摘要:

The60Co γ-radiolysis of aqueous solutions of sodium 9,10-anthraquinone-2-sulfonate has been studied in acidic, unbuffered, and alkaline conditions and with addition of N2O and 2-propanol. Mechanisms are proposed to account for the yields of H2O2and hydroxylated anthraquinone sulfonates. In neutral solution, in the absence of O2, the OH•and e−adducts undergo preferential cross termination. Reduction of the OH•adduct leads to dehydration and regeneration of the quinone.

ISSN:0008-4042    

DOI:10.1139/v76-069

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The aqueous photochemistry of sodium 9,10-anthraquinone-2-sulfonate is described and a new mechanism for the photohydroxylation is proposed. The participation of kinetically free hydroxyl radicals is ruled out.

ISSN:0008-4042    

DOI:10.1139/v76-070

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Some of the mechanistic conclusions of the title articles are criticized because they are inconsistent with other results available to the present authors. Further, the mechanisms of the title articles would not operate in aerobic systems for which alone the present authors' mechanisms were designed.

ISSN:0008-4042    

DOI:10.1139/v76-071

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The visible and uv photolysis oftrans-[Rh(A4)X2]+andcis-[Rh(A4)Y2]+have been studied where A4is the macromolecule 1,4,8,11-tetraazacyclotetradecane (cyclam) or two ethylenediamine (en) molecules, X is Cl, Br, or I, and Y is Cl. With the exception ofcis-[Rh(en)2Cl2]+, all photoreactions proceeded via halide aquation with complete isomeric retention for both ligand field and charge transfer excitation. In the case ofcis-[Rh(en)2Cl2]+, amine aquation is the principal reaction with some isomerization occurring through a secondary reaction. The quantum yield of halide increased in the order Cl < Br < I fortrans-[Rh(A4)X2]+, but was found to be almost equally sensitive to the degree of chelation of the amine system so that the photoactivity oftrans-[Rh(NH3)4Cl2]+andtrans-[Rh(cyclam)I2]+were nearly equalThese systems were also found to be more sensitive to charge transfer excitation than ligand field excitation withcis-[Rh(cyclam)Cl2]+being the most sensitive complexThe photochemistry of the systems studied has been interpreted in terms of a dominant influence of electronic factors in determining the type of photoreaction with the quantitative aspects being significantly influenced by mechanistic factors.

ISSN:0008-4042    

DOI:10.1139/v76-072

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A theoretical analysis has been performed of the effects of geometry optimization upon computed barriers to rotation and pyramidal inversion. It is shown that, where ΔEis the true energy difference between the energy minimum and the transition state for a particular conformational process, (barrier using the optimized geometry of the lower state) > ΔE > (barrier using the optimized geometry of the higher state). Some numerical tests of this inequality are discussed. These reveal certain limitations upon the assumption that an optimized geometry is transferable from one basis set to another.

ISSN:0008-4042    

DOI:10.1139/v76-073

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Using ∼20 ns electron pulses the spectra and kinetics of the electron and an absorption in the uv in 1-propanol have been determined at temperatures from 147 to 300 K. The uv absorption is attributed to the hydroxy propyl radical, CH3CH2ĊHOH; it is formed within ∼20 ns over this temperature range and disappears by second order kinetics. The results for the formation of the solvated electron are in agreement with those of Baxendale and Wardman. The temperature dependence of both the radical–radical reaction and the reaction of the solvated electron with N2O is very nearly the same as that ofT/η

ISSN:0008-4042    

DOI:10.1139/v76-074

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The flash thermolysis of allyl sulphides has been shown to generate thiocarbonyl compounds. The reaction provides a route to very reactive substances such as thioacrolein, thiobenzaldehyde. and monothiobiacetyl; these have been characterized spectroscopically.

ISSN:0008-4042    

DOI:10.1139/v76-075

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Treatment of 1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose (1) with sodium cyanide in anhydrous ethanol followed by addition of an equimolar amount of methyl nitro-acetate gave 3-C-cyano-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (2) in 57% yield. When methyl nitroacetate was first added to sodium cyanide in alcohol followed by the addition of ketose1then theallo-cyanohydrin epimer4was produced in 85% yield. 3-C-(Carbomethoxy-R,S-nitromethyl)-1,2:5,6-di-O-isopropylidene-α-D-allofuranose (6) was produced in low yield in the latter reaction and was isolated and characterized as its 3-O-acetate derivative7. Selective acetolysis of the 5,6-O-isopropylidene group of the branched-chain sugars was achieved using acetic anhydride andp-toluenesulfonic acid monohydrate. The proof of structure of the cyano-hydrins is described.

ISSN:0008-4042    

DOI:10.1139/v76-076

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Rotation around the bond joining the two naphthalene rings (i.e., racemization) in 1,1′-binaphthyl is very effectively catalyzed by carbon blacks and decolorizing carbons. In acetone at 20 °C where a small fraction of binaphthyl is reversibly absorbed, the activity of various carbons increases with surface area (relative catalytic rates are in the order Acetylene Black < Spheron 6 < Norit < Carbolac 1). The racemization is inhibited by structurally analogous compounds (naphthalene, anthracene) and poisoned by small concentrations (ca. 10−5 M) of larger polynuclear aromatics (pyrene, perylene). The barrier to inversion is lowered to ΔH≠ = 16 kcal/mol in acetone by Spheron 6 as catalyst (ΔH≠ = 22 kcal/mol for the uncatalyzed reaction). Although reaction via a relatively small number of specific active sites on the catalyst has not been eliminated, the kinetic data and inhibition effects also correlate with catalysis by more general adsorption of binaphthyl on the planar surfaces of the graphite-like lattice of active carbons.

ISSN:0008-4042    

DOI:10.1139/v76-077

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The radiolysis of gaseous methane has been studied in the presence of one of the three methylbutenes. We have observed an important isomerization of the added olefin. An ionic mechanism initiated by the CH5+and C2H5+ions seems to be compatible with the observations reported. Isomerization proceeds through a chain mechanism where the chain carrier may be thetert-C5H11+ion. In the presence of 3-methyl-1-butene, the initially formed (CH3)2CHCHCH3+ion isomerizes to the tertiary structure before producing the observed isomerization.

ISSN:0008-4042    

DOI:10.1139/v76-078

出版商:NRC Research Press    

年代:1976

数据来源: NRC