Hydrosilanes are not always a reducing reagent: a ruthenium-catalyzed introduction of primary alkyl groups to electron-rich aromatic rings using esters as a source of the alkyl groups

Tetrahedron ◽  
2011 ◽  
Vol 67 (40) ◽  
pp. 7667-7672 ◽  
Author(s):  
Hideo Nagashima ◽  
Yuichi Kubo ◽  
Mitsunobu Kawamura ◽  
Takashi Nishikata ◽  
Yukihiro Motoyama
Keyword(s):  
Aromatic Rings ◽  
Alkyl Groups

Syntheses of cytotoxic novel arctigenin derivatives bearing halogen and alkyl groups on aromatic rings

2017 ◽  
Vol 27 (17) ◽  
pp. 4199-4203 ◽  
Author(s):  
Satoshi Yamauchi ◽  
Tuti Wukirsari ◽  
Yoshiaki Ochi ◽  
Hisashi Nishiwaki ◽  
Kosuke Nishi ◽  
...  
Keyword(s):  
Aromatic Rings ◽  
Alkyl Groups

ChemInform Abstract: Hydrosilanes Are not Always a Reducing Reagent: A Ruthenium-Catalyzed Introduction of Primary Alkyl Groups to Electron-Rich Aromatic Rings Using Esters as a Source of the Alkyl Groups.

ChemInform ◽  
2012 ◽  
Vol 43 (7) ◽  
pp. no-no
Author(s):  
Hideo Nagashima ◽  
Yuichi Kubo ◽  
Mitsunobu Kawamura ◽  
Takashi Nishikata ◽  
Yukihiro Motoyama
Keyword(s):  
Aromatic Rings ◽  
Alkyl Groups

The Stereochemistry of SRN1 Reactions in Nitroacenaphthenes

1987 ◽  
Vol 40 (3) ◽  
pp. 523 ◽  
Author(s):  
FI McLure ◽  
RK Norris
Keyword(s):  
Nitro Group ◽  
Reaction Site ◽  
Aromatic Rings ◽  
Ethyl Group ◽  
Benzylic Carbon ◽  
Alkyl Groups ◽  
The Face

The reaction of the 2-chloro-1,l-dialkyl-6-nitroacenaphthenes (1)-(3) with azide and p- toluenethiolate ions takes place by the SRN1 mechanism, to give the substitution products (27)-(32), despite the fact that the nitro group and the chlorine-bearing benzylic carbon are attached to different aromatic rings. The reaction of the stereoisomers (2) and (3) of 2-chloro-1-ethyl-1-methyl-6-nitroacenaphthene takes place through an effectively planar benzylic radical (35), which is preferentially attacked from the face remote from the a-ethyl group. The presence of geminal alkyl groups α to the reaction site in the rigid acenaphthene system restricts the scope of the substitution processes to sterically unhindered nucleophiles, and the reaction fails with reagents such as sodium p- toluenesulfinate (23) and the salts, (24) and (25), derived from 2-ethylmalononitrile and 2-nitropropane.

scholarly journals Hydrogen distribution in primary coke oventar and its fractions

2021 ◽  
Vol 101 (1) ◽  
pp. 82-90
Author(s):  
D.E. Aitbekova ◽  
◽  
D.K. Makenov ◽  
E.I. Andreikov ◽  
A.G. Tsaur ◽  
...  
Keyword(s):  
Coke Oven ◽  
Atomic Ratio ◽  
Added Value ◽  
Aromatic Rings ◽  
Hydrogen Distribution ◽  
Alkyl Groups ◽  
Other Substances ◽  
Distillate Fractions ◽  
Physical And Chemical

