Arylamines alkylation

Aryl diazonium ions prepared by nitrous acid diazotization of primary arylamines are substantially more stable than alkyl diazonium ions and are of enormous synthetic value Their use m the synthesis of substituted aromatic compounds is described m the following two sections... 

Primary arylamines like primary alkylammes form diazonium ion salts on nitro sation Aryl diazonium 10ns are considerably more stable than their alkyl counterparts Whereas alkyl diazonium 10ns decompose under the conditions of their formation aryl diazonium salts are stable enough to be stored m aqueous solution at 0-5°C for a rea sonable time Loss of nitrogen from an aryl diazonium ion generates an unstable aryl cation and is much slower than loss of nitrogen from an alkyl diazonium ion... 

A number of A/-acyl-. A/-alkyl-, and /V-arylamin on apbtbalenol sulfonic acids are used as couplers for a2o dyes. Examples of such intermediates are shown in Table 8. 

Reductive alkylations and aminations requite pressure-rated reaction vessels and hiUy contained and blanketed support equipment. Nitrile hydrogenations are similar in thein requirements. Arylamine hydrogenations have historically required very high pressure vessel materials of constmction. A nominal breakpoint of 8 MPa (- 1200 psi) requites yet heavier wall constmction and correspondingly more expensive hydrogen pressurization. Heat transfer must be adequate, for the heat of reaction in arylamine ring reduction is - 50 kJ/mol (12 kcal/mol) (59). Solvents employed to maintain catalyst activity and improve heat-transfer efficiency reduce effective hydrogen partial pressures and requite fractionation from product and recycle to prove cost-effective. 

Monoureas can also be prepared using COS and an alkylamine, or an arylamine in the absence or presence of a catalyst, where R = H, alkyl, or aryl (39) ... 

Cl Acid Gieen 25 [4403-90-1] (3) (Cl 61570) was also invented in 1894. This dye shows improved wetfastness, and is prepared from leucoquinizarin by reaction with 2 moles of i)-toluidine in a similat manner to the preparation of Cl Acid Violet 43 (134). Wetfastness and leveling properties may be altered by choosing the substituents of arylamines. The introduction of alkyl groups into aromatic amines improves the wetfastness and affinity in neutral or weekly acid baths. Examples ate Cl Acid Blue 80 [4474-24-27] (131) (Cl 61585) and Cl Acid Gieen 27 [6408-57-7] (132) (Cl 61580). 

The synthesis can be conducted both in solution and without solvents. The reaction in solvent (e.g., methanol, ethanol, dioxane, dimethylformamide) is recommended for volatile 1,3-diynes and amines in this case the pyrroles are purer and the yield is higher. With disubstituted diacetylenes, ammonia and primary alkyl- and arylamines produce 1,2,3-trisubstituted pyrroles under the same conditions (65CB98 71MI1). Since disubstituted diacetylenes are readily obtained by oxidative coupling of acetylenes (98MI2), this reaction provides a preparative route to a wide range of pyrroles. 

Amines can be either alkyl-substituted (alkylamines) or aryl-substituted (arylamines).. Although much of the chemistry of the two classes is similar, there are also substantial differences. Amines are classified as primary (RNH2),... 

Research into the mechanism of diazotization was based on Bamberger s supposition (1894 b) that the reaction corresponds to the formation of A-nitroso-A-alkyl-arylamines. The TV-nitrosation of secondary amines finishes at the nitrosoamine stage (because protolysis is not possible), but primary nitrosoamines are quickly transformed into diazo compounds in a moderately to strongly acidic medium. The process probably takes place by a prototropic rearrangement to the diazohydroxide, which is then attacked by a hydroxonium ion to yield the diazonium salt (Scheme 3-1 see also Sec. 3.4). 

With ammonia (refs. 14 - 25), alkyl (refs. 26 - 28) or arylamines (refs. 29 - 44) as well with amides (refs. 37,45-49) (the Goldberg reaction (ref. 50)) the reaction affords substituted anilines. 

Rearrangement of arylamines or aryl alkyl ammonium salts... 

In order to understand these results it is necessary to consider the nature of the intermediates formed upon photolysis of arylamines. The absorption spectra of transients produced upon photolysis of aniline and various alkyl ring-substituted arylamines was obtained by Land and Porter (18) in different solvents using a flash photolysis apparatus. On this basis they identified both an anilinyl radical (PhNH-) and an anilinyl radical cation (PhNHj). The radical cation is present in polar media (H2O) but absent in cyclohexane. From these results, a homolytic cleavage... 

Molecular Orbital Description of Arylaminyl Radicals. Aryl-aminyl radicals, as previously discussed, are intermediates in both the photolysis of alkyl N-arylcarbamates (7, 8) and the photolysis of arylamines (18). A simplified mechanism for photolysis of arylamines and alkyl N-arylcarbamates is illustrated in Scheme IV for the general case. An indication of the reactivity of the... 

