Samuel Sass

Detection of various α-substituted ketones via chemiluminescence of 5-amino-2,3-dihydro-1,4-phthalazinedione

Abstract : A number of alpha-substituted ketones and related compounds are capable of inducing the chemiluminescence of 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol) with hydrogen peroxide in basic solution. The reaction apparently involves formation of intermediate hydroperoxides from attack of nucleophilic hydroperoxide anion on the carbonyl activated by the a-moiety. The intermediate oxidizes the luminol to give the characteristic chemiluminescence. (Author)

Bipotentiometry in organic redox systems: Oxidation of aromatic compounds in trifluoroacetic acid

Abstract Bipotentiometric titrations of various polynuclear aromatic hydrocarbons, benzenes substituted with electron-donating groups, and π-excessive heteroaromatics in trifluoroacetic acid-dichloromethane with lead(IV) or cobalt(III) acetate solution resulted in novel titration curves. Optimum qualitative results were obtained with a 15-sec delay between additions of titrant. Each reagent increment usually resulted in the formation of a potential “saw-tooth”, indicating formation and decay of reversible redox couples; the final titration curves had one or more potential minima regions before the end-point. Because of considerable differences in number, reversibility and stability of oxidation intermediates, no two aromatics of those tested gave identical curves. However, sufficient similarities existed to permit a system of curve classification and some degree of correlation. The technique is at present essentially a qualitative one. In almost all instances the titration curve for a given aromatic compound is characteristic, somewhat in the manner of a spectrophotometric curve.

Lead(IV) and thallium(III) acetates in trifluoroacetic acid as spot test reagents for aromatic compounds

Abstract Reagents consisting of lead(IV) or thallium (III) acetate in trifluoroacetic acid give intense colors with a number of aromatic compounds. The former is useful for identification of many polynuclear and polyphenyl hydrocarbons and their derivatives as well as aryl amines and methoxy ethers. The latter reagent gives positive tests with a smaller number of polynuclear hydrocarbons and with most phenols. While the reagents probably function similarly to Le Rosens formaldehyde in concentrated sulfuric acid in giving condensations and oxidations, they have the advantage of being appreciably more selective with respect to classes of compounds giving colors. Used in conjunction with the Le Rosen reagent they allow considerable differentiation among and within groups of aromatic compounds.

Analytical Reactions in Trifluoroacetic Acid. II. Organic Spot Test Parameters.

Summary Color formation observed in oxidation of aromatic compounds in trifluoroacetic acid will depend essentially upon three parameters, the latter two of which can be varied considerably: oxidation potential of the organic substrate and electrophilicity of its oxidation intermediates, oxidizing power of the reagent, and Lewis basicity of the cosolvent. The stability of the colors correlate well with theoretical predictions for radical cation stability.

Spot test for 3-pyridinols

Abstract A sensitive spot test to distinguish between 3-pyridinol and certain of its substitution products, on the one hand, and various phenols or 2-pyridinols giving a positive Folin-Denis test involves treatment with bromine water; then excess sodium arsenite followed by brief heating and basification. The blue color formed has spottest sensitivities of the order of 5 μg/0.25 ml in a test tube; or 1 μg/cm 2 on filter paper. Although the structure of the colored species has not been definitely established, it appears, on the basis of chemical and physical evidence, to be an azaquinone.

Analytical reactions of isomeric methoxycycloheptatrienes

Abstract Methods for distinguishing among the isomeric 1-, 3- and 7-methoxycycloheptatrienes are reported. Treatment with anisaldehyde in strong perchloric acid produced a blue solution for the first two compounds only (with detection limits of the order of 2 μg), while irradiation ar 256 nm prior to treatment gave magenta solutions for the first and third compounds only. Absorbance was linear with respect to concentration, at least in the range 0.5–8 μg m−1. Both the 1- and 3-isomers were oxidized by cerium(IV) to tropylium salts while the 7-isomer was resistant to attack. Similarly, the 7-isomer did not react with sodium tetrachloropalladate(II) on filter paper while the other two compounds gave black spots.

Bipotentiometry in organic redox systems: Oxidation of non-aromatics including sulfur compounds

Abstract Bipotentiometry has been found to be applicable in the oxidation with lead(IV) acetate of various polyenes and organosulfur compounds in trifluoroacetic acid. It is assumed that oxidation produces intermediates such as radical cations which are electrochemically reversible and capable of depolarizing electrodes. These radical cations are stabilized appreciably via charge delocalization through conjugated double bonds, hyperconjugation, etc. The net result is the production of titration curves composed of “saw tooth” potential increments owing to formation and decay of depolarizing species.

Detection of various alicyclic compounds via the Komarowsky reaction

Summary A considerable number of cycloalkanols, cycloakyl ketones, and cycloalkenes have been found to give colors on condensation with aromatic aldehydes in strong sulfuric acid. Cyclobutyl and cyclobutylphenyl compounds behave in a qualitatively different manner in these tests from the other cycloalkyl derivatives so that some degree of differentiation is possible.