The aim of this work is to determine the hydrogen distribution in primary coke oven tar and its fractions. The hydrogen distribution in the primary coke oven tar of «ShubarkolKomir» JSC, its distillate fractions and dis-tillation residue have been determined by the methods of elemental analysis, IR and PMR spectroscopy. The atomic ratio of C: H in the primary coke oven tar is 0.79. All fractions of the tar contain a large amount of al-kyl-substituted aromatic compounds, phenols and other substances with alkyl groups. The initial tarcharac-terized by a high content of hydrogen in the α-and β-positions to the aromatic ring, 29% and 34% respec-tively, which indicates a large number of alkyl substituents in the aromatic rings and near double bonds. The total amount of aliphatic and aromatic hydrogen in the tar is 79% and 21% respectively. Olefinic hydrogen is presented in the initial tar in an amount of 8%. It is possible to make a choice of techniques for further processing (hydrogenation, coking, thermal cracking) to obtain products with high added value on the basis of determination of the elemental composition, quantitative distribution of hydrogen in the primary coke oven tar and its fractions by the using of above mentioned physical and chemical methods.

FLUORESCENCE ENHANCEMENT FROM SELF-ASSEMBLED AGGREGATES II: FACTORS INFLUENCING FLORESCENCE COLOR FROM AZOBENZENE AGGREGATES

2013 ◽  
Vol 01 (03) ◽  
pp. 1340008 ◽  
Author(s):  
MINA HAN
Keyword(s):  
Polymer Films ◽  
Blue Shift ◽  
Spectral Shift ◽  
Ortho Position ◽  
Key Factors ◽  
Aromatic Rings ◽  
Factors Influencing ◽  
Alkyl Groups ◽  
Fluorescence Color ◽  
Fluorescence Wavelength

We have chosen two types of azobenzene derivatives to elucidate the correlation between molecular structure and fluorescence color of light-driven azobenzene-based aggregates. The fluorescence color from azobenzene molecules (1 and 2), adopting a planar structure, was obviously red-shifted from that of the corresponding twisted ortho-alkylated azobenzene 3. The steric hindrance resulting from bulky alkyl groups at the ortho position of the azo linkage was considered to lessen the intermolecular π – π stacking between aromatic rings, leading to the relatively smaller spectral shift in fluorescence from the absorption band of the initial azobenzene solution. The substitution of electron-withdrawing groups into the azobenzene core gave rise to a blue-shift in fluorescence wavelength. That is, the extended π-conjugated system consisting of a planar azobenzene core as well as the electronic properties of the substituents are key factors influencing the fluorescence color from the light-driven azobenzene aggregates. Moreover, we could prepare fluorescent polymer films by mixing fluorescent azobenzene aggregates with polymers. The fluorescence colors from the polymer films were comparable to those from the azobenzene aggregates.

Chemical and orientational imaging of polymeric samples

1994 ◽  
Vol 52 ◽  
pp. 68-69
Author(s):  
H. Ade ◽  
B. Hsiao ◽  
G. Mitchell ◽  
E. Rightor ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Ethylene Terephthalate ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Carbonyl Groups ◽  
Aromatic Rings ◽  
Edge Structure ◽  
X Ray ◽  
Scanning Transmission ◽  
Polymeric Samples ◽  
X Ray Absorption

We have used the Scanning Transmission X-ray Microscope at beamline X1A (X1-STXM) at Brookhaven National Laboratory (BNL) to acquire high resolution, chemical and orientation sensitive images of polymeric samples as well as point spectra from 0.1 μm areas. This sensitivity is achieved by exploiting the X-ray Absorption Near Edge Structure (XANES) of the carbon K edge. One of the most illustrative example of the chemical sensitivity achievable is provided by images of a polycarbonate/pol(ethylene terephthalate) (70/30 PC/PET) blend. Contrast reversal at high overall contrast is observed between images acquired at 285.36 and 285.69 eV (Fig. 1). Contrast in these images is achieved by exploring subtle differences between resonances associated with the π bonds (sp hybridization) of the aromatic groups of each polymer. PET has a split peak associated with these aromatic groups, due to the proximity of its carbonyl groups to its aromatic rings, whereas PC has only a single peak.

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

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