Ortho Products Research Articles

Photoreactions in liquid crystals 2. Photo-Fries rearrangement of aromatic esters in liquid crystalline matrices

Phenyl benzoates and phenyl- trans-cyclohexane-1-carboxylates react to rearrangement and fragmentation products on UV irradiation (photo-Fries reaction). Quantum yields for the formation of o-hydroxyphenones via the photo-Fries reaction of rod-like liquid crystalline esters were measured as a function of temperature in different liquid crystalline ordered solvents as well as in neat mesophases of esters. The quantum yields of the o-photo-Fries product increase generally with temperature and are influenced by the ordered matrix of liquid crystals. They are lower in smectic than in nematic mesophases and these are lower than those in isotropic melt or in solution. The activation energies for the ortho product formation are in paraffin 5.1, in the isotropic melt 5.2, in the nematic phase 24.6, and in the smectic mesophases 48.4 kJ mol −1. The density or better the packing of molecules in mesophases influences the quantum yield of the o-photo-Fries product formation in the photolysis of rod-like molecules.

ChemInform Abstract: Phenoxide Ions as Nucleophiles in SRN1 Aromatic Nucleophilic Substitution.

Phenoxide ions react with 4-bromobenzophenone under electrochemical catalysis in liquid NH3 and Me2SO, yielding ortho and para carbon coupling products, contrary to the belief that they are unreactive in SRN 1 aromatic nucleophilic substitution.

On the product distribution in the iodination of phenol

The product distribution in the iodination of phenol with I 2, in water solution is buffer and pH dependent with the ortho product increasing at low pH and low buffer concentration. This effect is attributed to different rates of proton transfer from the 4-iodo-2,5-; and 2-iodo-3,5-cyclohexadienone intermediate.

Aphicide Efficacy Evaluation, California, 1982

Abstract Seven pesticides were tested for efficacy against an aphid, Aphis sp. on chrysanthemum. There were 4 standardized 4-leaved chrysanthemum plants per material including a water check. Al I plants were heavily infested with aphids, and aphid numbers on each plant were reduced to 75 prior to pesticide application. All materials except the Ortho products were applied with a 1-gal hand sprayer at 60 psi until runoff. Post-treatment counts of all aphids per plant were made 3 and 10 days after application.

Acid-base and catalytic properties of Al 2O 3ZnO

Alumina-zinc oxide catalysts of various compositions were prepared from their nitrates by coprecipitation and the acidic and basic properties were measured by titrations with n-butylamine and benzoic acid using various indicators. The acidities (the numbers of acid sites) at H 0 = −3.0 and H 0 = −5.6 of Al 2O 3ZnO catalysts prepared from their nitrates, were found to be lower than those of Al 2O 3ZnO catalysts prepared from their chlorides by the same method. With the increase in ZnO content, the acidities per unit surface area decreased monotonously, whereas a maximum basicity was observed on Al 2O 3ZnO (1:1), the highest base strength (p K a ) being 12.2. The activity change for alkylation of phenol with methanol was correlated well with the acidity change and the highest selectivity (almost 100%) for formations of ortho products, o-cresol and 2,6-xylenol, was observed on Al 2O 3ZnO (1:9). Isomerization of 1-butene was suggested to proceed on basic sites on Al 2O 3ZnO catalysts. In isomerization of 3-carene (I), the selectivity for formation of 2-carene (II) was more than 90% over Al 2O 3ZnO (1:9). From poisoning experiments with CO 2 and pyridine, the active sites for formation of 2-carene were concluded to be both acidic and basic sites.

Photoinduzierte Dechlorierungsreaktion an Dichlorbenzolen, Anilinen und Phenolen in Gegenwart von Protonendonatoren/ Photoinduced Dechlorination Reaction of Dichlorobenzenes, Chloroanilins and Chlorophenols in the Presence of Protondonors

Abstract Photokinetic experiments show that the dechlorination reaction of dichlorobenzenes, chloroanilins, and chlorophenols is dependent on nature of solvent, but undependent on oxygen. Quantum yields determined in n-hexane indicate that there is a strong deviation within the ortho, meta, and para products.

Strukturbedingte variationen der Quantenausbeuten von arylamiden und arylestern in der Photo-Fries-Reaktion

The quantum yields of the photo-Fries reactions of 13 different N-arylamides, N-arylurethanes, N-arylureas and O-arylesters have been estimated photometrically by using the absorption band of the ortho product formed in the reaction as an indicator. A rather sensitive dependence of the quantum yields on the topology of the molecules investigated has been found. A combination of OH and COOR groups in the aromatic ring inhibits the photoactivity of the molecule considerably; substitution of the NH function by an NR group enhances the rate of photodecomposition. The energy contribution of the breaking CN and CO bonds to the total destabilization of the system, available from semiempirical quantum chemical PPP calculations, is in a fairly linear correlation to the quantum yields measured.