摘要:

Nitration of 4-(p-tolyl)butyric acid and of 3-(p-tolyl)propionic acid in acetic anhydride gives good yields of the diasteriomeric spiro lactone adducts1and12, respectively. Nitration of methyl 4-(p-tolyl)butyrate, 4-(p-tolyl)butanol, and 4-(p-tolyl)butyl acetate gives nitronium acetate adducts but does not give spiro adducts.

ISSN:0008-4042    

DOI:10.1139/v79-405

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The substrate specificity of acetimidylated (A-HLADH) and hydroxybutyrimidylated horse liver alcohol dehydrogenase (HB-HLADH) has been evaluated for the ethanol–acetaldehyde,trans-2-hexenol–trans-2-hexenal, furfural–furfuryl alcohol, benzaldehyde–benzyl alcohol, cyclobutanol–cyclobutanone, cyclopentanol–cyclopentanone, cyclohexanol–cyclohexanone, and cycloheptanol–cycloheptanone substrate couples. The pH-optima of A- and HB-HLADH are similar to that of native enzyme (∼pH 7) for the reduction mode, but are displaced from the broad ∼8–10.5 range for the native enzyme to ∼11.8 for the modified enzymes in the oxidative mode. However, because of coenzyme instability, the practical pH optimum for oxidations remains 9 for both native and modified HLADH's. The modified enzymes provide limited synthetic advantages for the substrates evaluated.

ISSN:0008-4042    

DOI:10.1139/v79-406

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v79-407

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Fluorescence and phosphorescence spectra of a fewp-substituted benzylideneaniline (BA) molecules have been obtained in the EPA solvent. Results show that theratio increases regularly with an increase in the static dipole moment of the molecules except for the most polar molecule where the fluorescence is much more intense.Moreover, it has been shown that the interaction of the BA molecules with aprotic polar solvents is solvatochromic in origin, meaning that no specific solute–solvent interactions had been detected. It has been shown that the BA molecules behave like the D—Ar—A molecular type as far as the photophysical aspect is concerned.

ISSN:0008-4042    

DOI:10.1139/v79-408

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The activity coefficients of lithium chloride in aqueous solution at temperatures of 50, 75, 100, 125, and 150 °C and concentrations varying from 0.5 to 3 mhave been determined. The method used was the application of the Gibbs–Duhem theorem, i.e., the activity of the solvent water was the quantity actually determined. The experimental determination was that of the vapour pressure of the solution using a differential manometer. At all temperatures the activity coefficient passes through a minimum and then increases progressively.

ISSN:0008-4042    

DOI:10.1139/v79-409

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

An analytical procedure was developed to determine the content of metallic impurities in metal-free phthalocyanine (H2Pc) pigments. The technique involves dissolving the pigment in concentrated sulfuric acid, followed by oxidative degradation using hydrogen peroxide. Phthalimide was the only organic oxidation product. The remaining trace metals in the solution were determined using plasma atomic emission. The trace metals content in a commercial α polymorph of phthalocyanine pigment (ICI-Monolite Fast Blue GS) was monitored as a function of purification processes. Experiment showed that Monolite Fast Blue contains 2500 ppm Na; 350 ppm Ca, and 370 ppm Fe. Purification of this material by extraction with hot dimethyl-formamide gave β-H2Pc, which contained 300 ppm Na, 110 ppm Ca, and 310 ppm Fe. Sulfuric acid purification (acid pasting) reduced the content of non-transition elements, but in-increased the content of transition metals.These results were compared to the trace metal content in H2Pc pigment which were synthesized.

ISSN:0008-4042    

DOI:10.1139/v79-410

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Reaction of [PtIMe(2,2′-bipyridine)],I, with MeO2CC≡CCO2Me gives first a 5 co-ordinate π-complex [PtIMe(MeO2CC≡CCO2Me)(bipy)],II, and then the product of insertion into the PtI bond[PtMe{C(CO2Me)=C(CO2Me)I}(bipy)],III. A study of the kinetics of dissociation ofIItoIand free alkyne shows that reaction occurs largely by dissociation of iodide followed by loss of alkyne from the resulting cationic alkyne complex. Formation ofIIImay involve nucleophilic attack byI−on the co-ordinated alkyne of this cationic intermediate.

ISSN:0008-4042    

DOI:10.1139/v79-411

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Crystals of the β-form of the title compound are monoclinic, space groupP21/c,a = 21.071(5),b = 17.716(5),c = 11.285(3) Å, β = 101.66(5)° andZ = 8. The structure was refined on 2741 independent observed reflections to anRfactor of 0.042.The crystals consist of two types of infinite chains with backbones of thiocyanate-bridged mercury atoms. In chain 1, mercury shows the same (3 + 2) coordination as observed in the α-form. It is bound to P of triphenylphosphine (Hg—P = 2.429(4) Å) and two S-bonded thiocyanate ligands (Hg—S = 2.491(5), 2.519(5) Å) in the equatorial plane of a distorted trigonal bipyramid. The axial positions are occupied by weakly-bonded N atoms from adjacent units (Hg—N = 2.74(1), 2.89(1) Å). Chain 2 contains four-coordinated mercury with an approximate tetrahedral geometry. A bridging SCN group links successive Hg atoms in the chain by moderately strong Hg—S (2.648(5) Å) and Hg—N (2.40(1) Å) bonds. The coordination sphere also includes phosphorus (Hg—P = 2.432(4) Å) and a unidentate S-bonded thiocyanate group (Hg—S = 2.454(5) Å). The chains are held together by normal van der Waals contacts.

ISSN:0008-4042    

DOI:10.1139/v79-412

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Electrosorption at the platinum rotating disc electrode in sulfuric acid solutions of selenite, selenate, selenide, and tellurite gives rise to isopotential points in the potential range where oxidation of platinum occurs. The data are analyzed with the framework of the model put forward by Untereker and Bruckenstein. Since similar behavior is observed for the selenite, selenate, and selenide systems, it is tentatively inferred that a common electrosorbed species, possibly selenium itself, may be involved in these systems.

ISSN:0008-4042    

DOI:10.1139/v79-413

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Two competing effects, secondary attractive interactions and closed-shell repulsions, provide the main control ofendo–exostereoselectivity of Diels–Alder cycloadditions.

ISSN:0008-4042    

DOI:10.1139/v79-414

出版商:NRC Research Press    

年代:1979

数据来源: NRC