Adjacent functional groups, effect

Substitution of fluorine into an organic molecule results in enhanced chemical stabiUty. The resulting chemical reactivity of adjacent functional groups is drastically altered due to the large inductive effect of fluorine. These effects become more pronounced as the degree of fluorine substitution is increased, especially on the same carbon atom. This effect demonstrates a maximum in fluorocarbons and their derivatives. 

Fig. 5. Effect of the nature of adjacent functional groups in copolymers on the rate of conversion of the nitrile groups into thioamide groups. (1) PAN (2) AN-VDC (3) AN-AA (4) AN-MA (5) AN-VC (6) AN-ST...

A number of photolyses of compounds containing a silicon atom have been studied in which the bonds to the silicon atom are not directly involved in the photolysis, but where the changes effected are potentially of synthetic interest. In many cases the presence of the silyl group may have an influence on the regiochemistry of the reaction, or an activating influence on an adjacent functional group. It is difficult to categorize these reactions, and thus they will simply be listed in an arbitrary order. 

On the other hand, H.B. Henbest realised that adjacent polar functional groups have a directing effect on the epoxidation of alkenes as well as on other related reactions [2]. A very well known example is the 5yn-directing effect of an ally lie hydroxyl group in epoxidations of cyclic alkenes (Scheme 10.1) ... 

Be able to identify simple organic molecules from their H NMR spectra through the interpretation of their integrals (the number of hydrogens in each environment), chemical shifts (the effect of functional groups on the electron density of the molecule) and coupling patterns (the number of spin active nuclei on adjacent atoms)... 

In aliphatic compounds, reactions of functional groups are often modified very significantly by an adjacent carbonyl group. As would be expected from the discussion in the preceding section, the reactions of certain substituents a and y to pyridine-like nitrogen atoms in azole rings are similarly influenced. Such effects on substituents can be classified into six groups. 

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