V-Dimethylaniline

A AlI lation. A number of methods are available for preparation of A/-alkyl and A[,A/-dialkyl derivatives of aromatic amines. Passing a mixture of aniline and methanol over a copper—zinc oxide catalyst at 250°C and 101 kPa (1 atm) reportedly gives /V-methylaniline [100-61-8] in 96% yield (1). Heating aniline with methanol under pressure or with excess methanol produces /V, /V-dimethylaniline [121 -69-7] (2,3). 

In the presence of sulfuric acid, aniline reacts with methanol to form /V-methyl- and /V,/V-dimethylaniline. This is a two-step process... 

Phthalic anhydride condenses with the aniline derivative in the presence of zinc or aluminum chlorides to yield the intermediate benzoyl-benzoic acid, which subsequently reacts with l,3-bis-V,V-dimethylaniline in acetic anhydride to yield the phthalide. The above compound gives a violet-gray image when applied to a clay developer. Clearly this synthesis is also very flexible and variations in shades of color formers have been obtained by varying the aniline components and also by using phthalic anhydrides substituted, for example, by nitro groups or chlorine atoms. Such products have excellent properties as color formers and have been used commercially. Furthermore, this synthetic route is of great importance for the preparation of heterocyclic substituted phthalides, as will be seen later. 

V,/V-dimethylaniline, especially when those strong donors are paired with the relatively electron-poor MES derivative of the bis(arene)iron(ll) acceptor. As such, the dark reactions arise via essentially the same multistep mechanism as that for charge-transfer de-ligation, the difference arising from an adiabatic electron transfer (10) as the initial step that is thermally allowed when the driving force -AGET is sufficient to surmount... 

In the ensuing discussion, the energy dependence of the rate constants for proton transfer within a variety of substituted benzophenone-lV, /V-dimethylaniline contact radical ion pairs is examined only the data for the nitrile solvents are discussed. This functional relationship is examined within the context of theories for non-adiabatic proton transfer. Finally, these results are viewed from the perspective of other proton-transfer studies that examine the energy dependence of the rate constants. 

The rate constants for proton transfer as a function of substituent and solvent are given in Table 2.3 [43]. All experiments involved the 355-nm irradiation of various benzophenones in the presence of 0.4 M N, /V-dimethylaniline. 

An interesting question then arises as to why the dynamics of proton transfer for the benzophenone-i V, /V-dimethylaniline contact radical IP falls within the nonadiabatic regime while that for the napthol photoacids-carboxylic base pairs in water falls in the adiabatic regime given that both systems are intermolecular. For the benzophenone-A, A-dimethylaniline contact radical IP, the presumed structure of the complex is that of a 7t-stacked system that constrains the distance between the two heavy atoms involved in the proton transfer, C and O, to a distance of 3.3A (Scheme 2.10) [20]. Conversely, for the napthol photoacids-carboxylic base pairs no such constraints are imposed so that there can be close approach of the two heavy atoms. The distance associated with the crossover between nonadiabatic and adiabatic proton transfer has yet to be clearly defined and will be system specific. However, from model calculations, distances in excess of 2.5 A appear to lead to the realm of nonadiabatic proton transfer. Thus, a factor determining whether a bimolecular proton-transfer process falls within the adiabatic or nonadiabatic regimes lies in the rate expression Eq. (6) where 4>(R), the distribution function for molecular species with distance, and k(R), the rate constant as a function of distance, determine the mode of transfer. 

Table 21 The a-carbon-12/carbon-14 and secondary a-hydrogen-tritium KIEs for the Sn2 reactions between Y-substituted jV,/V-dimethylanilines and Z-substituted benzyl X-substituted benzenesulfonates in acetone at 35°C.a...

Table 23 The secondary a-deuterium and incoming nucleophile nitrogen KIEs found for the Sn2 reactions between p-substituted N,/V-dimethylanilines and methyl iodide in ethanol at 25°C.a...

---