scholarly journals A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety

2018 ◽  
Vol 14 ◽  
pp. 3106-3111 ◽  
Author(s):  
Ilya V Taydakov ◽  
Yuliya M Kreshchenova ◽  
Ekaterina P Dolotova
Keyword(s):  
Methyl Group ◽  
Alkyl Radicals ◽  
Alkyl Groups ◽  
Practical Synthesis ◽  
Copper Chelates

A versatile and robust synthetic protocol for the preparation of β-diketones bearing 2-thienyl and perfluorinated alkyl radicals of different length or a methyl group was developed. This protocol is suitable for the preparation of multigram quantities of diketones without cumbersome purification procedures. Moreover, the known method for purification of diketones via copper chelates was improved considerably.

Kinetics of the Imidazolium Ring-Opening of mRNA 5'-cap Analogs in Aqueous Alkali

2006 ◽  
Vol 71 (4) ◽  
pp. 567-578 ◽  
Author(s):  
Alicja Stachelska ◽  
Zbigniew J. Wieczorek ◽  
Janusz Stępiński ◽  
Marzena Jankowska-Anyszka ◽  
Harri Lönnberg ◽  
...  
Keyword(s):  
Electrostatic Interaction ◽  
Ring Opening ◽  
Nucleophilic Attack ◽  
Amino Groups ◽  
Hydroxide Ion ◽  
Methyl Group ◽  
Structural Modifications ◽  
Alkyl Groups ◽  
Imidazolium Ring ◽  
Kinetics Of

Second-order rate constants for the hydroxide-ion-catalyzed imidazolium ring-opening of several mono- and dinucleosidic analogs of mRNA 5'-cap have been determined. Intramolecular stacking of the two nucleobases in the dinucleosidic analogs, m7GpppN (m7G = 7-methylguanosine, N = 5'-linked nucleoside), and electrostatic interaction between the N-alkylated imidazolium ring and phosphate moiety have been shown to shield the m7G moiety against the nucleophilic attack of hydroxide ion. In addition, the effect of methylation of the nucleobase amino groups and replacement of the 7-methyl group with other alkyl groups have been studied. The influence of all the structural modifications studied turned out to be modest, the cleavage rates of the most and least reactive analogs (with the exception of non-phosphorylated nucleosides) differing only by a factor of 5.

Isomerizations akin to the Dimroth rearrangement. IV. Formation of simple s-Triazolo[1,5-c]pyrimidines via their [4,3-c] isomers

1978 ◽  
Vol 31 (11) ◽  
pp. 2505 ◽  
Author(s):  
DJ Brown ◽  
T Nagamatsu
Keyword(s):  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Methyl Groups ◽  
Dimroth Rearrangement ◽  
Methyl Group ◽  
Alkyl Groups ◽  
Ring Fission

Pyrimidin-4-ylhydrazines and simple orthoesters are used in combination (1) to give N-ethoxyalkyl-idene-N'-pyrimidinylhydrazines (2) and thence s-triazolo[4,3-c]pyrimidine (3a) and its 3-, 5-, 7- or 8-alkylated derivatives (3b-s). In glacial acetic acid, these undergo rearrangement into the corresponding s-triazolo[1,5-c]pyrimidines (5) via the acylaminoalkenyltriazoles (4); in aqueous buffers, these reactions stop at the triazoles (4) except in the presence of a 7-methyl group which stimulates completion of the sequence. The ring-fission step, (3) → (4), is retarded markedly by 5- and/or 8-methyl groups but accelerated slightly by 3- and/or 7-alkyl groups; the slower ring-fission of triazolo[1,5-c]-pyrimidines (5) to the same triazoles (4) is retarded by 2-, 5- or 8-alkylation and precluded totally by a 7-methyl group. The recorded u.v. and N.M.R. spectra afford a ready means of distinguishing between the systems (3)-(5).

scholarly journals A STUDY OF THE ANTISEPTIC PROPERTIES OF CERTAIN ORGANIC COMPOUNDS

1918 ◽  
Vol 27 (4) ◽  
pp. 463-476 ◽  
Author(s):  
I. J. Kligler
Keyword(s):  
Quaternary Salt ◽  
Methyl Green ◽  
Triphenylmethane Dyes ◽  
Benzene Nucleus ◽  
Nitrogenous Compounds ◽  
Methyl Group ◽  
Alkyl Radicals ◽  
Alkyl Derivatives ◽  
Bacillus Coli ◽  
Inhibitive Action

