摘要:

The heat capacities per unit volume and the densities of sodium decanoate (NaDec) in water were measured as a function of concentration and temperature in the range 0.5 to 45 °C. Similar data were obtained for octylamine hydrobromide at 5 and 15 °C. Enthalpies of dilution of NaDec in water were measured at 25 °C. From these and previously published data the apparent and partial molal heat capacities, expansibilities, volumes, and relative enthalpies were determined as a function of temperature and concentration. The concentration dependence ofand, is similar to that of other surfactants such as alkyltrimethylammonium bromides and sodium dodecyl sulfate, but in contrast with the other surfactants,goes through a sharp maximum in the micellization region at the lower temperatures. These thermodynamic properties can be analysed with a phase-separation model to give the changes in volume, heat capacity, and enthalpy during micellization as a function of temperature. The limitations of this model are also discussed.

ISSN:0008-4042    

DOI:10.1139/v80-152

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Ionization constants of 2,4- and 2,5-dinitrophenol in dimethylsulfoxide were measured by the conductance method at five temperatures ranging from 20 to 40 °C. The ionization constants of 2,4-dinitrophenol are much larger than those of 2,5-dinitrophenol, and in both cases they increase with temperature. The thermodynamic functions of ionization are discussed in terms of Hepler's theory for substituent and solvent effects. The ionization of phenols in dimethylsulfoxide is controlled by the enthalpy factor, both internal and environmental, which is in contrast to the entropy-controlled process in water.

ISSN:0008-4042    

DOI:10.1139/v80-153

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The proton magnetic resonance (1H nmr) spectrum at 400 MHz of prostacyclin at pH 10.4 in glycine buffer has been completely analyzed utilizing homonuclear double resonance, inversion recovery, and difference nOe experiments. The spectral analysis shows that the two protons at C-4 are non-equivalent even though they are removed from the asymmetric centres at C-8 and C-9 by five bonds. The difference nOe measurements verify the configuration at C-5.Proton longitudinal relaxation times (T1) were measured at 400 and 200 MHz. From theT1frequency dependence, effective rotational correlation times ranging from 2.3 × 10−10to 3.0 × 10−10 s were calculated for H-5, H-9, H-11, and H-15. This indicates that the portion of the molecule encompassed by these protons has a longer correlation time than is observed for the C-2 and the C-17 to C-19 protons, for which the average correlation time is 1.2 × 10−10 s. Hence the aliphatic side chains have more segmental motion.

ISSN:0008-4042    

DOI:10.1139/v80-154

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The second order rate constants for the reaction of ethanethiol with a number of conjugated nuclear-substituted styryl ketones and related Mannich bases in 50% aqueous acetonitrile was undertaken. Variation of the alkyl group adjacent to the carbonyl function was accompanied by altered avidity to ethanethiol which was explained as being due in part to the varying inductive effects of the alkyl groups which would, in turn, affect the stability of the reaction intermediates. The greatest disparity in reactivity between groups of compounds was between the ketones and analogous Mannich bases which was in accord with the marked difference in bioactivities between these two groups of compounds.

ISSN:0008-4042    

DOI:10.1139/v80-155

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

From the emf measurements of the buffered cellthe standard potentials of the chloranil electrode have been determined in formamide at 15, 25, 35, and 45 °C. The standard molal potential of the chloranil electrode has been expressed through the equationThe standard thermodynamic quantifies, ΔG0, ΔH0, ΔS0, and ΔCP0for the electrode reaction have been calculated from the standard molal potential,Em0of the electrode at these temperatures.

