摘要:

Surface tensions were measured for the ten binary liquid systems: cyclopentane + carbon tetrachloride, cyclopentane + tetrachloroethylene, cyclopentane + benzene, cyclopentane + toluene, cyclohexane + tetrachloroethylene, cyclohexane + benzene, cyclohexane + toluene, cyclohexane +cis-decalin, cyclohexane +trans-decalin, and benzene +o-xylene. The system cyclohexane + benzene was studied at 20 and 30 °C. Measurements for the other nine systems were carried out at 25 °C. The principle of corresponding states was used to correlate the surface tension results with other properties of the pure component liquids and of their binary mixtures.

ISSN:0008-4042    

DOI:10.1139/v70-637

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The results of calorimetric, dilatometric, and circulation still studies of the systemn-propanol – isopropanol at 25 °C are reported. Examination of the behavior of the excess properties indicates that deviations from ideality can be attributed mainly to the formation of mixed association complexes.

ISSN:0008-4042    

DOI:10.1139/v70-638

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

In this paper, an attempt is made to interpret the π-bonding between a 4-methylpyridine ligand and the divalent ions of zinc, cadmium, and mercury, using the previously introducedRπparameter. To do this, the ν12mode in the complexes is assigned and confirmed by a normal coordinate analysis based on a valence force field model.

ISSN:0008-4042    

DOI:10.1139/v70-639

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The temperature dependence curves of the peak height, frequency, and half-width of the infrared intermolecular combination band absorbing at 1555 cm−1in liquid D2O has been observed to behave sigmoidally between 5 and 70 °C. No evidence of sharp discontinuities has been obtained but inflection points in the rather broad temperature interval of about 25 to 40 °C have been observed. Results are discussed in terms of structural changes occurring in the liquid.

ISSN:0008-4042    

DOI:10.1139/v70-640

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The thermal decomposition of benzoic acid has been studied in a Pyrex reaction vessel at 475, 486, and 499 °C over the pressure range 5 to 40 Torr. The main products, CO2and C6H6, were accompanied by smaller quantities of CO, H2, and biphenyl. The percentage of conversion varied from less than 1% for initial rate experiments to over 90 % in attempts to obtain a material balance. Moderately reproducible initial rates of formation of CO2were obtained after the vessel had been conditioned by pyrolysis of benzoic acid. The order for the initial rate of formation of CO2, 1.20 ± 0.03 at 475 °C and 1.28 ± 0.04 at 499 °C, is discussed in terms of a combination of first and three-halves order reactions. Formation of both C6H5D and C6H6in the presence of C6D5CD3is accepted tentatively as evidence of formation of benzene by both molecular and radical processes.

ISSN:0008-4042    

DOI:10.1139/v70-641

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The kinetics of exchange of free with complexed ethylene in the system PtCl(acac)(π-C2H4) have been investigated over a temperature and concentration range by proton magnetic resonance. First order kinetics are observed with respect to each component with no solvent dependence of rate. The activation energy and entropy are 2.7 kcal mole−1and −36 cal deg−1mole−1, respectively. A five coordinate intermediate is suggested, with complete retention of configuration at the platinum.

ISSN:0008-4042    

DOI:10.1139/v70-642

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The implication of Sneen and co-workers (2–5) that all SN2 substitutions at a primary carbon atom probably proceed via the intermediate production of an intimate ion-pair is examined with respect to the reactions of the methyl halides (MeX; X = F, Cl, Br, I) with various nucleophiles (H2O, OH−, F−, Cl−, Br−, I−, CN−, CSN−, S2O32−) in water. By establishing certain rules concerning the behavior of derived reactivity scales (essentially ρ values) as contrasted with absolute reactivity scales (observed rate constants), it is concluded that Sneen and Larsen's mechanistic description is consistent with the experimental facts, and that in such cases the substitution process involves a pre-equilibrium constant,Ke, which is independent of the attacking nucleophile. This is followed by a rate determining bimolecular rate constant,kn, which depends on the ion pair and the nature of the nucleophile. The observed rate (k°) is given byk = Kekn. A method of calculatingKeis described and values ofknfor nine nucleophiles attacking the four methyl halide ion-pairs are reported along with a number of confirmatory calculations. It is concluded that the classical Hughes–Ingold SN2 Heitler–London description of these reactions is inadequate. Some further suggestions to place the new mechanistic description on a firmer experimental basis are made.

ISSN:0008-4042    

DOI:10.1139/v70-643

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

In connection with mechanism of action studies on cardiac glycosides, the reactions of α-pyrone, γ-crotonolactone, digitoxigenin, and ouabagenin have been studied. No Michael addition reactions were observed with the cardenolide aglycones. The compound previously reported in the literature as ouabagenin has been shown to be 1β,3β,5β,11α,14β,19,21-heptahydroxycard-20,22-enoic acid and the preparation and properties of authentic ouabagenin are described.

ISSN:0008-4042    

DOI:10.1139/v70-644

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

SodiumN,N-diethyldithiocarbamate reacts smoothly with methylene chloride (even in the presence of various transition metal ions) to give the dithiocarbamate ester Et2NC(S)SCH2S(S)CNEt2in very high yield. With chloroform and acetonitrile, proton abstraction occurs followed by partial decomposition of theN,N-diethyldithiocarbamic acid so formed to give diethylammoniumN,N-diethyldithiocarbamate.

ISSN:0008-4042    

DOI:10.1139/v70-645

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Evidence is presented to show that in the acetolysis of isotopically labeledexo- orendo-2-norbornyl brosylate (exo- orendo-1-OBs) in NaOAc buffered HOAc, the initially formed product,exo-1-OAc, could undergo further isotopic scrambling during its subsequent contact with the reaction medium. These scramblings in the acetate apparently involved relatively large amounts of rearrangement of the label from C-2 to -3. After partial acetolysis ofexo- orendo-1-OBs-2-d, n.m.r. analysis showed that the recoveredendo-brosylate was unchanged, while the D-label in the recoveredexo-brosylate has definitely rearranged from C-2 to -1 and probably also to C-6. Thus, in the acetolysis of labeledexo-1-OBs as commonly carried out in HOAc–NaOAc, isotopic scramblings could occur not only in the solvolysis reaction itself, but also prior to the reaction due to internal return giving rise to scrambled brosylate and subsequent to the reaction due to further scrambling in the initial product. Other mechanistic implications of the results are also discussed.

ISSN:0008-4042    

DOI:10.1139/v70-646

出版商:NRC Research Press    

年代:1970

数据来源: NRC