نتایج جستجو برای: آشکارساز bf3

تعداد نتایج: 1657  

Journal: :The Journal of the Society of Chemical Industry, Japan 1970

Journal: :Angewandte Chemie 2014
Feng-Lian Zhang Yi-Feng Wang Geoffroy Hervé Lonca Xu Zhu Shunsuke Chiba

A method for the synthesis of amide-containing molecules was developed using vinyl azides as an enamine-type nucleophile towards carbon electrophiles, such as imines, aldehydes, and carbocations that were generated from alcohols in the presence of BF3 ⋅OEt2 . After nucleophilic attack of the vinyl azide, a substituent of the resulting iminodiazonium ion intermediate migrates to form a nitrilium...

Journal: :Organic & biomolecular chemistry 2015
B V Subba Reddy N Prudhvi Raju B Someswarao B Jagan Mohan Reddy B Sridhar Kanakaraju Marumudi A C Kunwar

A novel bicyclization of 2-(2-(hydroxymethyl)-1-methylene-2,3-dihydro-1H-inden-2-yl)ethanol with aldehydes in the presence of 10 mol% BF3·OEt2 in dichloromethane at 0-25 °C affords the biologically relevant indeno[2,1-c]pyran scaffolds in good yields with high selectivity. Similarly the bicyclization of 2-(1-(hydroxymethyl)-2-methylenecyclopentyl)ethanol with aldehydes generates the correspondi...

Journal: :Journal of chromatography. A 2001
S de Koning B van der Meer G Alkema H G Janssen U A Brinkman

The determination of the fatty acid composition (as methyl esters, FAMEs) of fats and oils and their cis/trans (CTME) distribution requires a simple, but manual and time-consuming sample preparation. The so-called BF3 method is often the preferred procedure. Because FAME/CTME analyses are encountered very frequently in the food industry, an automated, robot-based alternative is proposed which u...

2011
K. P. R. Chowdary

The objective of the present study is to develop etoricoxib rapidly dissolving tablet formulations by wet granulation and direct compression methods employing starch phosphate, a new modified starch. As per FDA guidelines on biowaivers, drug products containing weakly acidic BCS class II drugs with a dissolution of > 85% in 30 min are eligible for biowaiver. Hence a dissolution of > 85% in 30 m...

Journal: :The journal of physical chemistry. A 2015
D Ayuso M Kimura K Kooser M Patanen E Plésiat L Argenti S Mondal O Travnikova K Sakai A Palacios E Kukk P Decleva K Ueda F Martín C Miron

Photoelectron diffraction is a well-established technique for structural characterization of solids, based on the interference of the native photoelectron wave with those scattered from the neighboring atoms. For isolated systems in the gas phase similar studies suffer from orders of magnitude lower signals due to the very small sample density. Here we present a detailed study of the vibrationa...

Journal: :Organic & biomolecular chemistry 2013
Jorge Soto-Delgado José A Sáez Ricardo A Tapia Luis R Domingo

The thermal and Lewis acid (LA) catalyzed cyclizations of quinone 1 involved in the synthesis of Colombiasin A and Elipsaterosin B have been theoretically studied using DFT methods at the B3LYP/6-311G(d,p) computational level. B3LYP calculations suggest that the formal endo [4 + 2] cycloadduct allowing the synthesis of Colombiasin A is preferentially formed under thermal conditions, while in th...

Journal: :iranian journal of radiation research 0
d. rezaei ochbelagh department of physics, university of mohageg ardebily, ardebil, iran h. miri hakimabad department of physics, faculty of sciences, ferdowsi university of mashhad, mashhad, iran r. izadi najafabadi department of physics, faculty of sciences, ferdowsi university of mashhad, mashhad, iran

background: several landmine detection methods, based on nuclear techniques, have been suggested during the recent years. neutron energy moderation, neutron-induced gamma emission, neutron and gamma attenuation, and fast neutron backscattering are nuclear-based methods used for landmine detection. the aim of this study is to use backscattered neutron for landmine detection. materials and method...

در این پژوهش، بسته آشکارساز کیفی اورانیوم حاوی شناساگرهای آرسنازو و برموپاداپ ساخته شده و با استفاده از شناساگر دیتیزون جهت تشخیص و تعیین برخی مزاحمت‌های یونی به روش رنگ سنجی، آشکارساز یون فلزی نیز ساخته شد. نتایج نشان داد که حد تشخیص یون اورانیوم با استفاده از آشکارسازهای حاوی شناساگرهای آرسنازو و برموپاداپ به ترتیب ppm‌50 و ‌ppm20 است و در محیط‌های اسیدی (5pH=) آشکارسازهای ساخته شده عملکرد من...

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