Withdraw effects

An a hydrogen of an aide hyde or a ketone is more acidic than most other protons bound to carbon Aldehydes and ketones are weak acids with pK s in the 16 to 20 range Their enhanced acidity IS due to the electron withdrawing effect of the carbon yl group and the resonance stabi lization of the enolate anion... 

Chloroacetate anion is stabilized by electron withdrawing effect of chlonne... 

Electron withdrawing effects of the cx-chlorine give chloroacetic acid a higher dissociation constant than that of acetic acid. 

Nucleophilic Displacement Reactions. The strong electron-withdrawing effect of a trifluoromethyl group activates ortho and para halogen toward nucleophilic attack. Such chlorine labiUty is utili2ed in the manufacture of crop control chemicals containing trifluoromethyl and nitro groups. 

Much of the reactivity shown by the ring atoms and substituents of pyrimidine is akin to that of the corresponding parts of 1,3-dinitrobenzene and 3-nitropyridine. This arises from the quantitatively similar electron-withdrawing effects of doubly-bound ring nitrogen atoms and of nitro groups in reducing sharply the aromaticity of the cyclic system. 

The high reactivity of the acyl chlorides also reflects the polar electron-withdrawing effect of the chlorine, which more than outweighs the small 7t-donor effect. 

The behavior of aminopyrazole 88 (R = 4-NO2—C6H4) under these conditions was quite different diazotization using nitrous acid in concentrated hydrochloric acid afforded an alkynylpyrazole diazonium chloride, which did not participate in the Richter reaction, probably due to the electron-withdrawing effect of the nitro group. Instead, after neutralization of the hydrochloric acid with sodium hydrogen... 

The cyanide ion plays an important role in this reaction, for it has three functions in addition to being a good nucleophile, its electron-withdrawing effect allows for the formation of the carbanion species by proton transfer, and it is a good leaving group. These features make the cyanide ion a specific catalyst for the benzoin condensation. 

Taking into account the high structural similarity of dppf and cdpp, their different influence on the reaction s selectivity has to be attributable to electronic effects. The electron density at the phosphorus atoms is significantly lower in the case of cdpp, due to the electron-withdrawing effect of the formal cobalt(III) central atom... 

It reveals that either the steric effect of the bulky N-substituent on the interaction of Ce(IV) ion and urea reductant, or the electron withdrawing effect of the vinyl group, will reduce the coordination of Ce(lV) ion with the carbonyl group, thus resulting in a decrease of the Rp. 

Inductive effect (Sections 2.1, 6.9. 16.4) The electron-attracting or electron-withdrawing effect transmitted through a bonds. Electronegative elements have an electron-withdrawing inductive effect. 

The synthesis of porphyrins from bilanones is free of all symmetry restraints.77 The oxo function is necessary to stabilize the bilane system by its electron-withdrawing effect. The synthesis of porphyrins from the parent bilane without the oxo function and with /3-substituents is possible,54 but the method gives rise to preparative problems due to the sensitivity of these compounds to oxidation, to electrophiles and to acids. Nature circumvents these problems in the cellular environment by exclusion of oxygen, when porphyrinogens, the precursors of porphyrins, are produced from bilanes55 in the course of their biosynthesis. 

Nitration differs from halogenation since here the strongly electron-withdrawing effects of the nitro substituents first introduced influence the reactivity and the positions of further introduced substituents. Therefore, it is possible to prepare under carefully controlled reaction conditions different substitution products.100 103 The preparation of the tetrasubstituted product cannot be achieved since the deactivating effects of three nitro groups are too strong.104... 

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