Tris- -amine

Pyrimidine-2,4,5-triamine, 6-hydroxy-as cofactor of phenylalanine hydroxylase, 1, 261 Pyrimidine-2,4,5-tri amines basic p/fa, 3, 61 Pyrimidine-2,4,6-triamines synthesis, 3, 115... 

Aromatic amines, Sulfuric acid Nielsen, A. T. etal., J. Org. Chem., 1980, 45, 2341-2347 The acid, prepared from 90-98% hydrogen peroxide and oleum or 100% sulfuric acid, is one of the most powerful known oxidants and its use for oxidising aromatic amines to nitro compounds has been studied. Some mono- di- and tri-amines are destroyed exothermically with violent fume-off. Precautions for use are detailed. 

The synthetic and industrial importance of this reaction lies in its generality, and the ease with which the amino substituent in the products can be subsequently transformed into other functionalities. Pyridine itself is more difficult to aminate than quinoline or isoquinoline, and it does not react with potassium amide in liquid ammonia even on prolonged treatment. However, pyridine is aminated in good yield by sodamide in toluene, and di- and tri-amination can be achieved with excess sodamide at higher temperatures. The 4-position is substituted last in triamination y-amination is very difficult indeed and only takes place when all a -positions are occupied. 

The [Cr(en)3]2+ and [Cr(pn)3]2+ salts have reflectance spectra (Table 11) resembling those of the hexaammines, and the six N donor atoms are assumed to complete tetragonally distorted octahedra around the metal. Stability constant measurements (Table 39) have shown that the ions [Cr(en)(aq)]2+ (vmax= 18 300 cm-1, e = 25 dm3 mol-1 cm-1) and [Cr(en)2(aq)]2+ (vma = 17 500 cm-1, e = 17 dm3 mol-1 cm-1) exist in aqueous solution, but that, as in the copper(II) system, the third ethylenediamine molecule is only weakly bound, and care is needed to prevent loss of en from tris(amine) complexes in the preparations. Several bis(amine) complexes, e.g. [CrBr2(en)2], have been isolated, and these are assigned trans structures because of IR spectral resemblances to the corresponding oopper(II) complexes. Since the spectrum of [Cr(S04)(en)2] also shows the presence of bidentate sulfate, this is assigned a trans octahedral structure with bridging anions. 

Chromium(II) complexes of bipyridyls, terpyridyl and the phenanthrolines have been discussed in Section 35.2.2.1. Complexes of the ligands 2-aminomethylpyridine (pic, 2-picolyl-amine) and 8-aminoquinoline (amq), which have one heterocyclic and one amino nitrogen donor atom, have been prepared by methods similar to those in Scheme 10. The bis(amine) complexes are typical high-spin, distorted octahedral complexes, and the mono(amine) complexes, from their antiferromagnetic behaviour and reflectance spectra, are six-coordinate, halide-bridged polymers (Table 15).103 No tris(amine) complexes could be prepared so the attempt to find spin isomeric systems in octahedral chromium(II) systems was unsuccessful ([Cr(en)3]X2 are high-spin and [Cr(bipy)3]X3 and [CrX2(bipy)2] low-spin). 

All the linear triamines (27)-(31) are commerically available and there are others, such as 6,6-tri, which, as yet, do not appear to have been used in the preparation of coordination complexes. These linear polyamine ligands can coordinate in either meridional or facial topology and both bis(tri-amine) and mono(triamine) complexes are possible for octahedral central metal ions. 

Markus Albrecht and co-workers synthesised three M4L4 tetrahedra based on different C3-symmetric imine type ligands. The ligands are shown in Fig. 16. For the formation of these ligands, 2,3-dihydroxybenzaldehyde was reacted with the product of the reduction of the corresponding trinitro derivative (L21) or with a tris-amine derivative (L22, L23) [30, 135-141]. 

The trichloromethyl group in s-triazines is sufficiently reactive to he displaced by ammonia, amines, or alkoxides even if two deactivating groups have already been introduced. In contrast, under much more vigorous conditions benzotrichloride and 2,6-bis(trichloro-methyl)pyridine are unreactive towards ammonia in dimethyl-formamide (2 hr, 165°). Tris-amination of 2,4,6-tris-(trichloro-methyl)-s-triazine is complete in aprotic, but not in protic, solvents. 

An amine thus related to ammonia in that all three of the ammonia hydrogens are replaced by hydrocarbon radicals is called a tri-amine or a tertiary amine. 

Tetra-methyl Ammonium Salts.— Not only do these tri-amines unite directly with the hydrogen halides forming ammonium salts as above, but, being much more strongly basic than the mono- or di-amines, they unite also with the alkyl halides themselves forming salts of similar character. Thus ... 

In 2002, Ley reported the application of resin-bound reagents and polymers towards the synthesis of carpanone [57]. In the final steps towards carpanone, a resin-bound Co(salen) catalyst was used to give the desired intermediate along with the formation of a small amount of aldehyde by-product. To remove this byproduct, a resin-bound tris-amine scavenger was used, yielding the desired product in high purity (Scheme 8.42). 

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