The decreased distance between the adsorbate and graphene increases π–π repulsion, which is minimized by placing the BZ ring in a tilted geometry relative to the graphene surface. The presence of electron-withdrawing substituents on benzene diminishes both repulsive (π–π) and attractive (π–...
Methoxy substitution in the benzene ring accelerates the reaction but lowers the diastereoselectivity due to the easier equilibrium between trans- and cis-azulenones, and even more with the less bulky R substituents (Scheme 91).970 Sign in to download full-size image Scheme 91. Cyclization of ...
are attached,the average ring current values are higher than that of the cases when electron-donating substituents(+ R effect:NHMe,NMe2,OH,SH,etc.)are attached.The same trend was also observed for the anisotropy values of the induced current density(ACID)analysis.The isosurface contour diagram...
The formula of benzene (C6H6), caused a mystery for some time after its discovery, as no proposed structure could take account of all the bonds (carbon usually forms four single bonds and hydrogen one). The chemist Kekulé was the first to deduce the ring structure of benzene; after years ...
The manner in which specific substituents influence the orientation of electrophilic substitution of a benzene ring is shown in the following interactive diagram. As noted on the opening illustration, the product-determining step in the substitution mechanism is the first step, which is also the slow...
The relative energetics are discussed in terms of potential surface diagram having the benzene ring deformation as the "reaction coordinate". Comparison with the anthracene isomerization is made and the effect of substituents is pointed out.doi:10.1007/BF01374576Malte von Arnim...
the two substituents of the ring cannot simultaneously represent respectively -NO2 and -CH3 , with the proviso for the following particular cases : a) when R8 represents one of the following radicals : see diagramm : EP0007880,P13,F2 in which n=0, 1 or 2 or an ester thereof, one at ...
the two substituents of the ring cannot simultaneously represent respectively -NO2 and -CH3 , with the proviso for the following particular cases : a) when R8 represents one of the following radicals : see diagramm : EP0007880,P13,F2 in which n=0, 1 or 2 or an ester thereof, one at ...
[128] prepared the TR membranes from benzoxazole and different substituents (-H, –CH3, and -CF3) in the ortho-hydroxypolyimide (HPI). The membranes included 6FDA dianhydride, TR-able APAF diamine and non-TR-able codiamines (4,4′-diamino-2,2′-double trifluoromethyl benzol (TFMB) and ...
In case alkenes contain electron-donating substituents they probably react through a radical mechanism and isomerization to yield a mixture of products. Sign in to download full-size image The reaction pathway for the construction of the furan-fused oxetanes most likely involves excitation of the car...