, FT-IR, UV Vis and H-1, C-13 NMR techniques. The crystal structure of both compounds is stabilized with very strong O-H center dot center dot center dot N hydrogen-bond and pi-pi interactions. In the compound 1, an infinite chain structure with a trans-zigzag type was formed along the crystallographic 11011 direction. Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, NMR and electronic transitions were carried out by DFT using B3LYP functional combined with 6.31G(d,p) basis set. Calculated bond lengths, bond angles and dihedral angles were only slightly different from the experimental ones. The vibrational study was interpreted by means of potential energy distribution (PED). The electronic absorption spectra of the both compounds were predicted by using the time-dependent DFT methods and good agreement was found between the computational and the experimental values. The chemical shifts (H-1 and (1)3C NMR) and isotropic shielding values were calculated by using the gauge-invariant atomic orbital (GIAO) method. The analyses of HOMO and LUMO have been used to explain the charge transfer within the molecule. (C) 2015 Elsevier B.V. All rights reserved

Yeni bir manyetik tek-atom asetat köprülü schiff bazı -bakır(II) kompleksinin kristallografik, EPR ve DFT ile incelenmesi

A recent example of one-atom acetate bridged symmetric dinuclear copper(II) complexes, Di-µ-acetato-bis{1- ((pyridin-2-ylmethylimino)methyl)naphthoxo}copper(II) ([Cu2(NP)2(Ac)2]•2MetOH(1)) (HNP1-((pyridin-2- ylmethylimino)methyl)naphthol)) have been prepared and characterized by X-ray crystallography, Elemental analyses, ESI-mass, UV-Vis and IR spectroscopic techniques. Magnetic properties of the complex have been probed by EPR measurements and the presence of spin-only paramagnetism of the compound with none of significant exchange coupling has been demonstrated unlike ferro or antiferromagnetism that was otherwise observed in all other analogous structures previously reported. The existence of a trivial ferromagnetic exchange which is quantitatively ignorable has been suggested by DFT-Broken Symmetry calculations performed at crystallographically characterized experimental geometry.Tek-atom asetat köprülü simetrik dinükleer-bakır(II) komplekslerine yeni bir örnek olarak Di-µ-asetato-bis{1- ((piridin-2-ilmetilimino)metil)naftokso}bakır(II) ([Cu2(NP)2(Ac)2]•2MetOH(1)) (HNP1-((piridin-2-ilmetilimino) metil)naftol)) kompleksi sentezlendi ve X-ışını kristallografisi, elementel analiz, ESI-kütle, UV-Vis ve IR spektroskopik tekniklerle karakterize edildi. Kompleksin manyetik özellikleri EPR spektroskopisi tekniği ile incelendi ve daha önce çalışılmış diğer tüm benzer yapılarda görülen ferroya da antiferromanyetizmden farklı olarak sadece spine bağlı paramanyetizmin varlığı, önemli bir manyetik değiş-tokuşun gözlenmemesine bağlı olarak belirlendi. Büyüklük olarak önemsenmeyecek derecede küçük olan ferromanyetik etkileşimin varlığı ise kristal geometride gerçekleştirilen DFT-kırılmış simetri hesaplamaları ile belirlendi

Sensitive analysis of simazine based on platinum nanoparticles on polyoxometalate/multi-walled carbon nanotubes

Atar, Necip/0000-0001-8779-1412WOS: 000373096500003PubMed: 26928060In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H3PW12O40, POM) functionalized multi -walled carbon nanotubes (MWCNs) sheets was prepared for the determination of simazine (SIM). The developed surfaces were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. SIM imprinted GCE was prepared via electropolymerization process of 100 mM pyrrole as monomer in the presence of 0.1 M acetate buffer (pH 4.0) containing 25 mM SIM. The linearity range and the detection limit of the developed method were calculated as 1.0 x 10(-19)-5.0 x 10(-9) M and 2.0 x 10(-11) M, respectively. In addition, the voltammetric sensor was applied to wastewater samples. The stability and reproducibility of the voltammetric sensor were also reported. (C) 2016 Elsevier Inc. All rights reserved