Effect of aromatic rings

The dependence of the volatile product yield with structure can be a very sensitive probe of radiation resistance and the protective effect of aromatic rings. G(H ) was observed to decrease from 5.6 to 0.038 for cyclohexane (3) and benzene (A) after gamma irradiation at ambient temperature. Since all polymers under investigation contained the sulfone moiety, G(SO ) (Table III) is an ideal probe for radiation resistance for this series. 

T.C. Rosen, S. Yoshida, R. Frdhiich, K.L. Kirk, G. Haufe, Fiuorinated phenyicyciopropyiamines. 2. Effects of aromatic ring substitution and of absolute configuration on inhibition of microbial tyramine oxidase, J. Med. Chem. 47 (2004) 5860-5871. 

Nucleophile addition to a quinone methide is formally a Michael addition reaction.153 However, an important difference between 1,6-addition of nucleophiles to / -quinone methides and conventional Michael addition reactions is the aromatization of the cyclohexadiene ring that accompanies this addition. The effect of aromatic ring formation on the thermodynamic driving force for 1,6-addition of water to p-1 has been evaluated by comparing the thermodynamics... 

Figure 4. Effect of aromatic ring percent of feed, A, on maximum deposition level of coke, M,...

Figure 5. Effect of aromatic ring percent, on the initiation (non-catalytic) rate constant for coking, ki- (Reproduced with permission from Ref. 1. Copyright 1994 Elsevier.)...

M effect of aromatic ring delocalizes the lone pair electron into the ring, resulting in decreased basicity. 

Figure 13.17 shows that incorporating a flexible segment close to the center of mass of a rigid molecule allows us to obtain a much larger decrease in diffusion coefficients (D) than the effects of size described in Figure 13.16. In the case of diphenyl alkanes, D decreases by 10 when 1-3 carbons are incorporated between two aromatic rings. This is associated with an anchor effect of aromatic rings, which are temporarily trapped by the absence of free volumes facilitating the reorientation or tilting of the aromatic ring [FAN 13].

Effect of Aromatic Rings on Chain Stiffness, as Shown by... 

Table 6.5 Effect of aromatic rings on chain stiffness, as shown by the values ofT andT m g ...

One hydrocarbon polymer that gives positive spherulites is isotactic polystyrene here the effect of aromatic rings with strong polarizability perpendicular to the molecular chains dominates over the polarizability of the chain. 

Fig. 3. Shielding effects of aromatic rings on neighboring substituents...

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