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synopsisTitanium dioxide, zinc oxide, and other white pigments are widely used in protective coatings and textile applications. An undesirable property of such pigments is their behavior as photo-oxidation catalysts. As a measure of the activities of various pigments, quantum yields were determined for the photo-oxidation of isopropyl alcohol to acetone in a system where the pigment was the only absorbing species. An absolute quantum yield of 0.5 was found for reagenbgrade anatase; relative quantum yields were determined for various commercial anatase and rutile titanium dioxides, zinc oxide, barium sulfate, and barium tungstate. A good correlation was found between the photodegradation rates of pigmented polypropylenes, the photodegradation rates of the dyes in pigmented cellulose acetate butyrate, and the activities of the pigments determined by the isopropyl alcohol oxidation method.

The effects of solvents, including polymeric substrates, and substituentson the absorption spectra of 4,4'-donor acceptorsubstituted azo dyes were studied. The position of the intense, visible charge-transfer band was dependent on the dielectric properties of the solvent ; a linear relationship was found between observed and calculated frequency shifts. Spectral behavior obtained for the dyes in polymeric solvents was consistent with that obtained for the dyes in nonpolymeric solvents. The relationship between dye structure and solvent effects was also determined. Shifts in absorption maxima with substitution in positions insulated from the conjugated chromophoric system were consistent with Taft polar-substituent constants; the effects of such substituents were, therefore, primarily inductive in nature.

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5‐Methyl‐11H‐isoindolo[2,1‐α]benzirnidazolium halide (IV), obtained by direct quaternization of the precursor III, underwent facile condensation reactions at its 11‐methylene group similar to those of 11H‐isoindolo[1,2‐b]benzothiazolium cation II. Although the treatment of II with alkali regenerated its precursor I, treatment of IV with alkali caused ring opening to a phthalimidine. Attempted thermal cyclization of 2‐(alkylaminophenyl)phthalimidines, e.g., VII, resulted in dealkylation to produce III.

Derivatives 2 and 3 of 1,3-indandione having a carbonyl oxygen replaced by a strong electron-withdrawing group (1,3-dioxo-2-indanylidene or dicya nomethylene) were converted to chlorobenzofulvenes by reaction with phosphoryl chloride. The halogens of these chlorobenzofulvenes were displaced by various nucleophiles to produce colored products. Red to blue methine dyes were obtained by condensation of the methylene groups in both 2 and 3 with aromatic aldehydes. Visible spectra of the colored products showed that the 1,3-dioxo-2-indanylidene group was a better electron acceptor than the dicya nomethylene group.

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