Aniline reaction path

Fehrensen B, Luckhaus D and Quack M 1999 Inversion tunneling in aniline from high resolution infrared spectroscopy and an adiabatic reaction path Hamiltonian approach Z. Phys. Chem., NF 209 1-19... 

Path A involves N-formylation of anthranilic acid, condensation of the resultant 2-formaminobenzoic acid with the amine followed by intramolecular amidation of the intermediate amidine to form the product. On the other hand, the amine instead of anthranalic acid may be formylated and go through the known Niementowski reaction (path B). When the reaction of 2-formamidobenzoic acid with aniline and the condensation of formanilide with anthralic acid were conducted under microwave irradiation, the desired 3-phenylquinazolin-4(3 JT)-one was obtained in both cases in a few minutes in 68-87% yield. 

The halogenation of phenols and aromatic amines in aqueous solution also provides evidence for diffusion control, but the interpretation is complicated by the fact that either the formation of the o-complex or the proton loss from the (7-complex can be rate-determining. The reaction path for the halogenation of aromatic amines in aqueous acids is believed to be that shown for N,N-dialkyl anilines in Scheme 9. Where the formation of the o-complex is rate-determining, the kinetic form for attack by the molecular halogen is given by (39). In this equation, the observed rate coefficient (k ) is related to the rate coefficient for the reaction of the amine molecule (k) by (40), where KSH+ is the... 

Oxidation of tertiary amines with N-chloronylon 6,6 has also been investigated in several solvents Thus, N-chloronylon has been found to oxidize N J -dimethyl-aniline at room temperature to N-methylaniline in 15—50% yield, depending on the solvent used. The oxidation of NJM-dimethylbenzylamine gives benzddehyde in 15-30% yield and a small amount of N-methylbenzylamine. A comparison of these oxidations with those using the low molecular wei t analoges, e. g. N-chlorosuccin-imide, indicates that in both cases the reaction paths are similar. However, the poor yields observed in these oxidations of amines make these polymeric oxidizing agents unsuitable for amine oxidations. 

Additional support for the postulate of these two reaction paths comes from the thermolysis of cyclohexyl azide in ethyl benzoate and indene, where = 47.5 and 34.6 kcal.mole", and AS = 32.2 and 17.4 eu, respectively ". (The enormously high value of 32.2 eu may be due to some experimental error.) Ring enlargement has been observed in the thermolysis of phenyl azide in aniline solutions " " . 

The combination of Co Kbpy)2 -O2 with these substrates yields product profiles that are similar, which indicates that the reaction path probably involves the same reactive intermediate (species 2, Scheme 6-2). Scheme 6-2 outlines catalytic cycles for the demethylation of N-methyl anilines, and the dehydrogenation of benzylamine and benzyl alcohols. In the case of the latter catalyst [Con(bpy> ] is inactive and must be neutralized with one equivalent of HO-... 

From the data on feed rate, temperature and OPE curves, it can be concluded that aniline methylation on AlPO and AlPO -metal oxide catalysts follows a sequential reaction path of formation of NMA, to NNDMA and then C-alkylated products ... 

The formation of a significant amount of the C-substituted product with 2, 4-dinitro-N-methyl aniline is more unexpected (Table I, exp. C) and the possible reaction paths are best discussed in terms of the network in Scheme 1. The C-substituted product could be derived either directly (path b) or via the nitramine (path a and c). 

Pr, Bu", MeCO, CH2=CHCH2, aniline). The [Rhpy4Cl2] ion reacts with a variety of Schiff bases in boiling pyridine solution (in the presence of Zn dust and PF ), to generate a family of complexes of the form [Rh(SB)py2]PFt (121)." These all formed methyl adducts with Rh "—Me bonds when reacted with methyl iodide. " A similar reaction path ([Rh(py)4Cl2]Cl + Zn dust + Schiff base) was used to prepare [Rh(N—0)2py2] (122). In the absence of Zn dust, [Rh(py)4Cl2] is unreactive toward Schiff bases, even when refluxed in pyridine for many hours. The best yields are obtained when equivalent amounts of Zn and Rh are reacted." ... 

