Affecting Amino Groups

2-Amino-, 2,8-diamino-, and 4,8-diaminophenoxatellurins can be converted to diazonium salts that couple with 2-naphthol to produce red dyes.  

2-Aminophenoxatellurin was converted to 2-chlorophenoxatellurin 10,10-dichloride via the diazonium salt.  

2-Chlorophenoxatellurin 10,10-Dichloride A suspension of 2.0 g (6.4 mmol) of 2-aminophenoxateUurin in 5 ml of concentrated hydrochloric acid is diazotized at 0-5 with a solution of 0.4 g (5.8 mmol) of sodium nitrite in 4 ml of water. The diazonium salt solution is immediately filtered and poured into a solution of 2.0 g of copper(I) chloride in 10.2 ml of hydrochloric acid and the resultant mixture is boiled on a water bath for 30 min. The mixture is then cooled, filtered, the filter cake is washed with water, dried, and recrystallized from acetone yield 1.0 g (39%) m.p. 310°. 

Salts of 2-aminophenoxatellurin with rZ-tartaric acid and t(-camphorsulfonic acid were prepared in unsuccessful attempts to resolve 2-aminophenoxatellurin into optically active isomers. 

Phenoxatellurin forms 1 1 charge-transfer complexes with 1,3,5-trinitrobenzene, picric acid, and picryl chloride . 

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The presence of certain substituents e.g., the amino group) may markedly affect the solubibty and other properties of the sulphonic acid or carboxylic acid. Thus such sulphonic acids as the aminobenzenesul-phonic acids, pyridine- and quinoline-sulphonic acids exist in the form of inner salts or zwitter-ions that result from the interaction of the basic amino group and the acidic sulphonic acid. Sulphanilic acid, for example, is more accurately represented by formula (I) than by formula (II) ... 

Note that the dissociation constants of both the a-carboxyl and a-amino groups are affected by the presence of the other group. The adjacent a-amino group makes the a-COOH group more acidic (that is, it lowers the pAl, ) so... 

Tiazofurine (142) is an antimetabolite with antineoplastic activity. It preferentially affects leukemic lymphocytes over normal cells due to selective activation by formation of its adenine dinucleotide by transformed cells. Of the syntheses available, one starts by conversion of iniidate 138 to methyl 2,5-anhydroallonothioate (139). Next, condensation with ethyl 2-amino-2-cyanoac-etate leads to the thioamide which undergoes thiol addition to the nitrile function to produce the amminothiazolecarboxyester system of 140 directly. Sodium nitrite in aqueous hypophosphorus acid eliminates the superfluous amino group via the diazonium transformation to give 141. This synthesis of tiazofurine (142) concludes by ester amide exchange in methanolic ammonia [48]. 

The dominant interactions that take place with this novel phase are not clear. There will obviously be dispersive interactions with the propyl chain and some polar interactions with the amino group. Whether there are ionic interactions taking place as well is uncertain but, nevertheless, the material affects an excellent separation of glucose and fructose and this remains a baseline separation even when the two sugars are both present at about the 5% level. 

It might be unexpected for cationic groups, e.g., protonated amino groups, to be important in translocation of cations across the membrane bilayer. Indeed, Grin-stein et al. [19] found that amino reagents (pyridoxal phosphate, trinitrobenzene sulfonate and diisothiocyanostilbene disulfonate) did not affect the Na /H ex-... 

FIGURE 6.1 Constitutional factors affecting the reactivity of functional groups. (A) The reactivity of W depends on the location of the residue. (B) The amino group of a dipeptide ester reacts with the ester carbonyl to form a cyclic dipeptide amino groups of other peptide esters do not react in this manner. (C, D) Reactions between residues of identical configuration do not occur at the same rates as reactions between residues of opposite configuration. 

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