Aromatic monoamines

Secondary aromatic amines are catalytically dehydrogenated with 0  

The following N-benzylaniline derivatives (13) have been converted to N-benzylidene derivatives 14 (yields in EtOH at 60 and 1 atm 0  

Additional substrates that undergo dehydrogenation in the presence of Co(salen) are  

Planar tetradentate ligands afford the most active catalysts. Electron transfer from the aniline moiety to a hydroxocobalt(III) is believed to play a key role in the process [31]. Dioxygen probably reoxidizes the cobalt(II) complex formed. 

---

Earlier in this chapter we discussed the enthalpies of formation of both aliphatic and aromatic monoamines. We now turn to polyamines where an obvious question is whether the effect of multiple amino groups on enthalpies of formation is simply the additive effects... 

Aromatic Amines (Anilines) The molecular ion peak (odd number) of an aromatic monoamine is intense. Loss of one of the amino H atoms of aniline... 

Liquid Vesuvin dye solutions can be obtained by diazotization and coupling of aromatic diamines [3] or, if desired, also in mixture with aromatic monoamines [4] in carboxylic acid solutions. 

Aromatic Amines (Anilines). The molecular ion peak (odd number) of an aromatic monoamine is intense. Loss of one of the amino H atoms of aniline gives a moderately intense M - 1 peak loss of a neutral molecule of HCN followed by loss of a hydrogen atom gives prominent peaks at mlz 66 and 65, respectively. 

Aromatic monoamines, having a minimum one additional functional group, and being found in the patent literature of poly(ester-imide)s, are the aforementioned p-aminobenzoic acid [48, 77], the p-aminophenol [78], the aminoth-erephthalic acid [79] and the p-aminobenzenesulfonic acid [80], but probably none of these monomers were ever used for large scale production. Also the di-aminobenzenes had no economical success as wire enamel raw materials, probably because they were too expensive, too toxic and because they have, in bulk, insufficient storage stability. 3,5-Diaminotriazole-(l,2,4) was claimed as raw material for wire enamel resin yielding films with improved hardness [81]. 

As mentioned earlier, there are at least 50 putative transmitters that could potentially play a role in synaptic transmission or in neurochemical processes. These include acetylcholine, the aromatic monoamines (catecholamines and indole amines), a variety of primary and polyamines, certain amino acids, certain purine nucleosides and nucleotides, and a large number of peptides. The biosynthesis and regulation of the turnover of these putative transmitters will be discussed in another section of this article. However, it is worth noting here that the synthesis of these sundry transmitters is complex and variable, and in most cases the biologic control of the synthesis and degradation of these compounds is poorly understood at best. 

In contrast to the relatively simple mode of inactivation described for acteylcholine and perhaps some neuropeptides, the reuptake systems that have been the subject of intensive study, especially for the aromatic monoamines, are considerably more complex. These uptake systems demonstrate a high affinity for the transmitter that they are meant to accumulate. They exist in addition to transport systems that possess a lower affinity for the substrate in question. These low-affinity transport systems may exist for the accumulation of substrate for general metabolic requirements of the cell. Of interest is the fact that all studies on the high-affinity reuptake systems for monoaminergic transmitters have demonstrated an absolute requirement of the system for Na+. The system does not appear to require adenosine triphosphate, however, and so can be readily distinguished from the Na" "-K+ ATPase exchange system described earlier in this article. The high-... 

The transmitter that is taken up into the neuron and liberated into the intracellular fluid can then either be recycled into vesicular storage granules or metabolized by intracellular enzymes. The two enzymes that are of major importance for the catabolism of aromatic monoamines are monoamine oxidase, of which there may be two or more isozymes, and catechol-O-meth-yltransferase. In neurons, monoamine oxidase is associated with mitochondria, whereas catechol-O-methyltransferase is associated with the soluble cytoplasmic fraction. Both monoamine oxidase and catechol-O-methyltransferase can act on monoamines sequentially to form a variety of metabolic products. These have been identified by radioisotopic and chromatographic experiments. The major metabolites of the aromatic monoamines have been identified 3-methoxy-4-hydroxyphenylethylene glycol and 3-methoxy-4-hydroxymandelic acid (vanylmandelic acid) for norepinephrine and epinephrine 3,4-dihydroxyphenylacetic acid and 3-meth-... 