Fig. 23.—Liquid-solid Chromatogram of Formose Sugars. [Apparatus Hitachi Type 034-0004-KLA-3B Liquid Chromatograph. Column 1.5 diam. X 50 cm, column temp. 55°. Packing Bio-Rad Resin Type AG 1 X2. Sample formose 19.65 mg/ 0.5 ml. Eluant 1, 0.25 M H.BO, pH 8.2, 385 min 2, 0.60 M H.BO., pH 10.2. Effluent flow-rate 15 ml/hr (6.0 kg/cm ) reagent flow-rate 45 ml/hr (5.9 kg/cm ). Reagent phosphoric acid + acetic acid + aniline. Reaction bath-temp. 120°. Reaction coil 0.8 diam. X 23 cm. Cell path 2 mm, wave length 365 nm. Chart speed 6 cm/hr. Scale 0-0.2 expansion. ]...

Another category Ic indole synthesis involves cyclization of a-anilino aldehydes or ketones under the influence of protonic or Lewis acids. This corresponds to retro.synthetic path d in Scheme 4.1. Considerable work on such reactions was done in the early 1960s by Julia and co-workers. The most successful examples involved alkylation of anilines with y-haloacetoacetic esters or amides. For example, heating IV-substituted anilines with ethyl 4-bromoacetoacetate followed by cyclization w ith ZnClj gave indole-3-acetate esterfi]. Additional examples are given in Table 4.3. 

Anilines react with ct-haloacetophenones to give 2-arylindoles. In a typical procedure an W-phenacylaniline is heated with a tw o-fold excess of the aniline hydrobromide to 200-250°C[1]. The mechanism of the reaction was the subject of considerable investigation in the 1940s[2]. A crucial aspect of the reaction seems to be the formation of an imine of the acetophenone which can isomerize to an aldimine intermediate. This intermediate apparently undergoes cyclization more rapidly (path bl -> b2) than its precursor (Scheme 7.3). Only with very reactive rings, e.g, 3,5-dimethoxyaniline, has the alternative cydiz-ation (path al a2) to a 3-arylindole been observed and then only under modified reaction conditions[3],... 

Participation in the electrode reactions The electrode reactions of corrosion involve the formation of adsorbed intermediate species with surface metal atoms, e.g. adsorbed hydrogen atoms in the hydrogen evolution reaction adsorbed (FeOH) in the anodic dissolution of iron . The presence of adsorbed inhibitors will interfere with the formation of these adsorbed intermediates, but the electrode processes may then proceed by alternative paths through intermediates containing the inhibitor. In these processes the inhibitor species act in a catalytic manner and remain unchanged. Such participation by the inhibitor is generally characterised by a change in the Tafel slope observed for the process. Studies of the anodic dissolution of iron in the presence of some inhibitors, e.g. halide ions , aniline and its derivatives , the benzoate ion and the furoate ion , have indicated that the adsorbed inhibitor I participates in the reaction, probably in the form of a complex of the type (Fe-/), or (Fe-OH-/), . The dissolution reaction proceeds less readily via the adsorbed inhibitor complexes than via (Fe-OH),js, and so anodic dissolution is inhibited and an increase in Tafel slope is observed for the reaction. 

The fate of dissolved amines during disinfection of water by chlorination was determined by membrane injection MS. Aliphatic amines undergo TV-chlorination to exhaustion of the N-H atoms by one of the tentatively proposed paths shown in reaction 28. Aromatic amines undergo mainly ring substitution however, the possible intervention of N-C1 intermediates is not excluded. At pH 10.6 aniline chlorination is much slower than that of n-butylamine383. 

Alvernhe and Laurent first developed a procedure for conversion of Grignard reagents to primary amines using acetone oxime 6c and butanone oxime 6d (Scheme 55) 22 23 However, the yields were low. They expanded their study to investigate how well organo-lithiums perform in their reaction with 6c or 6d 23. Phenyllithium gave a 1 4 mixture of aniline and the addition product of phenyllithium to the imine (Scheme 53, path e product) in the reaction with 6c while aziridine was obtained in the reaction with 6d (Scheme 56). 

At pH >11, aniline production occurs via the anionic carbinolamine only and the overall reaction is first-order in hydroxide ion. At pH 8-10, the path via the carbinolanine gives a constant rate of hydrolysis and at pH 5.5-7 aniline arises solely through the neutral carbinolanine, present in its largest amounts. Eventually, acid catalysis leads to an increase in the rates of hydroly-... 

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