This study of the inhibitive effect of aniline and some of its derivatives and of the triphenylmethane dyes on certain bacteria warrants the following tentative conclusions: 1. The composition and reaction of the medium exert a marked influence on the behavior of the antiseptic. The higher the concentration of organic nitrogenous compounds (peptone) in the medium, the lower is the effective concentration of the dye. The reaction of the medium modifies the specific action of the antiseptic, owing probably to an alteration in the bacterial cell. 2. The germicidal action of the compounds is a function of the benzene nucleus, the added elements or radicals, their number, and, in the case of the dyes, probably the quinoid structure of the nucleus. 3. As far as tested, the increase in the number of alkyl radicals increases the antiseptic power. Methyl green is an interesting exception to this rule, for the change of one of the nitrogens to the quaternary salt is accompanied by an almost complete loss in inhibitive action. 4. The antiseptic power is enhanced to a greater extent by an ethyl than a methyl group, and the second alkyl produces a proportionately greater increase than the first. It appears that the relative position of the introduced group may be a factor in determining the relative improvement in the effectiveness of the compound. 5. The introduction of a methyl group in the nucleus consistently enhances the inhibitive action of the compound and its alkyl derivatives. This is evident from a comparison of the action of aniline and its derivatives with that of toluidine and its corresponding derivatives. 6. The simple aniline derivatives, as well as the dyes, are more toxic for the Gram-positive than the Gram-negative bacteria. Of the former, Bacillus subtilis is more sensitive to the dyes than Staphylococcus aureus, while the reverse is true in the case of the aniline compounds. 7. The most marked specific selective effect is manifested by the triphenylmethane dyes. Bacillus aerogenes and Bacillus typhosus possess a higher resistance to these substances than Bacillus coli orBacfflus dysenterice. The last is exceedingly sensitive. This partial specificity is apparently a function of the molecule as a whole.

Intramolecular 1,2-alkyl shifts in unsymmetric dialkoxycarbenes studied by very low vapour pressure (VLVP) pyroiysis – mass spectrometry

1996 ◽  
Vol 74 (4) ◽  
pp. 544-558 ◽  
Author(s):  
Dennis Suh ◽  
David L. Pole ◽  
John Warkentin ◽  
Johan K. Terlouw
Keyword(s):  
Mass Spectrometry ◽  
Transition State ◽  
Vapour Pressure ◽  
Negative Charge ◽  
Radical Cations ◽  
Pyrolysis Mass Spectrometry ◽  
Multiple Collision ◽  
Methyl Group ◽  
Alkyl Groups ◽  
Electron Reduction

Methoxy-(2,2,2-trifluoroethoxy)carbene radical cations, CH3O-C-OCH2CF3•+, 1•+, are cleanly generated by the dissociative electron ionization (EI) of 2-methoxy-5,5-dimethyl-2-(2,2,2-trifluoroethoxy)-Δ3-1,3,4-oxadiazoline I. Neutralization–reionization (NR) mass spectrometry of the neutral carbene 1, generated by one-electron reduction of 1•+, shows no recovery ion signal and thus 1 is not a viable species within the μs time scale of the experiment. Very low vapour pressure (VLVP) pyrolysis – mass spectrometry of I in conjunction with (multiple) collision experiments shows that 1 completely isomerizes, via a 1,2-trifluoroethyl shift, into methyl 3,3,3-trifluoropropionate, CF3CH2C(=O)OCH3, 1a. This technique was also used to study the related dialkoxycarbenes C2H5O-C-OCH2CF3, 2, CH3O-C-OC2H5, 3, and CH3O-C-OCH(CH3)2, 4, generated from the corresponding 2,2-dialkoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazolines. The pyrolytically generated carbene 2 behaves analogously to 1 and completely isomerizes to ethyl 3,3,3-trifluoropropionate, 2a. The neutral carbenes 3 and 4 undergo only a partial isomerization via 1,2-alkyl shifts in which the ethyl and isopropyl groups show a slightly greater migratory aptitude, respectively, than the methyl group. The differences in migratory aptitude are explained in terms of a transition state model similar to that of a 1,2-H shift in carbenes, with development of negative charge in the migrating group. The greater migratory aptitude of CF3CH2, as compared to CH3 and CH3CH2, is attributed to the stabilization of negative charge in the transition state by strongly electron-withdrawing β-fluorines whereas the differences in migratory aptitude between the alkyl groups in 3 and 4 are largely due to the greater polarizability of isopropyl and ethyl groups, as compared to the methyl group. Key words: dialkoxycarbenes, pyrolysis, tandem mass spectrometry.