Tricarbonyl(cyclohexadienyl)iron cations react with a variety of nucleophiles to give substituted tricarbonyl(cyclohexadienyl)iron complexes88 with arylamines, N- or C-alkylation can occur depending on the nature of aryl ring substituents. Deligation of C-alkylated arylamines can be achieved by either ferric chloride, which gives the free arylamine, or by iodine in the latter case, cyclization with concomitant oxidation occurs, and carbazoles are produced in moderate yield (Scheme 52).89... 

The second method is advantageous over the Gould-Jacobs method with respect to (a) the cyclization step which proceeds smoothly under mild conditions (b) one-pot synthesis of the 1-substituted derivatives and bypassing the alkylation/arylation of the Ni-position of l,4-dihydro-4-oxoquinoline-3-carboxylate, which usually gives rise to mixed N1/O4-substituted products and (c) product versatility due to the ability to utilize a wide range of alkyl-and arylamines in the step before cyclization. 

Arylalkanoic acid esters, 72 166 Arylaldehydes, microwave-accelerated transformation to nitriles, 76 580-581 Aryl alkyl ethers, acid cleavage of, 70 569 Arylalkylsulfones, 9 273 Arylamine dye intermediates, 9 272t... 

Af-EthyI-/V-[3-(4-pyridyl)phenyl]aminomethylenemalonate was prepared in the reaction of /V-ethyl-3-(4-pyridyl)aniline and EMME at 165°C for 0.5 hr (85USP4537735) (Scheme 19). In the reactions of N-alkyl-yV-arylamines (105) and EMME at 120-140°C for 20 min, /V-alkyl-AA-arylaminomethylenemalonates (106) were prepared in 54-81% yields (72HCA1319). 

The high-yield reductive methylation of numerous alkyl and arylamines and of dialkyl-and alkyl-arylamines with paraformaldehyde in the presence of zinc chloride and zinc borohydride has been reported (equation 52)151. 

The groups of Doyle and of Oae148 showed that the yields can be improved by the use of arylamines and alkyl nitrites in place of arenediazonium ion, i.e. by a one-pot diazotization-Meerwein procedure. A condition for good yields is, however, that the alkenes be activated by electron-withdrawing groups. 

The products from the N-alkylation of (anilinomethylene)malonodinitriles with a-haloacetic esters and a-haloketones spontaneously cyclize to produce pyrroles (Scheme 5.3) [21]. When the A -acylated product of the reaction of the dinitrile with ethyl chloroformate is treated with an arylamine, 5-cyanopyrimidones are obtained [21]. 

Arylamines and hydrazines react with tosyl azide under basic conditions to yield aryl azides [1] and arenes [2], respectively, by an aza-transfer process (Scheme 5.25). Traditionally, the reaction of anilines with tosyl azides requires strong bases, such as alkyl lithiums, but acceptable yields (>50%) have been obtained under liquidiliquid phase-transfer catalytic conditions. Not surprisingly, the best yields are obtained when the aryl ring is substituted by an electron-withdrawing substituent, and the yields for the corresponding reaction with aliphatic amines are generally poor (-20%). Comparison of the catalytic effect of various quaternary ammonium salts showed that tetra-/i-butylammonium bromide produces the best conversion, but differences between the various catalysts were minimal [ 1 ]. 

TEBA-Cl (50 mg, 0.2 mmol) is added to a well-stirred suspension of the alkyl isocyanide (10 mmol), the arylamine (10 mmol) and TosN(Cl)Na.3H20 (2.3 g, 10 mmol) in CH2C12 (50 ml) (CAUTION After an induction period, the reaction may become violent.) After 20 h, H20 is added and the organic phase is separated, dried (Na2S04), and evaporated to yield the N-tosylguanidine. 

The scope of allylic electrophiles that react with amines was shown to encompass electron-neutral and electron-rich ciimamyl methyl carbonates, as well as furan-2-yl and alkyl-substituted allylic methyl carbonates. An ort/io-substituted cinnamyl carbonate was found to react with lower enantioselectivity, a trend that has been observed in later studies of reactions with other nucleophiles. The electron-poor p-nitrocinnamyl carbonate also reacted, but with reduced enantioselectivity. Allylic amination of dienyl carbonates also occur in some cases with high selectivity for formation of the product with the amino group at the y-position over the s-position of the pentadienyl unit [66]. Arylamines did not react with allylic carbonates under these conditions. However, they have been shown to react in the presence of the metalacyclic iridium-phosphoramidite catalysts that are discussed in Sect. 4. 

The oxidation of arylhydroxylamines and their O-alkylated derivatives to the corresponding nitro compounds can be achieved with both ozone and nitric acid. This strategy is a useful alternative to the oxidation of arylamines. 

---