摘要:

The rate constantsk1for the reaction of solvated electrons with allyl alcohol in a number of hydroxylic solvents differ by up to two orders of magnitude and decrease in the ordertert-butyl alcohol > 2-propanol > 1-propanol ≈ ethanol > methanol ≈ ethylene glycol > water. In methanol and ethylene glycol the rate constants (7 × 107 M−1s−1at 298 K) and activation energies (16 kJ/mol) are equal, in spite of a 32-fold difference in solvent viscosity (0.54 and 17.3 cP, respectively) and 3-fold difference in its activation energy (11 and 32 kJ/mol, respectively). The reaction intert-butyl alcohol is nearly diffusion controlled and has a high activation energy that is characteristic of transport in that liquid (E1 = 31 kJ/mol,Eη = 39 kJ/mol). The activation energies in the other alcohols are all 16 kJ/mol, and it is 14 kJ/mol in water. They do not correlate with transport properties. The solvent effect is connected primarily with the entropy of activation. The rate constants correlate with the solvated electron trap depth. When the electron affinity of the scavenger is small, a favorable configuration of solvent molecules about the electron/scavenger encounter pair is required for the electron jump to take place. The behavior of the rate parameters for propargyl alcohol is similar to that for allyl alcohol, butk1,A1, andE1are larger for the former. The ratiok(propargyl)/k(allyl) at 298 K equals 10.5 in water and decreases through the series, reaching 1.3 intert-butyl alcohol. Rate parameters for several other scavengers are also repor

ISSN:0008-4042    

DOI:10.1139/v79-138

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Raman spectra of the three solid phases oftert-butyl chloride-d0and -d9have been recorded for the regions of the intramolecular vibrations. The spectra of solid I are typical of those seen for plastic crystals and those of solid II of solids with partial orientational order. The transition from solid I to solid II results in the ordering of the three-fold molecular symmetry axes but the axes perpendicular to the molecular symmetry axes remain randomly oriented. The transition from solid II to III results in a more-or-less ordered structure. The spectra of phase III at 90 K suggest an ordered solid with the molecules on sites of symmetryCsorC1.

ISSN:0008-4042    

DOI:10.1139/v79-139

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A series of eight carbon acids, α,α-bis(benzylsulfonyl)toluene and 7 substituted α,α-bis-(benzylsulfonyl)toluenes, was synthesized and their equilibrium ionization constants were determined by spectrophotometric measurement in 80% (w/w) dimethyl sulfoxide – water solvent at 25 °C. From a plot of −logKversus σ for the 'well-behaved' substituents and σ−forpara-cyano andpara-nitro substituents, a ρ value of 2.53 is obtained. The correlation co-efficient is 0.99. Comparing this ρ value with the reported ρ value of 12 for the substituted toluenes in dimethyl sulfoxide, it shows that the acidities of the disulfonyl toluenes are at least 8 to 9 orders of magnitude less sensitive to substituent effects than are the acidities of substituted toluenes implying that, for disulfonyl toluenes, the negative charge on the benzylic carbon is extensively delocalised into the two adjacent sulfonyl groups.

ISSN:0008-4042    

DOI:10.1139/v79-140

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Following previous studies of the desorption of salts from the surface of water, the desorption of several salts from various non-aqueous solvents has been investigated. Three protic and 3 dipolar-aprotic liquids were used. The surface properties of the solvents in the absence of electrolytes are discussed and it is observed that the molar excess surface entropies of the aprotic solvents are more positive than those of the protic solvents. Salt desorption, determined from measurements of surface tension, is discussed in terms of purely electrostatic models, and also ion solvation. The extent of salt desorption in systems where strong ion solvation exists is related to the thickness of the primary solvation sheath around the ions. In the present context water does not behave as an anomalous solvent but in a way similar to the other protic solvents.

ISSN:0008-4042    

DOI:10.1139/v79-141

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Photolysis of 2-methyl-1-butene (M2B1),cis-2-pentene (CP2), and 3-methyl-1-butene (M3B1) has been systematically studied at 163 nm. Pressure effect has been measured at 147, 163, and 174 nm. The main fragmentation process of the photoexcited olefine is the C—C split of the bond located in position β relative to the double bond:α-Methallyl radicals obtained in the M3B1 and CP2 photolysis decompose partly at low pressure, giving rise to the formation of 1,3-butadiene and hydrogen atoms. β-Methallyl radicals decompose also at low pressure into allene and methyl radicals. Butadiene and allene quantum yields follow the Stern–Volmer law, and this allows us to determine the ratio of the rate constant of dissociation relative to the rate constant of stabilization,kd/ks, through collision of the α- and β-methallyl radicals. From these values, we conclude that the excess of photon energy is not statistically distributed into the fragments, and that the decomposition process follows one (or several) particular law(s).

