نتایج جستجو برای: alkyl group

تعداد نتایج: 991429  

2016
Alena S Pankova Pavel R Golubev Alexander F Khlebnikov Alexander Yu Ivanov Mikhail A Kuznetsov

2-(Alkyl(aryl)amino)thiazol-4(5H)-ones can regioselectively be prepared from monoalkyl(aryl)thioureas and maleimides. In solution, the former heterocycles exist in a tautomeric equilibrium with 2-(alkyl(aryl)imino)thiazolidin-4-ones and the substituent on the exocyclic nitrogen atom governs the ratio of these tautomers. Isomers with the alkyl group in the endocyclic position can be obtained fro...

Journal: :Journal of the American Chemical Society 2013
Graham E Dobereiner Jian Yuan Richard R Schrock Alan S Goldman Jason D Hackenberg

n-Alkyl arenes were prepared in a one-pot tandem dehydrogenation/olefin metathesis/hydrogenation sequence directly from alkanes and ethylbenzene. Excellent selectivity was observed when ((tBu)PCP)IrH2 was paired with tungsten monoaryloxide pyrrolide complexes such as W(NAr)(C3H6)(pyr)(OHIPT) (1a) [Ar = 2,6-i-Pr2C6H3; pyr = pyrrolide; OHIPT = 2,6-(2,4,6-i-Pr3C6H2)2C6H3O]. Complex 1a was also esp...

Journal: :International journal of toxicology 2016
Monice M Fiume Bart Heldreth Wilma F Bergfeld Donald V Belsito Ronald A Hill Curtis D Klaassen Daniel C Liebler James G Marks Ronald C Shank Thomas J Slaga Paul W Snyder F Alan Andersen

The Cosmetic Ingredient Review (CIR) Expert Panel assessed the safety of 131 alkyl polyethylene glycol (PEG)/polypropylene glycol ethers as used in cosmetics, concluding that these ingredients are safe in the present practices of use and concentration described in this safety assessment when formulated to be nonirritating. Most of the alkyl PEG/PPG ethers included in this review are reported to...

Journal: :Langmuir : the ACS journal of surfaces and colloids 2004
K Heister S Frey A Ulman M Grunze M Zharnikov

The irradiation sensitivity of n-alkanethiolate SAMs can be enhanced by the incorporation of an irradiation-sensitive functionality as a predetermined breaking point into the alkyl chain. Following this general strategy, several different sulfur-derived functional entities with a variable position in the alkyl chain were tested. In some cases, the incorporation of these entities resulted in a n...

2007
J. P. Mahalik Giridhar Madras

Effect of alkyl group substituents on the thermal and enzymatic degradation of poly (n-alkyl acrylates) J. P. Mahalik and Giridhar Madras∗ Department of Chemical Engineering, Indian Institute of Science, Bangalore-12 Abstract The effect of alkyl group substituents on the thermal degradation kinetics of poly (n-alkyl acrylate) was investigated in pyrolysis and in solution. The activation energie...

2001
Ashok K. Prasad Najam A. Shakil Virinder S. Parmar

The capabilities of porcine pancreatic lipase (PPL), Candida antarctica lipase (CAL), and Candida rugosa lipase (CRL) were evaluated for enantioand/or regioselective acetylation/deacetylation of (±)-2,4-diacetoxyphenyl alkyl ketones, (±)-4-alkyl-3,4-dihydro3-hydroxyalkyl-2H-1,3-benzoxazines, and D-arabino and D-threo-polyhydroxyalkyltriazoles in organic solvents. PPL in tetrahydrofuran (THF) ex...

B. Tamami H. Allahyari R. Teymoori S. Ghasemi

Poly (vinylpyrrolidone)-grafted silica as an organic-inorganic hybrid material was used as an effective heterogeneous polymeric cosolvent catalyst in organic reactions. This modified silica catalyzed nucleophilic displacement of alkyl halides for easy preparation of alkyl thiocyanates, alkyl cyanides, alkyl azides and alkyl aryl ethers. Furthermore, the catalyst was applied for the conversion o...

2006
Giridhar Madras

The effect of alkyl group substituents on the degradation kinetics of poly(alkyl methacrylates) namely poly (n-butyl methacrylate) (PBMA), poly (iso-propyl methacrylate) (PPMA), poly (ethyl methacrylate) (PEMA), and poly (methyl methacrylate) (PMMA) in supercritical and subcritical conditions was studied at various temperatures (250 – 375 o C). The molecular weight distributions were measured b...

Journal: :Journal of the American Chemical Society 2003
Songping Liao David B Collum

Lithium diisopropylamide-mediated lithiations of N-alkyl ketimines derived from cyclohexanones reveal that simple substitutions on the N-alkyl side chain and the 2-position of the cyclohexyl moiety afford a 60,000-fold range of rates. Detailed rate studies implicate monosolvated monomers at the rate-limiting transition structures in all instances. Comparisons of experimentally derived regiosele...

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