Since both the core and the arms are rather reactive, essentially all Si-Cl undergo electrophilic substitution, and the resulting star-shaped polymers thus have a rather narrow polydispersity index.
22.
The deactivating groups on the core are often chlorosilanes, chlorine leaving groups, or living polymers; this reaction involves carbanions performing electrophilic substitution with the Si-Cl groups ( as shown in the below figure ).
23.
The reaction with nickel tetracarbonyl, for example, proceeds through an unstable acyl nickel carbonyl complex which then undergoes electrophilic substitution to give the desired aldehyde ( using H + as the electrophile ) or ketone ( using an alkyl halide ) product.
24.
The enzyme NovF catalyzes the decarboxylation of prephenate while simultaneously reducing nicotinamide adenine dinucleotide phosphate ( NADP + ) to produce NADPH . Following this NovQ catalyzes the electrophilic substitution of the phenyl ring with dimethylallyl pyrophosphate ( DMAPP ) otherwise known as prenylation.
25.
Substituents can generally be divided into two classes regarding electrophilic substitution : activating and deactivating towards the aromatic ring . "'Activating substituents "'or activating groups stabilize the cationic intermediate formed during the substitution by donating electrons into the ring system, by either inductive effect or resonance effects.
