Ethylamino group

There is a roughly inverse relationship for a series of structurally related dyes between the time of half-dyeing and the saturation solubility in an appropriate substrate, as illustrated for several 4-alkylamino derivatives of 1-anilinoanthraquinone on cellulose acetate (Table 3.17). It is interesting that methylamino and 2-hydroxyethylamino substituents confer good solubility in this substrate, but ethylamino groups are even less effective than isobutylamino groups in this respect [114]. 

Formation of imidazo[4,5-e]-1,2,4-triazines 119 has been observed to occur when 6-ethylamino-5-methylamino-1,2,4-triazines 118 react with benzamidine. However, in this case only the methylamino group at C-5 is substituted by the amidine, while the ethylamino group at C-6 participates itself as a nucleophile in an intramolecular cyclization reaction (Scheme 68) (78CPB3154). 

In the case of a cyclohexyl group, the modified enzyme showed a 2-fold improvement in kcat/Kin with the suc-AAPA-pNA substrate and a 51-fold improvement in suc-AAPA-pNA/suc-AAPF-pNA selectivity relative to WT-SBL. The enzymes modified with mono-, di-, and tricarboxyl groups displayed improved kCM/KM values toward suc-AAPR-pNA. Furthermore, these values increased in parallel with the number of carboxyl groups introduced, and led to a 9-fold improvement in kcat/kM for the suc-AAPR-pNA substrate and a 61-fold improvement in suc-AAPR-pNA/suc-AAPF-pNA selectivity compared with the wild-type SBL. Conversely, the introduction of the positively charged ethylamino group led to a 19-fold improvement in kcat/ Km for the suc-AAPE-pNA substrate and a 54-fold improvement in suc-AAPE-pNA/ suc-AAPF-pNA selectivity relative to the wild-type SBL. 

On the basis of the analysis of the CD spectra by the nonempirical DeVoe approach, it was possible to establish that each l-(l-naphthyl)ethylamino moiety assumes the same closed conformation with respect to the r-triazine aromatic ring (dihedral angle naphthalene-triazine, 90°), independently of the number or absolute configuration of the other l-(l-naphthyl)ethylamino groups linked to the r-triazine moiety <1998JOC8765>. 

---