Substitution of a Group

All of the foregoing reactions involve a formal nucleophilic substitution of a group (e.g., H and Cl) attached to the double bond of a coordinated olefin. Under different conditions, Pd(II)-catalyzed oxidations of olefins can give products (e.g., glycol esters) resulting from formal addition to the double bond of coordinated olefins.5613... 

A group 15 atom is isoelectronic and isolobal with a CH group. Therefore, one would expect that substitution of a group 15 element for a carbon group in a dicarbaborane would yield compounds with similar structures... 

Aminocyclopropanes (1) are typical representatives of the family of donor-substituted cyclopropanes. The combination of an amino moiety with the cyclopropane ring is not only of theoretical interest for possible donor-acceptor interactions, but is also the origin of an easy nucleophilic substitution of a group X in (1) or a ring-opening reaction. Intermediates 2 and 3 represent these two types of reactions according to the sequence 1 - 3 an aminocyclopropane is to be regarded as a homoenamine species. 

As well as those reactions that fall neatly into one or other of the three simple reaction types, there are some reactions where an addition reaction is followed by an elimination reaction, or vice versa, resulting in an overall substitution of a group. These reactions will be considered separately in this book under the heading of sequential addition/elimination reactions. 

Elimination/addition Overall a reaction that results in substitution of a group, but which proceeds via an initial elimination followed by an addition. 

In a study of the relative strengths of fatty acids, Derick observed (1) as a first approximation, that A log for a substitution of a group for a hydrogen atom depended on the group and position... 

A large group of pyridoxal-P-dependent enzymes catalyse reactions that affect as well as C of the amino acid and these can be divided into two main groups (Fig. 24) (a) those that involve the substitution of a group at ()8 replacement) and (b) those that involve the overall elimination of the a-hydrogen atom and the substituent with the formation of a-oxoacid and ammonia elimination-deamination). 

By the further substitution of a group (CHa) in acetanilid, methyl-acetanilid, or exalgine, Cmethyl iodid upon sodium acetanilid, CsHaiNNa CjHsO. It is a crystailine solid, sparingly soluble in. HsO, readily in dilute alcohol. Its odor is faintly aromatic. 

A large molecule in which neither the end groups nor the substitution of a group has any significant influence on the material properties. 

Hydrolysis of organic compounds usually results in the substitution of a group by a hydroxyl group. In water, the reaction is catalyzed by H, OH, and ions. In moist soils, labile complexes of calcium and copper act as catalysts. Sorption tends to increase a chemical s reactivity to or OH radicals. Mabey and Mill (1978) reviewed the kinetic data for hydrolysis of a variety of organic chemicals in aquatic systems and the chemical characteristics of most fresh-water systems. These data could be used to calculate the persistence (half-life for hydrolysis) of chemicals under natural environmental conditions. 

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