Polarographically inactive

Much attention has been given to devising tests for a) the identification of ephedrine, (i) means of distinction between ephedrine and -ephe-drine and (c) the recognition of the dZ-form of ephedrine.Ephedrine, according to Kirkpatrick, ) is polarographically inactive. 

In solutions of histidine and histamine containing pyruvic acid, another reaction takes place (9) in addition to the formation of Schiff base. With increasing concentration of these amino acids apart from the formation of the wave of the Schiff base at a more positive potential, a decrease of the total limiting current can be observed (Fig. 5). The decrease corresponds to the formation of a polarographically inactive compound this may be interpreted by reaction (6) ... 

The easy hydrolysis of the imine interferes with its polarographic or preparative reduction in aqueous solution. Polarographically inactive unconjugated ketones may,... 

Simple aliphatic sulfones, RS02R are polarographically inactive both in pro tic and aprotic media methylene disulfones are, however, reducible in DMF at potentials close to the decomposition potential of the medium. S-Disulfones and benzyl sulfones are rather acidic and may function as proton donors during the reduction, and their anions are generally not reducible [150]. Alkyl aryl sulfones and diaryl sulfones are reducible under protic and aprotic conditions [151-154] during the reduction of long chain aryl alkyl sulfones the EGB may induce a 6-cleavage, and in some cases dimerized products are observed [155]. The electrochemistry of sulfones has been reviewed by Chambers [103] and Simonet [156]. 

Narcotine is polarographically inactive (202, 203) but its polarographic estimation is possible, based upon the quantitative oxidation of narcotine to cotarnine (202-206). For the oscillopolarographic estimation of narcotine see Molnar et al. (207-209). 

Cantor and Peniston also studied the polarographic behavior of all four of these aldohexoses in relation to their concentration, the pH of the medium, and the temperature. They assumed that the polarographic waves obtained under a given set of conditions indicate the true ratio between polarographically inactive, cyclic forms and polarographically active, acyclic forms, so that the ratio of their concentration shoidd be a measure of the corresponding equilibrium constants between the forms. 

Whereas glycosylamines are polarographically inactive, some of their products formed by the Amadori rearrangement are polarographically reducible. It seems that only -amino ketones and derivatives of 1-amino-l-deoxy-D-fructose are reducible and can form tautomers with... 

The polarographically inactive carbon disulfide in alkaline solutions reacts with amines to form electroactive dithiocarbamates ... 

Polarographically-inactive alcohols or phenols, mercaptans and thiophenols could be transformed by reaction with 3,5-dinitrobenzoic acid into polarographically-active 3,5-dinitrobenzoic acid esters (see Figure 6). 

An example of such a current occurs in the reduction process in which the reducible form is formed from another species (present in excess in the bulk of the solution). This second form is either polarographically inactive or reducible at considerably more negative potentials. E.g. in aqueous solutions of formaldehyde, the nonreducible hydrated form predominates, The re-... 

Cyclopentanone and cyclohexanone can also be determined in complex mixtures by using the formation of ketimines, from 20 per cent solutions of hexamethylenediamine, at a pH above j2.(4oi>) The aldehydes, when present, give aldimine waves at potentials about 0-2 V more positive than the ketimine waves. However, moderate concentrations of aldehydes do not interfere in the determination of ketones as (at the concentrations of hexamethylenediamine used) a substantial part of the aldimine is converted into a polarographically inactive compound which, during the course of the reaction, is competitive to the aldimine formation. For the determination of aldehydes, a 2 per cent solution of hexamethylenediamine proved to be the most suitable. 

Polarography can be used for the detection of the type of skeleton, for the identification of a polarographically active group and for the identification of a polarographically inactive substituent. However, with the exception of some special cases, polarography is rarely applied to the detection of the skeleton. 

Zuman and Exner [64] investigated O- and N-substituted oximes and showed that aliphatic O-substituted oximes are polarographically inactive. Aliphatic N-substituted and aromatic O-substituted oximes in acidic medium behave like aromatic nitrones and are reduced to secondary amines with the intermediate formation of the respective Schiff s bases unlike the latter they are not reduced in alkaline solutions. The study of such problems has been continued recently [65-67]. 

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