The literature on ACh, GABA and aromatic monoamines as potential transmitters in the hippocampal region is reviewed. 

The model sequence for PrP helical Cu-binding region (VNITKQHTVTTTT) proposed by Brown et a/.4 was used since this sequence was shown to be active as the catalyst for generation of 02" in presence of some aromatic monoamines.3 Additionally, a peptide corresponding to the natural helical sequence, VNITIKQHTVTTTT, was also prepared (Fig. 1). Two peptides were chemically synthesized and purified on HPLC (purity, 99.20%, 99.10%, respectively) by Sigma Genosis Japan (Ishikari, Hokkaido). 

By structural similarity to aromatic monoamines, aromatic amino acids and phenolics namely tyrosine, salicylic acid, benzoic acid and its derivatives were tested as putative substrates. Fig. 2 shows the comparison of the peptides (V -generating activities in the presence of various substrates. Reaction was initiated and assessed by adding CL A, peptide, Cu, H202 and substrates (aromatic monoamines, amino acids, or phenolics) to phosphate buffered saline in this order. The extent of CLA-chemiluminescence was expressed using the relative luminescence unit (rlu). 

Kawano T Prion-derived copper-binding peptide fragments catalyze the generation of superoxide anion in the presence of aromatic monoamines. Int J Biol Sci 2007 3 57-63. 

Rate constants in Eq. (2) are 10-5 dm3 mol-1 s-1 for monoamines 9 and 10 and 10-2 dm3 mol-1 s l for PD 11 [50]. At a proper substitution, the amount of amines oxidized according to Eq. (2) is negligible in comparison with the process in Eq. (1). A considerable charge separation was observed in the transition state of Eq. (1) [51], Charge-transfer-complexes (CTC) have been envisaged for aromatic monoamines (40) and diamines (41) as the primary step preceding formation of the aminyl ... 

Aryl azides from diazonium salts and /7-toluenesulfonamide 266 An aromatic monoamine (1 mole) or diamine (0.5 mole) is dissolved in concentrated hydrochloric acid (2.5 moles), and the resulting solution or suspension of the amine hydrochloride is diazotized with the calculated amount of sodium nitrite. The diazonium salt solution is mixed with a solution of / -toluenesulfonamide (1 mole) and sodium hydroxide (5 moles) at —5° and set aside for 24-48 h, then brought to pH 8 and extracted with ether. The azide is distilled as above. Solid azides, however, are filtered off and washed with ether. 

Slocum, R.D. Flores, H.E. Galston, A.W. Weinstein, L.H. (1989). Improved method for HPLC analysis of polyamines, agmatine and aromatic monoamines in plant tissue. Plant Physiology, Vol. 89, No. 2, pp 512-517, ISSN 0032-0889. 

The cyclotrimerization of ethynylbenzene leads to 1,3,5-triphenylbenzene, and consequently polycyclotri-merization of bisethynylbenzene yields a high temperature stable polyphenylene resin.3° This chemical concept has been extended to develop the first ethynyl-terminated polyimide in the literature. " The following figure [7] outlines the synthetic route characterized by simply replacing some of the aromatic diamine with an ethynyl-substituted aromatic monoamine to provide a ethynyl-terminated polyimidf resin. 

Binuclear Co(II) complexes derived from 2,6-diformyl-4-methylphenol and various aromatic monoamines have been prepared and investigated. The Co(II) complexes have the composition C02L2CI2, where L represents the organic ligand. The complexes are active catalysts in the oxidation of 3,5 -di-tert-butylcatechol. 

When two molecular weights of an aromatic monoamine were allowed to condense with one molecular weight of DHDHTA, a -phenylenediamine was produced. Thus, Ph-NH-Ph-NH-Ph-NH-Ph-NH2 ("emeraldine base") afforded "COA blue", a material with an unknown number of Q s which could be reduced to COA (white, leuco) with phenyl hydrazine. 

The reactions of the various aromatic monoamines with formaldeh de in strong acid solution have j ielded a number of complicated products, including heterocyclic bydroquinaisolines such as Troeger s base, from p-toluidine and formaldehyde ... 

---