ISSN:0008-4042    

DOI:10.1139/v79-142

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

We have studied the 163 nm photolysis of propene and of 2-methyl-2-butene and a few results on the 174 nm photolysis of propene are also included. At 163 nm (7.6 eV), the main decomposition processes of the photoexcited propene molecule are β(C—H) split (Ф = 0.565) and α(C—C) split (Ф = 0.335). Thus, the β(C—H)/α(C—C) ratio is close to 1.69. In the case of the photolysis of 2-methyl-2-butene, the same ratio is reversed:In another work, the ratio obtained in the photolysis of 2-butene was close to unity. Finally, in order to explain the allene and 1,3-butadiene formation in the photolysis of 2-methyl-2-butene, isomerisation of vinylic radical intermediates is proposed, in agreement with observations made by Callear and Le

ISSN:0008-4042    

DOI:10.1139/v79-143

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The authors have investigated aqueous solution of the hydrogenooxalate ion by infrared and Raman spectroscopy. They show the existence of an equilibrium between a planar monomer structure linked by hydrogen bond to solvent molecules and an associated form. Such an equilibrium can provide a satisfactory explanation for the experimental spectra and their dependence upon temperature and concentration. The assignments for the monomeric form are supported by a normal coordinate analysis and by a calculation of the valence force field.

ISSN:0008-4042    

DOI:10.1139/v79-144

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

It has been observed that a tridentate Schiff base complex of nickel(II), triaquotribenzo-[b,f,j][1.5.9]-triazacyclodecinenickel(II), commonly called (TRI)Ni(OH2)32+, shows substantial stereoselectivity on complexing with several amino acids. This provides a convenient way to resolve (TRI)Ni(OH2)32+using histidine as a resolving agent, and either ion exchange or perchlorate salt crystallization techniques.The resolved (TRI)Ni(OH2)32+may then be used to resolve other amino acids or as a sensitive test of the stereochemistry of an amino acid. The test can be done on milligram quantities because of the insolubility of the complex perchlorate salt and because of the relatively large molecular rotation (2 × 105 deg at 283 nm) of (TRI)Ni(OH2)32+. The amino acid is easily released by treatment of the complex with dilute acid (Ph ≈ 2). The procedure has been tested with histidine, tyrosine, methionine, and phenylglycin

ISSN:0008-4042    

DOI:10.1139/v79-145

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

K2PO3F is orthorhombic, space groupPnma, witha = 7.554(4),b = 5.954(5),c = 10.171(6) Å, andZ = 4. Intensity data have been measured on an automatic diffractometer with CuKαradiation. The crystal structure was determined by analogy with that of K2SO4and shows an important interaction "F---K". The finalRindex is 0.065 for 353 observed reflections.

ISSN:0008-4042    

DOI:10.1139/v79-146

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The reactions of several substituted cuprous phenoxides with CCl4in acetonitrile were examined. Phenoxides withoutortho-substituents usually gave high yields of tetraarylorthocarbonates. It is shown that the latter are also produced catalytically from sodium phenoxides and CCl4in the presence of small amounts of cuprous chloride. Cuprous phenoxides withortho-chloro substituents, in the absence of facile hydrogen transfer agents, gave stable mixed oxidation state complexes of approximate composition: Cu2ICuIICl2(OAr)2. In the presence of facile hydrogen atom transfer agents, such as free phenol or ascorbic acid, both the phenoxides withoutortho-substituents and theortho-chlorinated phenoxides gave moderate yields of triarylorthoformates. Some reactions of tritertbutylphenol and tritertbutylphenoxyl with copper complexes are described. The mechanisms of the various reactions are interpreted in terms of homo- and cross-coupling between phenoxyl and•CCl3radicals.

ISSN:0008-4042    

DOI:10.1139/v79-147

出版商:NRC Research Press    

年代:1979

数据来源: NRC