Group electron attracting

Electrical effects also are important in influencing the ease of addition to carbonyl groups. Electron-attracting groups facilitate the addition of nucleophilic reagents to carbon by increasing its positive character ... 

Explain why the mono-, di- and tri-chloroethanoic acids are progressively stronger acids than the original ethanoic acid. You should consider the inductive effect of the chloro group (electron attracting) on the 0-H bond. 

The rate of hydrogenation is determined by the precious metal profile and the electronic properties of the substituent in the 4-position of the aromatic aldehyde. Unlike the electron-donating methyl group, electron-attracting groups, such as chlorine or carboxyl, increase the reaction rate. This is in agreement with similar observations made comparing... 

Electronegative groups Electron-attracting heteroatom functionalities that do not appreciably decrease the ionization energy of an alkane (e.g., IE, eV ... 

In unsaturated molecules electronic effects can be transmitted by mesomerism as well as by inductive effects. As with the latter, the mesomeric properties of a group are described by reference to hydrogen. Groups which release electrons to the unsaturated residue of the molecule are said to exert a +Af effect, whereas groups which attract electrons are said to exert a —Af effect. In aromatic structures the important feature of an M-substituent is that it influences the 0- and p-positions selectively. 

Any electron-attracting group, -NO2, -CN, -Ac, or -COjEt, on the a-carbon of the methine chain of a thiazole dye gives a bathochromic shift (120). A reverse effect is observed for an alkoxy group. 

Carboxylic acids are weak acids and m the absence of electron attracting substituents have s of approximately 5 Carboxylic acids are much stronger acids than alcohols because of the electron withdrawing power of the carbonyl group (inductive effect) and its ability to delocalize negative charge m the carboxylate anion (resonance effect)... 

Allenes 2000-1915 (m-s) Two bands when terminal allene or when bonded to electron-attracting groups... 

Unsaturated compounds activated by electron-attracting groups can also effect alkylation at the 3-position. An important example is the reaction with nitroethylene to form 3-(2-nitroethyl)indole [31731-23-4] (14). 

Experiments with unsymmetrical iodonium salts iadicate that the bismuth atom is preferentially arylated by the more electron-attracting aryl group. 

Because of the electron-attracting properties of the ring nitrogen atoms, methyl groups undergo aldol-like condensations. For example, 3- and 4-methylpyridazine react with chloral to give 3- or 4-(2-hydroxy-3,3,3-trichloropropyl)pyridazine, and 4-methylpyridazine reacts with anisaldehyde to yield 4-(p-methoxystyryl)pyridazine. 

Let us focus attention on the unfavorable ring closures. Why, for example, should formation of a five-membered ring by an endo-trig process be difficult The answer is provided by a consideration of the trajectory of approach of the nucleophile." If Z is an electron-attracting conjugating group of the type necessary to activate the double bond to nucleophilic attack, the reaction would involve the LUMO of the conjugated system, a 7t ... 

These effects are attributed to differences in the c-donor character of the C—C bonds as a result of substitution. Electron-attracting groups diminish the donor capacity and promote syn addition. An alternative explanation invokes a direct electrostatic effect arising from the C-X bond dipole. 

It should be noted that not all electron-attracting groups enhance reactivity. The sulfonyl and trifluoro groups, which cannot participate in diis type of n conjugation, retard the rate of substitution at an adjacent caibon. ... 

It has long been known that the Diels-Alder reaction is particularly efficient and rapid when the dienophile contains one or more electron-attracting groups. These substituent effects are illustrated by the data in Table 11.3. In the case of the diene, reactivity is increased by electron-releasing substituents. Some illustrative data are given in Table 11.4. 

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