ISSN:0008-4042    

DOI:10.1139/v80-156

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The products, resulting from addition under mild conditions of the gaseous molecules CO, O2, H2, and HCl, to some rhodium(I)–bis(ditertiaryphosphine) complexes, are described; thephosphines used were Ph2P(CH2)nPPh2,n = 1–4, and (+)-diop (diop = 2,3-O-isopropylidene 2,3-dihydroxy-1,4-bis(diphenylphosphino)butane). Monocarbonyls were isolated from addition of CO tocomplexes (n = 1 and 3), the reactions being reversible; there was no reaction with then = 2 system, while then = 4 and diop systems absorbed > 1 mol of CO per Rh to give mixtures of products. The same cation precursors add O2to yieldcis-adducts (n = 1–3), the binding being reversible for then = 2 system; pure products were not isolated with then = 4 cation which absorbs 3 molO2/Rh; the diop system was unreactive toward O2. Reversible additions of 1 mol H2yield isolablecis-complexes with then = 3 and diop systems; then = 1 and 2cations are unreactive toward H2, while a mixture of hydrides is formed from then = 4species. The chlorohydrido cations(A = Cl, BF4, PF6, SbF6),n = 1–3, were prepared via routes involving addition of gaseous HCl to precursorcomplexes; however, the reactions with then = 4 and diop systems did not yield pure products.The solution structures of all the isolated five- and six-coordinate addition products have been determined using1H and variable temperature31P nmr. The five-coordinate carbonyl withn = 1 shows equivalent phosphines from −50 to 25 °C, while then = 3 system shows inequivalent phosphines resulting from a trigonal bipyramidal structure with an equatorial carbonyl. Thecation,n = 3, hascisgeometry, whiletrans-structures are preferred for then = 1 and 2 species.

ISSN:0008-4042    

DOI:10.1139/v80-157

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The reaction of benzeneselenenyl chloride with tetracyclo[3.2.0.02,7.04,6]heptane (quadricyclene) yields, under conditions of kinetic control, adducts of both 1,3- and conjugative 1,6-addition, the latter being formed preferentially. Electrophilic cleavage of the cyclopropane ring occurs by both retention and inversion of configuration. In agreement with the known propensity for bond cleavage in this system only the C5—C6 and/or the C1—C7 bonds are broken. The rate of cyclopropane ring cleavage is found to follow second order kinetics, first order in quadricyclene and first order in selenenyl chloride;kobs = 1850 vs. 12 300 dm3 mol−1 s−1for bicyclo[2.2.1]hepta-2,5- diene at 24.5 °C in methylene chloride solvent. The use of nucleophilic solvents such as HOAc, CH3OH, and CH3CN gives products of solvent-incorporation, preferentially via 1,3-addition.

ISSN:0008-4042    

DOI:10.1139/v80-158

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The effect of increasing electron demand upon the product-determining transition state in the reaction of arenesulphenyl chlorides with tetracyclo[3.2.0.02,7.04,6]heptane has been investigated. As the electron donating ability of the remote substituents on the phenyl ring of the sulphenyl chloride is varied from nitro to methoxy the relative proportion of adducts derived from edge-on attack is found to increase relative to that of adducts derived from corner attack. Anortho-nitro group was found to lead to a stabilizing interaction only in the case of 2,4-dinitrobenzenesulphenyl chloride. A mechanism involving the competition between the two conceptual modes of approach is suggested.

ISSN:0008-4042    

DOI:10.1139/v80-159

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The rates and products of addition of a series of sixteen arenesulphenyl chlorides to 2-methylenebicyclo[2.2.1]hept-5-ene,7, and theE,Zisomeric 2-ethylidenebicyclo[2.2.1]hept-5-enes,8and9, have been determined in methylene chloride solution. The major species from attack on7is alwaysendo-3-arylthio-1-chloromethyltricyclo[2.2.1.02,6]heptane, the product ofexoattack upon theendocyclicdouble bond with homoallylic participation of theexocyclicπ system. No evidence was found for initial electrophilic attack upon theexocyclicdouble bond.

ISSN:0008-4042    

DOI:10.1139/v80-160

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The reaction of benzeneselenenyl chloride with some simple alkylsubstituted acyclic and cyclic alkenes has been investigated using methanol as the solvent. Products of solvent-incorporation, (β-methoxyalkyl phenyl selenides, are normally favoured over the analogous chloro species, but exceptions have been noted. The observation of products of solvent-incorporation, Wagner–Meerwein rearrangement, and homoallylic rearrangement is in accord with an AdE2 mechanism involving both intimate and solvent-separated ion-pairs prier to the product forming step.

ISSN:0008-4042    

DOI:10.1139/v80-161

出版商:NRC Research Press    

年代:1980

数据来源: NRC