Primary aromatic diamines

Primary aromatic diamines cannot be diazotised (tetrazotised) and coupled normally. Thus o-])henylenediamiiie yields a triazole derivative and m-phenylenediamine gives an azo dye (Bismarck brown) by selfcoupling. 

V-Phenylsuccinimide [83-25-0] (succanil) is obtained in essentially quantitative yield by heating equivalent amounts of succinic acid and aniline at 140—150°C (25). The reaction of a primary aromatic amine with phosgene leads to formation of an arylcarbamoyl chloride, that when heated loses hydrogen chloride to form an isocyanate. Commercially important isocyanates are obtained from aromatic primary diamines. 

Dyes. Sodium nitrite is a convenient source of nitrous acid in the nitrosation and diatozation of aromatic amines. When primary aromatic amines react with nitrous acid, the intermediate diamine salts are produced which, on coupling to amines, phenols, naphthols, and other compounds, form the important azo dyes (qv). The color center of the dye or pigment is the -N=N- group and attached groups modify the color. Many dyes and pigments (qv) have been manufactured with shades of the entire color spectmm. 

The reactions of 4-alkoxybut-3-en-2-ones with primary aromatic amines and diamines of the aromatic and heteroaromatic series follow analogous schemes. 

Formally, these pigments are disazomethine types, obtained by condensation of primary aromatic diamines with two equivalents of tetrachloroisoindoline-1-one ... 

Polycondensation of aromatic primary diamines and aromatic dibromides gave high molecular weight polyamine (Mw > 15 000) irrespective of the m-and p-substituted positions of both monomers (Scheme 12). In this polycondensation, BINAP was effective as a ligand of the Pd(0) catalyst use of P(f-butyl)3, which was effective for the above polymerization using secondary diamines, afforded polymer in a low yield [65,66]. When BINAP was used... 

Polymerization of Primary Aromatic Diamines to Azopolymers by Oxidative Coupling... 

In the last few years, the catalyzed oxidative coupling of primary aromatic diamines has been investigated extensively in our laboratories (1, 2, 3) and also by Kotlyarevskii (19, 20, 30). Results of these investigations are reviewed in this chapter as well as the properties of the class of aromatic azopolymers. 

Oxidative Coupling Reaction. Catalyzed oxidative coupling of primary aromatic diamines with oxygen as the oxidant yields linear polymers according to the following scheme ... 

Catalyzed oxidative coupling is generally applicable to simple primary aromatic diamines as well as to diamines of a complex structure. The scope of the reaction is exemplified by some of the polymers prepared ... 

Side reactions in the oxidative coupling of primary aromatic diamines to azopolymers could severely limit the molecular weights of polymers obtainable and disrupt their ordered, linear structure. To investigate this point the following polymer... 

In the oxidative coupling of primary aromatic diamines to azopolymers cupric ion/nitrogen base complexes serve as homogeneous catalysts. Such complexes are best prepared in situ by oxygenating a cuprous species, preferably CuCl or Cu O/HCl, in the presence of the nitrogen base. Cupric salts investigated except for cupric acetate yielded inactive species. 

In the cupric ion-catalyzed reaction of primary aromatic diamines with oxygen four key steps can be recognized (shown for a monoamine with nitrogen base ligands left out for convenience) ... 

Aromatic Azopolymers. Through the described catalyzed oxidative coupling of primary aromatic diamines a great variety of aromatic azopolymers has become easily accessible. Therefore, an investigation of their properties in bulk as well as fabricated form seemed warranted. 

NIR spectrophotometry in the region from 8000 to 4000 cm-1 was used to measure the kinetics of copolymerization of an aromatic bismaleimide (72) derived from an aromatic diamine (e.g. 5a), taking place at 160 to 180 °C. The following NIR spectral ranges were useful for this study primary amine first overtones (vn h) at 7000 to 6400 cm-1, double bond first overtone (vc=c-h) at 6100 cm-1, aromatic first overtones (vc-h) at 6000 to 5750 cm-1, aliphatic first overtones (vc-h) at 5750 to 5350 cm-1 and primary aromatic amine combination bands first overtones (vn h + <5nh2) at 5150 to 4800 cm-1. The process consisted mainly of a second-order Michael addition, as depicted in equation 14, and not the plausible imide opening to yield a maleic dianilide (119), as shown in equation 15. A Michael addition between maleimide moieties and secondary amine moieties present in the products (118) also takes place, however at a rate of about one fourth of that of the primary amine moieties. To improve the SNR of the measurements, usually the results of... 