scholarly journals Polymerizable Ionic Liquids for Solid-State Polymer Electrolytes

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 324 ◽  
Author(s):  
Robert Löwe ◽  
Thomas Hanemann ◽  
Andreas Hofmann
Keyword(s):  
Ionic Liquids ◽  
Ionic Conductivity ◽  
Polymer Electrolytes ◽  
High Yield ◽  
Dsc Analysis ◽  
Energy Storage Devices ◽  
Methyl Group ◽  
Storage Devices ◽  
Alkyl Groups ◽  
Phase Transition Temperatures

Eight new polymerizable ammonium-TFSI ionic liquids were synthesized and characterized with respect to an application in energy storage devices. The ionic liquids feature methacrylate or acrylate termination as polymerizable groups. The preparation was optimized to obtain the precursors and ionic liquids in high yield. All products were characterized by NMR and IR spectroscopy. Phase transition temperatures were obtained by DSC analysis. Density, viscosity and ionic conductivity of the ionic liquids were compared and discussed. The results reveal that the length of attached alkyl groups as well as the methyl group at the polymerizable function have significant influences on the ionic liquids physicochemical properties. Ionic conductivity values vary between 0.264 mS cm−1 for [C2NA,22]TFSI and 0.080 mS cm−1 for [C8NMA,22]TFSI at 25 °C. Viscosity values are within a range of 0.762 Pa s for [C2NA,22]TFSI and 1.522 Pa s for [C6NMA,22]TFSI at 25 °C.

Ionic and Radical Mechanisms in Olefinic Systems, with Special Reference to Processes of Double-Bond Displacement, Vulcanization and Photogelling

1942 ◽  
Vol 15 (4) ◽  
pp. 774-779
Author(s):  
Ernest Harold Farmer
Keyword(s):  
Double Bond ◽  
Special Reference ◽  
Methyl Substituent ◽  
Benzene Nucleus ◽  
Methyl Group ◽  
Unsaturated System ◽  
Alkyl Groups ◽  
Electron Release

Abstract The α-methylenic reactions discussed in the preceding two papers recall a series of interesting observations by Baker and Nathan, which indicate that a p-methyl substituent attached to the benzene nucleus can permit electron release to the nucleus in a manner that appears only in lesser degree in higher alkyl groups, and may be absent in some (e.g., Buγ). Thus in p-methylbenzyl bromide, the suggested function of the methyl group (dotted arrows in (I) permits (see PDF for diagram) additional electron release at the C—Br bond, and so facilitates the anionization of the bromine. Baker and Nathan suggest that the electrons of the duplet constituting the C—H bond of the methyl group are less localized than those in a similarly placed C—C bond, and hence that a methyl group attached to the necessary conjugated unsaturated system is capable of electron-release by a mechanism similar to the tautomeric effect:

A Convenient Method for Replacing theN-Methyl Group of Morphine, Codeine, and Thebaine by Other Alkyl Groups

Synthesis ◽  
1983 ◽  
Vol 1983 (10) ◽  
pp. 809-812 ◽  
Author(s):  
Thomas Samuel Manoharan ◽  
Kattigari Madhava Madyastha ◽  
Bajrang Bali Singh ◽  
Surendra P. Bhatnagar ◽  
Ulrich Weiss
Keyword(s):  
Convenient Method ◽  
Methyl Group ◽  
Alkyl Groups

Oxidation of alkyl groups accompanying the Zinin reduction of nitroarenes

1977 ◽  
Vol 30 (4) ◽  
pp. 927 ◽  
Author(s):  
DA Burgess ◽  
ID Rae
Keyword(s):  
Nitro Group ◽  
Methyl Group ◽  
Alkyl Groups

p-Aminobenzaldehydes have been prepared from several nitroxylenes and trimethylnitrobenzenes by reaction with aqueous alcoholic sodium polysulphide. The oxidation of the methyl group accompanying the Zinin reduction proceeds most readily when the nitro group is unhindered.

ChemInform Abstract: A CONVENIENT METHOD FOR REPLACING THE N-METHYL GROUP OF MORPHINE, CODEINE, AND THEBAINE BY OTHER ALKYL GROUPS

1984 ◽  
Vol 15 (5) ◽  
Author(s):  
T. S. MANOHARAN ◽  
K. M. MADYASTHA ◽  
B. B. SINGH ◽  
S. P. BHATNAGAR ◽  
U. WEISS
Keyword(s):  
Convenient Method ◽  
Methyl Group ◽  
Alkyl Groups
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