Nucleophilic addition reactivity order

Imines and iminium ions are nitrogen analogs of carbonyl compounds and they undergo nucleophilic additions like those involved in aldol reactions. The reactivity order is C=NR < C=0 < [C=NR2]+ < [C=OH]+. Because iminium ions are more reactive than imines, the reactions are frequently run under mildly acidic conditions. Under some circumstances, the iminium ion can be the reactive species, even though it is a minor constituent in equilibrium with the amine, carbonyl compound, and unprotonated imine. 

The selectivity of RNH2 on M/A1203 and Raney catalysts decreased in the order Co Ni Ru>Rh>Pd>Pt. This order corresponds to the opposite sequence of reducibility of metal-oxides [8] and standard reduction potentials of metalions [9], The difference between Group VIII metals in selectivity to amines can probably been explained by the difference in the electronic properties of d-bands of metals [3], It is interacting to note that the formation of secondary amine, i.e. the nucleophilic addition of primary amine on the intermediate imine can also take place on the Group VIII metal itself. Therefore, the properties of the metal d-band could affect the reactivity of the imine and its interaction with the amine. One could expect that an electron enrichment of the metal d-band will decrease the electron donation from the unsaturated -C=NH system, and the nucleophilic attack at the C atom by the amine [3], Correlation between selectivity of metals in nitrile hydrogenation and their electronic properties will be published elsewhere. 

Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions. 

This consideration is corroborated by calculations at different levels of theory [11-13], showing that 1,2-additions to C q occur preferentially at a and (3 bonds between C(l) and C(2) and C(5) and C(6), respectively (Figure 13.2). Also, Mulliken charges on the fullerene core have been used in predicting the regiochemistry of nucleophilic additions to C70 [11]. Finally, 7t-bond orders have also been employed to evaluate the reactivity of different types of bonds [14-16]. 

Probtom 15.24 Explain the order of reactivity ArCHjCOR > R C O > ArCOR > ArjCO in nucleophilic addition. ... 

Arrange these compounds in order of reactivity towards i) nucleophilic addition, ii) nucleophilic substitution, and iii)... 

The K-region oxides undergo nucleophilic addition with OH", C032", water, amines, and mercaptides.88,140 The second-order rate constants for the reactions of OH", water, and primary and secondary amines with 1 at 30°C and with ethylene oxide at 25°C141 can be simply related by Eq. (6),2 which shows that the sensitivity of the two oxides to the nature of the nucleophile is similar and that the arene oxide is more reactive. 

If the nucleophilic addition is the rate limiting step, the order of reactivity of the individual ring positions should run parallel to the order found by nucleophilic addition followed by elimination as discussed in Section I.5.I.3. With azole N-oxide as the starting material, the net result... 

Such a charge transfer from the ligated arene can lead to (a) nucleophilic addition or substitution, (b) electron transfer, and (c) proton elimination/transfer, thus revealing the dose relationship between all of these processes. The reactivity of the arene ligands towards nudeophiles in (arene)ML complexes depends on the electrophilidty of the metal fragments [MLn], this increasing in the order [Cr(CO)3] < [Mo(CO)3] [FeCp]+ < [Mn(CO)3]+ [2]. For example, in (arene)FeCp+, which is widely used for synthetic purposes, a chloro or nitro substituent on the arene is readily substituted by such nudeophiles as amides, eno-lates, thiolates, alkoxides, and carbanions [45]. 

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