Combinatorial parallel synthesis of head-to-tail bisbenzimidazoles 41 has been performed using polymer-immobilized 1,2-diaminobenzenes (Fig. 2). The PEG-bound diamines were hf-acylated at the primary aromatic amino group with 4-fluoro-3-nitrobenzoic acid. The substituted amides were cy-clized to benzimidazoles under acidic conditions. Successive reduction and cyclization with various aldehydes yielded 5-(benzimidazol-2-yl)benzimid-azoles. Finally, the desired products 41 were released from the polymer support to afford the bisbenzimidazoles in good yields and with high purity [46]. 

Although this methodology is widely applicable for the preparation of many 1,1-enediamines, 2- aroylmethylene)benzimidazolines (29) cannot be obtained from the reaction of benzoyl-substituted ketene dithioacetals 30 and o-phenylenediamine. Instead of 29, 3/f-l,5-benzodiazepines 31 are isolated from the reaction . Similar results have been reported for the reaction of 30 and other primary aromatic diamines . A recent study has revealed that an enamine-imine tautomeric equilibrium is involved in the reaction process (Scheme 2). This equilibrium between 33A and 33B is affected by the... 

Aniline polycondensate 188 was reported to impart ozone and heat resistances to NR. Condensates of BQ with primary aromatic diamines are of potential interest as stabilizers [290],... 

In this type of reaction, when heated in the presence of acid catalysts (hydrochloric, phosphoric, or />-toluenesulfonic acid), primary aromatic amines often condense smoothly with loss of ammonia to afford diamines. Diphenyl-amine, for example, can be obtained by heating aniline and aniline hydrochloride for 20 hours at 230°/6 atm.355b... 

In 1955, Terent ev and Mogilyanskii reported the catalytic oxidative coupling of aniline to azobenzene with a yield of 88%, mediated by copper chloride in pyridine (which acts as both a metal ligand and solvent) in the presence of molecular oxygen [1]. This system was subsequently used for the generation of various conjugated and nonconjugated main-chain aromatic azo polymers from primary aromatic diamines [2]. In contrast, the use of CUCI-O2 with phenol produces tars [3] as a result of the inherent properties of this reactant. Indeed, while the metal salt produces iV-centered aniline radicals that dimerize to form azobenzene... 

Primary aromatic diamines cannot be diazotized, but other reactions might occur. Thus o-phenylenediamine yields a triazole derivative, and m-phenylenediamine yields an azodye (bismarck brown) by self-coupling if submitted to the test conditions, and this reaction too has been used for the determination of nitrites. ... 

On the other hand, the primary thermal decomposition of polyamides of aliphatic-diamine and aromatic-dicarboxylic acid proceeded via the cis elimination process with formation of the products containing amide and olefin end groups. Nitrile end groups also proved to be formed by dehydration of the anfide groups formed in the primary process. 

Working in the area of elastomers, Itovaclc (U. S. Patent 2,818,407 Dec. 31, 1957) reported the Michael addition of amine capped prepolymers to bls-maleimides. Similarly, Sheremeteva euid co-workers found that reaction of stoichiometric amounts of bls-maleimides and primary aromatic diamines in refluxing ethanol afforded polymers, vAiich thermally degraded so rapidly that they could not be considered heat resistant. 

Primary amines and amino acids selectively react with carbonyl compounds such as benzaldehyde, furfural, and pentafluorobenzaldehyde in aqueous medium at room temperature, and give Shiff s bases in good yields. This reaction is used for the determination of aliphatic diamines and aromatic amines by GC with a flame photometric detector or an electron capture detector. However, a cleanup step for sample preparation is required to remove the excess reagent. 

Combined tertiary/secondary amine curatives, prepared from ter-tiary/primary diamines and epoxy resins, have been used as accelerators for primary aromatic amine cures of DGEBA-type epoxy resins. For example, diethylaminopropylamine/DGEBA resin adducts have been used in m-phenylenediamine-cured epoxy resin systems to provide relatively low temperature cures (50-160°C). The cured resin systems have good toughness and heat distortion temperatures near 130°C. 

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