A/.V’-Dimethylaniline

Electron-rich aromatic compounds, such as phenol, anisole and A,./V-dimethylaniline, add to bis(2-trichloroethyl) azodicarboxylate under the influence of lithium perchlorate, boron trifluoride etherate or zinc chloride to yield para-substituted products 74, which are transformed into the anilines 75 by means of zinc and acetic acid86. Triflic acid (trifluoromethanesulphonic acid) catalyses the reactions of phenyl azide with benzene, toluene, chlorobenzene and naphthalene, to give TV-arylanilines (equation 34)87. 

The s pT a of five weak electrolytes of different chemical nature (butylamine, A,A-dimethylaniline, phenol, and benzoic acid) in 50% methanol/water at 20-50°C were determined by Castells et al. [108], and the values are shown in Table 4-15. The effect of temperature was the greatest for the basic compound butylamine, and a lesser effect was observed for the weaker bases pyridine and A,/V-dimethylaniline and the weakly acidic phenol. 

Abbreviations CTAB = hexadecyltrimethylammonium bromide SHDTE = sodium hexadecyl-trioxyethylene sulfate SDS = sodium dodecyl sulfate DTAB = dodecyltrimethylammonium bromide TTAB = tetradecyltrimethylammonium bromide bpy = 2,2 -bipyridyl MV- = N,N -dimethyl-4,4 -bipyridinium Rh = octadecylrhodamine DMA = A, .V-dimethylaniline. 

The methylene group in 3-oxo-2,3-dihydrobenzotellurophene condenses with dimethyl-formamide, aromatic aldehydes, bis[ethoxy](dimethylamino)methane, and 4-nitroso-A(,(V-dimethylaniline. ... 

The reaction of aromatic amines with nitrous acid is of considerable importance and the formation of diazonium salts from the primary amines is discussed in detail in Section 8.6. Reaction of nitrous acid with secondary amines does not give diazonium salts, but results instead in /V-nitrosation. Tertiary amines such as A, /V-dimethylaniline do not N-nitrosate, but undergo electrophilic substitution by the nitrosonium cation (NO+) to give A ,A -dimethyl-4-nitrosoaniline (Scheme 8.8). 

A A -Dialkylarylamines react under classical conditions at C-4 if that position is unsubstituted. For example, A. )V-dimethylaniline reacts with formaldehyde and dimethylamine to afford 4-)V, A -dimethyl-amino-A, Af-dimethylbenzylamine in 82% yield (equation 20). Under acidic conditions fragmentation of the initial product can occur, leading to the formation of diarylmethanes. In the reaction of A A -dimethy-laniline with formaldehyde and pyrrolidine the best yield of the Mannich base (44%) is obtained in the presence of 1.5 mol equiv. of acetic acid with 4.0 mol equiv. the yield is only 7%. The reaction of N-methylenemorpholinium chloride with 4-A -morpholinylmethyl-)V,A -dimethylaniline results in the introduction of a second A -morpholinylmethyl residue at the 2-position, but with other iminium chlorides quaternary salts are formed by reaction with the nitrogen of the 4-dialkylaminomethyl group. There is dso a brief report of the use of the mixed A. Af-dialkylmethyleneiminium salt, A -f-butyl-A -methyl-methyleneiminium perchlorate, with A. Af-dimethylaniline. °... 

Fig. 42. Transient absorption spectra taken with a delay of 35 ps after excitation at 355 nm (a) A, A -di-n-pentylpyromelliti-mide-A, V-dimethylaniline CTC in dichloromethane and (b) A, A/ -dimethylaniline-loaded Kapton film. Reproduced with permission from Macromolecules 1987 20 973. 1987 American Chemical Society [125].

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... 

Penton and Zollinger (1979, 1981 b) reported that this could indeed be the case. The coupling reactions of 3-methylaniline and A,7V-dimethylaniline with 4-methoxy-benzenediazonium tetrafluoroborate in dry acetonitrile showed a number of unusual characteristics, in particular an increase in the kinetic deuterium isotope effect with temperature. C-coupling occurs predominantly (>86% for 3-methylaniline), but on addition of tert-butylammonium chloride the rate became much faster, and triazenes were predominantly formed (with loss of a methyl group in the case of A V-di-methylaniline). Therefore, the initial attack of the diazonium ion is probably at the amine N-atom, and aminoazo formation occurs via rearrangement. 

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. 

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...

The kinetics and mechanism for oxygen transfer between 4-cyano-V,V,-dimethylaniline V-oxide and a C2-capped mexo-tetraphenylporphyrinatoiron(III) and mc5 o-tetrakis(pentafiuorophenyl)-porphyrinatoiron(III) have been established. Addition of a copper(II) porphyrin cap to an iron(II)-porphyrin complex has the expected effect of reducing both the affinities and rate constants for addition of dioxygen or carbon monoxide. These systems were studied for tetradecyl-substituted derivatives solubilized by surfactants such as poly(ethylene oxide) octaphenyl ether. ... 

---