1,2-Diamines coupling reactions

Other noncychc reactions are observed, especially in polyamides of longer carbon chain monomers for example, the linear analogue to the cychc amine reaction is diamine coupling (eq. 10) to form secondary amines that can act as branch points (eq. 11). 

Toluene diisocyanate Midget impinger 15 ml Marcali solution 1 25 95 Diazotlzation and coupling reaction Materials containing reactive hydrogen attached to oxygen (phenol) certain other diamines... 

If an aromatic o-diamine such as 1,2-diaminobenzene (2.24) is diazotized in dilute aqueous acid, the 2-aminobenzene-l-diazonium ion formed first (2.25) undergoes a rapid intramolecular N-azo coupling reaction to give 1,2,3-benzotri-azole (2.26). Both amino groups of 2.24 can, however, be diazotized in concentrated acid (Scheme 2-18), forming the bis-diazonium ion 2.27. 1,3- and 1,4-diamines must also be bisdiazotized in concentrated acids in order to avoid inter-molecular N- or C-coupling. 

Cascade Blue diamine derivatives are soluble in aqueous solution. A concentrated stock solution may be prepared in water, dissolved quickly, and an aliquot immediately added to a buffered reaction medium. For aqueous reactions, 0.1M MES, pH 4.7-6.5, may be used to stabilize the pH during the coupling process. Avoid amine- or carboxylate-containing buffers such as Tris or glycine, since these can compete with the coupling reaction. 

In order to manufacture a diarylide yellow pigment, the diamine, dissolved in hydrochloric acid or sulfuric acid, is bisdiazotized with an aqueous sodium nitrite solution. The resulting diazonium compound is subsequently coupled onto two equivalents of acetoacetarylide. Since a material with a very fine particle size is needed for a fast and complete coupling reaction, the coupling component is prepared by dissolution in an alkaline medium and reprecipitation with an acid, such as acetic acid or hydrochloric acid. Dichlorobenzidine cannot be diazotized stepwise. A lack of sodium nitrite does not produce the monodiazonium compound, but an excess of 3,3 -dichlorodiaminodiphenyl remains. 

The enantioselective oxidative coupling of 2-naphthol itself was achieved by the aerobic oxidative reaction catalyzed by the photoactivated chiral ruthenium(II)-salen complex 73. 2 it reported that the (/ ,/ )-chloronitrosyl(salen)ruthenium complex [(/ ,/ )-(NO)Ru(II)salen complex] effectively catalyzed the aerobic oxidation of racemic secondary alcohols in a kinetic resolution manner under visible-light irradiation. The reaction mechanism is not fully understood although the electron transfer process should be involved. The solution of 2-naphthol was stirred in air under irradiation by a halogen lamp at 25°C for 24 h to afford BINOL 66 as the sole product. The screening of various chiral diamines and binaphthyl chirality revealed that the binaphthyl unit influences the enantioselection in this coupling reaction. The combination of (/f,f )-cyclohexanediamine and the (R)-binaphthyl unit was found to construct the most matched hgand to obtain the optically active BINOL 66 in 65% ee. 

In a manner similar to the Sml2-mediated homocoupling of enantiomerically pure (o-methylbenzaldehyde)-Cr(CO)3, the coupling reaction of the [methyl(o-tolylmethylene)amine]Cr(CO)3 complex 17 with SmE gives only ry -diamine 18 along with the reduced amine 19 (Equation (63)). ... 

The reaction is carried out by adding the allene dropwise to a solution of sodium amide in ethylene diamine-ether (30 70) maintained at room temperature. The reaction mixture is agitated during addition and for about two to three hours thereafter, followed by quenching with aqueous ammonium chloride and distillation. The presence of the diene does not interfere in the subsequent coupling reaction of the acetylene with "isoprene chloroacetate" (l-acetoxy-4-chloro-3-methylbut-2-ene) (3), as it is merely an inert component in the reaction mixture. 

Transition metal-catalysed carbon-heteroatom coupling reactions primarily comprise the carbonylation polycondensation of dibromoarenes with aromatic diamines and bisphenols in the presence of carbon monoxide... 

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

One can note that for this step the ratio of reagents 3 2 is 2 1, the excess diamine, 3, playing the role of base which takes up the hydrogen chloride liberated by the coupling reaction. The separation of the monocyclic diamide 4 from the reaction mixture containing amide oligomers is easy as the latter... 

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